Docs: queue TASK 55 — disk hygiene (log rotation, temp alert-clip cleanup, low-disk recording guard) (Unit: task catalog)

The zoom feature shipped without a task record while its index rows carried the
"TASK 51" label — which belongs to the webcam background effects (Remove + Blur).
For an honest catalogue and handoff:

- TASKS/task-52-zoom-box.md: feature provenance (creator-requested), the three
  2026-10-08 corrections (loupe -> anchored capture over the full composite drawn
  last -> never show the dim shading), shapes, implementation map, tests, DONE.
- TASKS.md: row 52 added (shipped); row 51 reworded — unblocked now that the
  zoom build shipped.
- TASK 51 -> TASK 52 in Models/index.md, ViewModels/index.md, and the two code
  comments that pointed at the zoom as "TASK 51".
- HANDOFF.md: pre-push readiness notes (5 commits ahead, push-safe).

.gitignore

@@ -1,6 +1,10 @@
 bin/
 obj/
 Helpers/OAuthCredentials.cs
+
+# Bundled FFmpeg (135 MB of DLLs). Fetched once by scripts/fetch-ffmpeg.sh, which pins
+# the URL + SHA-256; the build then copies it to the output. Never committed — see the
+# script header for why the hash, not the binaries, is the audit trail.
 *.user
 *.suo
 .vs/
@@ -10,3 +14,5 @@ Helpers/OAuthCredentials.cs
 MONETIZATION.md
 MARCOM.md
 CREDENTIALS.md
+.aider*
+ffmpeg/

AGENTS.md

@@ -38,7 +38,7 @@ conventions live here and in `ai.md`.
 
 1. [`schema.md`](schema.md) — the memory-map conventions (what lives where, how to keep it true).
 2. [`ai.md`](ai.md) — the AI guide: architecture, patterns, decisions, current state.
-3. [`TASKS.md`](TASKS.md) — the task queue + authoritative YouTube API research.
+3. [`TASKS.md`](TASKS.md) — the task catalog (index + queue state); open items and API research facts are in [`TASKS/`](TASKS/).
 4. [`HANDOFF.md`](HANDOFF.md) — current operational state: what's in flight, landmines, next step.
 5. `<dir>/index.md` — the index for any directory you're about to touch.
 

App.xaml.cs

@@ -26,6 +26,10 @@ public partial class App : Application
             AppLog.Write(args.Exception, "Dispatcher unhandled exception");
 
         AppLog.Write("App OnStartup begin");
+        // Attribution (2026-09-04): every take must be traceable to the exact binary
+        // that produced it — the wordmark shows the release counter (BuildStamp.Release);
+        // the per-build GUID is forensic only and lands here.
+        AppLog.Write($"Build {ytLive.Helpers.BuildStamp.Id} (compiled {ytLive.Helpers.BuildStamp.BuiltLocal})");
 
         // Velopack auto-update bootstrap — checks for updates on startup and
         // applies them (the app restarts automatically if an update is found).

Controls/BottomBar.xaml

@@ -9,22 +9,6 @@
                 <ColumnDefinition Width="Auto"/>
             </Grid.ColumnDefinitions>
 
-            <!-- Gear icon: far left -->
-            <Button Grid.Column="0" ToolTip="Menu" Style="{StaticResource IconButton}"
-                    VerticalAlignment="Center" Click="GearButton_Click">
-                <Button.ContextMenu>
-                    <ContextMenu DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
-                        <MenuItem Header="App Settings" Command="{Binding OpenSettingsCommand}"/>
-                        <Separator/>
-                        <MenuItem Header="Report Bug" Command="{Binding OpenBugCommand}"/>
-                        <MenuItem Header="Feature Request" Command="{Binding OpenFeatureCommand}"/>
-                        <MenuItem Header="About" Command="{Binding OpenAboutCommand}"/>
-                    </ContextMenu>
-                </Button.ContextMenu>
-                <Path Data="M19.14,12.94c0.04,-0.3 0.06,-0.61 0.06,-0.94c0,-0.32 -0.02,-0.64 -0.07,-0.94l2.03,-1.58c0.18,-0.14 0.23,-0.41 0.12,-0.61l-1.92,-3.32c-0.12,-0.22 -0.37,-0.29 -0.59,-0.22l-2.39,0.96c-0.5,-0.38 -1.03,-0.7 -1.62,-0.94L14.4,2.81c-0.04,-0.24 -0.24,-0.41 -0.48,-0.41h-3.84c-0.24,0 -0.43,0.17 -0.47,0.41L9.25,5.35C8.66,5.59 8.12,5.92 7.63,6.29L5.24,5.33c-0.22,-0.08 -0.47,0 -0.59,0.22L2.74,8.87C2.62,9.08 2.66,9.34 2.86,9.48l2.03,1.58C4.84,11.36 4.8,11.69 4.8,12s0.02,0.64 0.07,0.94l-2.03,1.58c-0.18,0.14 -0.23,0.41 -0.12,0.61l1.92,3.32c0.12,0.22 0.37,0.29 0.59,0.22l2.39,-0.96c0.5,0.38 1.03,0.7 1.62,0.94l0.36,2.54c0.05,0.24 0.24,0.41 0.48,0.41h3.84c0.24,0 0.44,-0.17 0.47,-0.41l0.36,-2.54c0.59,-0.24 1.13,-0.56 1.62,-0.94l2.39,0.96c0.22,0.08 0.47,0 0.59,-0.22l1.92,-3.32c0.12,-0.22 0.07,-0.47 -0.12,-0.61L19.14,12.94zM12,15.6c-1.98,0 -3.6,-1.62 -3.6,-3.6s1.62,-3.6 3.6,-3.6s3.6,1.62 3.6,3.6S13.98,15.6 12,15.6z"
-                      Fill="#d0d0d0" Width="16" Height="16" Stretch="Uniform"/>
-            </Button>
-
             <!-- Stream stats: centered under the preview pane -->
             <StackPanel Grid.Column="1" Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
                 <TextBlock Text="Bitrate:" Style="{StaticResource YtLabel}" Margin="0,0,4,0"/>

Controls/BottomBar.xaml.cs

@@ -1,4 +1,3 @@
-using System.Windows;
 using System.Windows.Controls;
 
 namespace ytLive.Controls;
@@ -9,14 +8,4 @@ public partial class BottomBar : UserControl
     {
         InitializeComponent();
     }
-
-    private void GearButton_Click(object sender, RoutedEventArgs e)
-    {
-        if (sender is Button { ContextMenu: { } menu } button)
-        {
-            menu.PlacementTarget = button;
-            menu.Placement = System.Windows.Controls.Primitives.PlacementMode.Bottom;
-            menu.IsOpen = true;
-        }
-    }
 }

Controls/LeftPanel.xaml

@@ -17,6 +17,7 @@
                             <RowDefinition Height="Auto"/>
                             <RowDefinition Height="Auto"/>
                             <RowDefinition Height="Auto"/>
+                            <RowDefinition Height="Auto"/>
                             <RowDefinition Height="*"/>
                         </Grid.RowDefinitions>
 
@@ -29,7 +30,7 @@
                                 <ContextMenu DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
                                     <MenuItem Header="Webcam" Command="{Binding AddWebcamCommand}"
                                               IsEnabled="{Binding CanAddWebcam}"
-                                              ToolTip="One webcam at a time — it's already in your stream"/>
+                                              ToolTip="{Binding WebcamAddToolTip}"/>
                                     <MenuItem Header="Image" Command="{Binding AddImageCommand}"/>
                                     <MenuItem Header="Text" Command="{Binding AddSourceCommand}" CommandParameter="{x:Static models:SourceType.TextOverlay}"/>
                                     <MenuItem Header="Countdown" Command="{Binding AddSourceCommand}" CommandParameter="{x:Static models:SourceType.Countdown}"
@@ -40,6 +41,9 @@
                                     <MenuItem Header="YouTube Chat" Command="{Binding AddSourceCommand}" CommandParameter="{x:Static models:SourceType.ChatBox}"
                                               IsEnabled="{Binding CanAddYouTubeChat}"
                                               ToolTip="One chat layer at a time — it's already in your stream"/>
+                                    <MenuItem Header="Stream Alerts" Command="{Binding AddSourceCommand}" CommandParameter="{x:Static models:SourceType.AlertBox}"
+                                              IsEnabled="{Binding CanAddAlerts}"
+                                              ToolTip="Celebration zone for Super Chat &amp; memberships — one alert layer at a time"/>
                                 </ContextMenu>
                             </Button.ContextMenu>
                             <Path Data="M12,4 L12,20 M4,12 L20,12" Stroke="#e94560" StrokeThickness="2"
@@ -61,6 +65,11 @@
                                     <DataTrigger Binding="{Binding IsVisible}" Value="False">
                                         <Setter Property="Opacity" Value="0.45"/>
                                     </DataTrigger>
+                                    <!-- The transient zoom layer has no editing UI — never
+                                         show it as a layer row (TASK 51). -->
+                                    <DataTrigger Binding="{Binding IsZoomLayer}" Value="True">
+                                        <Setter Property="Visibility" Value="Collapsed"/>
+                                    </DataTrigger>
                                 </Style.Triggers>
                             </Style>
                         </Helpers:FocusPreservingListBox.ItemContainerStyle>
@@ -93,6 +102,31 @@
                                                     </MultiBinding>
                                                 </MenuItem.Visibility>
                                             </MenuItem>
+                                            <MenuItem Header="Capture Window…"
+                                                      ItemsSource="{Binding DataContext.OpenWindows, RelativeSource={RelativeSource AncestorType=Window}}">
+                                                <MenuItem.Visibility>
+                                                    <MultiBinding Converter="{StaticResource AllTrueToVis}">
+                                                        <Binding Path="IsBackground"/>
+                                                        <Binding Path="PlacementTarget.Tag" RelativeSource="{RelativeSource AncestorType={x:Type ContextMenu}}"/>
+                                                    </MultiBinding>
+                                                </MenuItem.Visibility>
+                                                <MenuItem.ItemContainerStyle>
+                                                    <Style TargetType="MenuItem">
+                                                        <Setter Property="Header" Value="{Binding Label}"/>
+                                                        <Setter Property="Command"
+                                                                Value="{Binding DataContext.CaptureWindowCommand, RelativeSource={RelativeSource AncestorType=Window}}"/>
+                                                        <Setter Property="CommandParameter" Value="{Binding}"/>
+                                                    </Style>
+                                                </MenuItem.ItemContainerStyle>
+                                            </MenuItem>
+                                            <MenuItem Header="Refresh Window List" Click="BackgroundMenu_RefreshWindowList">
+                                                <MenuItem.Visibility>
+                                                    <MultiBinding Converter="{StaticResource AllTrueToVis}">
+                                                        <Binding Path="IsBackground"/>
+                                                        <Binding Path="PlacementTarget.Tag" RelativeSource="{RelativeSource AncestorType={x:Type ContextMenu}}"/>
+                                                    </MultiBinding>
+                                                </MenuItem.Visibility>
+                                            </MenuItem>
                                             <Separator>
                                                 <Separator.Visibility>
                                                     <MultiBinding Converter="{StaticResource AllTrueToVis}">
@@ -167,15 +201,30 @@
                                HorizontalAlignment="Center" VerticalAlignment="Center"
                                Visibility="{Binding ShowSourcesEmptyHint, Converter={StaticResource BoolToVis}}"/>
 
+                    <!-- Resource alert: pinned to the bottom of the Layers panel.
+                         Red when a required resource (the one-and-only webcam)
+                         could not be locked; persists and re-polls until resolved. -->
+                    <Border Grid.Row="3" Margin="0,8,0,0" Padding="8,6" CornerRadius="4"
+                            Background="#3a1216" BorderBrush="#e94560" BorderThickness="1"
+                            Visibility="{Binding WebcamLockAlert, Converter={StaticResource NotNullToVis}}">
+                        <StackPanel>
+                            <TextBlock Text="{Binding WebcamLockAlert}" Foreground="#ffb4b4" FontSize="11"
+                                       TextWrapping="Wrap"/>
+                            <Button Content="Retry" Command="{Binding RetryWebcamLockCommand}"
+                                    Style="{StaticResource YtButtonSecondary}" Padding="10,2"
+                                    HorizontalAlignment="Right" Margin="0,6,0,0"/>
+                        </StackPanel>
+                    </Border>
+
                     <!-- ELEMENTS panel: per-element config beneath Sources.
                          Collapses entirely when no element is selected. -->
-                    <Rectangle Grid.Row="3" Height="1" Fill="#2c3a5c" Margin="0,10,0,2"
+                    <Rectangle Grid.Row="4" Height="1" Fill="#2c3a5c" Margin="0,10,0,2"
                                Visibility="{Binding SelectedElement, Converter={StaticResource NotNullToVis}}"/>
-                    <StackPanel Grid.Row="4" Orientation="Horizontal" Margin="0,8,0,0"
+                    <StackPanel Grid.Row="5" Orientation="Horizontal" Margin="0,8,0,0"
                                 Visibility="{Binding SelectedElement, Converter={StaticResource NotNullToVis}}">
                         <TextBlock Text="PROPERTIES" Style="{StaticResource SectionHeader}" VerticalAlignment="Center"/>
                     </StackPanel>
-                    <ScrollViewer x:Name="ElementsScrollViewer" Grid.Row="5" VerticalScrollBarVisibility="Auto" Background="Transparent"
+                    <ScrollViewer x:Name="ElementsScrollViewer" Grid.Row="6" VerticalScrollBarVisibility="Auto" Background="Transparent"
                                   Visibility="{Binding SelectedElement, Converter={StaticResource NotNullToVis}}">
                         <StackPanel x:Name="ElementsPanel" Margin="0,4,0,0">
                             <!-- Opacity + mirror/shape (draggable elements: image, webcam) -->
@@ -400,6 +449,70 @@
                                           IsChecked="{Binding SelectedElement.ChatShowBadges, Mode=TwoWay}"/>
                             </StackPanel>
 
+                            <!-- Stream Alerts config -->
+                            <StackPanel Visibility="{Binding SelectedElement.IsAlertBox, Converter={StaticResource BoolToVis}}" Margin="0,0,0,8">
+                                <TextBlock Text="Stream Alerts" Foreground="#a0a0b0" FontSize="11" FontWeight="SemiBold" Margin="0,0,0,6"/>
+                                <TextBlock Text="The built-in clip plays on every alert (Super Chat, membership…) unless a custom video is picked."
+                                           Foreground="#888" FontSize="10" TextWrapping="Wrap" Margin="0,0,0,6"/>
+
+                                <DockPanel Margin="0,0,0,4">
+                                    <TextBlock DockPanel.Dock="Left" Text="Built-in video" Foreground="#a0a0b0" FontSize="11" VerticalAlignment="Center" Width="84"/>
+                                    <ToggleButton Style="{StaticResource PillToggle}"
+                                                  IsChecked="{Binding SelectedElement.AlertUseDefaultVideo, Mode=TwoWay}"
+                                                  HorizontalAlignment="Left"/>
+                                </DockPanel>
+
+                                <Grid Margin="0,0,0,4"
+                                      Visibility="{Binding SelectedElement.AlertUseDefaultVideo, Converter={StaticResource InverseBoolToVis}}">
+                                    <Grid.ColumnDefinitions>
+                                        <ColumnDefinition Width="*"/>
+                                        <ColumnDefinition Width="Auto"/>
+                                    </Grid.ColumnDefinitions>
+                                    <TextBox Grid.Column="0" Text="{Binding SelectedElement.AlertVideoPath, Mode=OneWay}"
+                                             IsReadOnly="True" Background="#0f3460" Foreground="#a0a0b0"
+                                             FontSize="11" VerticalAlignment="Center"/>
+                                    <Button Grid.Column="1" Content="Browse…" Command="{Binding BrowseAlertVideoCommand}"
+                                            CommandParameter="{Binding SelectedElement}" Style="{StaticResource YtButtonSecondary}"
+                                            Margin="4,0,0,0" Padding="8,2"/>
+                                </Grid>
+
+                                <Button Content="Reset to built-in" Command="{Binding ResetAlertVideoCommand}"
+                                        CommandParameter="{Binding SelectedElement}" Style="{StaticResource YtButtonSecondary}"
+                                        HorizontalAlignment="Left" Padding="8,2" Margin="0,0,4,0"/>
+                                <TextBlock Text="Custom clips are referenced from disk — never stored in the layout."
+                                           Foreground="#888" FontSize="10" TextWrapping="Wrap" Margin="0,4,0,6"/>
+
+                                <DockPanel Margin="0,0,0,4">
+                                    <TextBlock DockPanel.Dock="Left" Text="Message ticker" Foreground="#a0a0b0" FontSize="11" VerticalAlignment="Center" Width="84"/>
+                                    <ToggleButton Style="{StaticResource PillToggle}"
+                                                  IsChecked="{Binding SelectedElement.AlertShowTicker, Mode=TwoWay}"
+                                                  HorizontalAlignment="Left"/>
+                                </DockPanel>
+
+                                <!-- Announcement display: scroll (marquee), flash (pulse) or
+                                     solid (still). Inline items, not a bound ItemsSource —
+                                     same shape as the chat Font selector above. -->
+                                <DockPanel Margin="0,0,0,4">
+                                    <TextBlock DockPanel.Dock="Left" Text="Display" Foreground="#a0a0b0" FontSize="11" VerticalAlignment="Center" Width="84"/>
+                                    <ComboBox SelectedValue="{Binding SelectedElement.AlertDisplayMethod, Mode=TwoWay}"
+                                              SelectedValuePath="Tag"
+                                              Background="#0f3460" Foreground="#e0e0e0" FontSize="11"
+                                              Width="140" VerticalAlignment="Center">
+                                        <ComboBoxItem Content="Scroll" Tag="TickerScroll"/>
+                                        <ComboBoxItem Content="Flash" Tag="Flash"/>
+                                        <ComboBoxItem Content="Solid" Tag="Solid"/>
+                                    </ComboBox>
+                                </DockPanel>
+
+                                <DockPanel Margin="0,0,0,4">
+                                    <TextBlock DockPanel.Dock="Left" Text="Volume" Foreground="#a0a0b0" FontSize="11" VerticalAlignment="Center" Width="84"/>
+                                    <Slider Width="120" Minimum="0" Maximum="1"
+                                            Value="{Binding SelectedElement.AlertVideoVolume, Mode=TwoWay}"
+                                            VerticalAlignment="Center"/>
+                                    <TextBlock DockPanel.Dock="Right" Text="{Binding SelectedElement.AlertVideoVolume, StringFormat={}{0:0%}}" Foreground="#e0e0e0" FontSize="11" Margin="6,0,0,0" VerticalAlignment="Center" Width="32"/>
+                                </DockPanel>
+                            </StackPanel>
+
                             <!-- Background properties -->
                             <StackPanel Margin="0,8,0,0"
                                         Visibility="{Binding SelectedElement.IsBackground, Converter={StaticResource BoolToVis}}">

Controls/LeftPanel.xaml.cs

@@ -20,6 +20,7 @@ public partial class LeftPanel : UserControl
     private int _dragIndex = -1;
     private bool _isDragging;
     private object? _lastHoveredItem;
+    private bool _dragReordered;
 
     public LeftPanel()
     {
@@ -115,6 +116,11 @@ public partial class LeftPanel : UserControl
         (DataContext as MainViewModel)?.RefreshBackgroundAutoCapture();
     }
 
+    private void BackgroundMenu_RefreshWindowList(object sender, RoutedEventArgs e)
+    {
+        (DataContext as MainViewModel)?.RefreshWindowsCommand.Execute(null);
+    }
+
     private void OpacitySlider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
         => OpacityValueText.Text = $"{Math.Round(e.NewValue * 100)}%";
 
@@ -159,6 +165,7 @@ public partial class LeftPanel : UserControl
         _dragStartPoint = e.GetPosition(listBox);
         _isDragging = false;
         _lastHoveredItem = null;
+        _dragReordered = false;
     }
 
     private void List_PreviewMouseMove(object sender, MouseEventArgs e)
@@ -196,6 +203,7 @@ public partial class LeftPanel : UserControl
         items.Insert(targetIndex, dragged);
         _dragIndex = targetIndex;
         _lastHoveredItem = targetItem;
+        _dragReordered = true;
     }
 
     private void List_PreviewMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
@@ -207,9 +215,13 @@ public partial class LeftPanel : UserControl
     {
         if (_isDragging)
             listBox.ReleaseMouseCapture();
+        var reordered = _dragReordered;
         _dragIndex = -1;
         _isDragging = false;
         _lastHoveredItem = null;
+        _dragReordered = false;
+        if (reordered && DataContext is MainViewModel vm)
+            vm.OnSceneElementsReordered();
     }
 
     private static ListBoxItem? FindItemContainerAt(ListBox listBox, Point position)

Controls/OverlayHost.xaml

@@ -1,7 +1,8 @@
 <UserControl x:Class="ytLive.Controls.OverlayHost"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:Helpers="clr-namespace:ytLive.Helpers">
+             xmlns:Helpers="clr-namespace:ytLive.Helpers"
+             xmlns:Models="clr-namespace:ytLive.Models">
         <Grid Grid.RowSpan="3"
               Visibility="{Binding IsAnyOverlayOpen, Converter={StaticResource BoolToVis}}">
             <Button Background="#99000000" BorderThickness="0" Cursor="Hand"
@@ -42,12 +43,18 @@
                         <TextBox Style="{StaticResource YtTextBox}" 
                                  Text="{Binding RecordFolderDisplay, Mode=OneWay}"
                                  IsReadOnly="True" Margin="0,0,0,12" Foreground="#a0a0b0"/>
-                        <StackPanel Orientation="Horizontal">
+                        <StackPanel Orientation="Horizontal" Margin="0,0,0,16">
                             <Button Content="Browse…" Command="{Binding ChooseRecordFolderCommand}"
                                     Style="{StaticResource YtButtonSecondary}" Margin="0,0,8,0"/>
                             <Button Content="Use Downloads" Command="{Binding ResetRecordFolderCommand}"
                                     Style="{StaticResource YtButtonSecondary}"/>
                         </StackPanel>
+                        <TextBlock Text="Zoom View Shape" Style="{StaticResource YtLabel}" Margin="0,0,0,4"/>
+                        <ComboBox Style="{StaticResource YtComboBox}" SelectedValue="{Binding ZoomShape}" SelectedValuePath="Tag">
+                            <ComboBoxItem Content="Circle" Tag="{x:Static Models:ZoomShape.Circle}"/>
+                            <ComboBoxItem Content="Phone (Vertical Rectangle)" Tag="{x:Static Models:ZoomShape.VerticalRectangle}"/>
+                            <ComboBoxItem Content="Tablet (Horizontal Rectangle)" Tag="{x:Static Models:ZoomShape.HorizontalRectangle}"/>
+                        </ComboBox>
                     </StackPanel>
 
                     <!-- Report Bug -->

Controls/PreviewPane.xaml

@@ -14,9 +14,18 @@
                     <Grid x:Name="PreviewGrid" Grid.Row="0"
                           PreviewMouseLeftButtonDown="Preview_MouseLeftButtonDown"
                           PreviewMouseMove="Preview_MouseMove"
-                          PreviewMouseLeftButtonUp="Preview_MouseLeftButtonUp">
+                          PreviewMouseLeftButtonUp="Preview_MouseLeftButtonUp"
+                          PreviewMouseRightButtonDown="Preview_MouseRightButtonDown"
+                          PreviewMouseRightButtonUp="Preview_MouseRightButtonUp">
                         <Viewbox Stretch="Uniform">
+                            <Canvas x:Name="PreviewCanvas" Width="1920" Height="1080" ClipToBounds="True">
                             <Grid x:Name="CanvasGrid" Width="1920" Height="1080" ClipToBounds="True" Background="Transparent">
+                                <Grid.RenderTransform>
+                                    <TransformGroup>
+                                        <ScaleTransform x:Name="ZoomScale"/>
+                                        <TranslateTransform x:Name="ZoomTranslate"/>
+                                    </TransformGroup>
+                                </Grid.RenderTransform>
                                 <Grid.ContextMenu>
                                     <ContextMenu DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
                                         <MenuItem Header="Show Desktop" IsCheckable="True"
@@ -35,18 +44,33 @@
                                                 </Style>
                                             </MenuItem.ItemContainerStyle>
                                         </MenuItem>
+                                        <MenuItem Header="Capture Window…"
+                                                  Visibility="{Binding CanChangeBackground, Converter={StaticResource BoolToVis}}"
+                                                  ItemsSource="{Binding OpenWindows}">
+                                            <MenuItem.ItemContainerStyle>
+                                                <Style TargetType="MenuItem">
+                                                    <Setter Property="Header" Value="{Binding Label}"/>
+                                                    <Setter Property="Command"
+                                                            Value="{Binding DataContext.CaptureWindowCommand, RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
+                                                    <Setter Property="CommandParameter" Value="{Binding}"/>
+                                                </Style>
+                                            </MenuItem.ItemContainerStyle>
+                                        </MenuItem>
+                                        <MenuItem Header="Refresh Window List" Command="{Binding RefreshWindowsCommand}"
+                                                  Visibility="{Binding CanChangeBackground, Converter={StaticResource BoolToVis}}"/>
                                         <MenuItem Header="Refresh Desktop" Command="{Binding RefreshCaptureCommand}"
                                                   Visibility="{Binding CanChangeBackground, Converter={StaticResource BoolToVis}}"/>
                                     </ContextMenu>
                                 </Grid.ContextMenu>
                                 <!-- Live desktop/game background (bottom layer; the static
-                                     image renders above it). -->
-                                <Image Source="{Binding BackgroundImage}" Stretch="UniformToFill"
-                                       Visibility="{Binding BackgroundVisible, Converter={StaticResource BoolToVis}}"
-                                       IsHitTestVisible="False"/>
-                                <Image Source="{Binding ActiveBackgroundImage}" Stretch="UniformToFill"
-                                       IsHitTestVisible="False"/>
-                                <Rectangle Stroke="#22c55e" StrokeThickness="6" IsHitTestVisible="False"/>
+                                     image renders above it). The zoom box samples the
+                                     whole CanvasGrid, not just this layer (TASK 51). -->
+                                <Grid x:Name="BackdropLayer" IsHitTestVisible="False">
+                                    <Image Source="{Binding BackgroundImage}" Stretch="UniformToFill"
+                                           Visibility="{Binding BackgroundVisible, Converter={StaticResource BoolToVis}}"/>
+                                    <Image Source="{Binding ActiveBackgroundImage}" Stretch="UniformToFill"/>
+                                    <Rectangle Stroke="#22c55e" StrokeThickness="6"/>
+                                </Grid>
                                 <Canvas x:Name="OverlayCanvas" Width="1920" Height="1080">
                                     <ItemsControl ItemsSource="{Binding StagedScene.Elements}"
                                                   Width="1920" Height="1080">
@@ -80,6 +104,12 @@
                                                                 <DataTrigger Binding="{Binding IsBackground}" Value="True">
                                                                     <Setter Property="IsHitTestVisible" Value="False"/>
                                                                 </DataTrigger>
+                                                                <!-- The zoom layer never renders here — the ZoomBox magnifier (and the
+                                                                     output resolver) own its pixels (TASK 51). -->
+                                                                <DataTrigger Binding="{Binding IsZoomLayer}" Value="True">
+                                                                    <Setter Property="Visibility" Value="Collapsed"/>
+                                                                    <Setter Property="IsHitTestVisible" Value="False"/>
+                                                                </DataTrigger>
                                                             </Style.Triggers>
                                                         </Style>
                                                     </Grid.Style>
@@ -99,6 +129,13 @@
                                                                     <DataTrigger Binding="{Binding IsChatBox}" Value="True">
                                                                          <Setter Property="Visibility" Value="Visible"/>
                                                                      </DataTrigger>
+                                                                     <!-- TASK 47: the alert box's frame (the decoded clip) is written onto
+                                                                          VideoImageSource exactly like the chat box's, so it needs the same
+                                                                          trigger. Without it the Image stayed Collapsed and every alert was
+                                                                          invisible in the preview while the decode logged healthy (2026-09-26). -->
+                                                                     <DataTrigger Binding="{Binding IsAlertBox}" Value="True">
+                                                                         <Setter Property="Visibility" Value="Visible"/>
+                                                                     </DataTrigger>
                                                                      <DataTrigger Binding="{Binding IsWebSource}" Value="True">
                                                                          <Setter Property="Visibility" Value="Visible"/>
                                                                          <Setter Property="Stretch" Value="Fill"/>
@@ -279,64 +316,44 @@
                                                  HorizontalAlignment="Right" VerticalAlignment="Bottom" Margin="0,0,-13,-13"/>
                                     </Grid>
 
-                                    <ItemsControl ItemsSource="{Binding DimRects}" IsHitTestVisible="False">
-                                        <ItemsControl.ItemsPanel>
-                                            <ItemsPanelTemplate>
-                                                <Canvas/>
-                                            </ItemsPanelTemplate>
-                                        </ItemsControl.ItemsPanel>
-                                        <ItemsControl.ItemContainerStyle>
-                                            <Style TargetType="ContentPresenter">
-                                                <Setter Property="Canvas.Left" Value="{Binding X}"/>
-                                                <Setter Property="Canvas.Top" Value="{Binding Y}"/>
-                                            </Style>
-                                        </ItemsControl.ItemContainerStyle>
-                                        <ItemsControl.ItemTemplate>
-                                            <DataTemplate>
-                                                <Rectangle Width="{Binding Width}" Height="{Binding Height}"
-                                                           Fill="#000000" Opacity="0.55"/>
-                                            </DataTemplate>
-                                        </ItemsControl.ItemTemplate>
-                                    </ItemsControl>
-
                                     <Rectangle IsHitTestVisible="False" Stroke="#e94560" StrokeThickness="3"
                                                Canvas.Left="{Binding OutputRectX}" Canvas.Top="{Binding OutputRectY}"
                                                Width="{Binding OutputRectWidth}" Height="{Binding OutputRectHeight}"
                                                Visibility="{Binding IsOutputCropped, Converter={StaticResource BoolToVis}}"/>
 
-                                    <Grid x:Name="BrandFlashLayer" Width="1920" Height="1080" IsHitTestVisible="False" Opacity="0">
-                                        <Grid.Style>
-                                            <Style TargetType="Grid">
-                                                <Setter Property="Opacity" Value="0"/>
-                                                <Style.Triggers>
-                                                    <DataTrigger Binding="{Binding BrandFlashActive}" Value="True">
-                                                        <DataTrigger.EnterActions>
-                                                            <BeginStoryboard>
-                                                                <Storyboard>
-                                                                    <DoubleAnimation Storyboard.TargetProperty="Opacity"
-                                                                                     From="0" To="0.25" Duration="0:0:0.25"/>
-                                                                </Storyboard>
-                                                            </BeginStoryboard>
-                                                        </DataTrigger.EnterActions>
-                                                        <DataTrigger.ExitActions>
-                                                            <BeginStoryboard>
-                                                                <Storyboard>
-                                                                    <DoubleAnimation Storyboard.TargetProperty="Opacity"
-                                                                                     From="0.25" To="0" Duration="0:0:0.25"/>
-                                                                </Storyboard>
-                                                            </BeginStoryboard>
-                                                        </DataTrigger.ExitActions>
-                                                    </DataTrigger>
-                                                </Style.Triggers>
-                                            </Style>
-                                        </Grid.Style>
-                                        <Viewbox Stretch="Uniform" MaxWidth="1600" MaxHeight="800"
-                                                 HorizontalAlignment="Center" VerticalAlignment="Center">
-                                            <TextBlock Text="made with LlamaCasty!" FontWeight="Bold" Foreground="White"
-                                                       FontSize="180" TextAlignment="Center"/>
-                                        </Viewbox>
+                                    <!-- Free-tier branding credit. The source is the SAME rendered
+                                         frame FramePump composites into the recording/stream
+                                         (BrandFlashPresenter → MainViewModel.BrandFlashFrame), so
+                                         the preview cannot drift from the broadcast. It replaces a
+                                         preview-only TextBlock that no viewer ever saw, and the
+                                         fade/spread/placement is the renderer's — there is no
+                                         storyboard here to keep in sync. -->
+                                    <Grid x:Name="BrandFlashElement" Width="1920" Height="1080"
+                                          Canvas.Left="0" Canvas.Top="0"
+                                          Background="Transparent" IsHitTestVisible="False"
+                                          Visibility="{Binding BrandFlashVisible, Converter={StaticResource BoolToVis}}">
+                                        <Image Source="{Binding BrandFlashImageSource}"
+                                               Stretch="Fill" RenderOptions.BitmapScalingMode="HighQuality"/>
                                     </Grid>
 
+                                    <!-- Alert announcement strip (TASK 47): the same global
+                                         1920px overlay the output compositor blits along the
+                                         top edge. Global resource — never a Source. Without it
+                                         the strip reached the stream but never the preview. -->
+                                    <!-- Alert ticker: the announcement strip draws INSIDE the Stream
+                                         Alerts box (creator ruling 2026-09-26), so this element is
+                                         placed and sized to that box's rect rather than pinned as a
+                                         1920px bar to the top edge of the preview. -->
+                                    <Grid x:Name="AlertTickerElement"
+                                          Canvas.Left="{Binding AlertTickerLeft}"
+                                          Canvas.Top="{Binding AlertTickerTop}"
+                                          Width="{Binding AlertTickerWidth}"
+                                          Height="{Binding AlertTickerHeight}"
+                                          Background="Transparent" IsHitTestVisible="False"
+                                          Visibility="{Binding AlertTickerVisible, Converter={StaticResource BoolToVis}}">
+                                        <Image Source="{Binding AlertTickerImageSource}"
+                                               Stretch="Fill" RenderOptions.BitmapScalingMode="HighQuality"/>
+                                    </Grid>
                                     <!-- Social bar: one centered horizontal row at the top or bottom of
                                          the frame, green glow while enabled. Global resource — never a
                                          Source, no Sources entry. Click toggles top ⇄ bottom. -->
@@ -367,11 +384,56 @@
                                                                    Margin="8,0,0,0"/>
                                                     </StackPanel>
                                                 </DataTemplate>
-                                            </ItemsControl.ItemTemplate>
-                                        </ItemsControl>
-                                    </Grid>
-                                </Canvas>
+</ItemsControl.ItemTemplate>
+                                         </ItemsControl>
+                                     </Grid>
+                                 </Canvas>
                             </Grid>
+
+                            <!-- The zoom dims: preview chrome ONLY — a SIBLING of CanvasGrid,
+                                 never a descendant — so the zoom box's VisualBrush sample of
+                                 CanvasGrid can never pick up the dim shading. The box must show
+                                 the captured area clean at all times, even when dragged over the
+                                 dims (creator ruling 2026-10-08). Renders above the composed
+                                 content (dims the whole scene outside the box incl. the global
+                                 overlays) and below the ZoomBox. -->
+                            <ItemsControl x:Name="DimRectsLayer" ItemsSource="{Binding DimRects}" IsHitTestVisible="False">
+                                <ItemsControl.ItemsPanel>
+                                    <ItemsPanelTemplate>
+                                        <Canvas/>
+                                    </ItemsPanelTemplate>
+                                </ItemsControl.ItemsPanel>
+                                <ItemsControl.ItemContainerStyle>
+                                    <Style TargetType="ContentPresenter">
+                                        <Setter Property="Canvas.Left" Value="{Binding X}"/>
+                                        <Setter Property="Canvas.Top" Value="{Binding Y}"/>
+                                    </Style>
+                                </ItemsControl.ItemContainerStyle>
+                                <ItemsControl.ItemTemplate>
+                                    <DataTemplate>
+                                        <Rectangle Width="{Binding Width}" Height="{Binding Height}"
+                                                   Fill="#000000" Opacity="0.55"/>
+                                    </DataTemplate>
+                                </ItemsControl.ItemTemplate>
+                            </ItemsControl>
+
+                            <!-- The zoom box: layer n+1 — a SIBLING of CanvasGrid (not a
+                                 descendant), so its VisualBrush can sample the whole
+                                 composed preview (CanvasGrid = backdrop + every element
+                                 layer) without a circular reference, and it renders ABOVE
+                                 everything. It shows a fixed capture window (box/2 at the
+                                 click); dragging the box relocates it, never the capture. -->
+                            <Grid x:Name="ZoomBox" IsHitTestVisible="False"
+                                  Canvas.Left="{Binding ZoomState.X}" Canvas.Top="{Binding ZoomState.Y}"
+                                  Width="{Binding ZoomState.Width}" Height="{Binding ZoomState.Height}"
+                                  Visibility="{Binding IsZoomActive, Converter={StaticResource BoolToVis}}">
+                                <Rectangle x:Name="ZoomRectOutline" Stroke="#d8a72b" StrokeThickness="3" Fill="Transparent"/>
+                                <Ellipse x:Name="ZoomCircleOutline" Stroke="#d8a72b" StrokeThickness="3" Fill="Transparent" Visibility="Collapsed"/>
+                                <Grid.Background>
+                                    <VisualBrush x:Name="ZoomVisualBrush" ViewboxUnits="Absolute" Stretch="Fill"/>
+                                </Grid.Background>
+                            </Grid>
+                            </Canvas>
                         </Viewbox>
                         <Border HorizontalAlignment="Left" VerticalAlignment="Top" Margin="8,8,0,0"
                                 Background="#CCe94560" CornerRadius="4" Padding="8,3" IsHitTestVisible="False"
@@ -399,13 +461,16 @@
                         </StackPanel>
                     </Grid>
 
-                    <!-- ═══ BROADCAST TEXT PULL-OUT (always visible) ═══
-                         White "Stream Settings" tab on the preview's right edge; clicking it
-                         toggles the broadcast-metadata form, and any click outside
-                         the form collapses it. Edits persist locally immediately;
-                         Update pushes liveBroadcasts.update. -->
+                    <!-- ═══ RIGHT-EDGE PULL-OUTS (always visible) ═══
+                         White "Stream Settings" + "YPP" tabs stacked on the preview's right
+                         edge; each toggles its own drawer (the same animated-width pattern).
+                         Only one drawer is open at a time — IsDrawerOpen exclusivity is
+                         VM-enforced (opening one collapses the other). Any click outside
+                         the rail collapses whichever is open (MainWindow code-behind). -->
                     <Grid Grid.Row="0">
-                        <StackPanel x:Name="TextPullOutHost" Orientation="Horizontal" HorizontalAlignment="Right" VerticalAlignment="Stretch">
+                        <StackPanel x:Name="TextPullOutHost" Orientation="Horizontal"
+                                    HorizontalAlignment="Right" VerticalAlignment="Stretch">
+                            <!-- The broadcast-metadata drawer -->
                             <Border Background="#16213e" ClipToBounds="True">
                                 <Border.Style>
                                     <Style TargetType="Border">
@@ -495,21 +560,283 @@
                                     </StackPanel>
                                 </Grid>
                             </Border>
-                            <!-- The white tab -->
-                            <Border Width="30" VerticalAlignment="Center" Background="#ffffff"
-                                    CornerRadius="4,0,0,4" Padding="0,10" Cursor="Hand"
-                                    ToolTip="Broadcast text fields">
-                                <Border.InputBindings>
-                                    <MouseBinding Gesture="LeftClick"
-                                                  Command="{Binding BroadcastForm.ToggleDrawerCommand}"/>
-                                </Border.InputBindings>
-                                <TextBlock Text="Stream Settings" Foreground="#e94560" FontWeight="Bold" FontSize="15"
-                                           HorizontalAlignment="Center">
-                                    <TextBlock.LayoutTransform>
-                                        <RotateTransform Angle="90"/>
-                                    </TextBlock.LayoutTransform>
-                                </TextBlock>
+                            <!-- The YPP-progress drawer (below Stream Settings on the rail) -->
+                            <Border Background="#16213e" ClipToBounds="True">
+                                <Border.Style>
+                                    <Style TargetType="Border">
+                                        <Setter Property="Width" Value="0"/>
+                                        <Style.Triggers>
+                                            <DataTrigger Binding="{Binding Ypp.IsDrawerOpen}" Value="True">
+                                                <DataTrigger.EnterActions>
+                                                    <BeginStoryboard>
+                                                        <Storyboard>
+                                                            <DoubleAnimation Storyboard.TargetProperty="Width"
+                                                                             To="320" Duration="0:0:0.2">
+                                                                <DoubleAnimation.EasingFunction>
+                                                                    <CubicEase EasingMode="EaseOut"/>
+                                                                </DoubleAnimation.EasingFunction>
+                                                            </DoubleAnimation>
+                                                        </Storyboard>
+                                                    </BeginStoryboard>
+                                                </DataTrigger.EnterActions>
+                                                <DataTrigger.ExitActions>
+                                                    <BeginStoryboard>
+                                                        <Storyboard>
+                                                            <DoubleAnimation Storyboard.TargetProperty="Width"
+                                                                             To="0" Duration="0:0:0.2">
+                                                                <DoubleAnimation.EasingFunction>
+                                                                    <CubicEase EasingMode="EaseOut"/>
+                                                                </DoubleAnimation.EasingFunction>
+                                                            </DoubleAnimation>
+                                                        </Storyboard>
+                                                    </BeginStoryboard>
+                                                </DataTrigger.ExitActions>
+                                            </DataTrigger>
+                                        </Style.Triggers>
+                                    </Style>
+                                </Border.Style>
+                                <Grid Width="320" Margin="14,10,14,12">
+                                    <Grid.RowDefinitions>
+                                        <RowDefinition Height="Auto"/>
+                                        <RowDefinition Height="*"/>
+                                        <RowDefinition Height="Auto"/>
+                                    </Grid.RowDefinitions>
+                                    <Grid Grid.Row="0" Margin="0,0,0,8">
+                                        <TextBlock Text="YPP PROGRESS" Style="{StaticResource SectionHeader}"
+                                                   HorizontalAlignment="Left"/>
+                                        <Button HorizontalAlignment="Right" VerticalAlignment="Top"
+                                                Background="Transparent" BorderThickness="0" Cursor="Hand"
+                                                Command="{Binding Ypp.CloseDrawerCommand}"
+                                                ToolTip="Close">
+                                            <Button.Template>
+                                                <ControlTemplate TargetType="Button">
+                                                    <ContentPresenter/>
+                                                </ControlTemplate>
+                                            </Button.Template>
+                                            <TextBlock Text="✕" Foreground="#a0a0b0" FontSize="14" FontWeight="Bold"/>
+                                        </Button>
+                                    </Grid>
+                                    <ScrollViewer Grid.Row="1" VerticalScrollBarVisibility="Auto">
+                                        <StackPanel>
+                                            <TextBlock Text="Sign in to YouTube to see your Partner Program progress and eligibility checklist here."
+                                                       Foreground="#d0d0e0" FontSize="13" TextWrapping="Wrap"
+                                                       Visibility="{Binding Ypp.IsSignedOut, Converter={StaticResource BoolToVis}}"/>
+                                            <TextBlock Text="Refreshing from YouTube…" Foreground="#a0a0b0" FontSize="12"
+                                                       Margin="0,0,0,4"
+                                                       Visibility="{Binding Ypp.IsLoading, Converter={StaticResource BoolToVis}}"/>
+                                            <TextBlock Text="{Binding Ypp.LoadError}" Foreground="#ef4444" FontSize="11"
+                                                       TextWrapping="Wrap" Margin="0,0,0,4"
+                                                       Visibility="{Binding Ypp.LoadError, Converter={StaticResource NotNullToVis}}"/>
+                                            <StackPanel Visibility="{Binding Ypp.IsSignedOut, Converter={StaticResource InverseBoolToVis}}">
+                                                <TextBlock Text="{Binding Ypp.DisplayName}" Foreground="#e0e0e0" FontSize="13"
+                                                           FontWeight="SemiBold" Margin="0,0,0,10"/>
+                                                <TextBlock Text="SUBSCRIBERS — TIER 1 · FAN FUNDING" Style="{StaticResource YtLabel}" Margin="0,0,0,2"/>
+                                                <TextBlock Text="{Binding Ypp.Tier1SubsText}" Foreground="#e0e0e0" FontSize="13"/>
+                                                <Border Height="8" Background="#2a2a40" CornerRadius="4" Margin="0,4,0,10">
+                                                    <Border Height="8" Background="#e94560" CornerRadius="4" HorizontalAlignment="Left"
+                                                            Width="{Binding Ypp.Tier1SubsBarWidth}"/>
+                                                </Border>
+                                                <TextBlock Text="SUBSCRIBERS — TIER 2 · AD REVENUE" Style="{StaticResource YtLabel}" Margin="0,0,0,2"/>
+                                                <TextBlock Text="{Binding Ypp.Tier2SubsText}" Foreground="#e0e0e0" FontSize="13"/>
+                                                <Border Height="8" Background="#2a2a40" CornerRadius="4" Margin="0,4,0,10">
+                                                    <Border Height="8" Background="#e94560" CornerRadius="4" HorizontalAlignment="Left"
+                                                            Width="{Binding Ypp.Tier2SubsBarWidth}"/>
+                                                </Border>
+                                                <TextBlock Text="PUBLIC UPLOADS (90 DAYS)" Style="{StaticResource YtLabel}" Margin="0,0,0,2"/>
+                                                <TextBlock Text="{Binding Ypp.UploadsText}" Foreground="#e0e0e0" FontSize="13"/>
+                                                <Border Height="8" Background="#2a2a40" CornerRadius="4" Margin="0,4,0,6">
+                                                    <Border Height="8" Background="#e94560" CornerRadius="4" HorizontalAlignment="Left"
+                                                            Width="{Binding Ypp.UploadsBarWidth}"/>
+                                                </Border>
+                                                <TextBlock Text="LONG-FORM WATCH HOURS + SHORTS VIEWS" Style="{StaticResource YtLabel}" Margin="0,10,0,2"/>
+                                                <TextBlock Text="These arrive with the extended analytics update — subscriber + upload + standing progress is live now."
+                                                           Foreground="#666677" FontSize="12" TextWrapping="Wrap"/>
+
+                                                <TextBlock Text="COMPLIANCE CHECKLIST" Style="{StaticResource YtLabel}" Margin="0,14,0,4"/>
+                                                <TextBlock Text="CHANNEL STANDING" Style="{StaticResource YtLabel}" Margin="0,0,0,2"/>
+                                                <TextBlock Text="{Binding Ypp.StandingDetailText}" Foreground="#888899" FontSize="11"
+                                                           TextWrapping="Wrap" Margin="0,0,0,8"/>
+                                                <CheckBox Content="Two-Step Verification switched on" Foreground="#e0e0e0" FontSize="12"
+                                                          Margin="0,2,0,0"
+                                                          IsChecked="{Binding Ypp.TwoFactorEnabled}"/>
+                                                <Button Background="Transparent" BorderThickness="0" Cursor="Hand" HorizontalAlignment="Left"
+                                                        Command="{Binding Ypp.OpenTwoStepCommand}" ToolTip="Open Google's 2-Step Verification page">
+                                                    <Button.Template>
+                                                        <ControlTemplate TargetType="Button">
+                                                            <ContentPresenter/>
+                                                        </ControlTemplate>
+                                                    </Button.Template>
+                                                    <TextBlock Text="Set up on Google →" Foreground="#5aa7ff" FontSize="12" Margin="0,0,0,6"/>
+                                                </Button>
+                                                <CheckBox Content="AdSense account linked" Foreground="#e0e0e0" FontSize="12"
+                                                          Margin="0,2,0,0"
+                                                          IsChecked="{Binding Ypp.AdSenseLinked}"/>
+                                                <Button Background="Transparent" BorderThickness="0" Cursor="Hand" HorizontalAlignment="Left"
+                                                        Command="{Binding Ypp.OpenEarnCommand}" ToolTip="Open the YouTube Earn page">
+                                                    <Button.Template>
+                                                        <ControlTemplate TargetType="Button">
+                                                            <ContentPresenter/>
+                                                        </ControlTemplate>
+                                                    </Button.Template>
+                                                    <TextBlock Text="How to link on YouTube →" Foreground="#5aa7ff" FontSize="12" Margin="0,0,0,6"/>
+                                                </Button>
+
+                                                <TextBlock Text="WHAT COUNTS" Style="{StaticResource YtLabel}" Margin="0,10,0,4"/>
+                                                <TextBlock Text="{Binding Ypp.WhatCountsText}" Foreground="#a0a0b0" FontSize="12"
+                                                           TextWrapping="Wrap" Margin="0,0,0,6"/>
+                                            </StackPanel>
+                                        </StackPanel>
+                                    </ScrollViewer>
+                                    <StackPanel Grid.Row="2" Margin="0,10,0,0">
+                                        <Button Style="{StaticResource YtButton}" Content="Refresh from YouTube"
+                                                Command="{Binding Ypp.RefreshCommand}"/>
+                                        <TextBlock Text="{Binding Ypp.LastUpdatedText}" Foreground="#888899" FontSize="11" Margin="0,6,0,0"/>
+                                    </StackPanel>
+                                </Grid>
                             </Border>
+                            <!-- The Test-stream drawer (below YPP on the rail) -->
+                            <Border Background="#16213e" ClipToBounds="True">
+                                <Border.Style>
+                                    <Style TargetType="Border">
+                                        <Setter Property="Width" Value="0"/>
+                                        <Style.Triggers>
+                                            <DataTrigger Binding="{Binding TestSession.IsDrawerOpen}" Value="True">
+                                                <DataTrigger.EnterActions>
+                                                    <BeginStoryboard>
+                                                        <Storyboard>
+                                                            <DoubleAnimation Storyboard.TargetProperty="Width"
+                                                                             To="320" Duration="0:0:0.2">
+                                                                <DoubleAnimation.EasingFunction>
+                                                                    <CubicEase EasingMode="EaseOut"/>
+                                                                </DoubleAnimation.EasingFunction>
+                                                            </DoubleAnimation>
+                                                        </Storyboard>
+                                                    </BeginStoryboard>
+                                                </DataTrigger.EnterActions>
+                                                <DataTrigger.ExitActions>
+                                                    <BeginStoryboard>
+                                                        <Storyboard>
+                                                            <DoubleAnimation Storyboard.TargetProperty="Width"
+                                                                             To="0" Duration="0:0:0.2">
+                                                                <DoubleAnimation.EasingFunction>
+                                                                    <CubicEase EasingMode="EaseOut"/>
+                                                                </DoubleAnimation.EasingFunction>
+                                                            </DoubleAnimation>
+                                                        </Storyboard>
+                                                    </BeginStoryboard>
+                                                </DataTrigger.ExitActions>
+                                            </DataTrigger>
+                                        </Style.Triggers>
+                                    </Style>
+                                </Border.Style>
+                                <Grid Width="320" Margin="14,10,14,12">
+                                    <Grid.RowDefinitions>
+                                        <RowDefinition Height="Auto"/>
+                                        <RowDefinition Height="*"/>
+                                        <RowDefinition Height="Auto"/>
+                                    </Grid.RowDefinitions>
+                                    <Grid Grid.Row="0" Margin="0,0,0,8">
+                                        <TextBlock Text="TEST STREAM" Style="{StaticResource SectionHeader}"
+                                                   HorizontalAlignment="Left"/>
+                                        <Button HorizontalAlignment="Right" VerticalAlignment="Top"
+                                                Background="Transparent" BorderThickness="0" Cursor="Hand"
+                                                Command="{Binding TestSession.CloseDrawerCommand}"
+                                                ToolTip="Close">
+                                            <Button.Template>
+                                                <ControlTemplate TargetType="Button">
+                                                    <ContentPresenter/>
+                                                </ControlTemplate>
+                                            </Button.Template>
+                                            <TextBlock Text="✕" Foreground="#a0a0b0" FontSize="14" FontWeight="Bold"/>
+                                        </Button>
+                                    </Grid>
+                                    <ScrollViewer Grid.Row="1" VerticalScrollBarVisibility="Auto">
+                                        <StackPanel>
+                                            <TextBlock Text="{Binding TestSession.SessionCaption}"
+                                                       Foreground="#d0d0e0" FontSize="13" TextWrapping="Wrap" Margin="0,0,0,8"/>
+                                            <TextBlock Text="{Binding TestSession.ChatIdLine}"
+                                                       Foreground="#888899" FontSize="11"
+                                                       Visibility="{Binding TestSession.IsTestSession, Converter={StaticResource BoolToVis}}"/>
+
+                                            <TextBlock Text="MOCK CHAT INPUT" Style="{StaticResource YtLabel}" Margin="0,10,0,3"/>
+                                            <TextBlock Text="Sends a real live chat message — it round-trips through the actual chat poll and renders on your chat overlay."
+                                                       Foreground="#a0a0b0" FontSize="11" TextWrapping="Wrap" Margin="0,0,0,4"/>
+                                            <TextBox Style="{StaticResource YtTextBox}" Margin="0,0,0,6"
+                                                     Text="{Binding TestSession.SendMessageText, UpdateSourceTrigger=PropertyChanged}"/>
+                                            <Button Style="{StaticResource YtButton}" Content="Send Message"
+                                                    Command="{Binding TestSession.SendTestMessageCommand}"/>
+
+                                            <TextBlock Text="SIMULATED EVENTS" Style="{StaticResource YtLabel}" Margin="0,14,0,3"/>
+                                            <TextBlock Text="Fired into your chat overlay locally — YouTube's insert API only creates text, so these never reach YouTube."
+                                                       Foreground="#a0a0b0" FontSize="11" TextWrapping="Wrap" Margin="0,0,0,4"/>
+                                            <StackPanel Orientation="Horizontal" Margin="0,0,0,4">
+                                                <Button Style="{StaticResource YtButtonSecondary}" Content="Subscriber" Padding="10,4" FontSize="11"
+                                                        Margin="0,0,6,0" Command="{Binding TestSession.SimulateSubscriberCommand}"/>
+                                                <Button Style="{StaticResource YtButtonSecondary}" Content="New Member" Padding="10,4" FontSize="11"
+                                                        Margin="0,0,6,0" Command="{Binding TestSession.SimulateMemberCommand}"/>
+                                            </StackPanel>
+                                            <Button Style="{StaticResource YtButtonSecondary}" Content="Super Chat (5.00)" Padding="10,4" FontSize="11"
+                                                    HorizontalAlignment="Left" Command="{Binding TestSession.SimulateSuperChatCommand}"/>
+
+                                            <TextBlock Text="{Binding TestSession.LastEventText}"
+                                                       Foreground="#22c55e" FontSize="11" TextWrapping="Wrap" Margin="0,10,0,0"
+                                                       Visibility="{Binding TestSession.LastEventText, Converter={StaticResource NotNullToVis}}"/>
+                                        </StackPanel>
+                                    </ScrollViewer>
+                                    <StackPanel Grid.Row="2" Margin="0,10,0,0">
+                                        <Button Style="{StaticResource YtButton}" Content="End Test"
+                                                Command="{Binding TestSession.EndTestCommand}"
+                                                Visibility="{Binding TestSession.IsTestSession, Converter={StaticResource BoolToVis}}"/>
+                                        <TextBlock Text="Test broadcasts are private — nobody is notified, and it runs through the exact same pipeline as a real live."
+                                                   Foreground="#666677" FontSize="11" TextWrapping="Wrap" Margin="0,6,0,0"/>
+                                    </StackPanel>
+                                </Grid>
+                            </Border>
+                            <!-- The stacked white tabs -->
+                            <StackPanel Orientation="Vertical" HorizontalAlignment="Right" VerticalAlignment="Stretch">
+                                <Border Width="30" VerticalAlignment="Center" Background="#ffffff"
+                                        CornerRadius="4,0,0,4" Padding="0,10" Cursor="Hand" Margin="0,4,0,0"
+                                        ToolTip="Broadcast text fields">
+                                    <Border.InputBindings>
+                                        <MouseBinding Gesture="LeftClick"
+                                                      Command="{Binding BroadcastForm.ToggleDrawerCommand}"/>
+                                    </Border.InputBindings>
+                                    <TextBlock Text="Stream Settings" Foreground="#e94560" FontWeight="Bold" FontSize="15"
+                                               HorizontalAlignment="Center">
+                                        <TextBlock.LayoutTransform>
+                                            <RotateTransform Angle="90"/>
+                                        </TextBlock.LayoutTransform>
+                                    </TextBlock>
+                                </Border>
+                                <Border Width="30" VerticalAlignment="Center" Background="#ffffff"
+                                        CornerRadius="4,0,0,4" Padding="0,10" Cursor="Hand" Margin="0,4,0,0"
+                                        ToolTip="YouTube Partner Program progress">
+                                    <Border.InputBindings>
+                                        <MouseBinding Gesture="LeftClick"
+                                                      Command="{Binding Ypp.ToggleDrawerCommand}"/>
+                                    </Border.InputBindings>
+                                    <TextBlock Text="YPP" Foreground="#e94560" FontWeight="Bold" FontSize="15"
+                                               HorizontalAlignment="Center">
+                                        <TextBlock.LayoutTransform>
+                                            <RotateTransform Angle="90"/>
+                                        </TextBlock.LayoutTransform>
+                                    </TextBlock>
+                                </Border>
+                                <Border Width="30" VerticalAlignment="Center" Background="#ffffff"
+                                        CornerRadius="4,0,0,4" Padding="0,10" Cursor="Hand" Margin="0,4,0,0"
+                                        ToolTip="Test stream — mock chat input and simulated events">
+                                    <Border.InputBindings>
+                                        <MouseBinding Gesture="LeftClick"
+                                                      Command="{Binding TestSession.ToggleDrawerCommand}"/>
+                                    </Border.InputBindings>
+                                    <TextBlock Text="TEST" Foreground="#9c6f1c" FontWeight="Bold" FontSize="15"
+                                               HorizontalAlignment="Center">
+                                        <TextBlock.LayoutTransform>
+                                            <RotateTransform Angle="90"/>
+                                        </TextBlock.LayoutTransform>
+                                    </TextBlock>
+                                </Border>
+                            </StackPanel>
                         </StackPanel>
                     </Grid>
 
@@ -657,6 +984,16 @@
                                     PreviewMouseLeftButtonDown="VolumeSlider_PreviewMouseLeftButtonDown"
                                     PreviewMouseLeftButtonUp="VolumeSlider_PreviewMouseLeftButtonUp"
                                     LostMouseCapture="VolumeSlider_LostMouseCapture"/>
+                            <StackPanel Orientation="Horizontal" Margin="10,0,0,0" VerticalAlignment="Center"
+                                        ToolTip="Audio sync (−500..+500 ms). Positive: delays the audio when it runs ahead of the video. Negative: advances it (drops the first |N| ms of the recording) when it runs behind. Calibrate with a clap: is the clap late in the video, move negative; early, move positive.">
+                                <TextBlock Text="AUDIO SYNC" FontSize="9" Foreground="#9898aa"
+                                           VerticalAlignment="Center" Margin="0,0,5,0"/>
+                                <Slider Width="70" Minimum="-500" Maximum="500"
+                                        Value="{Binding AudioSyncOffsetMs, Mode=TwoWay}"
+                                        IsEnabled="{Binding IsEditMode}"
+                                        VerticalAlignment="Center"
+                                        ToolTip="{Binding AudioSyncOffsetMs, StringFormat=Audio sync: {0} ms}"/>
+                            </StackPanel>
                         </StackPanel>
                     </StackPanel>
                 </Grid>

Controls/PreviewPane.xaml.cs

@@ -17,6 +17,7 @@ public partial class PreviewPane : UserControl
 {
     private bool _isDraggingOverlay;
     private bool _isResizing;
+    private bool _isZoomDragging;
     private Point _grabOffset;
     private double _resizeAspect;
 
@@ -29,8 +30,30 @@ public partial class PreviewPane : UserControl
     public PreviewPane()
     {
         InitializeComponent();
+        DataContextChanged += PreviewPane_DataContextChanged;
     }
 
+    private void PreviewPane_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
+    {
+        if (e.OldValue is MainViewModel oldVm)
+            oldVm.PropertyChanged -= ViewModel_PropertyChanged;
+        if (e.NewValue is MainViewModel newVm)
+        {
+            newVm.PropertyChanged += ViewModel_PropertyChanged;
+            UpdateZoomBox();
+        }
+    }
+
+    private void ViewModel_PropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
+    {
+        if (e.PropertyName == nameof(MainViewModel.IsZoomActive) || e.PropertyName == nameof(MainViewModel.ZoomState) || e.PropertyName == nameof(MainViewModel.ZoomShape))
+        {
+            UpdateZoomBox();
+        }
+    }
+
+
+
     // Static images and the webcam share the move/resize/selection behavior.
     public static bool IsDraggableElement(SceneElement element)
         => element.IsDraggable;
@@ -387,12 +410,29 @@ public partial class PreviewPane : UserControl
     private void Preview_MouseMove(object sender, MouseEventArgs e)
     {
         var vm = DataContext as MainViewModel;
-        if (vm is null || !vm.IsEditMode) return;
-        if (!_isDraggingOverlay && !_isResizing) return;
-
+        if (vm is null) return;
         var grid = (Grid)sender;
         var toCanvas = CanvasGrid.TransformToVisual(grid).Inverse;
         var p = toCanvas.Transform(e.GetPosition(grid));
+
+        if (e.LeftButton == MouseButtonState.Pressed && vm.IsZoomActive)
+        {
+            if (!_isZoomDragging)
+            {
+                vm.StartZoomMove(p.X, p.Y);
+                _isZoomDragging = true;
+                grid.CaptureMouse();
+            }
+            else
+            {
+                vm.UpdateZoomMove(p.X, p.Y);
+            }
+            return;
+        }
+
+        if (!vm.IsEditMode) return;
+        if (!_isDraggingOverlay && !_isResizing) return;
+
         var selected = vm.SelectedElement;
         if (selected == null)
         {
@@ -429,14 +469,60 @@ public partial class PreviewPane : UserControl
     }
 
     private void Preview_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
-        => EndPreviewDrag((Grid)sender);
+    {
+        if (_isZoomDragging && DataContext is MainViewModel vm)
+        {
+            vm.EndZoomMove();
+            _isZoomDragging = false;
+            ((Grid)sender).ReleaseMouseCapture();
+            e.Handled = true;
+            return;
+        }
+        EndPreviewDrag((Grid)sender);
+    }
+
+    private void Preview_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
+    {
+        var vm = DataContext as MainViewModel;
+        if (vm == null) return;
+        var grid = (Grid)sender;
+        var toCanvas = CanvasGrid.TransformToVisual(grid).Inverse;
+        var p = toCanvas.Transform(e.GetPosition(grid));
+        if ((vm.IsLive || vm.IsRecording) && !vm.IsEditMode)
+        {
+            if (vm.IsZoomActive)
+            {
+                vm.DismissZoom();
+                e.Handled = true;
+                return;
+            }
+            vm.ActivateZoom(p.X, p.Y);
+            e.Handled = true;
+            return;
+        }
+        vm.ToggleZoom();
+        e.Handled = true;
+    }    private void Preview_MouseRightButtonUp(object sender, MouseButtonEventArgs e)
+    {
+        if (_isZoomDragging)
+        {
+            var grid = (Grid)sender;
+            grid.ReleaseMouseCapture();
+            _isZoomDragging = false;
+            if (DataContext is MainViewModel vm) vm.EndZoomMove();
+            e.Handled = true;
+            return;
+        }
+    }
 
     private void EndPreviewDrag(Grid grid)
     {
-        if (_isDraggingOverlay || _isResizing)
+        if (_isDraggingOverlay || _isResizing || _isZoomDragging)
             grid.ReleaseMouseCapture();
         _isDraggingOverlay = false;
         _isResizing = false;
+        _isZoomDragging = false;
+        if (DataContext is MainViewModel vm) vm.EndZoomMove();
     }
 
     private bool HitHandle(Point mouseScreen, SceneElement element)
@@ -461,4 +547,40 @@ public partial class PreviewPane : UserControl
         }
         return null;
     }
-}
+
+    private void UpdateZoomBox()
+    {
+        if (DataContext is not MainViewModel vm) return;
+        if (vm.IsZoomActive && ZoomVisualBrush != null)
+        {
+            // The preview mirrors the output zoom layer: sample the WHOLE composed
+            // preview (CanvasGrid = backdrop + every element layer — the same all-layer
+            // source the output compositor magnifies) at the FIXED capture window (the
+            // box/2 region centred on the click) → 2x via Stretch=Fill. Moving the box
+            // only moves the ZoomBox element; the Viewbox stays glued to the capture.
+            ZoomVisualBrush.Visual = CanvasGrid;
+            ZoomVisualBrush.Viewbox = new Rect(
+                vm.ZoomState.CaptureX,
+                vm.ZoomState.CaptureY,
+                vm.ZoomState.Width / 2,
+                vm.ZoomState.Height / 2);
+            ZoomVisualBrush.ViewboxUnits = BrushMappingMode.Absolute;
+            if (vm.ZoomShape == Models.ZoomShape.Circle)
+            {
+                ZoomCircleOutline.Visibility = Visibility.Visible;
+                ZoomRectOutline.Visibility = Visibility.Collapsed;
+                ZoomBox.Clip = new EllipseGeometry(new Rect(0, 0, vm.ZoomState.Width, vm.ZoomState.Height));
+            }
+            else
+            {
+                ZoomCircleOutline.Visibility = Visibility.Collapsed;
+                ZoomRectOutline.Visibility = Visibility.Visible;
+                ZoomBox.Clip = null;
+            }
+        }
+        else if (!vm.IsZoomActive && ZoomVisualBrush != null && ReferenceEquals(ZoomVisualBrush.Visual, CanvasGrid))
+        {
+            ZoomVisualBrush.Visual = null;
+        }
+    }
+}

Controls/TopBar.xaml

@@ -1,8 +1,8 @@
 <UserControl x:Class="ytLive.Controls.TopBar"
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:helpers="clr-namespace:ytLive.Helpers"
              x:Name="TopBarRoot">
-    <!-- LOGO / BRAND — clicking opens the in-app About overlay -->
     <Grid>
         <Grid.ColumnDefinitions>
             <ColumnDefinition Width="Auto"/>
@@ -10,109 +10,124 @@
             <ColumnDefinition Width="Auto"/>
         </Grid.ColumnDefinitions>
 
-        <!-- Logo / Brand — clicking opens the in-app About overlay -->
-        <Button Grid.Column="0" Background="Transparent" BorderThickness="0" Cursor="Hand"
-                VerticalAlignment="Center" Margin="0,0,24,0" ToolTip="About LlamaCasty"
-                Command="{Binding OpenAboutCommand}">
-            <Button.Template>
-                <ControlTemplate TargetType="Button">
-                    <ContentPresenter/>
-                </ControlTemplate>
-            </Button.Template>
-            <TextBlock FontSize="22" FontWeight="Bold">
-                <Run Text="LlamaCas" Foreground="#e0e0e0"/><Run Text="ty" Foreground="#e94560"/>
-            </TextBlock>
-        </Button>
-
-        <!-- REC / ON-AIR pills (intent) + status signs (reality) -->
-        <StackPanel Grid.Column="1" Orientation="Horizontal"
-                    HorizontalAlignment="Center" VerticalAlignment="Center">
-            <!-- REC pill: local recording needs no sign-in -->
-            <TextBlock Text="REC" Foreground="#e94560" FontWeight="Bold" FontSize="12"
-                       VerticalAlignment="Center" Margin="0,0,6,0"/>
-            <ToggleButton Style="{StaticResource PillToggle}" VerticalAlignment="Center"
-                          IsChecked="{Binding RecordPillOn}"/>
-            <!-- ON-AIR pill: greyed out until signed in -->
-            <TextBlock Text="ON-AIR" Foreground="#e94560" FontWeight="Bold" FontSize="12"
-                       VerticalAlignment="Center" Margin="16,0,6,0"/>
-            <ToggleButton Style="{StaticResource PillToggle}" VerticalAlignment="Center"
-                          IsChecked="{Binding OnAirPillOn}"
-                          IsEnabled="{Binding CanToggleOnAir}"
-                          ToolTip="{Binding AccountStatusLightToolTip}"/>
-            <!-- Status signs: REC dot + ON-AIR dot -->
-            <Ellipse Width="12" Height="12" VerticalAlignment="Center" Margin="16,0,0,0"
-                     Fill="{Binding RecDotBrush}" Opacity="{Binding RecDotOpacity}"/>
-            <TextBlock Text="REC" Style="{StaticResource StatusSignText}"/>
-            <!-- ON-AIR sign: gray offline, red public, green private -->
-            <Ellipse Width="12" Height="12" VerticalAlignment="Center" Margin="16,0,0,0"
-                     Fill="{Binding OnAirBrush}"/>
-            <TextBlock Text="ON-AIR" Style="{StaticResource StatusSignText}"/>
-            <Border Background="#8f1f1f" CornerRadius="3" Padding="6,1" Margin="8,0,0,0"
-                    VerticalAlignment="Center"
-                    Visibility="{Binding IsLivePrivate, Converter={StaticResource BoolToVis}}">
-                <TextBlock Text="PRIVATE" FontSize="11" FontWeight="Bold" Foreground="White"/>
-            </Border>
-            <TextBlock Text="{Binding LiveElapsedText}" Foreground="White" FontSize="14"
-                       FontFamily="Consolas" VerticalAlignment="Center" Margin="14,0,0,0"
-                       Visibility="{Binding IsLive, Converter={StaticResource BoolToVis}}"/>
+        <!-- LOGO / BRAND — clicking opens the in-app About overlay; the gear sits
+             a couple characters past the build stamp and opens App Settings. -->
+        <StackPanel Grid.Column="0" Orientation="Horizontal" VerticalAlignment="Center"
+                    Margin="0,0,24,0">
+            <Button Background="Transparent" BorderThickness="0" Cursor="Hand"
+                    VerticalAlignment="Center" ToolTip="About LlamaCasty"
+                    Command="{Binding OpenAboutCommand}">
+                <Button.Template>
+                    <ControlTemplate TargetType="Button">
+                        <ContentPresenter/>
+                    </ControlTemplate>
+                </Button.Template>
+                <TextBlock FontSize="22" FontWeight="Bold" VerticalAlignment="Center">
+                    <Run Text="LlamaCas" Foreground="#e0e0e0"/><Run Text="ty" Foreground="#e94560"/><Run
+                        x:Name="BuildIdStamp" Text="{x:Static helpers:BuildStamp.Label}" FontSize="9"
+                        BaselineAlignment="Superscript" Foreground="#8888aa"
+                        ToolTipService.ToolTip="{x:Static helpers:BuildStamp.Label}"/><Run Text=" " FontSize="4"/>
+                </TextBlock>
+            </Button>
+            <!-- Settings gear (user directive): a couple characters beyond the brand,
+                 nudged right a couple more places 2026-09-22 (build 77 feedback).
+                 Moved up from the bottom bar — one menu: App Settings / Bug / Feature / About. -->
+            <Button Style="{StaticResource IconButton}" Margin="18,0,0,2" VerticalAlignment="Center"
+                    ToolTip="Menu" Click="GearButton_Click">
+                <Button.ContextMenu>
+                    <ContextMenu DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
+                        <MenuItem Header="App Settings" Command="{Binding OpenSettingsCommand}"/>
+                        <Separator/>
+                        <MenuItem Header="Report Bug" Command="{Binding OpenBugCommand}"/>
+                        <MenuItem Header="Feature Request" Command="{Binding OpenFeatureCommand}"/>
+                        <MenuItem Header="About" Command="{Binding OpenAboutCommand}"/>
+                    </ContextMenu>
+                </Button.ContextMenu>
+                <Path Data="M19.43,12.98c0.04,-0.32 0.07,-0.65 0.07,-0.98c0,-0.33 -0.03,-0.66 -0.07,-0.98l2.11,-1.65c0.19,-0.15 0.24,-0.42 0.12,-0.64l-2,-3.46c-0.12,-0.22 -0.38,-0.31 -0.61,-0.22l-2.49,1c-0.52,-0.4 -1.08,-0.73 -1.69,-0.98l-0.38,-2.65C14.46,2.18 14.25,2 14,2h-4c-0.25,0 -0.46,0.18 -0.49,0.42l-0.38,2.65c-0.61,0.25 -1.17,0.59 -1.69,0.98l-2.49,-1c-0.23,-0.09 -0.49,0 -0.61,0.22l-2,3.46c-0.13,0.22 -0.07,0.49 0.12,0.64l2.11,1.65c-0.04,0.32 -0.07,0.65 -0.07,0.98c0,0.33 0.03,0.66 0.07,0.98l-2.11,1.65c-0.19,0.15 -0.24,0.42 -0.12,0.64l2,3.46c0.12,0.22 0.38,0.31 0.61,0.22l2.49,-1c0.52,0.4 1.08,0.73 1.69,0.98l0.38,2.65c0.03,0.24 0.24,0.42 0.49,0.42h4c0.25,0 0.46,-0.18 0.49,-0.42l0.38,-2.65c0.61,-0.25 1.17,-0.59 1.69,-0.98l2.49,1c0.23,0.09 0.49,0 0.61,-0.22l2,-3.46c0.12,-0.22 0.07,-0.49 -0.12,-0.64L19.43,12.98zM12,15.5c-1.93,0 -3.5,-1.57 -3.5,-3.5c0,-1.93 1.57,-3.5 3.5,-3.5c1.93,0 3.5,1.57 3.5,3.5C15.5,13.93 13.93,15.5 12,15.5z"
+                      Fill="#a0a0b0" Width="18" Height="18" Stretch="Uniform"/>
+            </Button>
         </StackPanel>
 
-        <!-- Three-state top bar: logged-out / idle / live -->
+        <!-- Session surface (top bar redesign): the bar is ONE surface rendered by
+             the FIRST decision — Record or Stream. Each world is the whole bar; the
+             other world never exists on screen. While running, the bar drops to a
+             reality line + End so nothing mid-session can be re-armed. -->
+        <StackPanel Grid.Column="1" Orientation="Horizontal"
+                    HorizontalAlignment="Center" VerticalAlignment="Center">
+            <!-- IDLE: the mode switch + the action(s) of the armed world. The three
+                 controls share one height (build 77 feedback) so they read as one
+                 family — segments host, Start/Go Live, and Test all sit at 32. -->
+            <StackPanel Orientation="Horizontal"
+                        Visibility="{Binding ShowIdleWorld, Converter={StaticResource BoolToVis}}">
+                <Border Background="#0f1622" CornerRadius="4" Padding="2" Height="32" VerticalAlignment="Center">
+                    <StackPanel Orientation="Horizontal">
+                        <ToggleButton Style="{StaticResource SegmentToggle}"
+                                      IsChecked="{Binding RecordPillOn}">
+                            <TextBlock Text="REC" Style="{StaticResource SegmentLabel}"/>
+                        </ToggleButton>
+                        <ToggleButton Style="{StaticResource SegmentToggle}"
+                                      IsChecked="{Binding OnAirPillOn}">
+                            <TextBlock Text="ON-AIR" Style="{StaticResource SegmentLabel}"/>
+                        </ToggleButton>
+                    </StackPanel>
+                </Border>
+                <!-- Go face names the world: "Start Recording" vs "Go Live".
+                     (Signed-out ON-AIR Start routes to the sign-in — StartSession.) -->
+                <Button Content="{Binding PrimaryStartButtonLabel}" Style="{StaticResource YtButton}"
+                        Height="32" Margin="10,0,0,0" Command="{Binding StartStreamCommand}"
+                        Visibility="{Binding ShowPrimaryStartButton, Converter={StaticResource BoolToVis}}"/>
+                <!-- Test is a child of Stream — a dry-run of the livestream, so it
+                     exists only inside the Stream world (stream armed + signed in). -->
+                <Button Content="Test" Style="{StaticResource YtButtonSecondary}" Padding="12,4" FontSize="11"
+                        Height="32" Margin="8,0,0,0" VerticalAlignment="Center"
+                        Command="{Binding StartTestCommand}"
+                        ToolTip="Run a private test broadcast to check your chat overlay."
+                        Visibility="{Binding ShowTestButton, Converter={StaticResource BoolToVis}}"/>
+            </StackPanel>
+
+            <!-- RUNNING: one reality line (dot + word + elapsed) and the stop -->
+            <StackPanel Orientation="Horizontal"
+                        Visibility="{Binding RunningVisible, Converter={StaticResource BoolToVis}}">
+                <Ellipse Width="12" Height="12" VerticalAlignment="Center"
+                         Fill="{Binding RunningDotBrush}"/>
+                <TextBlock Text="{Binding RunningText}" FontSize="16" FontWeight="Bold"
+                           Foreground="White" Margin="8,0,0,0" VerticalAlignment="Center"/>
+                <TextBlock Text="{Binding LiveElapsedText}" Foreground="White" FontSize="14"
+                           FontFamily="Consolas" VerticalAlignment="Center" Margin="8,0,0,0"/>
+                <Button Content="{Binding EndButtonText}" Style="{StaticResource YtButton}"
+                        Background="#333" Margin="14,0,0,0" Command="{Binding EndStreamCommand}"/>
+            </StackPanel>
+        </StackPanel>
+
+        <!-- Account zone: lives only in the Stream world. Signed out → Sign In;
+             signed in → a big avatar of the streaming account (build 77 feedback:
+             "make the user icon much bigger"). Record world has no YouTube
+             identity at all. -->
         <StackPanel Grid.Column="2" Orientation="Horizontal" VerticalAlignment="Center">
-            <!-- Status light -->
-            <Ellipse Width="8" Height="8" Margin="0,0,8,0" VerticalAlignment="Center"
-                     ToolTip="{Binding AccountStatusLightToolTip}">
-                <Ellipse.Style>
-                    <Style TargetType="Ellipse">
-                        <Setter Property="Fill" Value="#ef4444"/>
-                        <Style.Triggers>
-                            <DataTrigger Binding="{Binding IsConnected}" Value="True">
-                                <Setter Property="Fill" Value="#22c55e"/>
-                            </DataTrigger>
-                            <DataTrigger Binding="{Binding IsLive}" Value="True">
-                                <Setter Property="Fill" Value="#e94560"/>
-                            </DataTrigger>
-                        </Style.Triggers>
-                    </Style>
-                </Ellipse.Style>
-            </Ellipse>
-            <!-- Avatar (connected only); shows the channel initial when
-                 the profile image is missing or fails to download -->
-            <Border Width="26" Height="26" CornerRadius="13" Background="#16213e" ClipToBounds="True"
-                    Margin="0,0,8,0" VerticalAlignment="Center"
+            <Button Content="Sign In" Style="{StaticResource YtButtonSecondary}"
+                    Margin="0,0,8,0" Command="{Binding SignInCommand}"
+                    ToolTip="Sign in to YouTube to go live."
+                    Visibility="{Binding ShowSignInButton, Converter={StaticResource BoolToVis}}"/>
+            <Button Style="{StaticResource IconButton}" Margin="0,0,0,0"
                     ToolTip="{Binding AccountDisplayName}"
-                    Visibility="{Binding IsConnected, Converter={StaticResource BoolToVis}}">
-                <Grid>
-                    <Image x:Name="AvatarImage" Stretch="UniformToFill"/>
-                    <TextBlock x:Name="AvatarInitial" Foreground="#e0e0e0" FontSize="13"
-                               FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center"
-                               Visibility="Collapsed"/>
-                </Grid>
-            </Border>
-            <!-- Sign In button (disconnected + offline) -->
-            <Button Content="Sign In" Style="{StaticResource YtButton}"
-                    Margin="0,0,12,0"
-                    Command="{Binding StartStreamCommand}"
-                    Visibility="{Binding ShowLogInButton, Converter={StaticResource BoolToVis}}"/>
-            <!-- Primary Start button (offline): dynamic label from the pills -->
-            <Button Content="Start" Style="{StaticResource YtButton}"
-                    Command="{Binding StartStreamCommand}"
-                    Visibility="{Binding ShowPrimaryStartButton, Converter={StaticResource BoolToVis}}">
+                    Visibility="{Binding ShowAvatarButton, Converter={StaticResource BoolToVis}}">
                 <Button.ContextMenu>
                     <ContextMenu>
-                        <MenuItem Header="Choose Record Folder" Command="{Binding ChooseRecordFolderCommand}"/>
-                        <Separator/>
                         <MenuItem Header="Change Account" Command="{Binding ChangeAccountCommand}"/>
                         <Separator/>
                         <MenuItem Header="Logout" Command="{Binding LogoutCommand}"/>
                     </ContextMenu>
                 </Button.ContextMenu>
+                <Border Width="40" Height="40" CornerRadius="20" Background="#16213e"
+                        ClipToBounds="True" BorderBrush="#3a4a66" BorderThickness="1">
+                    <Grid>
+                        <Image x:Name="AvatarImage" Stretch="UniformToFill"/>
+                        <TextBlock x:Name="AvatarInitial" Foreground="#e0e0e0" FontSize="20"
+                                   FontWeight="Bold" HorizontalAlignment="Center" VerticalAlignment="Center"
+                                   Visibility="Collapsed"/>
+                    </Grid>
+                </Border>
             </Button>
-            <!-- End button (live OR recording) — the only button whose
-                 label changes; "Stop Recording" while recording -->
-            <Button Content="{Binding EndButtonText}" Style="{StaticResource YtButton}"
-                    Background="#333" Command="{Binding EndStreamCommand}"
-                    Visibility="{Binding ShowEndStreamButton, Converter={StaticResource BoolToVis}}"/>
         </StackPanel>
     </Grid>
 </UserControl>

Controls/TopBar.xaml.cs

@@ -1,6 +1,7 @@
 using System;
 using System.IO;
 using System.Net.Http;
+using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Media.Imaging;
 using ytLive.Helpers;
@@ -25,6 +26,18 @@ public partial class TopBar : UserControl
         _ = LoadAvatarImageAsync();
     }
 
+    private void GearButton_Click(object sender, RoutedEventArgs e)
+    {
+        // One menu (Settings / Bug / Feature / About), opened on click — moved up
+        // from the bottom bar so app-level actions live next to the brand.
+        if (sender is Button { ContextMenu: { } menu } button)
+        {
+            menu.PlacementTarget = button;
+            menu.Placement = System.Windows.Controls.Primitives.PlacementMode.Bottom;
+            menu.IsOpen = true;
+        }
+    }
+
     private async System.Threading.Tasks.Task LoadAvatarImageAsync()
     {
         var vm = DataContext as MainViewModel;

Controls/index.md

@@ -7,9 +7,9 @@ See [`schema.md`](../schema.md) for the memory-map conventions.
 
 | File | Purpose |
 |------|---------|
-| `BottomBar.xaml(.cs)` | Footer (Row 3): gear menu (stop/mic/game-mute/quality dropdown), stream stats (bitrate/fps/dropped/duration/health), resolution dropdown |
+| `BottomBar.xaml(.cs)` | Footer (Row 3): stream stats (bitrate/fps/dropped/duration/health), resolution dropdown (gear menu moved up to TopBar 2026-09-22) |
 | `HealthBanner.xaml(.cs)` | Row 1 status banner + the 7 value→visibility converters live in the app theme, not here |
-| `TopBar.xaml(.cs)` | Row 0 stream controls: REC/ON-AIR pills+signs, elapsed timer, start/stop, account avatar/name (`RefreshAvatar()`) |
+| `TopBar.xaml(.cs)` | Row 0 session surface (2026-09-22 redesign): brand + gear menu (left), one segmented REC|ON-AIR mode switch + world actions (Record: Start Recording · Stream: Go Live + Test) + reality line while running (dot/word/elapsed) + End (center), account zone — Sign In or avatar w/ Change Account/Logout context menu (right). `RefreshAvatar()`, `GearButton_Click` |
 | `PreviewPane.xaml(.cs)` | Row 1 Col 1 center: the 1920×1080 `OverlayCanvas`/`SelectionOverlay`/`BrandFlashLayer`/`SocialBarElement`, text pull-out drawer, and the live-controls row (TRAX / game / mic meters + sliders + speakers + socials) |
 | `SceneThumbnailStrip.xaml(.cs)` | Row 0 scene-picker strip (`ItemsControl` over `Scenes`), staged-red / live-green border highlight |
 | `LeftPanel.xaml(.cs)` | Row 1 Col 0 left panel: edit mode → layers+properties; live → YouTube chat. Source add/edit/remove, list drag-to-reorder, snapshot revert-accept |
@@ -47,7 +47,10 @@ cross-cutting calls through it:
   `WebViewHostPanel` (ctor `InitWebView2(WebViewHostPanel)`) and `ToastArea`
   (`NotificationService.InArea("ToastArea")`) are resolved by name from the
   window root — so `OverlayHost` deliberately leaves them as thin window-root
-  children (Commit 18).
+  children (Commit 18). Since the 2026-09-14 composition-capture redesign only
+  `ToastArea` remains — `WebViewHostPanel` is deleted (web sources no longer
+  host a multiline XAML control; `InitWebView2()` runs from `MainWindow_Loaded`
+  with no panel argument).
 - When cutting visual wrappers, don't drop the outer `Border`'s
   background/glow/margin — Commit 15 initially lost the preview's outer border
   and had to restore it same-commit.

Distribution.md

@@ -1,12 +1,42 @@
 # Distribution & IP Protection Plan
 
-> 360-degree protection strategy for LlamaCasty (.NET 8 / WPF), built around Polar.sh.
+> 360-degree protection strategy for LlamaCasty (.NET 8 / WPF).
+
+> ## ⛔ SUPERSEDED IN PART — 2026-09-27
+>
+> **Distribution is now the Microsoft Store: MSIX package + Store IAP.** The creator's criteria
+> were *"zero headaches, minimal maintenance (for me) while still providing accountability and
+> a reasonably easy upgrade flow"*, and that ruling deleted this document's central premise.
+>
+> **What still stands below:** §1 (code architecture / IP protection), §5 (obfuscation posture),
+> §6 (legal), §7 (hardening) — those are about protecting the *binary*, and an MSIX package is
+> still a binary. **§1.2's build-posture ceiling (HARDENED + MOCK_REWARDS, additive-only)
+> remains the agreed ceiling.**
+>
+> **What is dead:**
+> - **Polar as the distribution backbone** — the entire section below. Store IAP handles
+>   checkout, entitlements, refunds, tax, and the customer portal. So does **file hosting**:
+>   the Store is the delivery mechanism, so "upload `LlamaCasty.exe` to Polar as a File
+>   Download benefit" (§2) no longer exists as a step.
+> - **Code signing as our problem** — MSIX is signed by **Microsoft**. There is no certificate
+>   to buy, no HSM, no annual renewal. See §4.3, which was already corrected to say this, and
+>   `TASKS/research-store-certification.md` §2–3.
+> - **Velopack / the update URL / the DO droplet** — Store auto-update.
+>
+> **The authoritative plan is now [`TASKS/task-48-distribution-msix.md`](TASKS/task-48-distribution-msix.md).**
+> Keep this file for the protection sections; do not re-derive a delivery strategy from it.
 
 ---
 
-## Polar.sh as the Distribution Backbone
+## Polar.sh as the Distribution Backbone — ⛔ OBSOLETE (2026-09-27)
 
-Polar handles everything between "customer wants to pay" and "customer has a working license key." We don't build any of that. What Polar gives us:
+> **Historical record only.** Retained because the fee tables and the reasoning about *why*
+> one-time beat subscription were worth working out. **None of the "How We Use It" rows are
+> current**, with one exception worth keeping: the Merchant-of-Record point — *someone else
+> collects and remits VAT/GST* — is still true under Store IAP, because **Microsoft** is now
+> that someone. That fact alone was the strongest argument for the ruling.
+
+Polar handled everything between "customer wants to pay" and "customer has a working license key." We didn't build any of that. What Polar *was* going to give us:
 
 | Capability | How We Use It |
 |------------|---------------|
@@ -14,13 +44,15 @@ Polar handles everything between "customer wants to pay" and "customer has a wor
 | **File hosting** (up to 10GB) | Upload `LlamaCasty.exe` (self-contained, ~80-120MB) as a "File Download" benefit. Customers get signed, personal download URLs. SHA-256 checksums included. |
 | **Checkout** | Polar's hosted checkout page handles payment. No Stripe integration, no PCI scope, no custom checkout UI. |
 | **Customer portal** | Customers self-serve: view/copy license keys, see expiry, deactivate devices, rotate compromised keys. We don't build a portal. |
-| **Subscriptions** | If we go subscription model (deferred), Polar handles recurring billing, dunning, cancellation. |
+| **One-time orders** | **Chosen model (2026-09-21):** perpetual license via a one-time Polar order — no subscription. Polar also supports recurring billing if ever needed, but we do not use it. |
 | **Merchant of Record** | Polar collects and remits VAT/GST/sales tax globally. We never touch tax compliance. |
 | **Webhooks** | Polar notifies our backend on purchase, cancellation, key rotation. Used for optional telemetry (section 6.3). |
 
-**Polar pricing (2026):** 5% + $0.50 per transaction (Starter plan). No monthly fee.
+**Polar pricing (2026):** 5% + $0.50 per transaction (Starter plan). No monthly fee. ⛔ *No
+longer paid to anyone — the equivalent cost is now inside the Store revenue share, whose rate
+is unverified (see `TASKS/research-store-certification.md` §11).*
 
-**What Polar does NOT handle:** Obfuscation, code signing, anti-tamper, runtime protection, EULA, DMCA. That's all us — sections 1-3, 5-7 below.
+**What Polar did NOT handle:** Obfuscation, code signing, anti-tamper, runtime protection, EULA, DMCA. That's all us — sections 1-3, 5-7 below.
 
 ---
 
@@ -286,11 +318,19 @@ Single-file means everything is inside the `.exe`. No DLLs, no runtime dependenc
 
 **Caveat:** Self-contained single-file means ~80-120MB due to bundled .NET runtime. For smaller size, use framework-dependent publishing (requires .NET 8 runtime on user machines) — drops to ~5-10MB.
 
-### 4.2 Distribution via Polar
+### 4.2 Distribution via Polar — ⛔ OBSOLETE (2026-09-27)
 
-**Product setup on Polar:**
+> **Superseded by Microsoft Store MSIX + Store IAP** (ruling in
+> `TASKS/task-48-distribution-msix.md` item 0). The Store re-signs, hosts, updates, and takes
+> payment — so file hosting, license keys, checkout, the customer portal, device deactivation and
+> key rotation are **all** handled by Microsoft and none of it needs building. Retained below as a
+> record of the model that was designed and abandoned. ⚠️ **The `$29`/`$49` one-time prices in this
+> section are dead** — the settled pricing is **`$10/mo` or `$400` lifetime**, net of a verified
+> 15% Store share.
 
-1. Create a product: "LlamaCasty" — one-time purchase (or subscription if deferred).
+**Product setup on Polar (as designed, never shipped):**
+
+1. Create a product: "LlamaCasty" — **one-time purchase** (perpetual license; $29 founder / $49 list).
 2. Add two benefits:
    - **License Key** — brandable prefix `LLAMA-****`, activation limit (e.g., 3 devices), optional expiry.
    - **File Download** — upload the signed `LlamaCasty.exe` (~80-120MB). Polar generates signed, personal download URLs. SHA-256 checksum included.
@@ -313,9 +353,43 @@ Single-file means everything is inside the `.exe`. No DLLs, no runtime dependenc
 - If a key is compromised, customer or merchant can rotate it via Polar.
 - Previous key stops validating immediately. Status, usage, limits, expiry preserved.
 
+**What the Store does instead:** the customer installs from the Store listing, pays through Store
+checkout, and the app reads the entitlement the OS already holds. There is no key to enter, no
+activation call, no portal to visit, and no offline-grace period to maintain — which also retires
+the whole "network flaky → app thinks I'm expired" bug class in §4.5.
+
 ### 4.3 Code Signing
 
-**Certificate:** Buy an EV (Extended Validation) code-signing certificate from DigiCert or Sectigo ($200-400/year). EV certificates get instant SmartScreen reputation; DV/OV certs trigger SmartScreen warnings for months.
+> ⚠️ **The cert choice below is a live decision, and the old plan's EV recommendation is
+> dead.** Microsoft **removed the SmartScreen instant-bypass for EV certificates in March
+> 2024** — an EV-signed file now accrues reputation exactly like an OV-signed one, so paying
+> $400+/yr buys precisely what paying ~$150 buys. **Do not buy EV.**
+>
+> **But the more interesting finding is that you may not need a certificate at all.** Three
+> costs, current as of 2026-09-27:
+>
+> | Route | Cert/yr | SmartScreen | Note |
+> |---|---|---|---|
+> | **Microsoft Store (MSIX)** | **$0** — Microsoft re-signs | **No warning** | Requires MSIX packaging; Store review; public listing |
+> | **Microsoft Store (EXE/MSI)** | $120–300 — *your* cert | Warning ramp | Store does **not** re-sign; silent install mandatory. Strictly dominated — cert required anyway |
+> | **Direct + OV cert** | $150–300 | Warning ramp | Worldwide availability |
+> | **Direct + Azure Artifact Signing** | ~$9.99/mo ≈ $120 | Warning ramp | **Individuals: USA/Canada only.** Identity validation required |
+>
+> Signing does **not** clear the warning on day one either way: a valid cert stops the
+> *malware* warning immediately, but "unrecognized publisher" clears as SmartScreen accrues
+> reputation from real download volume. Budget cert validity at **460 days** (CA/B Forum
+> CSC-31) — this is a recurring line item, not a one-time purchase — and note that private
+> keys must sit on an **HSM or hardware token**.
+>
+> **The full comparison, the four real combinations, and the policy analysis live in
+> [`TASKS/research-store-certification.md`](TASKS/research-store-certification.md) §2–3.
+> The executable checklist is [`TASKS/task-48-distribution-msix.md`](TASKS/task-48-distribution-msix.md),
+> and the route decision is the creator's.**
+
+**Certificate:** Buy an **OV (Organization Validation)** code-signing certificate from DigiCert
+or Sectigo (~$150–300/year), or an **Azure Artifact Signing** profile (~$9.99/month,
+USA/Canada individuals only) if the geography allows. ⛔ **Not EV** — no SmartScreen benefit
+since March 2024. **Or buy nothing at all** if the route is the Microsoft Store.
 
 **Signing process:**
 ```powershell
@@ -332,7 +406,13 @@ Set-AuthenticodeSignature -FilePath "LlamaCasty.exe" `
 
 **Storage:** Certificate `.pfx` file stored in GitHub Secrets (or Azure DevOps secure files). Never committed to the repo.
 
-### 4.4 Update Mechanism
+### 4.4 Update Mechanism — ⛔ OBSOLETE (2026-09-27)
+
+> **Superseded by Store updates.** Microsoft delivers and updates the app from the listing, so
+> there is nothing to check and no manifest to host. The Velopack updater currently in
+> `App.xaml.cs` **downloads *and executes***, which Store policy **10.2.2** does not permit — its
+> removal is a **compliance action**, not optional cleanup (TASK 48 item 3). The Polar-native design
+> below is retained as a record of the approach that was rejected; it is not an option.
 
 **Polar-native approach (no custom infrastructure):**
 
@@ -367,10 +447,18 @@ public class UpdateCheckService
 - Download link points to Polar's customer portal (not direct download).
 - This adds one external dependency (GitHub) but keeps Polar as the source of truth.
 
-### 4.5 Licensing Logic (already implemented)
+### 4.5 Licensing Logic — ⛔ BEING DELETED (2026-09-27)
+
+> ⚠️ **"Already implemented" was true as of 2026-09-21 and is no longer.** `PolarLicenseService`
+> and `Helpers/PolarLicense.cs` are being **removed** as part of the TASK 10 teardown (TASK 48 item 0).
+> Store IAP replaces the whole validation hop: `IsPremium` is derived from the **OS-supplied Store
+> entitlement**, so there is no network call, no key, and — importantly — **no 14-day offline-grace
+> machine to protect**, which retires the entire "network flaky → app thinks I'm expired" bug class.
+> What survives is only `IsPremium` → `BrandFlashEnabled = !value`. Retained below as the record of
+> what shipped and why it no longer applies.
 
 ```csharp
-// Services/PolarLicenseService.cs — already ships
+// Services/PolarLicenseService.cs — shipped under Polar; being deleted
 // Calls Polar's customer-portal validation endpoint (no auth required)
 // Survives obfuscation — property names excluded via [Obfuscation(Exclude = true)]
 [Obfuscation(Exclude = true)]
@@ -383,11 +471,11 @@ public class LicenseValidationResult
 }
 ```
 
-**What's already done:**
-- `PolarLicenseService` validates keys against Polar API.
-- `OrganizationId` is hardcoded (safe — it's public knowledge, tied to our Polar account).
-- License state persists in `LayoutStore.Settings` (SQLite) with offline grace period.
-- `PremiumUrl` points to Polar checkout.
+**What shipped under Polar (now being deleted):**
+- `PolarLicenseService` validated keys against the Polar API.
+- `OrganizationId` was hardcoded.
+- License state persisted in `LayoutStore.Settings` (SQLite) with an offline grace period.
+- `PremiumUrl` pointed to Polar checkout.
 
 **What survives obfuscation:** The validation logic in `Services.dll` is obfuscated. An attacker who decompiles the exe sees only the UI calling an interface — the actual Polar API call is in the obfuscated DLL.
 

HANDOFF.md

@@ -1,99 +1,60 @@
-# HANDOFF — Session State
+# HANDOFF — 2026-10-08 (zoom box shipped, READY FOR PUSH)
 
-## Branch / Commit State
+## Branch
+- main (no feature branch)
 
-**`main`**, working tree is **CLEAN**.
+## Push readiness
+- **5 commits ahead of origin/main, clean to push** (fetch confirmed origin has not moved):
+  `966e718` zoom box visuals → `4b3d82f` zoom as layered + TASK 51 booking → `6bff21b`
+  anchored-capture rework → `948dd08` dims-shading fix → (docs unit: TASK 52 record +
+  numbering fixes + this HANDOFF).
+- The pinned-chat work unit below is **uncommitted on purpose** — `git push` sends only
+  commits, so pushing is safe; the dirty files stay local.
 
-Both split phases are now complete. Phase 1 (view-model partials) is pushed;
-Phase 2 (MainWindow.xaml → UserControls) is complete but **local-only**.
+## Dirty files (NOT mine — the in-flight "pinned chat" work unit; do NOT commit or co-edit)
+- `Models/YouTube.cs`
+- `ViewModels/MainViewModel.Chat.cs`
+- `Controls/LeftPanel.xaml` (pinned-message UI)
+- Untracked: `Helpers/RelayCommandGeneric.cs`
 
-**Pushed** (reached `origin/main` == `14d3ed4`, incl. tags): Phase 1 commit `0`
-and refactor commits `1..11` (`refactor-commit-0..11`), plus policy/HANDOFF.
+## What just happened (2026-10-08, third zoom pass — dims shading)
+The zoom box shipped as a **loupe** (`4b3d82f`), then was corrected to an **anchored-capture
+magnifier over the full composite drawn last** (commit `6bff21b`). The final correction: as the box
+is dragged, the dim rectangles (55% black "div shading" around the box) were sliding under the
+capture region — shown inside the box because its `VisualBrush` samples all of `CanvasGrid`, and the
+`DimRects` ItemsControl previously lived INSIDE `CanvasGrid`.
 
-**LOCAL ONLY (Phase 2 — 12, 13, 14, 15, 16, 17, 18)** — policy 2026-08-30: no
-per-commit push; `git push` only at a user-agreed milestone / "push it".
-**Push pending on explicit user approval:**
+Fix: the `DimRects` overlay is now a **sibling of `CanvasGrid`** (renders above the composed
+content, below the `ZoomBox`), never a descendant — so the zoom sample can never pick up the shading
+and the captured area stays clear no matter where the box is dragged. Behavior consequence to note:
+in non-zoom ("quality dims") mode the dims now also shade the global overlays (brand flash, alert
+ticker, social bar) that sit above them in the old tree — consistent with "chrome outside the crop
+is dimmed". Structural invariant added to `ZoomBoxInteractionTests`: `DimRectsLayer` is a direct
+child of `PreviewCanvas`, not inside `CanvasGrid`, and renders below the `ZoomBox`.
 
-| Commit | Hash | Tag | Control | From Loc |
-|--------|------|-----|---------|----------|
-| 12 | `bc23b64` | `refactor-commit-12` | `Controls/BottomBar` | footer |
-| 13 | `6914252` | `refactor-commit-13` | `Controls/HealthBanner` | row 1 banner |
-| 14 | `90f5ad5` | `refactor-commit-14` | `Controls/TopBar` | row 0 top bar |
-| 15 | `c5e3466` | `refactor-commit-15` | `Controls/PreviewPane` | center preview |
-| 16 | `73397cf` | `refactor-commit-16` | `Controls/SceneThumbnailStrip` | row 0 strip |
-| 17 | `c9fd1bd` | `refactor-commit-17` | `Controls/LeftPanel` | row 1 col 0 |
-| 18 | `544208e` | `refactor-commit-18` | `Controls/OverlayHost` | overlay dialogs |
+## Zoom feature state
+- **TASK 52 (zoom box) is now a first-class record** — see [`TASKS/task-52-zoom-box.md`](TASKS/task-52-zoom-box.md):
+  feature provenance + the three creator corrections, shapes, implementation map, tests.
+  TASK 51 (webcam background Remove + Blur) is unblocked for the next unit.
+- Models: `ZoomState.cs`, `ZoomShape.cs` (Circle/VerticalRectangle/HorizontalRectangle), `ZoomSceneElement.cs`.
+- ViewModel (`MainViewModel.Zoom.cs`): `ActivateZoom`/`ToggleZoom`/`DismissZoom`/`StartZoomMove`/`UpdateZoomMove`/`EndZoomMove` + `RebuildDimRectsForZoom`; transient element healed/mirrored by `HealZoomLayers`/`EnsureZoomLayer`.
+- Output: box composited last via `BlitZoom`/`ZoomMagnifier`; output crop = tier (box never the crop).
+- Preview: `ZoomBox` + `DimRectsLayer` are both SIBLINGS of `CanvasGrid` (box above dims above content); box samples the full composite at the fixed capture, 2x; circle→ellipse clip, rect/square outline per shape; `LeftPanel` hides the placeholder row via `IsZoomLayer`.
+- Rectangle shape = 4:3; Circle square; Phone 9:16. Capture anchored on click (`CaptureX/Y`); dragging the box never changes it.
 
-## What's In Flight
+## Tests
+- Full suite: **406 passed / 0 failed** on a clean full run (the pre-existing audio-loopback timing
+  flake and `RealMouseDrag`'s interactive-desktop requirement recur occasionally — not zoom
+  regressions). Zoom tests 3/3 green, 0 build warnings.
 
-Nothing code-in-flight — working tree clean, **Phase 2 complete**.
+## Known issues / follow-ups
+- **Background "Use default background" toggle still not working** (carried from 2026-10-07):
+  binding exists (`UseDefaultBackground`), VM handler invalidates bake; investigate when time permits.
+- The 3px selection / crop-outline strokes could still show in the zoom box IF the capture overlaps
+  them in edit mode — not shading, thin outlines only; the dims (the user's complaint) are gone.
 
-**Phase 2 result:** `MainWindow.xaml` carved 1,681 → **123 lines** (a shell over
-6 UserControls under `Controls/`, namespace `ytLive.Controls`). Every change:
-0-warning build, `scripts/verify.sh` (246 pass + 2 known only), explicit-file
-`scripts/scope-check.sh`, `ViewModels/index.md` in the SAME commit, tagged
-`refactor-commit-N`, no per-commit push.
-
-**Next:** 
-- If user says "push": `git push origin main && git push --tags` (7 commits 12-18
-  + their tags).
-- Then optional Phase 3 if queued. Nothing is queued beyond Phase 2.
-
-**Pending bus:** `ViewModels/index.md` Phase 2 tracker has rows 12–18 (closed);
-Phase 1 tracker closed. `Controls/` has `index.md`-style facts only if needed.
-
-## Landmines
-
-- **Pre-existing test failures (do not chase):**
-  `AudioPipelineTests.Mix_HonorsProviderGains_AndGameMute_KillsTheLoopback` +
-  `RoundClipInteractionTests.Round_Clip_Corner_Is_Grabbable_And_Shape_Is_Circle`.
-- **Tests occasionally abort early (236/237)** — known flake, accepted by `verify.sh`.
-- **App running locks `ytLive.exe`** → build fails MSB3027. Kill PID before building.
-- **WinForm crash from `Window_PreviewMouseLeftButtonDown`** — handled in-side the
-  preview/left panel; don't add handlers that deref `OriginalSource` unguarded.
-- **Controls cannot see `Window.Resources`** (converter rule, Commit 13): any
-  StaticResource the window once supplied must live at app level in
-  `Themes/Controls.xaml`. The 7 converters were promoted there.
-- **Some control XAML needs its own `xmlns:models` / `xmlns:Helpers`** — a moved
-  block lost its namespace when it left MainWindow's root (LeftPanel hit this,
-  MC2000 "key null"). Always add the model/helper xmlns on each control root.
-- **Name-looked-up host stubs must stay in the window:** `WebViewHostPanel`
-  (ctor `InitWebView2(WebViewHostPanel)`) and `ToastArea`
-  (`NotificationService.InArea("ToastArea")`) are resolved by name from the
-  window — keep them as window-root children, don't bury them in a control.
-  OverlayHost deliberately left them in place (Commit 18) for this reason.
-- **Pre-commit gate:** `scripts/verify.sh` (0-warning build + full tests) and
-  `scripts/scope-check.sh "file1" …` — scope-check REQUIRES explicit file args.
-- Build from WSL with the Windows dotnet host only (see `AGENTS.md`).
-
-## Todo state
-
-- MainViewModel refactor: **Phase 1 complete (11/11 partials)**, pushed.
-- MainWindow.xaml refactor: **Phase 2 complete (6/6 controls)**, local-only.
-- TASK 3: 27/30 (preview compositor 16, text source 17, alerts 20 still open).
-- TASK 4: ✅ shipped. TASK 9: items 1–3 shipped; 4–7 open. TASK 10: steps 1–7; Velopack pending.
-- TASK 18: shipped, creator verification pending. TASK 19/23, 20, 21-A: shipped.
-- TASK 22 (audio sync offset): not started — required for v1.
-
-## Session summary (2026-08-30)
-
-- Ran the **MainWindow.xaml split to completion** under the standing "continue
-  without stopping" directive — no interruption prompts, no `question` tool.
-- Commits 12–18 landed locally, each: cut → 0-warning build → verify (246 pass +
-  2 known) → scope-check → index.md in-commit → `git tag refactor-commit-N`. No push.
-- **Commit 15 (PreviewPane** the hardest: 1920×1080 canvas + drag/select/resize/
-  hit-test, webcam menu handlers, social glow, audio meters. A dropped outer
-  `Border` (background/glow/margin) was caught and restored same-commit.
-- **Commit 17 (LeftPanel)** the biggest: property editors + chat autoscroll
-  (moved to self-subscribe on `Loaded`), drag-to-reorder, snapshot revert/accept
-  family; window routes via `_leftPanel.IsClickInside` and
-  `_leftPanel.OnSelectionChanged(vm)`.
-- **Commit 18 (OverlayHost)** the scope-decision: moved only the three dialogs;
-  kept `WebViewHostPanel` + `ToastArea` as window-root stubs because their
-  name-based lookups (WebView2 init, toast `InArea`) would break if buried in a
-  control — a spin-guard decision, not a guess.
-- Two XAML extraction gotchas recorded: (a) a moved block losing its `xmlns`
-  → MC2000 "key null" (Line n col m), fixed by adding `xmlns:models` on the
-  control root; (b) re-deriving line numbers after each edit before `sed`/awk
-  deletion ranges (the edit tool shifts numbers).
-- Push checkpoint reached; awaiting explicit "push" for commits 12–18 + tags.
+## Next step
+- User runs the app live to eyeball: drag the zoom box anywhere and the captured content stays clean
+  (no dim shading in the box; the scene outside the box stays dimmed). Then TASK 51 (webcam
+  background Remove + Blur) per `TASKS/task-51-webcam-bg-effects.md`, and the background-toggle
+  investigation if still open.

Helpers/AppLog.cs

@@ -5,15 +5,13 @@ namespace ytLive.Helpers;
 /// <summary>
 /// Minimal file logger used to diagnose startup/shutdown crashes on Windows,
 /// where the WPF app has no visible console. Writes to
-/// %APPDATA%\ytLlive\startup.log, appending synchronously so entries survive
-/// a hard crash.
+/// %APPDATA%\ytLlive\startup.log (or a per-instance subfolder in DEBUG — see
+/// InstanceProfile), appending synchronously so entries survive a hard crash.
 /// </summary>
 public static class AppLog
 {
     private static readonly string LogPath = Path.Combine(
-        Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
-        "ytLlive",
-        "startup.log");
+        InstanceProfile.DataRoot, "startup.log");
 
     private static readonly object Gate = new();
 

Helpers/FrameCadence.cs

@@ -0,0 +1,123 @@
+using System;
+using System.Diagnostics;
+
+namespace ytLive.Helpers;
+
+/// <summary>
+/// Arrival cadence for one window of a timestamped frame stream: how many frames
+/// arrived, how far apart they were, and how many gaps were long enough to read
+/// as a hitch. Fed any shared monotonic clock (<see cref="Stopwatch.GetTimestamp"/>
+/// values, or a device's system-relative stamps on the same clock) and read through
+/// <see cref="Summarize"/>.
+///
+/// Why it exists: a 60fps container makes a missing camera frame indistinguishable
+/// from a padded repeat. rawvideo carries no per-frame timestamps — ffmpeg stamps
+/// frames by ARRIVAL at the declared rate — so the OBS "duplicate on lag" loop
+/// (FramePump) emits 300 authored frames per 5s whether the renderer managed 300
+/// composites or 84. The recorded file therefore cannot name the stage that lost
+/// the frames; only these counters can. The same counter run twice tells the two
+/// apart: the camera's OWN timestamps vs our ARRIVAL timestamps. Steady camera
+/// stamps with ragged arrivals means WE dropped it (compositor/reader); ragged in
+/// both means the camera, USB link, or driver did.
+/// </summary>
+public sealed class FrameCadence
+{
+    /// <summary>Default hitch threshold in ms. 50ms is ~1.5x a 30fps period — a
+    /// missed 30fps frame arrives as ~66ms — so this counts dropped frames without
+    /// flagging ordinary jitter (a 33ms frame can legitimately measure 35ms).</summary>
+    public const double DefaultHitchThresholdMs = 50;
+
+    private readonly double _hitchThresholdMs;
+    private long _firstTicks;
+    private long _previousTicks;
+    private double _gapTicksTotal;
+    private int _frames;
+    private int _gaps;
+    private int _hitches;
+    private double _longestGapMs;
+
+    public FrameCadence(double hitchThresholdMs = DefaultHitchThresholdMs)
+    {
+        if (hitchThresholdMs <= 0)
+            throw new ArgumentOutOfRangeException(nameof(hitchThresholdMs), hitchThresholdMs,
+                "Hitch threshold must be positive.");
+        _hitchThresholdMs = hitchThresholdMs;
+    }
+
+    public int Frames => _frames;
+    public int Gaps => _gaps;
+    public int Hitches => _hitches;
+    public double HitchThresholdMs => _hitchThresholdMs;
+
+    /// <summary>Records one frame at <paramref name="timestampTicks"/> on the shared
+    /// monotonic clock. Monotonicity is asserted, not trusted: an out-of-order stamp
+    /// (a device whose clock domain differs from ours, a wrapped counter, a dropped
+    /// timestamp) is counted as a frame but produces no gap AND does not become the
+    /// reference for the next one — otherwise a single bad stamp would poison both
+    /// its own interval and the one after it, inventing a multi-second "hitch".</summary>
+    public void Add(long timestampTicks)
+    {
+        if (_frames == 0)
+        {
+            _firstTicks = timestampTicks;
+            _previousTicks = timestampTicks;
+            _frames++;
+            return;
+        }
+
+        var delta = timestampTicks - _previousTicks;
+        _frames++;
+        if (delta <= 0) return;
+        var gapMs = delta * 1000d / Stopwatch.Frequency;
+        _gaps++;
+        _gapTicksTotal += gapMs;
+        if (gapMs > _longestGapMs) _longestGapMs = gapMs;
+        if (gapMs >= _hitchThresholdMs) _hitches++;
+        _previousTicks = timestampTicks;
+    }
+
+    public FrameCadenceSummary Summarize()
+    {
+        var spanMs = _frames >= 2
+            ? (_previousTicks - _firstTicks) * 1000d / Stopwatch.Frequency
+            : 0d;
+        // Rate is gaps-per-span, not frames-per-span: N frames span N-1 periods, and
+        // counting the extra interval would report one extra frame per window.
+        var rate = _gaps > 0 && spanMs > 0 ? _gaps / (spanMs / 1000d) : 0d;
+        return new FrameCadenceSummary(
+            _frames, rate, spanMs, _gaps, _hitches, _longestGapMs,
+            _gaps > 0 ? _gapTicksTotal / _gaps : 0d, _hitchThresholdMs);
+    }
+
+    /// <summary>Starts a fresh window, keeping the configured threshold.</summary>
+    public void Reset()
+    {
+        _firstTicks = 0;
+        _previousTicks = 0;
+        _gapTicksTotal = 0;
+        _frames = 0;
+        _gaps = 0;
+        _hitches = 0;
+        _longestGapMs = 0;
+    }
+}
+
+/// <summary>One measured cadence window — see <see cref="FrameCadence"/>.</summary>
+public readonly record struct FrameCadenceSummary(
+    int Frames,
+    double RatePerSecond,
+    double SpanMs,
+    int Gaps,
+    int Hitches,
+    double LongestGapMs,
+    double AverageGapMs,
+    double HitchThresholdMs)
+{
+    /// <summary>One-line log form. Identical in shape from every producer (camera
+    /// source, frame pump) so two lines can be read against each other: same window
+    /// length, same fields, same order.</summary>
+    public string Describe(string label) => Frames == 0
+        ? $"{label} no frames"
+        : $"{label} {Frames}f/{SpanMs / 1000d:F1}s {RatePerSecond:F1}/s, {Gaps} gaps, " +
+          $"{Hitches} >= {HitchThresholdMs:F0}ms, avg {AverageGapMs:F1}ms, longest {LongestGapMs:F1}ms";
+}

Helpers/InstanceProfile.cs

@@ -0,0 +1,77 @@
+using System;
+using System.IO;
+
+namespace ytLive.Helpers;
+
+/// <summary>
+/// Which run of LlamaCasty this process is, and where its private state lives.
+/// <para><b>Dev-only affordance (creator directive, 2026-09-26).</b> Pre-1.0 the creator
+/// needs two instances side by side: one streaming, one screen-capturing the other.
+/// Two instances on one Windows profile collide on state, and two of those collisions
+/// are hard failures rather than annoyances:
+/// <list type="bullet">
+/// <item><b>The SQLite layout DB.</b> The app's model is read-whole-scene / write-whole-scene,
+/// so two instances saving different layouts clobber each other.</item>
+/// <item><b>The WebView2 user data folder.</b> Chromium takes an exclusive lock on it; the
+/// second instance of the same exe simply fails to start.</item>
+/// <item><b>The auth token store.</b> A test instance would overwrite the real YouTube
+/// sign-in.</item>
+/// <item><b>startup.log.</b> Two appenders interleave into one file, so a crash in either
+/// instance is ambiguous.</item>
+/// </list>
+/// So in <c>DEBUG</c> a process can claim an identity and gets its own private root
+/// under <c>instances\&lt;id&gt;</c>: <c>$env:YTLIVE_INSTANCE=2; dotnet run</c>.
+/// Recording, screen capture and the ffmpeg <c>tools\</c> cache are deliberately LEFT
+/// shared — the cache should be shared, and the creator chooses the record folder.
+/// Global hotkeys are also left alone: if both instances register the same one, Windows
+/// refuses the second, which is the correct answer.</para>
+/// <para><b>At 1.0 this disappears.</b> The whole implementation is inside
+/// <c>#if DEBUG</c>; a Release build compiles to the two pass-throughs at the bottom —
+/// no environment variable, no alternate folder, not even the variable's NAME in the
+/// binary. Call sites are unconditional, so Release cannot accidentally diverge: it
+/// always resolves the one real user profile.</para>
+/// </summary>
+public static class InstanceProfile
+{
+#if DEBUG
+    /// <summary>Environment variable naming this instance. Absent or blank = the primary
+    /// instance on the real user profile.</summary>
+    public const string InstanceVariable = "YTLIVE_INSTANCE";
+
+    /// <summary>This instance's id, or null for the primary instance.</summary>
+    public static string? Id => Sanitize(Environment.GetEnvironmentVariable(InstanceVariable));
+
+    /// <summary>Private state root: the real profile normally, a per-instance subfolder
+    /// when an id is claimed.</summary>
+    public static string DataRoot => Id is { } id
+        ? Path.Combine(DefaultRoot, "instances", id)
+        : DefaultRoot;
+
+    /// <summary>Chromium's user data folder, or null to let WebView2 pick its default
+    /// (which is what Release always does). Must be per-instance or the second
+    /// instance dies on Chromium's exclusive lock.</summary>
+    public static string? WebViewDataFolder => Id is null ? null : Path.Combine(DataRoot, "webview2");
+
+    /// <summary>Reject anything that is not a plain path segment, so the variable can
+    /// never be used to walk out of the profile directory or name a UNC path.</summary>
+    private static string? Sanitize(string? raw)
+    {
+        if (string.IsNullOrWhiteSpace(raw)) return null;
+        var trimmed = raw.Trim();
+        foreach (var c in trimmed)
+            if (!char.IsLetterOrDigit(c) && c != '-' && c != '_') return null;
+        return trimmed;
+    }
+#else
+    // Release: one profile, no alternate paths, no environment variable. Multi-instance
+    // is a development affordance, not a shipping feature.
+    public static string DataRoot => DefaultRoot;
+    public static string? WebViewDataFolder => null;
+#endif
+
+    /// <summary>The one real user profile: <c>%APPDATA%\ytLlive</c>. Note the historical
+    /// double-L — do not "fix" it, users already have their layouts there.</summary>
+    public static string DefaultRoot => Path.Combine(
+        Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
+        "ytLlive");
+}

Helpers/StripPool.cs

@@ -0,0 +1,204 @@
+using System;
+using System.Threading;
+
+namespace ytLive.Helpers;
+
+/// <summary>
+/// A fixed pool of four DEDICATED background threads at <see cref="ThreadPriority.BelowNormal"/>
+/// that split one composite into horizontal row strips. The compositor needs the split to get
+/// render inside a 16.67ms slot, but it must not compete with the encoder, the WGC capture
+/// callbacks, the WebView2 chat or the game the user is playing — hence the hard cap of four
+/// and the demotion.
+///
+/// Research (2026-10-05, Unit 5): the demotion must NOT be done by poking
+/// <c>Thread.CurrentThread.Priority</c> inside <c>Parallel.For</c> — the pool is shared, so the
+/// demotion leaks into every unrelated work item that thread later runs
+/// (https://stackoverflow.com/questions/524483/net-backgroundworker-objects-thread-priority:
+/// "you have next to no control of which thread pool thread will actually run your task");
+/// https://stackoverflow.com/questions/1578599/c-sharp-lower-thread-priority-in-thread-pool:
+/// "You shouldn't mess with the priority of the regular ThreadPool, since you aren't the only
+/// consumer ... write your own producer/consumer queue, using your own Thread(s) as the
+/// consumer(s) — setting the thread priority yourself"). A real failed attempt confirmed it: a
+/// full test run after demoting the pool threads broke an unrelated audio-mix timing test.
+/// This class IS that producer/consumer queue; the caller thread is the producer and also runs
+/// one strip itself, so four workers never means five-way oversubscription.
+///
+/// Contract: <see cref="For"/> blocks until every strip has run, each strip must write only its
+/// own rows (the compositor's blits already partition by row), and it must not be called from
+/// inside a strip (the blits never nest).
+/// </summary>
+internal static class StripPool
+{
+    /// <summary>Four workers: the measured sweet spot on this box. Fewer leaves render over
+    /// budget; more steals cycles from the game and the encoder and made render worse, not better.</summary>
+    public const int Workers = 4;
+
+    /// <summary>Below this many rows the fan-out costs more than it saves — run it inline.</summary>
+    private const int MinRowsForFanOut = 64;
+
+    private static readonly object[] _queueLocks = CreateLocks();
+    private static readonly Queue<Strip>[] _queues = CreateQueues();
+    private static readonly Queue<Strip>[] _free = CreateQueues();
+    private static readonly SemaphoreSlim[] _signals = CreateSignals();
+    private static Thread[]? _threads;
+    private static int _roundRobin = -1;
+
+    private sealed class Strip
+    {
+        public int From;
+        public int To;              // exclusive
+        public Action<int>? Body;
+        public Batch? Owner;
+    }
+
+    private sealed class Batch
+    {
+        public int Remaining;
+        public Exception? Error;
+    }
+
+    /// <summary>Run <paramref name="body"/> for every row in [from, to), split across the pool.</summary>
+    public static void For(int from, int to, Action<int> body)
+    {
+        if (from >= to) return;
+
+        var rows = to - from;
+        if (rows < MinRowsForFanOut || !EnsureStarted())
+        {
+            for (var y = from; y < to; y++) body(y);
+            return;
+        }
+
+        // Strips are handed to whole workers (not per-row tasks) so the strip boundaries —
+        // and therefore the destination row each strip owns — are fixed before any of them run.
+        var strips = Math.Min(Workers, rows);
+        var chunk = (rows + strips - 1) / strips;
+        var batch = new Batch { Remaining = strips - 1 }; // the caller runs the last one
+
+        var first = from;
+        for (var k = 0; k < strips - 1; k++)
+        {
+            var end = Math.Min(first + chunk, to);
+            var w = NextWorker();
+            var strip = Rent(w);
+            strip.From = first;
+            strip.To = end;
+            strip.Body = body;
+            strip.Owner = batch;
+            lock (_queueLocks[w]) _queues[w].Enqueue(strip);
+            _signals[w].Release();
+            first = end;
+        }
+
+        try
+        {
+            for (var y = first; y < to; y++) body(y);
+        }
+        catch (Exception ex)
+        {
+            batch.Error ??= ex;
+        }
+
+        if (batch.Remaining > 0)
+        {
+            lock (batch)
+            {
+                while (batch.Remaining > 0) Monitor.Wait(batch);
+            }
+        }
+
+        if (batch.Error != null) throw new InvalidOperationException("A compositor strip failed.", batch.Error);
+    }
+
+    private static void Worker(int index)
+    {
+        var signal = _signals[index];
+        while (true)
+        {
+            signal.Wait();
+            Strip? strip = null;
+            lock (_queueLocks[index])
+            {
+                if (_queues[index].Count > 0) strip = _queues[index].Dequeue();
+            }
+            if (strip == null) continue; // released for an already-drained queue
+            var batch = strip.Owner!;
+            try
+            {
+                for (var y = strip.From; y < strip.To; y++) strip.Body!(y);
+            }
+            catch (Exception ex)
+            {
+                batch.Error ??= ex;
+            }
+            finally
+            {
+                strip.Body = null;
+                strip.Owner = null;
+                lock (_queueLocks[index]) _free[index].Enqueue(strip);
+                lock (batch)
+                {
+                    if (--batch.Remaining == 0) Monitor.PulseAll(batch);
+                }
+            }
+        }
+    }
+
+    private static Strip Rent(int worker)
+    {
+        lock (_queueLocks[worker])
+            return _free[worker].Count > 0 ? _free[worker].Dequeue() : new Strip();
+    }
+
+    private static int NextWorker()
+    {
+        var w = Interlocked.Increment(ref _roundRobin) % Workers;
+        return w < 0 ? w + Workers : w;
+    }
+
+    /// <summary>Start the workers on first use, so a WPF cold start pays nothing for them.</summary>
+    private static bool EnsureStarted()
+    {
+        if (_threads != null) return true;
+        lock (_signals)
+        {
+            if (_threads != null) return true;
+            var threads = new Thread[Workers];
+            for (var i = 0; i < Workers; i++)
+            {
+                var index = i; // capture per-iteration: the loop variable would be Workers by the time the thread runs
+                var t = new Thread(() => Worker(index), 256 * 1024)
+                {
+                    IsBackground = true,
+                    Name = $"compositor-strip-{i}",
+                    Priority = ThreadPriority.BelowNormal,
+                };
+                threads[i] = t;
+                t.Start();
+            }
+            _threads = threads;
+            return true;
+        }
+    }
+
+    private static object[] CreateLocks()
+    {
+        var l = new object[Workers];
+        for (var i = 0; i < Workers; i++) l[i] = new object();
+        return l;
+    }
+
+    private static Queue<Strip>[] CreateQueues()
+    {
+        var q = new Queue<Strip>[Workers];
+        for (var i = 0; i < Workers; i++) q[i] = new Queue<Strip>();
+        return q;
+    }
+
+    private static SemaphoreSlim[] CreateSignals()
+    {
+        var s = new SemaphoreSlim[Workers];
+        for (var i = 0; i < Workers; i++) s[i] = new SemaphoreSlim(0, int.MaxValue);
+        return s;
+    }
+}

Helpers/TokenStore.cs

@@ -14,9 +14,7 @@ namespace ytLive.Helpers;
 public static class TokenStore
 {
     public static string DefaultPath => Path.Combine(
-        Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData),
-        "ytLlive",
-        "ytLlive.auth");
+        InstanceProfile.DataRoot, "ytLlive.auth");
 
     public static void Save(YouTubeChannel channel, string? path = null)
     {

Helpers/index.md

@@ -14,6 +14,8 @@ Cross-cutting utilities. See [`schema.md`](../schema.md) for the memory-map conv
 | `InverseBoolToVisibilityConverter.cs` / `NotNullToVisibilityConverter.cs` | XAML value converters for visibility bindings |
 | `AllTrueToVisibilityConverter.cs` | Multi-value AND-gate → Visible; gates the layer-row capture menu items on row-IsBackground + staged-scene-is-Live (TASK 25) |
 | `CameraConflictProbe.cs` | Best-effort diagnostic: when a camera won't start, enumerates running processes known to hold cameras (OBS, Zoom, Teams, NVIDIA Broadcast, browsers, etc.) — Windows doesn't expose "which process has this device" via any public API, so this is a suspect list, not a verdict |
+| `StripPool.cs` | Four DEDICATED background threads at `BelowNormal` priority that split one composite into horizontal row strips (the caller runs a strip too); started lazily, runs inline below 64 rows. UNIT 5 — do NOT demote the ThreadPool from `Parallel.For`, it leaks into unrelated work (see ai.md "Render budget") |
+| `FrameCadence.cs` | Pure arrival-cadence counter (`FrameCadence` + `FrameCadenceSummary.Describe`): frames, gaps, hitches, longest/avg gap for a window of a timestamped stream. Fed by `MediaCaptureFrameSource` (camera stamps vs our arrivals) and `FramePump` (distinct webcam Epochs that reached the output) — UNIT 0, see ai.md "Frame cadence" |
 
 Related: [`Themes/Controls.xaml`](../Themes/Controls.xaml) styles the lists this
 class backs; [`Models/index.md`](../Models/index.md) and

MainWindow.xaml

@@ -45,24 +45,10 @@
             </DrawingImage.Drawing>
         </DrawingImage>
 
-        <!-- Eye icon: open when visible, slashed when hidden (source rows) -->
-        <Style x:Key="EyeIconStyle" TargetType="Path">
-            <Setter Property="Data" Value="M12,4.5C7,4.5 2.73,7.61 1,12c1.73,4.39 6,7.5 11,7.5s9.27,-3.11 11,-7.5c-1.73,-4.39 -6,-7.5 -11,-7.5zM12,17c-2.76,0 -5,-2.24 -5,-5s2.24,-5 5,-5 5,2.24 5,5 -2.24,5 -5,5zM12,9c-1.66,0 -3,1.34 -3,3s1.34,3 3,3 3,-1.34 3,-3 -1.34,-3 -3,-3z"/>
-            <Style.Triggers>
-                <DataTrigger Binding="{Binding IsVisible}" Value="False">
-                    <Setter Property="Data" Value="M12,7c2.76,0 5,2.24 5,5 0,0.65 -0.13,1.26 -0.36,1.83l2.92,2.92c1.51,-1.26 2.7,-2.89 3.43,-4.75 -1.73,-4.39 -6,-7.5 -11,-7.5 -1.4,0 -2.74,0.25 -3.98,0.7l2.16,2.16C10.74,7.13 11.35,7 12,7zM2,4.27l2.28,2.28 0.46,0.46C3.08,8.3 1.78,10.02 1,12c1.73,4.39 6,7.5 11,7.5 1.55,0 3.03,-0.3 4.38,-0.84l0.42,0.42L19.73,22 21,20.73 3.27,3 2,4.27zM7.53,9.8l1.55,1.55c-0.05,0.21 -0.08,0.43 -0.08,0.65 0,1.66 1.34,3 3,3 0.22,0 0.44,-0.03 0.65,-0.08l1.55,1.55c-0.67,0.33 -1.41,0.53 -2.2,0.53 -2.76,0 -5,-2.24 -5,-5 0,-0.79 0.2,-1.53 0.53,-2.2zM11.84,9.02l3.15,3.15 0.02,-0.16c0,-1.66 -1.34,-3 -3,-3l-0.17,0.01z"/>
-                </DataTrigger>
-            </Style.Triggers>
-        </Style>
-
-        <Style x:Key="EyeButton" TargetType="Button" BasedOn="{StaticResource IconButton}">
-            <Setter Property="ToolTip" Value="Hide Layer"/>
-            <Style.Triggers>
-                <DataTrigger Binding="{Binding IsVisible}" Value="False">
-                    <Setter Property="ToolTip" Value="Show Layer"/>
-                </DataTrigger>
-            </Style.Triggers>
-        </Style>
+        <!-- EyeButton/EyeIconStyle MOVED to Themes/Controls.xaml (2026-09-01): Controls/
+             LeftPanel.xaml consumes them via StaticResource, and window-scope resources
+             are invisible to a UserControl at parse time — the "known test failure" that
+             was actually an app-crash regression from the LeftPanel extraction. -->
         </ResourceDictionary>
     </Window.Resources>
 
@@ -110,10 +96,6 @@
         <!-- ═══ OVERLAY: Settings / Bug / Feature / About ═══ -->
         <controls:OverlayHost Grid.RowSpan="3"/>
 
-        <!-- ═══ WEB SOURCE HOST: hidden panel for WebView2 controls ═══ -->
-        <Canvas x:Name="WebViewHostPanel" Grid.RowSpan="4"
-                Opacity="0" IsHitTestVisible="False" Background="Transparent"/>
-
         <!-- ═══ TOASTS: non-blocking notifications (bottom-right, above footer) ═══ -->
         <notifications:NotificationArea x:Name="ToastArea"
                                         Grid.RowSpan="4"

MainWindow.xaml.cs

@@ -22,7 +22,6 @@ public partial class MainWindow : Window
         InitializeComponent();
         AppLog.Write("MainWindow ctor: after InitializeComponent");
         _viewModel = (MainViewModel)DataContext;
-        _viewModel.InitWebView2(WebViewHostPanel);
         _viewModel.PropertyChanged += OnViewModelPropertyChanged;
         _topBar = (Controls.TopBar)FindName("TopBar")!;
         _previewPane = (Controls.PreviewPane)FindName("PreviewPane")!;
@@ -37,33 +36,62 @@ public partial class MainWindow : Window
     private void MainWindow_Loaded(object sender, RoutedEventArgs e)
     {
         AppLog.Write("MainWindow loaded");
+        // Web sources need the window HWND as the composition controller's parent,
+        // which does not exist in the ctor — InitWebView2 runs here (Loaded), after
+        // SourceInitialized. Nothing renders from web frames before this.
+        _viewModel.InitWebView2();
     }
 
-    // ─── Window geometry persistence (launch size/position) ───
-    // Saved on close (RestoreBounds so a maximized window remembers its
-    // un-maximize rect); restored in the ctor before the window is shown.
-    // Values clamp to the minimums and to the primary work area — a position
-    // saved on a since-disconnected secondary monitor falls back on-screen.
+    // ─── Window geometry (launch position/size) ───
+    // Launch POSITION is derived, never restored: upper-left of the work area plus
+    // padding (creator ruling 2026-10-04). The old restore clamped the saved position
+    // to [work.Left - width + 120, work.Right - 120] horizontally and
+    // [work.Top, work.Bottom - 80] vertically — ranges wide enough to leave the window
+    // almost entirely off-screen, which is what the creator was seeing ("below the
+    // fold"). Size and maximized state are still persisted. Placement math is pure and
+    // tested (WindowPlacementTests); changing it back to restore position is reverting
+    // this block only, since the saved values are still written.
+
+    /// <summary>Launch inset from the work-area corner, in device-independent units —
+    /// so it scales with DPI rather than being a fixed physical pixel count.</summary>
+    internal const double LaunchPadding = 75;
+
+    /// <summary>Upper-left of <paramref name="workArea"/> plus padding, clamped so the
+    /// window is never pushed off-screen. The clamp is the point: a window that fits
+    /// stays wholly visible, and one too big to fit falls back to the work-area origin
+    /// rather than hanging off an edge.</summary>
+    internal static Point TopLeftPlacement(Rect workArea, double width, double height, double padding)
+    {
+        var left = workArea.Left + padding;
+        var top = workArea.Top + padding;
+
+        if (width <= workArea.Width) left = Math.Min(left, workArea.Right - width);
+        else left = workArea.Left;
+
+        if (height <= workArea.Height) top = Math.Min(top, workArea.Bottom - height);
+        else top = workArea.Top;
+
+        return new Point(left, top);
+    }
 
     private void RestoreWindowGeometry()
     {
         try
         {
-            var saved = _viewModel.RestoreWindowState();
-            if (saved == null) return;
-            var (left, top, width, height, state) = saved.Value;
-
             var work = SystemParameters.WorkArea;
-            width = Math.Clamp(width, MinWidth, work.Width);
-            height = Math.Clamp(height, MinHeight, work.Height);
-            left = Math.Clamp(left, work.Left - width + 120, work.Right - 120);
-            top = Math.Clamp(top, work.Top, work.Bottom - 80);
+            var saved = _viewModel.RestoreWindowState();
 
-            Left = left;
-            Top = top;
+            // No saved state: keep the XAML-declared size rather than collapsing to Min*.
+            var width = Math.Clamp(saved?.Width ?? Width, MinWidth, work.Width);
+            var height = Math.Clamp(saved?.Height ?? Height, MinHeight, work.Height);
             Width = width;
             Height = height;
-            if (state == "Maximized") WindowState = WindowState.Maximized;
+
+            var place = TopLeftPlacement(work, width, height, LaunchPadding);
+            Left = place.X;
+            Top = place.Y;
+
+            if (saved?.State == "Maximized") WindowState = WindowState.Maximized;
         }
         catch (Exception ex)
         {
@@ -139,8 +167,14 @@ public partial class MainWindow : Window
     {
         if (e.OriginalSource is not DependencyObject original) return;
         var form = _viewModel.BroadcastForm;
-        if (form.IsDrawerOpen && !_previewPane.IsClickInsideDrawer(original))
-            form.CloseDrawerCommand.Execute(null);
+        var ypp = _viewModel.Ypp;
+        var test = _viewModel.TestSession;
+        if (!_previewPane.IsClickInsideDrawer(original))
+        {
+            if (form.IsDrawerOpen) form.CloseDrawerCommand.Execute(null);
+            if (ypp.IsDrawerOpen) ypp.CloseDrawerCommand.Execute(null);
+            if (test.IsDrawerOpen) test.CloseDrawerCommand.Execute(null);
+        }
         if (_previewPane.IsClickInsidePreview(original)) return;
         if (_leftPanel.IsClickInside(original)) return;
         _viewModel.SelectedElement = null;

Models/SceneElement.cs

@@ -19,6 +19,17 @@ public enum BorderAnimation
     Sparkles
 }
 
+/// <summary>Whether an element's pixel content is fixed (bake once into the
+/// compositor's cached base) or changes every frame (composite each tick).
+/// See ai.md "SceneGraph component + baked-crust compositor" (TASK 31).</summary>
+public enum ElementKind
+{
+    /// <summary>Pixels never change at runtime (images, background art).</summary>
+    Static,
+    /// <summary>Pixels change every frame (webcam, live capture, chat, web source).</summary>
+    Dynamic
+}
+
 /// <summary>
 /// A thing rendered in a scene: a multi-instance Source (image/background/text)
 /// or a singleton resource's per-scene config (webcam). Carries the shared
@@ -44,6 +55,15 @@ public abstract class SceneElement : INotifyPropertyChanged
     private string _name = string.Empty;
     public string Name { get => _name; set => Set(ref _name, value); }
 
+    /// <summary>Whether this element's pixels are fixed (Static) or change every
+    /// frame (Dynamic). The compositor bakes all Static layers below the first
+    /// Dynamic layer once (see <c>SceneGraph.GetSplitPoint</c>).</summary>
+    public virtual ElementKind Kind => ElementKind.Static;
+
+    /// <summary>True only for the transient zoom layer. Gates zoom-only UI:
+    /// hidden from the layers list, never selectable/draggable in the preview.</summary>
+    public virtual bool IsZoomLayer => false;
+
     /// <summary>True only for singleton resources (webcam). Gates webcam-only UI.</summary>
     public virtual bool IsWebcam => false;
 
@@ -61,6 +81,9 @@ public abstract class SceneElement : INotifyPropertyChanged
 
     /// <summary>True only for Countdown-type sources. Gates timer properties panel.</summary>
     public virtual bool IsCountdown => false;
+
+    /// <summary>True only for AlertBox-type sources. Gates stream alerts properties panel.</summary>
+    public virtual bool IsAlertBox => false;
     public virtual bool IsBackground { get; set; }
 
     private bool _useDefaultBackground = true;

Models/Source.cs

@@ -13,7 +13,10 @@ public enum SourceType
     Countdown,
     WebSource,
     ChatBox,
-    MediaSource
+    MediaSource,
+    /// <summary>The designated alert zone: the six monetization events play their
+    /// unique celebration animations here (OBS alert-box equivalent, native).</summary>
+    AlertBox
 }
 
 /// <summary>Distinguishes how a media source presents its content (TASK 21).</summary>
@@ -37,6 +40,19 @@ public enum ClipShape
     Round
 }
 
+/// <summary>How an alert box presents its announcement strip (TASK 47). The strip is
+/// the full-width pill naming the event ("Viewer — Super Chat · $12.34").</summary>
+public enum AlertDisplayMethod
+{
+    /// <summary>Marquee: the pill scrolls across the top edge, paced so the text is
+    /// read <see cref="AlertOverlayLayer.TickerReadsPerAlert"/> times per alert.</summary>
+    TickerScroll,
+    /// <summary>Pulse: the static pill blinks on and off for the whole alert.</summary>
+    Flash,
+    /// <summary>Static: the pill sits centred and still for the whole alert.</summary>
+    Solid
+}
+
 /// <summary>
 /// A multi-instance scene object: image/background/text (screen/window later).
 /// The webcam is NOT a Source — it's a singleton resource whose per-scene usage
@@ -61,7 +77,12 @@ public class Source : SceneElement
         }
     }
 
-    public override bool IsDraggable => Type is SourceType.Image or SourceType.WebSource or SourceType.ChatBox;
+    public override bool IsDraggable => Type is SourceType.Image or SourceType.WebSource or SourceType.ChatBox or SourceType.AlertBox;
+
+    /// <summary>Live captures, chat, web sources and media are dynamic; static art is fixed.</summary>
+    public override ElementKind Kind => Type is SourceType.DisplayCapture or SourceType.WindowCapture
+        or SourceType.ChatBox or SourceType.WebSource or SourceType.MediaSource or SourceType.AlertBox
+        ? ElementKind.Dynamic : ElementKind.Static;
 
     public override bool IsWebSource => Type == SourceType.WebSource;
 
@@ -113,7 +134,7 @@ public class Source : SceneElement
 
     public override ImageSource? DisplaySource => IsLiveCapture
         ? (VideoImageSource ?? _imageSource)
-        : (Type is SourceType.ChatBox or SourceType.WebSource ? VideoImageSource : _imageSource);
+        : (Type is SourceType.ChatBox or SourceType.WebSource or SourceType.MediaSource or SourceType.AlertBox ? VideoImageSource : _imageSource);
 
     public override bool IsImageSource => Type == SourceType.Image;
 
@@ -171,6 +192,54 @@ public class Source : SceneElement
 
     public bool IsMediaSource => Type == SourceType.MediaSource;
 
+    // Alert video config (TASK 47): the shipped default clip lives in the Asset
+    // table (seeded like image assets); the creator's replacement is a FILE PATH
+    // reference only — never into the DB (creator ruling, 2026-09-26). Runtime
+    // order: replacement path exists → DB default → six celebration animations.
+    private string? _alertVideoAssetId;
+    public string? AlertVideoAssetId
+    {
+        get => _alertVideoAssetId;
+        set => Set(ref _alertVideoAssetId, value);
+    }
+
+    private string? _alertVideoPath;
+    public string? AlertVideoPath
+    {
+        get => _alertVideoPath;
+        set => Set(ref _alertVideoPath, value);
+    }
+
+    private bool _alertUseDefaultVideo = true;
+    public bool AlertUseDefaultVideo
+    {
+        get => _alertUseDefaultVideo;
+        set => Set(ref _alertUseDefaultVideo, value);
+    }
+
+    private bool _alertShowTicker = true;
+    public bool AlertShowTicker
+    {
+        get => _alertShowTicker;
+        set => Set(ref _alertShowTicker, value);
+    }
+
+    private double _alertVideoVolume = 1.0;
+    public double AlertVideoVolume
+    {
+        get => _alertVideoVolume;
+        set => Set(ref _alertVideoVolume, Math.Clamp(value, 0.0, 1.0));
+    }
+
+    private AlertDisplayMethod _alertDisplayMethod = AlertDisplayMethod.TickerScroll;
+    public AlertDisplayMethod AlertDisplayMethod
+    {
+        get => _alertDisplayMethod;
+        set => Set(ref _alertDisplayMethod, value);
+    }
+
+    public override bool IsAlertBox => Type == SourceType.AlertBox;
+
     // Chat box config (TASK 3.18)
     private double _chatFontSize = 16;
     public double ChatFontSize

Models/WebcamSceneConfig.cs

@@ -13,5 +13,6 @@ public class WebcamSceneConfig : SceneElement
     public string WebcamId { get; init; } = string.Empty;
     public override bool IsWebcam => true;
     public override bool IsDraggable => true;
+    public override ElementKind Kind => ElementKind.Dynamic;
     public override ImageSource? DisplaySource => VideoImageSource;
 }

Models/WindowInfo.cs

@@ -0,0 +1,27 @@
+namespace ytLive.Models;
+
+/// <summary>One user-visible open window offered by the "Capture Window…"
+/// submenu. Carries its owning process name for disambiguation and the raw
+/// HWND that becomes the "window:&lt;hwnd&gt;" capture key.</summary>
+public sealed class WindowInfo
+{
+    public WindowInfo(string title, string processName, long hwnd, int processId)
+    {
+        Title = title;
+        ProcessName = processName;
+        Hwnd = hwnd;
+        ProcessId = processId;
+    }
+
+    public string Title { get; }
+    public string ProcessName { get; }
+    public long Hwnd { get; }
+    public int ProcessId { get; }
+
+    /// <summary>Menu label: "Title — ProcessName" (e.g. "bash — WindowsTerminal").</summary>
+    public string Label => $"{Title} — {ProcessName}";
+
+    /// <summary>The capture key fed to the screen-capture factory
+    /// ("window:&lt;hwnd&gt;").</summary>
+    public string CaptureKey => $"window:0x{Hwnd:X}";
+}

Models/YouTube.cs

@@ -18,6 +18,21 @@ public record ReusableStream(string Id, string IngestionAddress, string StreamNa
     public string RtmpUrl => $"{IngestionAddress}/{StreamName}";
 }
 
+/// <summary>The six monetization events YouTube's live chat feed emits (the ONLY
+/// native event stream there is — free subscribers produce no event). Each kind
+/// drives its own celebration animation in the AlertBox. <c>None</c> = a normal
+/// chat row: it never enqueues an alert (subscriber mentions stay chat rows).</summary>
+public enum ChatEventKind
+{
+    None,
+    SuperChat,
+    SuperSticker,
+    NewMember,
+    MemberGift,
+    GiftReceived,
+    MemberMilestone,
+}
+
 public class ChatMessage
 {
     public string Id { get; init; } = Guid.NewGuid().ToString();
@@ -29,6 +44,30 @@ public class ChatMessage
     public bool IsSuperChat { get; set; }
     public double SuperChatAmount { get; set; }
     public string? SuperChatCurrency { get; set; }
+
+    /// <summary>YouTube's own pre-rendered amount ("$12.34") — preferred over
+    /// recomposing amount+currency ourselves, which mangles non-dollar locales.</summary>
+    public string? SuperChatDisplayString { get; set; }
+
     public bool IsMember { get; set; }
     public string? MembershipLevel { get; set; }
+
+    public ChatEventKind Kind { get; set; }
+
+    public string? SuperStickerDescription { get; set; }
+
+    /// <summary>membershipGiftingEvent: how many memberships were bought.</summary>
+    public int GiftNewMembersCount { get; set; }
+
+    /// <summary>giftMembershipReceivedEvent: who gifted this one.</summary>
+    public string? GifterName { get; set; }
+
+    /// <summary>memberMilestoneChatEvent: streak months (0 = YouTube didn't
+    /// expose a count — the animation falls back to the message text).</summary>
+    public int MilestoneMonths { get; set; }
+
+    /// <summary>TASK 41: the Test Stream dock injects synthetic member / SuperChat /
+    /// subscriber events locally (YouTube's insert API only supports text), so the
+    /// buffer can label them honestly — simulated events never reach YouTube.</summary>
+    public bool IsSimulated { get; set; }
 }

Models/YppStatSnapshot.cs

@@ -0,0 +1,17 @@
+namespace ytLive.Models;
+
+/// <summary>One captured snapshot of a connected channel's YPP-relevant numbers
+/// (TASK 39). Appended on every refresh and archived in SQLite so a later slice
+/// can compute velocity/(de)acceleration/ETA from the history.</summary>
+public sealed class YppStatSnapshot
+{
+    public DateTime CapturedAtUtc { get; set; }
+    public long SubscriberCount { get; set; }
+    public long VideoCount { get; set; }
+    public long TotalViews { get; set; }
+    public int UploadsLast90Days { get; set; }
+    public bool CommunityGuidelinesGoodStanding { get; set; }
+    public bool CopyrightStrikesGoodStanding { get; set; }
+    public bool ContentIdClaimsGoodStanding { get; set; }
+    public bool OverallGoodStanding { get; set; }
+}

Models/YppThresholds.cs

@@ -0,0 +1,31 @@
+namespace ytLive.Models;
+
+/// <summary>YPP eligibility thresholds as versioned, date-aware DATA — never
+/// constants (ai.md "Journey tracker"). Tier 1 (fan funding) is time-invariant;
+/// Tier 2 (ad revenue) doubles its long-form-hours and Shorts-view bars for NEW
+/// applicants after 2027-02-01. Hardcoding the pre-2027 numbers would show the
+/// wrong ETA once the doubling lands, so callers resolve the active Tier 2
+/// threshold through <see cref="Tier2For"/>.</summary>
+public static class YppThresholds
+{
+    public sealed record TierThreshold(string Name, long Subscribers, long WatchHours, long ShortsViews);
+
+    /// <summary>The date the Tier-2 ad-revenue bars double for new applicants.</summary>
+    public static readonly DateTime Tier2DoublingDate = new(2027, 2, 1);
+
+    /// <summary>Fan-funding tier (before the full ad/YouTube Premium revenue tier).</summary>
+    public static TierThreshold Tier1 { get; } = new("Fan funding", 500, 3_000, 3_000_000);
+
+    /// <summary>The Tier-2 bar for a given point in time — 4,000h / 10M Shorts
+    /// before the doubling date, 8,000h / 20M Shorts on or after it.</summary>
+    public static TierThreshold Tier2For(DateTime when) => when >= Tier2DoublingDate
+        ? new TierThreshold("Ad revenue", 1_000, 8_000, 20_000_000)
+        : new TierThreshold("Ad revenue", 1_000, 4_000, 10_000_000);
+
+    /// <summary>The currently-active Tier-2 threshold (resolved against today).</summary>
+    public static TierThreshold Tier2Now => Tier2For(DateTime.UtcNow);
+
+    /// <summary>Valid public long-form uploads required in the trailing 90 days
+    /// to keep each tier route eligible.</summary>
+    public const int UploadsRequiredPer90Days = 3;
+}

Models/ZoomSceneElement.cs

@@ -0,0 +1,36 @@
+using System.Windows.Media;
+
+namespace ytLive.Models;
+
+/// <summary>
+/// The transient zoom layer. It is a real scene element, but a special one: while
+/// active the SceneCompositor draws it LAST (layer n+1, above everything) as a live
+/// 2x view of a FIXED capture window (the box/2 region centred on where the creator
+/// clicked), sampled from the just-composited frame — so it captures ALL layers and
+/// keeps showing the same content no matter where the box is dragged (creator ruling
+/// 2026-10-08). Its X/Y/W/H are the movable BOX placement; CaptureX/CaptureY is the
+/// anchored capture window. While inactive it is an invisible placeholder that is
+/// never persisted (LayoutStore hand-rolls only Source/WebcamSceneConfig rows) — the
+/// VM re-inserts it on load and on scene creation, mirroring how backgrounds heal.
+/// </summary>
+public sealed class ZoomSceneElement : SceneElement
+{
+    /// <summary>True only while a zoom box is live; flips Kind so the layer leaves
+    /// the baked static base and composites per-frame.</summary>
+    public bool IsZoomActive { get; set; }
+
+    /// <summary>Master-space top-left of the fixed capture window. Set once by
+    /// <c>ActivateZoom</c>; moving the box must never touch it.</summary>
+    public double CaptureX { get; set; }
+    public double CaptureY { get; set; }
+
+    public override ElementKind Kind => IsZoomActive ? ElementKind.Dynamic : ElementKind.Static;
+
+    public override bool IsZoomLayer => true;
+
+    public override bool IsDraggable => false;
+
+    /// <summary>Never rendered by the element template or the resolver — the preview
+    /// magnifier (ZoomBox) and the output compositor's zoom pass own its pixels.</summary>
+    public override ImageSource? DisplaySource => null;
+}

Models/ZoomShape.cs

@@ -0,0 +1,8 @@
+namespace ytLive.Models;
+
+public enum ZoomShape
+{
+    Circle,
+    VerticalRectangle,
+    HorizontalRectangle
+}

Models/ZoomState.cs

@@ -0,0 +1,27 @@
+using System;
+
+namespace ytLive.Models;
+
+public class ZoomState
+{
+    public bool IsActive { get; set; }
+    public double X { get; set; }
+    public double Y { get; set; }
+    public double Width { get; set; }
+    public double Height { get; set; }
+
+    /// <summary>Master-space top-left of the FIXED capture window (the box/2 region
+    /// centred on the click). The box can be dragged anywhere; this never changes —
+    /// the box always shows this same region magnified 2x (creator ruling 2026-10-08).</summary>
+    public double CaptureX { get; set; }
+    public double CaptureY { get; set; }
+
+    public bool IsMoving { get; set; }
+    public double GrabOffsetX { get; set; }
+    public double GrabOffsetY { get; set; }
+
+    public double Left => X;
+    public double Top => Y;
+    public double Right => X + Width;
+    public double Bottom => Y + Height;
+}

Models/index.md

@@ -7,14 +7,15 @@ Plain data types. No logic beyond what a property can carry. See
 |------|---------|
 | `Scene.cs` | A scene: `Name`, `IsHidden`, `IsChatScene`, `IsEditing`, **`HasBackdrop`** (Live-only policy flag, default off — only the canonical Live scene has one, see `SceneCatalog`), `Elements` collection (images + webcam config), `WebcamConfig` accessor |
 | `SceneCatalog.cs` | The five canonical scenes (Starting/Live/BRB/Chat/Ending) — the product, by name: `All`, `IsCanonical`, `Is(name, canonical)` (case-insensitive trim), `IsChat`, `HasBackdrop(name)` (true only for Live). Drives the empty-DB seed, the "+" missing-scenes menu, and `MainViewModel.EnforceBackdropPolicy` |
-| `Source.cs` | A source: `SourceType` enum (DisplayCapture/WindowCapture/Background/Image/TextOverlay — **Webcam removed**), `X`/`Y`/`Width`/`Height`, `Opacity`, `IsEnabled`, `ImageSource` (static) / `VideoImageSource` (live frames), `DisplaySource` (`IsLiveCapture` → video, else static), `ClipShape` enum (Traditional/Round), `IsMirrored` + `MirrorScale`, `MirrorButtonText`/`ShapeButtonText`, asset identity, `IsImageSource` (XAML binds this, never `Type`), **backdrop surface**: `IsBackdrop` (permanent bottom layer, never removable), `CaptureKey` (persisted `monitor:<n>`/`window:<hwnd>`/`picker:<name>`), `IsLiveCapture` (`Type` is Display/WindowCapture) |
-| `SceneElement.cs` | Base for anything placeable in a scene: shared layout/clip/mirror/border surface, `virtual IsWebcam`/`virtual IsImageSource`; `ToggleClipShape` + persisted `RectWidth`/`RectHeight` (pre-Round rect so round→rect restores after reload) |
+| `Source.cs` | A source: `SourceType` enum (DisplayCapture/WindowCapture/Background/Image/TextOverlay/ChatBox/Countdown/WebSource/MediaSource/**AlertBox (TASK 43 — the celebration zone, one per layout)** — **Webcam removed**), `X`/`Y`/`Width`/`Height`, `Opacity`, `IsEnabled`, `ImageSource` (static) / `VideoImageSource` (live frames), `DisplaySource` (`IsLiveCapture` → video, else static), `ClipShape` enum (Traditional/Round), `IsMirrored` + `MirrorScale`, `MirrorButtonText`/`ShapeButtonText`, asset identity, `IsImageSource` (XAML binds this, never `Type`), **backdrop surface**: `IsBackdrop` (permanent bottom layer, never removable), `CaptureKey` (persisted `monitor:<n>`/`window:<hwnd>`/`picker:<name>`), `IsLiveCapture` (`Type` is Display/WindowCapture) |
+| `SceneElement.cs` | Base for anything placeable in a scene: shared layout/clip/mirror/border surface, `virtual IsWebcam`/`virtual IsImageSource`/`virtual IsZoomLayer` (TASK 52); `ToggleClipShape` + persisted `RectWidth`/`RectHeight` (pre-Round rect so round→rect restores after reload) |
+| `ZoomSceneElement.cs` | **Transient zoom box (TASK 52, creator-corrected 2026-10-08):** carries the box rect AND the anchored `CaptureX`/`CaptureY` (the fixed box/2 capture window set on `ActivateZoom`; moving the box never touches it). `IsZoomActive` flips `Kind` Static→Dynamic (leaves the baked base while active); never persisted (LayoutStore save skips non-Source/non-WebcamSceneConfig rows), never shown in the layers list or the element template (`IsZoomLayer` gates both). The compositor SKIPS the active element in every layer loop and draws its 2x content LAST (layer n+1) via `ZoomMagnifier`. |
 | `Webcam.cs` | Singleton webcam identity: `Id`, `DeviceId`, `Name` (one row app-wide) |
 | `WebcamSceneConfig.cs` | Per-scene webcam placement (subclass of `SceneElement`): geometry + `IsVisible` + border (`BorderColor`/`BorderOpacity`/`BorderWidth`/`BorderAnimation`) + `VideoImageSource`; `WebcamId` links to `Webcam` |
 | `QualityOption.cs` | Resolution tier record `(Display, Fps, Bitrate, Width, Height)`; `Label` formats as `1080p60 (8Mbps)` — drives the bottom-bar dropdown and the output-rect math |
 | `StreamConfig.cs` | `StreamConfig` (note: `TargetBitrate`/`Resolution` defaults are stale — not yet wired to the dropdown), `StreamHealth` (bitrate/FPS/dropped/duration), `StreamStatus` enum |
 | `MicStatus.cs` | Footer mic indicator: `NotConnected` / `Connected` / `Problem` — the state behind the MIC button's status dot (red = no device/capture off, green = capturing, yellow = a requested mic failed: in use/unplugged) |
-| `YouTube.cs` | `YouTubeChannel` and `ChatMessage` (chat feed) |
+| `YouTube.cs` | `YouTubeChannel` and `ChatMessage` (chat feed) — since TASK 43 every message carries `Kind` (`ChatEventKind` None/SuperChat/SuperSticker/NewMember/MemberGift/GiftReceived/MemberMilestone) + event payload fields (`SuperChatDisplayString`, `SuperStickerDescription`, `GiftNewMembersCount`, `GifterName`, `MilestoneMonths`) |
 | `Socials.cs` | **Social bar** (global layer, never a Source): `SocialService` enum (YouTube/Twitch/X/Instagram/TikTok/Facebook/Discord/Kick/Threads/Bluesky/GitHub/LinkedIn/Pinterest/Snapchat/Reddit/WhatsApp/Telegram/Link/Website/**Fediverse**), `SocialEntry` (Service/Handle/ProfileUrl/`FediverseSoftware`), `SocialsConfig` (Entries + `BarPosition` Top/Bottom + `BarEnabled` on/off — `BarJustify` dropped, column back-compat), `SocialServiceIcons` (canonical URL builder + `DetectService` (URL domain / fediverse `@user@domain` → **Fediverse** / bare→Website) + bundled SVG logo path data per service (`LogoDataFor`) + `LogoDataForFediverse(software)` mapping nodeinfo software names (mastodon/peertube/pixelfed/misskey/lemmy/pleroma/firefish) to logos with a generic fediverse glyph fallback (`FediverseIconData`) + `LockedIconData`/`DoNotIconData` — initials/colors gone) |
 
 Related: [`ViewModels/index.md`](../ViewModels/index.md) consume these;

README.md

@@ -28,6 +28,14 @@ ytLlive assumes you already have a YouTube creator account — connecting uses "
 to link that existing account. **ytLlive does not create accounts.** If you don't have a YouTube
 channel yet, set one up on YouTube first, then connect it here.
 
+## Audio Assumption
+
+ytLlive uses your **default** microphone and desktop/game output — it never hunts for a device or
+contends for one. **It assumes your audio is already configured and working** (default input and
+output set, not hijacked by another app). Audio issues are a Windows/device matter outside ytLlive's
+scope: we don't debug, detect, or try to fix them. If it doesn't sound right, fix the system's audio
+settings first — it's on the OS, not on us.
+
 ## Run
 
 ```bash
@@ -37,25 +45,28 @@ dotnet run
 
 ## Version Roadmap
 
-| Version | Scope |
-|---------|-------|
-| v0.1     | Scene/source management, YouTube RTMP ingest, YouTube OAuth2, live chat, stream health |
-| v0.2     | Recording to local file |
-| v0.3     | Stream scheduling |
-| v0.4     | Multi-destination restreaming |
-| 1.0      | General availability |
+**v1 is the finished product** (creator ruling, 2026-09-01 — there are no v1.x releases).
+Everything still queueing lands in v1; anything not on the feature list is on the closed
+**"Out of product — permanently"** list in `TASKS.md` — read that page before asking for a feature.
+
+What v1 ships: the five-scene director's control surface, webcam + screen capture, media + web +
+text sources, chat on-stream, the social bar, mic/desktop audio with auto-duck and TRAX, local
+recording, variable quality tiers with auto step-down, one-click go-live + scheduling, stream
+resilience (auto-reconnect inside YouTube's grace, one-click back on air), built-in monetization
+awareness (reward capture, session reports, YPP journey tracker), Alerts — all free and ungated;
+the paid tier only removes the branding flash.
 
 ## Structure
 
 | Path | Role |
 |------|------|
-| `Models/` | Scene, Source, QualityOption, StreamConfig, StreamHealth, YouTube channel/chat, Socials (social bar) |
-| `ViewModels/` | MainViewModel — scenes, stream controls, chat; GoLiveViewModel, ReuseImageViewModel, SocialsDialogViewModel |
-| `Services/` | YouTubeAuthService (OAuth2), YouTubeStreamService (broadcast/health), YouTubeChatService (chat polling), LayoutStore (SQLite), SocialValidator (social link/fediverse validation + nodeinfo icon resolution) |
-| `Helpers/` | ViewModelBase, RelayCommand, ImageCache, AppLog, FocusPreservingListBox, OAuthCredentials |
+| `Models/` | Scene, Source, WebcamSceneConfig, SceneElement, SceneCatalog, QualityOption, StreamConfig/Health, chat, Socials, BroadcastMetadata, Music, MicStatus |
+| `ViewModels/` | MainViewModel (partial classes per area) + dialogs: GoLive, CameraPicker, MicPicker, HotkeyConfig, Socials, LiveBroadcastForm |
+| `Services/` | YouTube (OAuth, streams/broadcasts, chat polling), LayoutStore (SQLite), capture (camera/screen-capture/media-file via FFmpeg), SceneCompositor + FramePump, FFmpeg encoder + RTMP, audio pipeline (WASAPI loopback + mic, mixer, filters, ducker, limiter, TRAX), SocialValidator, notifications, hotkeys, SceneGraph, ChatOverlayLayer |
+| `Helpers/` | ViewModelBase, RelayCommand, ImageCache, AppLog, TokenStore (DPAPI), OAuthCredentials, converters |
 | `Themes/` | `Controls.xaml` — the dark-theme control styles, merged once in `App.xaml` |
-| `MainWindow.xaml` | Dark-theme main UI: scene/source panel, preview, chat, status bar |
-| `SocialsDialog.xaml` | Social Media Site Promotion dialog — 6-slot social bar editor with sign-in gate and validation |
+| `MainWindow.xaml` | Dark-theme control surface: thumbnails + central preview, two-state left panel (layers/properties ↔ live chat), top bar, footer |
+| `Distribution.md` | GA-time plan: signing, installer, EULA, hardening — executed as TASK 36 |
 
 ## Docs (memory map)
 

RenameRecordingDialog.xaml

@@ -1,8 +1,8 @@
 <Window x:Class="ytLive.RenameRecordingDialog"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-        Title="Rename Recording" Height="230" Width="460"
-        Icon="/Assets/llamacasty-icon.png"
+        Title="Rename Recording" Height="304" Width="460"
+        Icon="/ytLive;component/Assets/llamacasty-icon.png"
         WindowStartupLocation="CenterOwner" ResizeMode="NoResize"
         ShowInTaskbar="False" Background="#1a1a2e">
 
@@ -32,7 +32,7 @@
                     Margin="0,20,0,0">
             <Button Content="Cancel" Click="Cancel_Click"
                     Style="{StaticResource YtButtonSecondary}" Margin="0,0,8,0"/>
-            <Button Content="Save" Click="Save_Click" Style="{StaticResource YtButton}" MinWidth="90"/>
+            <Button Content="Save" Click="Save_Click" Style="{StaticResource YtButton}" MinWidth="90" x:Name="SaveRecordingButton"/>
         </StackPanel>
     </Grid>
 </Window>

RenameRecordingDialog.xaml.cs

@@ -6,12 +6,16 @@ namespace ytLive;
 
 /// <summary>Modal that lets the creator rename an auto-named recording before it is
 /// finalized. Returns the chosen file stem (no extension) via <see cref="ResultFileName"/>,
-/// or <c>null</c> on Cancel / keep-auto-name.</summary>
+/// or <c>null</c> when the creator cleared the box and hit Save (keep the auto name).
+/// <para><c>DialogResult == false</c> means DISCARD — the caller deletes the footage
+/// rather than saving it (CREATOR RULING 2026-09-26). Enter on the pre-filled default
+/// is a Save.</para></summary>
 public partial class RenameRecordingDialog : Window
 {
     private readonly string _autoStem;
 
-    /// <summary>Stem (no extension) the creator chose, or <c>null</c> to keep auto-name.</summary>
+    /// <summary>Stem (no extension) the creator chose, or <c>null</c> when the box was
+    /// cleared on an explicit Save. Never set on Cancel.</summary>
     public string? ResultFileName { get; private set; }
 
     public RenameRecordingDialog(string autoStem)

Services/AlertClipDecoder.cs

@@ -0,0 +1,227 @@
+using System.Diagnostics;
+using System.IO;
+using ytLive.Helpers;
+using ytLive.Services.Audio;
+using ytLive.Services.Encoder;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// TASK 47: one alert clip's playback — video frames + on-stream audio from the
+/// same file, both paced to real time. The alert box owns a decoder per event
+/// (start at play, dispose at drain) — unlike MediaSource's app-wide refcounted
+/// session, an alert REPLAYS the same clip each event, so a fresh decode per
+/// play is required. Video is rawvideo BGRA scaled to the box rect (the
+/// <see cref="MediaVideoSource"/> shape); audio is ffmpeg <c>f32le</c> at the
+/// mixer's native 48 kHz stereo (so the mixer ring needs no resampler). The
+/// fade is applied by the alert layer, not here.
+/// </summary>
+public interface IAlertClipDecoder : IDisposable
+{
+    /// <summary>Starts the decode loop (video + audio); raises the events off the
+    /// calling thread. Paced to real time so playback matches wall clock.</summary>
+    void Start();
+
+    /// <summary>Stops and kills any running decode subprocesses.</summary>
+    void Stop();
+
+    /// <summary>One decoded video frame (box-sized, straight-alpha BGRA).</summary>
+    event Action<VideoFrame>? FrameAvailable;
+
+    /// <summary>One chunk of on-stream audio (48 kHz stereo float).</summary>
+    event Action<AudioSample>? AudioReady;
+
+    /// <summary>Raised once when both streams have fully played out.</summary>
+    event Action? Completed;
+}
+
+/// <summary>Default <see cref="IAlertClipDecoder"/>: two ffmpeg subprocesses on
+/// the same file. Video via <see cref="RawVideoFrameReader"/> on a <c>rawvideo
+/// bgra</c> pipe (-an), audio via an <c>f32le -ac 2 -ar 48000</c> pipe (-vn).
+/// The seams (locator, process factory, frame-rate probe, delay) let tests drive
+/// a fake decoder without a real codec or Windows.</summary>
+public sealed class AlertClipDecoder : IAlertClipDecoder
+{
+    public event Action<VideoFrame>? FrameAvailable;
+    public event Action<AudioSample>? AudioReady;
+    public event Action? Completed;
+
+    private const int AudioSampleRate = 48000;
+    private const int AudioChannels = 2;
+    private const int AudioChunkFloats = 4800; // 50ms of stereo
+
+    private readonly string _path;
+    private readonly int _width;
+    private readonly int _height;
+    private readonly IFfmpegLocator _locator;
+    private readonly Func<IDecodeProcess> _processFactory;
+    private readonly IFrameRateProbe? _probe;
+    private readonly Func<TimeSpan, CancellationToken, Task> _delay;
+    private readonly CancellationTokenSource _cts = new();
+    private Task? _run;
+
+    public AlertClipDecoder(
+        string path,
+        int width,
+        int height,
+        IFfmpegLocator locator,
+        Func<IDecodeProcess> processFactory,
+        IFrameRateProbe? frameRateProbe = null,
+        Func<TimeSpan, CancellationToken, Task>? delay = null)
+    {
+        _path = path;
+        _width = width;
+        _height = height;
+        _locator = locator;
+        _processFactory = processFactory;
+        _probe = frameRateProbe;
+        _delay = delay ?? ((t, ct) => Task.Delay(t, ct));
+    }
+
+    public void Start()
+    {
+        if (_run != null) return;
+        _run = Task.Run(RunAsync, CancellationToken.None);
+    }
+
+    public void Stop() => _cts.Cancel();
+
+    public void Dispose()
+    {
+        _cts.Cancel();
+        _cts.Dispose();
+    }
+
+    private async Task RunAsync()
+    {
+        var ct = _cts.Token;
+        var videoFrames = 0;
+        var audioChunks = 0;
+        var failed = false;
+        try
+        {
+            double? frameRate = null;
+            if (_probe != null)
+                frameRate = await _probe.ProbeAsync(_path, ct).ConfigureAwait(false);
+            var frameDuration = frameRate is > 0 ? TimeSpan.FromSeconds(1.0 / frameRate.Value) : TimeSpan.Zero;
+
+            var ffmpegPath = await _locator.LocateAsync(ct).ConfigureAwait(false);
+
+            var videoTask = RunVideoAsync(ffmpegPath, frameDuration, ct);
+            var audioTask = RunAudioAsync(ffmpegPath, ct);
+            videoFrames = await videoTask.ConfigureAwait(false);
+            audioChunks = await audioTask.ConfigureAwait(false);
+        }
+        catch (OperationCanceledException)
+        {
+            failed = true;
+            return;
+        }
+        catch (Exception ex)
+        {
+            // A failed decode is not fatal: the alert layer falls back to the six
+            // animations (or the frame it already holds) exactly as a missing file.
+            // Logged so a silent blank box traces back to a decode failure.
+            failed = true;
+            AppLog.Write(ex, $"Alert clip decode failed ({Path.GetFileName(_path)})");
+        }
+
+        if (!ct.IsCancellationRequested)
+        {
+            AppLog.Write($"Alert clip end: {Path.GetFileName(_path)} frames={videoFrames} audioChunks={audioChunks} failed={failed}");
+            Completed?.Invoke();
+        }
+    }
+
+    private async Task<int> RunVideoAsync(string ffmpegPath, TimeSpan frameDuration, CancellationToken ct)
+    {
+        var args =
+            $"-hide_banner -loglevel error -i \"{_path}\" " +
+            $"-f rawvideo -pix_fmt bgra -vf scale={_width}:{_height} -an -";
+        using var process = _processFactory();
+        process.Start(new ProcessStartInfo
+        {
+            FileName = ffmpegPath,
+            Arguments = args,
+            UseShellExecute = false,
+            RedirectStandardOutput = true,
+            RedirectStandardError = true,
+            CreateNoWindow = true,
+        });
+
+        var reader = new RawVideoFrameReader(_width, _height);
+        var buffer = new byte[65536];
+        var stream = process.StandardOutput;
+        var frames = 0;
+        while (!ct.IsCancellationRequested && !process.HasExited)
+        {
+            var read = await stream.ReadAsync(buffer, 0, buffer.Length, ct).ConfigureAwait(false);
+            if (read <= 0) break;
+            var chunk = new byte[read];
+            Buffer.BlockCopy(buffer, 0, chunk, 0, read);
+            foreach (var frame in reader.Feed(chunk))
+            {
+                frames++;
+                FrameAvailable?.Invoke(frame);
+                if (frameDuration > TimeSpan.Zero)
+                    await _delay(frameDuration, ct).ConfigureAwait(false);
+            }
+        }
+        return frames;
+    }
+
+    private async Task<int> RunAudioAsync(string ffmpegPath, CancellationToken ct)
+    {
+        var args =
+            $"-hide_banner -loglevel error -i \"{_path}\" " +
+            $"-f f32le -ac {AudioChannels} -ar {AudioSampleRate} -vn -";
+        using var process = _processFactory();
+        process.Start(new ProcessStartInfo
+        {
+            FileName = ffmpegPath,
+            Arguments = args,
+            UseShellExecute = false,
+            RedirectStandardOutput = true,
+            RedirectStandardError = true,
+            CreateNoWindow = true,
+        });
+
+        var stream = process.StandardOutput;
+        var raw = new byte[65536];
+        var carry = new byte[0];
+        var floatScratch = new float[AudioChunkFloats];
+        var floatIndex = 0;
+        var chunks = 0;
+        // The pipe is byte-delimited only: a read may split a float, so leftover
+        // bytes are carried into the next read instead of dropped (a dropped
+        // half-float would desync the entire stream).
+        while (!ct.IsCancellationRequested && !process.HasExited)
+        {
+            var read = await stream.ReadAsync(raw, 0, raw.Length, ct).ConfigureAwait(false);
+            if (read <= 0) break;
+            var total = carry.Length + read;
+            var bytes = total <= raw.Length ? raw : new byte[total];
+            if (carry.Length > 0)
+            {
+                Buffer.BlockCopy(carry, 0, bytes, 0, carry.Length);
+                Buffer.BlockCopy(raw, 0, bytes, carry.Length, read);
+            }
+            var floatsTo = total - (total % 4);
+            for (var i = 0; i < floatsTo && floatIndex < floatScratch.Length; i += 4)
+                floatScratch[floatIndex++] = BitConverter.ToSingle(bytes, i);
+            carry = total > floatsTo ? bytes[floatsTo..total] : new byte[0];
+
+            while (floatIndex == floatScratch.Length)
+            {
+                chunks++;
+                AudioReady?.Invoke(new AudioSample(floatScratch, AudioSampleRate, AudioChannels));
+                // Pace the NEXT chunk so the whole clip's audio lands at real-time
+                // cadence (the fade in the alert layer tracks the same wall clock).
+                await _delay(TimeSpan.FromSeconds(AudioChunkFloats / (double)(AudioSampleRate * AudioChannels)), ct).ConfigureAwait(false);
+                floatScratch = new float[AudioChunkFloats];
+                floatIndex = 0;
+            }
+        }
+        return chunks;
+    }
+}

Services/AlertOverlayLayer.cs

@@ -0,0 +1,541 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Windows;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Threading;
+using ytLive.Helpers;
+using ytLive.Models;
+using ytLive.Services.Audio;
+using ytLive.Services.Compositor;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// The native alert box (OBS-style celebration zone, no third party). Owns the
+/// event queue and the animation clock: <see cref="ChatEventKind"/> events from
+/// the chat feed are enqueued one-at-a-time and played through a celebration
+/// animation (<see cref="AlertRenderer"/>) OR — when the alert-box video is
+/// configured and resolves — through a decoded clip. Frames are served to the
+/// stream compositor via <see cref="RenderFrame"/> and mirrored to the preview
+/// via <see cref="UpdatePreview"/>. Idle = transparent (null frame); playback is
+/// advanced by a 33ms dispatch ticker. The clock is exposed as
+/// <see cref="Advance"/> so tests drive playback deterministically without the
+/// timer. Ordinary chat rows (<see cref="ChatEventKind.None"/>) never enqueue —
+/// a subscriber mention is a chat row, not an alert.
+///
+/// TASK 47 (Stream Alerts video): a video-backed alert replaces the animation
+/// while a clip decodes (<see cref="IAlertClipDecoder"/>, one per play). The
+/// clip plays at its own media pace; the layer applies a ~300ms fade-in/out
+/// alpha envelope to the frames AND the audio samples (freeze-frame fade-out on
+/// the tail), clips the alert to the clip length, and forwards the scaled audio
+/// to the mixer's alert ring via <paramref name="audioSink"/> (no duck). The
+/// per-source config (path/default/ticker/volume) is resolved through
+/// <paramref name="clipPathResolver"/>; the ticker strip is served via
+/// <see cref="AlertTickerFrame"/>.
+/// </summary>
+public sealed class AlertOverlayLayer : IDisposable
+{
+    /// <summary>The fade-in/out ramp length (video alpha AND audio gain). Measured
+    /// against a real clip in the AlertLayerVideoTests unit; keep the ramp short
+    /// enough to read as a "pop-in" on stream (see ai.md).</summary>
+    internal const double FadeDurationSeconds = 0.30;
+
+    /// <summary>How long an alert waits for the first decoded frame or audio slab
+    /// before treating the clip as unplayable and falling back to the animations
+    /// (a silent decoder must never blank the alert box).</summary>
+    internal const double NoFrameFallbackSeconds = 1.0;
+
+    private static readonly TimeSpan TickInterval = TimeSpan.FromMilliseconds(33);
+
+    private readonly AlertRenderer _renderer;
+    private readonly Func<string, int, int, IAlertClipDecoder>? _clipDecoderFactory;
+    private readonly Func<Source, string?>? _clipPathResolver;
+    private readonly Action<AudioSample>? _audioSink;
+    private readonly Action<VideoFrame?>? _tickerPreviewSink;
+    private readonly Queue<ChatMessage> _queue = new();
+    private readonly DispatcherTimer? _ticker;
+
+    private ChatMessage? _current;
+    private Source? _currentBox;
+    private IAlertClipDecoder? _clip;
+    private VideoFrame? _latestClipFrame;
+    private bool _clipEof;
+    private double _clipEofElapsed;
+    private int _clipWidth;
+    private int _clipHeight;
+    private bool _clipSawFrame;
+    private bool _clipAudioHeard;
+    private string? _tickerText;
+    private AlertDisplayMethod _tickerMethod = AlertDisplayMethod.TickerScroll;
+    private double _elapsed;
+    private IEnumerable<Scene>? _scenes;
+
+    private int _contentVersion;
+    private int _frameVersion = -1;
+    private string? _frameKey;
+    private VideoFrame? _cachedFrame;
+    private DateTime _lastPreviewLog = DateTime.MinValue;
+
+    public AlertOverlayLayer(
+        AlertRenderer renderer,
+        Func<string, int, int, IAlertClipDecoder>? clipDecoderFactory = null,
+        Func<Source, string?>? clipPathResolver = null,
+        Action<AudioSample>? audioSink = null,
+        Action<VideoFrame?>? tickerPreviewSink = null)
+    {
+        _renderer = renderer;
+        _clipDecoderFactory = clipDecoderFactory;
+        _clipPathResolver = clipPathResolver;
+        _audioSink = audioSink;
+        _tickerPreviewSink = tickerPreviewSink;
+        if (Application.Current != null)
+        {
+            _ticker = new DispatcherTimer { Interval = TickInterval };
+            _ticker.Tick += (_, _) =>
+            {
+                Advance(TickInterval.TotalSeconds);
+                RefreshAlertPreviews();
+            };
+        }
+    }
+
+    /// <summary>Production entry from the chat feed: enqueue one event. Messages
+    /// arrive on the chat poller thread, so this marshals to the UI thread (same
+    /// rule as <see cref="ChatOverlayLayer.OnMessageReceived"/>) — the preview
+    /// writes create WPF <see cref="WriteableBitmap"/> instances, and creating a
+    /// DependencySource off the UI thread crashes the WPF binding engine
+    /// (ArgumentException "Must create DependencySource on same Thread").</summary>
+    public void OnMessageReceived(ChatMessage message, IEnumerable<Scene> scenes)
+    {
+        var app = Application.Current;
+        if (app != null && !app.Dispatcher.CheckAccess())
+        {
+            app.Dispatcher.Invoke(() => Ingest(message, scenes));
+            return;
+        }
+        Ingest(message, scenes);
+    }
+
+    private void Ingest(ChatMessage message, IEnumerable<Scene> scenes)
+    {
+        _scenes = scenes;
+        Enqueue(message);
+        _ticker?.Start();
+        RefreshAlertPreviews();
+    }
+
+    /// <summary>Queue an event (pure — also the test seam). Chat rows carry
+    /// <see cref="ChatEventKind.None"/> and are ignored: no alert for a mention.</summary>
+    public void Enqueue(ChatMessage message)
+    {
+        if (message.Kind == ChatEventKind.None) return;
+        if (_queue.Count >= 10) return; // back-to-back floods drop the tail, never stall playback
+        _queue.Enqueue(message);
+        if (_current == null)
+        {
+            _current = _queue.Dequeue();
+            _elapsed = 0;
+            BeginClip();
+        }
+        _contentVersion++;
+    }
+
+    /// <summary>Advance the playback clock (the ticker's beat — and the test seam;
+    /// tests call this directly and never start the timer). Draining the queue to
+    /// nothing stops the ticker and leaves the box transparent.</summary>
+    public void Advance(double deltaSeconds)
+    {
+        // Video-backed alert: duration is clip-driven. The clip plays at media
+        // pace; once it EOFs the last frame sweeps through the fade-out before
+        // the alert moves on (a hard cut at EOF would pop, not fade).
+        if (_clip != null)
+        {
+            _elapsed += deltaSeconds;
+            // A decoder that starts but produces not a single frame (or slab of
+            // audio) is dead weight — the box would sit transparent for the whole
+            // alert. Give it a short grace, then fall back to the animations so an
+            // alert ALWAYS renders (the live decode failure at 2026-09-26 11:44 was
+            // this exact void, invisible in the log).
+            if (!_clipSawFrame && !_clipAudioHeard && _elapsed >= NoFrameFallbackSeconds)
+            {
+                System.Diagnostics.Debug.WriteLine("Alert clip yielded no frames in 1s — falling back to the animation");
+                StopClip();
+                _elapsed = 0;
+                _contentVersion++;
+                return;
+            }
+            if (_clipEof && _elapsed - _clipEofElapsed >= FadeDurationSeconds)
+            {
+                _clipEof = false;
+                StopClip();
+                _current = null;
+                _elapsed = 0;
+                AdvanceToNext();
+            }
+            _contentVersion++;
+            return;
+        }
+
+        if (_current == null)
+        {
+            if (_queue.Count == 0) return;
+            _current = _queue.Dequeue();
+            _elapsed = 0;
+            BeginClip();
+            _contentVersion++;
+            return;
+        }
+
+        _elapsed += deltaSeconds;
+        if (_elapsed >= DurationOf(_current))
+        {
+            _current = null;
+            _elapsed = 0;
+            AdvanceToNext();
+        }
+        _contentVersion++;
+    }
+
+    /// <summary>Whether an alert is currently playing or queued.</summary>
+    public bool IsPlaying => _current != null || _queue.Count > 0;
+
+    /// <summary>The live-output frame for one AlertBox element: the decoded clip
+    /// frame (faded) while a clip is active, else the animation frame, null
+    /// (transparent) when idle.</summary>
+    public VideoFrame? RenderFrame(Source alertBox)
+    {
+        if (_current == null)
+        {
+            _frameKey = null;
+            return null;
+        }
+
+        if (_clip != null)
+            return RenderClipFrame(alertBox);
+
+        var width = (int)Math.Max(1, alertBox.Width);
+        var height = (int)Math.Max(1, alertBox.Height);
+        var key = $"{width}x{height}|{_current.Id}|{Progress()}";
+
+        if (_frameKey == key && _frameVersion == _contentVersion)
+            return _cachedFrame;
+
+        var app = Application.Current;
+        if (app != null && !app.Dispatcher.CheckAccess())
+        {
+            var capturedKey = key;
+            var capturedVersion = _contentVersion;
+            return app.Dispatcher.Invoke(() =>
+            {
+                if (_frameKey == capturedKey && _frameVersion == capturedVersion)
+                    return _cachedFrame;
+                return RenderCore(alertBox, width, height, capturedKey, capturedVersion);
+            });
+        }
+
+        return RenderCore(alertBox, width, height, key, _contentVersion);
+    }
+
+    /// <summary>The ticker strip as the alert box shows it: a marquee, a pulse or a
+    /// static pill naming the event while an alert plays, else null. Pure byte-math
+    /// per call so the frame pump can read it on any thread (the text strip is
+    /// rasterized once on the UI thread and cached).
+    /// <para><b>Creator ruling 2026-09-26:</b> the strip is composited INSIDE the
+    /// Stream Alerts box, not as a full-width bar at the top edge of the frame — "the
+    /// ticker should appear over the stream alerts video, not over the entire preview
+    /// window". So the frame is rendered at the box's own size and carries the box's
+    /// origin on <see cref="VideoFrame.Placement"/>; every blit site reads
+    /// <see cref="VideoFrame.OriginX"/>/<see cref="VideoFrame.OriginY"/> instead of
+    /// a hardcoded 0. <b>No alert box in the scene means no ticker at all</b> — there
+    /// is no longer a global position for it to live in.</para></summary>
+    public VideoFrame? AlertTickerFrame
+    {
+        get
+        {
+            if (_current == null || string.IsNullOrWhiteSpace(_tickerText)) return null;
+            var box = _currentBox;
+            if (box == null) return null;
+
+            var w = (int)Math.Max(1, Math.Round(box.Width));
+            var h = (int)Math.Max(1, Math.Min(
+                Math.Round(box.Height), AlertTickerRenderer.Height));
+            var frame = AlertTickerRenderer.Render(
+                _tickerText!, _elapsed, _tickerMethod, AlertSeconds(),
+                TickerReadsPerAlert, w, h);
+            return frame == null
+                ? null
+                : new VideoFrame(frame.Width, frame.Height, frame.BgraPixels)
+                {
+                    Placement = ((int)Math.Round(box.X), (int)Math.Round(box.Y)),
+                };
+        }
+    }
+
+    /// <summary>How many times the marquee must cross the frame per alert, so the
+    /// announcement is actually readable inside a 10s clip (2026-09-26: the old
+    /// fixed 140px/s took ~17s per pass, so a 10s alert showed it barely once).</summary>
+    internal const int TickerReadsPerAlert = 3;
+
+    /// <summary>Assumed alert length for the marquee rhythm. The clip's real length
+    /// isn't known until it EOFs, and the shipped default clip is 10s — the number
+    /// the creator's "three reads" target is stated against.</summary>
+    internal const double AssumedAlertSeconds = 10.0;
+
+    private double AlertSeconds() => _clip != null ? AssumedAlertSeconds : DurationOf(_current!);
+
+
+    private VideoFrame? RenderClipFrame(Source alertBox)
+    {
+        var frame = _latestClipFrame;
+        if (frame == null) return null;
+
+        var w = (int)Math.Max(1, alertBox.Width);
+        var h = (int)Math.Max(1, alertBox.Height);
+        if (frame.Width != w || frame.Height != h)
+            frame = StretchMath.BilinearScale(frame, w, h);
+
+        var fade = FadeAt();
+        if (fade >= 1.0) return frame;
+
+        // Straight-alpha source-over on the compositor side: scale the source
+        // alpha by the envelope so the clip blends out (a 680x200 copy per fade
+        // tick is trivial; outside the ramps fade==1 returns the raw frame).
+        var copy = new byte[frame.BgraPixels.Length];
+        Buffer.BlockCopy(frame.BgraPixels, 0, copy, 0, copy.Length);
+        var a = (byte)(fade * 255 + 0.5);
+        for (var i = 3; i < copy.Length; i += 4)
+            copy[i] = (byte)((copy[i] * a) >> 8);
+        return new VideoFrame(frame.Width, frame.Height, copy);
+    }
+
+    private double FadeAt()
+    {
+        if (_clip == null) return 1.0;
+        if (_clipEof)
+            return Math.Clamp(1.0 - (_elapsed - _clipEofElapsed) / FadeDurationSeconds, 0.0, 1.0);
+        return Math.Clamp(_elapsed / FadeDurationSeconds, 0.0, 1.0);
+    }
+
+    private void BeginClip()
+    {
+        StopClip();
+        _tickerText = null;
+        if (_current == null) return;
+
+        var box = _scenes?.SelectMany(s => s.Elements).OfType<Source>()
+            .FirstOrDefault(s => s.Type == SourceType.AlertBox);
+        _currentBox = box;
+        if (box != null && box.AlertShowTicker)
+        {
+            _tickerText = ComposeTicker(_current);
+            _tickerMethod = box.AlertDisplayMethod;
+        }
+
+        if (box == null || _clipDecoderFactory == null) return;
+        var path = _clipPathResolver?.Invoke(box);
+        if (string.IsNullOrWhiteSpace(path)) return;
+
+        _clipWidth = (int)Math.Max(1, box.Width);
+        _clipHeight = (int)Math.Max(1, box.Height);
+        try
+        {
+            _clipSawFrame = false;
+            _clipAudioHeard = false;
+            _clip = _clipDecoderFactory(path, _clipWidth, _clipHeight);
+            _clip.FrameAvailable += OnClipFrame;
+            _clip.AudioReady += OnClipAudio;
+            _clip.Completed += OnClipCompleted;
+            _clip.Start();
+            AppLog.Write($"Alert clip start: box {box.Id} path '{path}' {_clipWidth}x{_clipHeight}");
+        }
+        catch (Exception ex)
+        {
+            AppLog.Write(ex, "Alert clip setup failed");
+            StopClip(); // decode setup failed (bad path) — fall back to animations
+        }
+    }
+
+    private void StopClip()
+    {
+        var clip = _clip;
+        _clip = null;
+        _latestClipFrame = null;
+        _clipEof = false;
+        _clipSawFrame = false;
+        _clipAudioHeard = false;
+        if (clip == null) return;
+        clip.FrameAvailable -= OnClipFrame;
+        clip.AudioReady -= OnClipAudio;
+        clip.Completed -= OnClipCompleted;
+        try { clip.Stop(); } catch { /* already stopped */ }
+        clip.Dispose();
+    }
+
+    private void OnClipFrame(VideoFrame frame)
+    {
+        _clipSawFrame = true;
+        _latestClipFrame = frame;
+    }
+
+    private void OnClipCompleted()
+    {
+        _clipEof = true;
+        _clipEofElapsed = _elapsed;
+    }
+
+    private void OnClipAudio(AudioSample sample)
+    {
+        if (_audioSink == null) return;
+        _clipAudioHeard = true;
+        var volume = (float)Math.Clamp(_currentBox?.AlertVideoVolume ?? 1.0, 0.0, 1.0);
+        if (volume <= 0f) return;
+        var fade = FadeAt();
+        if (fade <= 0.0) return;
+
+        var data = sample.Samples;
+        if (fade < 1.0 || Math.Abs(volume - 1f) > 0.001f)
+        {
+            data = new float[data.Length];
+            var gain = volume * (float)fade;
+            for (var i = 0; i < sample.Samples.Length; i++)
+                data[i] = sample.Samples[i] * gain;
+        }
+        _audioSink(new AudioSample(data, sample.SampleRate, sample.Channels));
+    }
+
+    private void AdvanceToNext()
+    {
+        if (_queue.Count > 0)
+        {
+            _current = _queue.Dequeue();
+            _elapsed = 0;
+            BeginClip();
+        }
+        else
+        {
+            _ticker?.Stop();
+        }
+    }
+
+    private VideoFrame? RenderCore(Source alertBox, int width, int height, string key, int version)
+    {
+        _frameKey = key;
+        _frameVersion = version;
+        if (_current == null) return _cachedFrame = null;
+        return _cachedFrame = _renderer.Render(_current, Progress(), width, height);
+    }
+
+    private double Progress()
+    {
+        if (_current == null) return 0;
+        return Math.Clamp(_elapsed / DurationOf(_current), 0.0, 1.0);
+    }
+
+    private static double DurationOf(ChatMessage m) => m.Kind switch
+    {
+        ChatEventKind.SuperChat => 4.6,
+        ChatEventKind.SuperSticker => 4.2,
+        ChatEventKind.NewMember => 4.0,
+        ChatEventKind.MemberGift => 5.0,
+        ChatEventKind.GiftReceived => 4.4,
+        ChatEventKind.MemberMilestone => 4.8,
+        _ => 4.0,
+    };
+
+    private static string ComposeTicker(ChatMessage m)
+    {
+        var label = m.Kind switch
+        {
+            ChatEventKind.SuperChat => "Super Chat",
+            ChatEventKind.SuperSticker => "Super Sticker",
+            ChatEventKind.NewMember => "New Member",
+            ChatEventKind.MemberGift => "Membership Gift",
+            ChatEventKind.GiftReceived => "Gifted Membership",
+            ChatEventKind.MemberMilestone => "Member Milestone",
+            _ => "Stream Alert",
+        };
+        var amount = m.Kind is ChatEventKind.SuperChat or ChatEventKind.SuperSticker
+            && m.SuperChatDisplayString is { Length: > 0 } s
+                ? $" · {s}"
+                : "";
+        return $"{m.AuthorName} — {label}{amount}";
+    }
+
+    /// <summary>Render the current state onto one AlertBox preview (mirrors chat):
+    /// the playing frame, or null when idle so the source shows nothing until an
+    /// event actually fires.</summary>
+    public void UpdatePreview(Source alertBox)
+    {
+        try
+        {
+            var frame = RenderFrame(alertBox);
+            // Preview eyes (TASK 47, 2026-09-26): a healthy decode painted nothing on
+            // the canvas. UpdatePreview swallows its failures to Debug, so say once a
+            // second whether the box is being handed a frame at all.
+            if (IsPlaying)
+            {
+                var now = DateTime.UtcNow;
+                if (now - _lastPreviewLog >= TimeSpan.FromSeconds(1))
+                {
+                    _lastPreviewLog = now;
+                    AppLog.Write($"Alert preview: box {alertBox.Id} frame="
+                        + (frame == null ? "null" : $"{frame.Width}x{frame.Height} a{frame.BgraPixels[3]}"));
+                }
+            }
+            if (frame == null)
+            {
+                alertBox.VideoImageSource = null;
+                return;
+            }
+            var width = (int)Math.Max(1, alertBox.Width);
+            var height = (int)Math.Max(1, alertBox.Height);
+            var bitmap = new WriteableBitmap(width, height, 96, 96, PixelFormats.Bgra32, null);
+            bitmap.WritePixels(new Int32Rect(0, 0, width, height), frame.BgraPixels, frame.Stride, 0);
+            alertBox.VideoImageSource = bitmap;
+        }
+        catch (Exception ex)
+        {
+            System.Diagnostics.Debug.WriteLine($"Alert preview failed: {ex.Message}");
+        }
+    }
+
+    /// <summary>Wire property-change subscriptions for all AlertBox sources across
+    /// every scene (geometry changes re-render), and clear/reset their previews.</summary>
+    public void UpdateConfiguredBoxes(IEnumerable<Scene> scenes)
+    {
+        _scenes = scenes;
+        foreach (var scene in scenes)
+        foreach (var alertBox in scene.Elements.OfType<Source>().Where(s => s.Type == SourceType.AlertBox))
+        {
+            alertBox.PropertyChanged += (_, e) =>
+            {
+                if (e.PropertyName is nameof(Source.Width) or nameof(Source.Height))
+                    UpdatePreview(alertBox);
+            };
+            UpdatePreview(alertBox);
+        }
+    }
+
+    private void RefreshAlertPreviews()
+    {
+        // The announcement strip is a GLOBAL 1920px overlay, not a per-box frame, so
+        // it gets its own sink: until this existed the strip went only to the frame
+        // pump and was therefore invisible in the preview pane the creator watches
+        // (2026-09-26 — "I do not see the scrolling text").
+        _tickerPreviewSink?.Invoke(AlertTickerFrame);
+
+        if (_scenes == null) return;
+        foreach (var alertBox in _scenes.SelectMany(s => s.Elements).OfType<Source>()
+                     .Where(s => s.Type == SourceType.AlertBox))
+            UpdatePreview(alertBox);
+    }
+
+    public void Dispose()
+    {
+        _ticker?.Stop();
+        _queue.Clear();
+        _current = null;
+        StopClip();
+    }
+}

Services/AlertRenderer.cs

@@ -0,0 +1,389 @@
+using System.Globalization;
+using System.Windows;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using ytLive.Models;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// Renders one event's celebration animation into a BGRA8 frame for the AlertBox.
+/// Six event kinds, six UNIQUE animations — each a distinct gesture, palette and
+/// layout (the creator's ruling: these are the monetization shout-outs and free
+/// branded product placement; a one-template recoloring loses all interest in two
+/// iterations). Each card carries the bottom-right brand line so every broadcast
+/// of an event is an in-video ad placement.
+///
+/// <paramref name="t01"/> walks 0→1 over the whole animation; each kind splits it
+/// into enter / hold / exit phases with its own easing.
+/// </summary>
+public sealed class AlertRenderer
+{
+    private const double EnterEnd = 0.16;
+    private const double ExitStart = 0.80;
+    private const string Brand = "made with LlamaCasty!";
+
+    private static readonly CultureInfo Invariant = CultureInfo.InvariantCulture;
+    private static readonly Color White = Colors.White;
+    private static readonly Color[] ConfettiPalette =
+    {
+        Color.FromRgb(0xf4, 0x2f, 0x5f), Color.FromRgb(0xff, 0xd1, 0x66),
+        Color.FromRgb(0x38, 0xb6, 0xf8), Color.FromRgb(0xa7, 0x8b, 0xfa),
+        Color.FromRgb(0x39, 0xd3, 0x53),
+    };
+
+    public VideoFrame Render(ChatMessage e, double t01, int width, int height)
+    {
+        return e.Kind switch
+        {
+            ChatEventKind.SuperChat => SuperChat(e, t01, width, height),
+            ChatEventKind.SuperSticker => SuperSticker(e, t01, width, height),
+            ChatEventKind.NewMember => NewMember(e, t01, width, height),
+            ChatEventKind.MemberGift => MemberGift(e, t01, width, height),
+            ChatEventKind.GiftReceived => GiftReceived(e, t01, width, height),
+            ChatEventKind.MemberMilestone => Milestone(e, t01, width, height),
+            _ => SuperChat(e, t01, width, height),
+        };
+    }
+
+    private static VideoFrame SuperChat(ChatMessage e, double t, int w, int h)
+    {
+        var dpi = 96.0;
+        var visual = new DrawingVisual();
+        using (var ctx = visual.RenderOpen())
+        {
+            var margin = Math.Max(w, h) * 0.03;
+            var cardX = margin;
+            var cardW = w - margin * 2;
+            var cardH = h - margin * 2;
+            var cardCX = cardX + cardW / 2;
+
+            var enter = Clamp01(t / EnterEnd);
+            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
+            var exitEase = EaseInCubic(exit);
+            var cardY = Lerp(h + cardH, margin, EaseOutCubic(enter));
+            cardY = Lerp(cardY, -cardH, exitEase);
+
+            DrawCard(ctx, cardX, cardY, cardW, cardH, "#0d3b2b", "#14532d", 14);
+            DrawBrand(ctx, cardX, cardY, cardW, cardH);
+
+            var shownAmount = e.SuperChatDisplayString
+                ?? (e.SuperChatCurrency is { Length: > 0 } cur ? $"{cur}{e.SuperChatAmount:0.00}" : $"${e.SuperChatAmount:0.00}");
+            var fontSize = cardH * 0.24;
+            DrawCentered(ctx, shownAmount, cardCX, cardY + cardH * 0.24, fontSize, FontWeights.Bold, Color.FromRgb(0xff, 0xd1, 0x66), cardW);
+
+            DrawCentered(ctx, e.AuthorName, cardCX, cardY + cardH * 0.56, cardH * 0.13, FontWeights.SemiBold, White, cardW);
+            DrawCentered(ctx, e.Message, cardCX, cardY + cardH * 0.74, cardH * 0.10, FontWeights.Normal, Color.FromRgb(0xdd, 0xff, 0xf0), cardW * 0.92);
+
+            if (t >= EnterEnd && t <= ExitStart)
+            {
+                var sweep = (t - EnterEnd) / (ExitStart - EnterEnd);
+                var shineX = cardX + (sweep * 2 - 0.5) * cardW;
+                ctx.DrawRectangle(
+                    new LinearGradientBrush(
+                        Colors.Transparent,
+                        Color.FromArgb(0x30, 0xff, 0xff, 0xff),
+                        new Point(0, 0),
+                        new Point(1, 0)),
+                    null,
+                    new Rect(shineX - cardW * 0.25, cardY, cardW * 0.5, cardH));
+            }
+        }
+        return CreateFrame(visual, w, h, dpi);
+    }
+
+    private static VideoFrame SuperSticker(ChatMessage e, double t, int w, int h)
+    {
+        var dpi = 96.0;
+        var visual = new DrawingVisual();
+        using (var ctx = visual.RenderOpen())
+        {
+            var margin = Math.Max(w, h) * 0.04;
+            var cardW = w - margin * 2;
+            var cardH = h - margin * 2;
+            var cardCX = w / 2.0;
+
+            var enter = Clamp01(t / EnterEnd);
+            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
+            var scale = EaseOutBack(enter) * (0.85 + 0.15 * (1 - exit));
+            if (t > EnterEnd && t <= ExitStart)
+                scale = 1.0 + 0.02 * Math.Sin(t * 26.0);
+            var alpha = 1.0 - exit;
+
+            ctx.PushOpacity(alpha);
+
+            var slick = new RotateTransform(-6, w / 2.0, h / 2.0);
+            ctx.PushTransform(slick);
+            ctx.PushTransform(new ScaleTransform(scale, scale, w / 2.0, h / 2.0));
+
+            DrawCard(ctx, margin, margin, cardW, cardH, "#4a044e", "#7e22ce", 20);
+            DrawBrand(ctx, margin, margin, cardW, cardH);
+
+            var desc = string.IsNullOrWhiteSpace(e.SuperStickerDescription) ? "SUPER STICKER" : e.SuperStickerDescription.ToUpperInvariant();
+            DrawCentered(ctx, desc, cardCX, h / 2.0 - cardH * 0.12, cardH * 0.17, FontWeights.Bold, White, cardW * 0.9);
+
+            DrawCentered(ctx, e.AuthorName, cardCX, h / 2.0 + cardH * 0.16, cardH * 0.12, FontWeights.SemiBold, Color.FromRgb(0xff, 0xb3, 0xd9), cardW * 0.9);
+            var tier = e.SuperChatDisplayString ?? (e.SuperChatCurrency is { Length: > 0 } cur ? $"{cur}{e.SuperChatAmount:0.00}" : null);
+            if (!string.IsNullOrWhiteSpace(tier))
+                DrawCentered(ctx, tier, cardCX, h / 2.0 + cardH * 0.32, cardH * 0.10, FontWeights.Bold, Color.FromRgb(0xff, 0xd1, 0x66), cardW * 0.9);
+
+            ctx.Pop();
+            ctx.Pop();
+            ctx.Pop();
+        }
+        return CreateFrame(visual, w, h, dpi);
+    }
+
+    private static VideoFrame NewMember(ChatMessage e, double t, int w, int h)
+    {
+        var dpi = 96.0;
+        var visual = new DrawingVisual();
+        using (var ctx = visual.RenderOpen())
+        {
+            var margin = Math.Max(w, h) * 0.035;
+            var cardW = w - margin * 2;
+            var cardH = h - margin * 2;
+            var cardCX = w / 2.0;
+
+            var enter = Clamp01(t / EnterEnd);
+            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
+            var cardY = Lerp(-cardH, margin, EaseOutCubic(enter));
+            cardY = Lerp(cardY, h, EaseInCubic(exit));
+
+            DrawCard(ctx, margin, cardY, cardW, cardH, "#2e1065", "#5b21b6", 16);
+            DrawBrand(ctx, margin, cardY, cardW, cardH);
+
+            if (t <= ExitStart)
+            {
+                var bandP = EaseOutCubic(Clamp01(t / 0.22));
+                ctx.DrawRectangle(
+                    new LinearGradientBrush(Color.FromArgb(0, 0xff, 0xff, 0xff), Colors.Transparent, new Point(0, 0), new Point(0, 1)),
+                    null,
+                    new Rect(margin, cardY + cardH * 0.30, cardW * bandP, cardH * 0.18));
+            }
+
+            DrawCentered(ctx, e.AuthorName, cardCX, cardY + cardH * 0.36, cardH * 0.22, FontWeights.Bold, White, cardW * 0.9);
+            DrawCentered(ctx, "JOINED THE MEMBERSHIP", cardCX, cardY + cardH * 0.62, cardH * 0.11, FontWeights.SemiBold, Color.FromRgb(0xf5, 0xd0, 0xfe), cardW * 0.9);
+
+            var level = string.IsNullOrWhiteSpace(e.MembershipLevel) ? "MEMBER" : e.MembershipLevel.ToUpperInvariant();
+            DrawCentered(ctx, level, cardCX, cardY + cardH * 0.80, cardH * 0.10, FontWeights.Bold, Color.FromRgb(0xff, 0xd1, 0x66), cardW * 0.9);
+        }
+        return CreateFrame(visual, w, h, dpi);
+    }
+
+    private static VideoFrame MemberGift(ChatMessage e, double t, int w, int h)
+    {
+        var dpi = 96.0;
+        var visual = new DrawingVisual();
+        using (var ctx = visual.RenderOpen())
+        {
+            var margin = Math.Max(w, h) * 0.035;
+            var cardW = w - margin * 2;
+            var cardH = h - margin * 2;
+            var cardCX = w / 2.0;
+
+            var enter = Clamp01(t / EnterEnd);
+            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
+            var cardX = Lerp(-cardW, margin, EaseOutCubic(enter));
+            cardX = Lerp(cardX, -cardW, EaseInCubic(exit));
+
+            DrawCard(ctx, cardX, margin, cardW, cardH, "#422006", "#a16207", 16);
+            DrawBrand(ctx, cardX, margin, cardW, cardH);
+
+            var count = Math.Max(1, e.GiftNewMembersCount);
+            var spread = 1.0 - exit;
+            var hero = count > 1 ? $"×{count}" : "MEMBERSHIP";
+            DrawCentered(ctx, hero, cardCX, margin + cardH * 0.24, cardH * 0.26, FontWeights.Bold, Color.FromRgb(0xff, 0xd1, 0x66), cardW * 0.8);
+            DrawCentered(ctx, $"{e.AuthorName} is gifting", cardCX, margin + cardH * 0.52, cardH * 0.11, FontWeights.SemiBold, White, cardW * 0.9);
+
+            var chipCount = Math.Min(count, 6);
+            for (var i = 0; i < chipCount; i++)
+            {
+                var slot = (chipCount - 1) * 0.5;
+                var gap = cardH * 0.13 * EaseOutCubic(Clamp01(t / 0.30)) * spread;
+                var chipX = cardCX + (i - slot) * gap;
+                var chipY = margin + cardH * 0.70 + Math.Sin((i + t * 6) * 2.4) * cardH * 0.015;
+                ctx.DrawRoundedRectangle(
+                    new SolidColorBrush(Color.FromRgb(0xff, 0xf3, 0xc4)),
+                    null,
+                    new Rect(chipX - cardH * 0.05, chipY, cardH * 0.10, cardH * 0.10),
+                    cardH * 0.03, cardH * 0.03);
+            }
+        }
+        return CreateFrame(visual, w, h, dpi);
+    }
+
+    private static VideoFrame GiftReceived(ChatMessage e, double t, int w, int h)
+    {
+        var dpi = 96.0;
+        var visual = new DrawingVisual();
+        using (var ctx = visual.RenderOpen())
+        {
+            var margin = Math.Max(w, h) * 0.04;
+            var cardW = w - margin * 2;
+            var cardH = h - margin * 2;
+            var cardCX = w / 2.0;
+
+            var enter = Clamp01(t / (EnterEnd * 1.4));
+            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
+            var scale = 0.5 + 0.5 * EaseOutBack(enter);
+            var alpha = Math.Min(1.0, enter * 1.6) * (1 - exit);
+
+            ctx.PushOpacity(alpha);
+            ctx.PushTransform(new ScaleTransform(scale, scale, w / 2.0, h / 2.0));
+
+            DrawCard(ctx, margin, margin, cardW, cardH, "#14532d", "#4c1d95", 18);
+            DrawBrand(ctx, margin, margin, cardW, cardH);
+
+            // Confetti falling inside the card during the hold (deterministic seed).
+            if (t >= EnterEnd && t <= ExitStart)
+            {
+                var hold = (t - EnterEnd) / (ExitStart - EnterEnd);
+                for (var i = 0; i < 14; i++)
+                {
+                    var seed = i * 37 + 11;
+                    var dotX = margin + cardW * (((seed * 53) % 97) / 97.0);
+                    var dotY = margin + cardH * (((seed + hold * 0.85) % 1.0));
+                    var size = cardH * 0.02 + (i % 3) * cardH * 0.006;
+                    ctx.DrawRectangle(
+                        new SolidColorBrush(ConfettiPalette[i % ConfettiPalette.Length]),
+                        null,
+                        new Rect(dotX, dotY, size, size));
+                }
+            }
+
+            DrawCentered(ctx, "GIFTED MEMBERSHIP", cardCX, margin + cardH * 0.22, cardH * 0.12, FontWeights.Bold, Color.FromRgb(0xff, 0xd1, 0x66), cardW * 0.9);
+            var giver = string.IsNullOrWhiteSpace(e.GifterName) ? e.AuthorName : e.GifterName;
+            DrawCentered(ctx, giver, cardCX, margin + cardH * 0.42, cardH * 0.20, FontWeights.Bold, White, cardW * 0.9);
+            DrawCentered(ctx, "gave you a membership — celebrate!", cardCX, margin + cardH * 0.68, cardH * 0.11, FontWeights.Normal, Color.FromRgb(0xdb, 0xff, 0xf0), cardW * 0.9);
+
+            ctx.Pop();
+            ctx.Pop();
+        }
+        return CreateFrame(visual, w, h, dpi);
+    }
+
+    private static VideoFrame Milestone(ChatMessage e, double t, int w, int h)
+    {
+        var dpi = 96.0;
+        var visual = new DrawingVisual();
+        using (var ctx = visual.RenderOpen())
+        {
+            var margin = Math.Max(w, h) * 0.04;
+            var cardW = w - margin * 2;
+            var cardH = h - margin * 2;
+            var cardCX = w / 2.0;
+
+            var enter = Clamp01(t / EnterEnd);
+            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
+            var cardY = Lerp(h + cardH, margin, EaseOutCubic(enter));
+            cardY = Lerp(cardY, -cardH, EaseInCubic(exit));
+
+            DrawCard(ctx, margin, cardY, cardW, cardH, "#431407", "#c2410c", 14);
+            DrawBrand(ctx, margin, cardY, cardW, cardH);
+
+            var hero = e.MilestoneMonths > 0 ? $"{e.MilestoneMonths}" : "MILESTONE";
+            DrawCentered(ctx, hero, cardCX, cardY + cardH * 0.26, cardH * 0.30, FontWeights.Bold, Color.FromRgb(0xff, 0xdd, 0x66), cardW * 0.8);
+
+            var sub = e.MilestoneMonths > 0 ? "MONTHS STRONG" : "SUPPORTING THE STREAM";
+            DrawCentered(ctx, sub, cardCX, cardY + cardH * 0.52, cardH * 0.11, FontWeights.SemiBold, White, cardW * 0.9);
+            DrawCentered(ctx, "— " + e.AuthorName + " —", cardCX, cardY + cardH * 0.70, cardH * 0.10, FontWeights.Normal, Color.FromRgb(0xff, 0xe8, 0xd0), cardW * 0.9);
+
+            // Tenure bar: grows through the first half, retracts on exit.
+            var barP = Clamp01((t - 0.10) / 0.55) * (1 - exit);
+            var barW = cardW * 0.6 * barP;
+            ctx.DrawRoundedRectangle(
+                new SolidColorBrush(Color.FromRgb(0xff, 0xd1, 0x66)),
+                null,
+                new Rect(cardCX - barW / 2, cardY + cardH * 0.84, barW, cardH * 0.045),
+                4, 4);
+        }
+        return CreateFrame(visual, w, h, dpi);
+    }
+
+    // ─── Shared drawing ───
+
+    private static void DrawCard(DrawingContext ctx, double x, double y, double w, double h, string fromHex, string toHex, double radius)
+    {
+        var brush = new LinearGradientBrush(ParseColor(fromHex), ParseColor(toHex), new Point(0, 0), new Point(1, 1));
+        ctx.DrawRoundedRectangle(brush, new Pen(new SolidColorBrush(Color.FromArgb(0x66, 0xff, 0xff, 0xff)), Math.Max(1, radius * 0.06)), new Rect(x, y, w, h), radius, radius);
+    }
+
+    private static void DrawBrand(DrawingContext ctx, double x, double y, double w, double h)
+    {
+        var formatted = new FormattedText(
+            Brand, Invariant, FlowDirection.LeftToRight,
+            new Typeface(new FontFamily("Segoe UI"), FontStyles.Normal, FontWeights.Normal, FontStretches.Normal),
+            Math.Max(9, h * 0.055),
+            new SolidColorBrush(Color.FromArgb(0x88, 0xff, 0xff, 0xff)),
+            96.0);
+        ctx.DrawText(formatted, new Point(x + w - formatted.Width - h * 0.08, y + h - formatted.Height - h * 0.05));
+    }
+
+    private static void DrawCentered(DrawingContext ctx, string text, double cx, double cy, double size, FontWeight weight, Color color, double maxWidth)
+    {
+        var formatted = new FormattedText(
+            text, Invariant, FlowDirection.LeftToRight,
+            new Typeface(new FontFamily("Segoe UI"), FontStyles.Normal, weight, FontStretches.Normal),
+            size,
+            new SolidColorBrush(color),
+            96.0);
+        formatted.MaxTextWidth = maxWidth;
+        formatted.MaxLineCount = 1;
+        formatted.Trimming = TextTrimming.CharacterEllipsis;
+        ctx.DrawText(formatted, new Point(cx - formatted.Width / 2, cy - formatted.Height / 2));
+    }
+
+    private static Color ParseColor(string hex)
+    {
+        hex = hex.Trim().TrimStart('#');
+        if (hex.Length == 6)
+        {
+            var r = byte.Parse(hex.AsSpan(0, 2), NumberStyles.HexNumber);
+            var g = byte.Parse(hex.AsSpan(2, 2), NumberStyles.HexNumber);
+            var b = byte.Parse(hex.AsSpan(4, 2), NumberStyles.HexNumber);
+            return Color.FromRgb(r, g, b);
+        }
+        if (hex.Length == 8)
+        {
+            var a = byte.Parse(hex.AsSpan(0, 2), NumberStyles.HexNumber);
+            var r = byte.Parse(hex.AsSpan(2, 2), NumberStyles.HexNumber);
+            var g = byte.Parse(hex.AsSpan(4, 2), NumberStyles.HexNumber);
+            var b = byte.Parse(hex.AsSpan(6, 2), NumberStyles.HexNumber);
+            return Color.FromArgb(a, r, g, b);
+        }
+        return Colors.White;
+    }
+
+    private static VideoFrame CreateFrame(DrawingVisual visual, int width, int height, double dpi)
+    {
+        var rtb = new RenderTargetBitmap(width, height, dpi, dpi, PixelFormats.Pbgra32);
+        rtb.Render(visual);
+
+        var stride = width * 4;
+        var pixels = new byte[stride * height];
+        rtb.CopyPixels(pixels, stride, 0);
+
+        for (var i = 0; i < pixels.Length; i += 4)
+        {
+            (pixels[i], pixels[i + 2]) = (pixels[i + 2], pixels[i]);
+        }
+
+        return new VideoFrame(width, height, pixels);
+    }
+
+    private static double Clamp01(double v) => Math.Clamp(v, 0.0, 1.0);
+
+    private static double Lerp(double a, double b, double p) => a + (b - a) * p;
+
+    private static double EaseInCubic(double p) => p * p * p;
+
+    private static double EaseOutCubic(double p) => 1 - Math.Pow(1 - p, 3);
+
+    private static double EaseOutBack(double p)
+    {
+        const double c1 = 1.70158;
+        const double c3 = c1 + 1;
+        return 1 + c3 * Math.Pow(p - 1, 3) + c1 * Math.Pow(p - 1, 2);
+    }
+}

Services/Audio/AudioGainProvider.cs

@@ -28,8 +28,12 @@ public sealed class AudioGainProvider
     /// <summary>Mic gain for the live mix (0 = muted).</summary>
     public double MicGain() => _micMuted() ? 0 : _micVolume();
 
-    /// <summary>Loopback (desktop/game) gain for the live mix (0 = muted, 1 = unity).
-    /// Unity because the slider now drives system volume via PushSystemVolume,
-    /// so the WASAPI loopback signal is already scaled by the user's volume choice.</summary>
-    public double LoopbackGain() => _gameMuted() ? 0 : 1.0;
+    /// <summary>Loopback (desktop/game) gain for the live mix (0 = muted).
+    /// Honesty rule (2026-09-01): WASAPI loopback capture does NOT shrink with the
+    /// endpoint volume — the creator dropped system volume to 20% and the captured
+    /// level stayed pegged — so the mixer must multiply by GameAudioVolume itself
+    /// for the stream to follow the knob (the old unity assumption left the stream
+    /// at full desktop volume while the headphones went quiet; ai.md always
+    /// specified loopbackGain = GameAudioVolume — the code had drifted).</summary>
+    public double LoopbackGain() => _gameMuted() ? 0 : _gameVolume();
 }

Services/Audio/AudioMixer.cs

@@ -1,3 +1,4 @@
+using ytLive.Helpers;
 using ytLive.Services;
 
 namespace ytLive.Services.Audio;
@@ -13,7 +14,9 @@ namespace ytLive.Services.Audio;
 /// queues, applies the honest gains (mic = MicVolume, loopback = unity
 /// × auto-duck when the mic is hot — the slider drives system volume via mixes them to stereo float, runs the
 /// master limiter (a -1 dBFS ceiling so the sum never clips the encoder), and
-/// writes the chunk to the encoder's audio pipe.
+/// writes the chunk to the encoder's audio pipe. Since TASK 47 the alert layer's
+/// clip audio joins the same mix (pre-scaled, unity-added, never ducked) through
+/// <see cref="EnqueueAlertAudio"/>.
 /// </summary>
 public sealed class AudioMixer : IDisposable
 {
@@ -29,12 +32,16 @@ public sealed class AudioMixer : IDisposable
     private readonly Func<double>? _micGain;
     private readonly Func<double>? _loopbackGain;
     private readonly TimeSpan _mixInterval;
+    private readonly Func<int>? _syncOffsetMs;
+    private readonly AudioSyncDelay _syncDelay;
+    private int _advanceSamplesRemaining;
     private bool _started;
 
     // Live path (TASK 9): per-source resampling → voice chain on the mic →
     // thread-safe queues → the ducker + gain/mix loop → the encoder's pipe.
     private readonly AudioRingBuffer _micBuffer;
     private readonly AudioRingBuffer _loopbackBuffer;
+    private readonly AudioRingBuffer _alertBuffer;
     private readonly VoiceFilterChain _voiceChain;
     private readonly AutoDucker _ducker;
     private readonly MasterLimiter _masterLimiter = new();
@@ -44,7 +51,14 @@ public sealed class AudioMixer : IDisposable
     private NamedPipeAudioWriter _pipe = new();
     private float[]? _micChunk;
     private float[]? _loopbackChunk;
+    private float[]? _alertChunk;
     private float[]? _mixBuffer;
+    private float[]? _delayedMix;
+    private DateTime _lastLoopErrorLogged = DateTime.MinValue;
+    private DateTime _nextStatsLog = DateTime.UtcNow + TimeSpan.FromSeconds(5);
+    private long _micDrainedTotal;
+    private long _loopDrainedTotal;
+    private float _peakMix;
 
     public AudioMixer(
         IAudioSource mic,
@@ -52,6 +66,7 @@ public sealed class AudioMixer : IDisposable
         Action<string>? log = null,
         Func<double>? micGain = null,
         Func<double>? loopbackGain = null,
+        Func<int>? syncOffsetMs = null,
         TimeSpan? mixInterval = null)
     {
         _mic = mic;
@@ -61,17 +76,22 @@ public sealed class AudioMixer : IDisposable
         _log = log;
         _micGain = micGain;
         _loopbackGain = loopbackGain;
+        _syncOffsetMs = syncOffsetMs;
+        _syncDelay = new AudioSyncDelay(OutputSampleRate);
         _mixInterval = mixInterval ?? DefaultMixInterval;
 
         var seconds = _mixInterval.TotalSeconds;
         var framesPerTick = Math.Max(1, (int)Math.Round(OutputSampleRate * seconds));
         _micBuffer = new AudioRingBuffer(OutputSampleRate * 2);
         _loopbackBuffer = new AudioRingBuffer(OutputSampleRate * 2 * 2);
+        _alertBuffer = new AudioRingBuffer(OutputSampleRate * 2 * 8);
         _voiceChain = new VoiceFilterChain(OutputSampleRate);
         _ducker = new AutoDucker();
         _micChunk = new float[framesPerTick];
         _loopbackChunk = new float[framesPerTick * 2];
+        _alertChunk = new float[framesPerTick * 2];
         _mixBuffer = new float[framesPerTick * 2];
+        _delayedMix = new float[framesPerTick * 2];
 
         _mic.Started += OnMicStarted;
         _mic.SampleReady += OnMicSample;
@@ -146,19 +166,48 @@ public sealed class AudioMixer : IDisposable
         if (_liveCts != null)
             return;
 
+        // Capture runs from app STARTUP for the meters, so both rings carry up
+        // to a full ring depth (~2s) of pre-live backlog by the time the user
+        // hits record; draining it made every recorded event land ~2s late in
+        // the audio track (2026-09-14, two confirmed takes). Discard it so the
+        // recording starts at go-live. The writers keep running concurrently;
+        // Clear under the ring's lock, so only the in-flight chunk is dropped.
+        _micBuffer.Clear();
+        _loopbackBuffer.Clear();
+        _alertBuffer.Clear();
+
+        // Negative sync offset (audio runs BEHIND video): OBS's fix is to "eat
+        // the head of the buffer" — discard the first |N| ms of the live stream
+        // so every subsequent audio event lands |N| ms EARLIER in the recording.
+        // Armed once at go-live (you can't eat the head mid-stream); positive
+        // offsets stay live-reactive through the delay line in FillAndMix.
+        var syncMs = _syncOffsetMs?.Invoke() ?? 0;
+        _advanceSamplesRemaining = syncMs < 0
+            ? (int)Math.Round(OutputSampleRate / 1000.0 * -syncMs) * 2
+            : 0;
+        if (_advanceSamplesRemaining > 0)
+            _log?.Invoke($"Audio live: advance armed ({-syncMs} ms ahead)");
+
         var cts = new CancellationTokenSource();
         _liveCts = cts;
         _pipe = new NamedPipeAudioWriter();
         _pipe.Start(pipeName);
+        _log?.Invoke($"Audio live: started, pipe '{pipeName}'");
         _ = Task.Run(() => LiveLoopAsync(_pipe, cts.Token));
     }
 
     /// <summary>Ends the live mix loop and closes the audio pipe — ffmpeg sees
-    /// EOF on the audio input. Safe when not live.</summary>
+    /// EOF on the audio input. Safe when not live: the writer's Stop() is idempotent
+    /// (StopStream now calls this on every rollback path).</summary>
     public void StopLive()
     {
-        _liveCts?.Cancel();
+        var cts = _liveCts;
         _liveCts = null;
+        if (cts != null)
+        {
+            _log?.Invoke("Audio live: stopped");
+            cts.Cancel();
+        }
         _pipe.Stop();
     }
 
@@ -204,6 +253,34 @@ public sealed class AudioMixer : IDisposable
         LoopbackLevelChanged?.Invoke(level);
     }
 
+    /// <summary>Drops the alert clip's audio into its own ring (TASK 47 — the
+    /// stream-alert video's soundtrack, pre-scaled by the alert layer to
+    /// volume × fade). Mixed at unity into the live output — NO auto-duck: an
+    /// alert must be heard over the mic, so the Creator's per-alert volume
+    /// slider is the honest gain and nothing else is stacked on top. Monno and
+    /// non-48k sources are normalized (the decoder already emits 48k stereo).</summary>
+    public void EnqueueAlertAudio(AudioSample sample)
+    {
+        var data = sample.Samples;
+        if (data.Length == 0) return;
+        if (sample.SampleRate != OutputSampleRate)
+            data = ResampleLoopback(data, sample.SampleRate);
+        if (sample.Channels == 1)
+            data = UpmixToStereo(data);
+        _alertBuffer.Write(data);
+    }
+
+    private static float[] UpmixToStereo(float[] mono)
+    {
+        var stereo = new float[mono.Length * 2];
+        for (var i = 0; i < mono.Length; i++)
+        {
+            stereo[i * 2] = mono[i];
+            stereo[i * 2 + 1] = mono[i];
+        }
+        return stereo;
+    }
+
     private void OnMicFailed(Exception ex)
     {
         _log?.Invoke($"Mic capture failed: {ex.Message}");
@@ -263,8 +340,42 @@ public sealed class AudioMixer : IDisposable
             var nextTick = DateTime.UtcNow + _mixInterval;
             try
             {
-                FillAndMix(micChunk, loopbackChunk, mixBuffer);
-                await pipe.WriteAsync(mixBuffer, cancellationToken).ConfigureAwait(false);
+                var (_, micDrained, loopDrained) = FillAndMix(micChunk, loopbackChunk, mixBuffer);
+
+                // Negative offset: skip the armed |N| ms of stream head. The pipe
+                // writer tolerates a partial chunk (any float length is valid);
+                // dropping the head re-anchors the audio stream against the video
+                // stream, making each event land earlier — OBS's eat-the-head fix.
+                var writeFrom = 0;
+                if (_advanceSamplesRemaining > 0)
+                {
+                    var drop = Math.Min(_advanceSamplesRemaining, mixBuffer.Length);
+                    _advanceSamplesRemaining -= drop;
+                    writeFrom = drop;
+                }
+
+                if (writeFrom < mixBuffer.Length)
+                    await pipe.WriteAsync(mixBuffer.AsMemory(writeFrom), cancellationToken).ConfigureAwait(false);
+
+                _micDrainedTotal += micDrained;
+                _loopDrainedTotal += loopDrained;
+                for (var i = writeFrom; i < mixBuffer.Length; i++)
+                {
+                    var abs = Math.Abs(mixBuffer[i]);
+                    if (abs > _peakMix) _peakMix = abs;
+                }
+
+                var now = DateTime.UtcNow;
+                if (now >= _nextStatsLog && _log != null)
+                {
+                    _nextStatsLog = now + TimeSpan.FromSeconds(5);
+                    _log($"Audio live: pipe connected={pipe.IsConnected} dropped writes={pipe.DroppedWrites} " +
+                         $"micLevel={_meter.Level:F3} loopLevel={_loopbackMeter.Level:F3} " +
+                         $"drained {_micDrainedTotal:N0}/{_loopDrainedTotal:N0} samples peakMix {_peakMix:F3} (per 5s)");
+                    _micDrainedTotal = 0;
+                    _loopDrainedTotal = 0;
+                    _peakMix = 0;
+                }
             }
             catch (OperationCanceledException)
             {
@@ -272,7 +383,18 @@ public sealed class AudioMixer : IDisposable
             }
             catch (Exception ex)
             {
-                _log?.Invoke($"Audio live loop error: {ex.Message}");
+                // Throttled + never on a dead session: the 2026-09-01 first-launch flood
+                // was one logged NRE every 10ms tick (see _delayedMix fix). Log at most
+                // once per 5s, and stop looping if the pipe writer is gone for good.
+                if (cancellationToken.IsCancellationRequested)
+                    break;
+                var now = DateTime.UtcNow;
+                if (now - _lastLoopErrorLogged >= TimeSpan.FromSeconds(5))
+                {
+                    _lastLoopErrorLogged = now;
+                    AppLog.Write(ex, "Audio live loop error");
+                    _log?.Invoke($"Audio live loop error: {ex.Message}");
+                }
             }
 
             var delay = nextTick - DateTime.UtcNow;
@@ -291,11 +413,16 @@ public sealed class AudioMixer : IDisposable
     }
 
     /// <summary>Drains one tick's worth of mic + loopback, silence-fills any
-    /// underrun, applies the ducker and the honest gains, and mixes to stereo.</summary>
-    private float FillAndMix(float[] micChunk, float[] loopbackChunk, float[] mix)
+    /// underrun, applies the ducker and the honest gains, and mixes to stereo.
+    /// Returns the pre-duck mic RMS and how many samples each buffer contributed
+    /// (the 5s live-loop telemetry reads those to name whether capture or the
+    /// pipe starved a silent recording).</summary>
+    private (float MicRms, int MicDrained, int LoopDrained) FillAndMix(float[] micChunk, float[] loopbackChunk, float[] mix)
     {
         var micCount = _micBuffer.Read(micChunk, micChunk.Length);
         var loopCount = _loopbackBuffer.Read(loopbackChunk, loopbackChunk.Length);
+        var alertChunk = _alertChunk!;
+        var alertCount = _alertBuffer.Read(alertChunk, alertChunk.Length);
 
         float micRms = 0;
         if (micCount == 0)
@@ -321,6 +448,15 @@ public sealed class AudioMixer : IDisposable
             Array.Clear(loopbackChunk, loopCount, loopbackChunk.Length - loopCount);
         }
 
+        if (alertCount == 0)
+        {
+            Array.Clear(alertChunk, 0, alertChunk.Length);
+        }
+        else if (alertCount < alertChunk.Length)
+        {
+            Array.Clear(alertChunk, alertCount, alertChunk.Length - alertCount);
+        }
+
         var duck = _ducker.Update(micRms);
         var micGain = (float)(_micGain?.Invoke() ?? 1.0);
         var loopGain = (float)(_loopbackGain?.Invoke() ?? 1.0) * duck;
@@ -329,10 +465,17 @@ public sealed class AudioMixer : IDisposable
         for (var i = 0; i < frames; i++)
         {
             var m = micChunk[i] * micGain;
-            mix[i * 2] = m + loopbackChunk[i * 2] * loopGain;
-            mix[i * 2 + 1] = m + loopbackChunk[i * 2 + 1] * loopGain;
+            mix[i * 2] = m + loopbackChunk[i * 2] * loopGain + alertChunk[i * 2];
+            mix[i * 2 + 1] = m + loopbackChunk[i * 2 + 1] * loopGain + alertChunk[i * 2 + 1];
         }
         _masterLimiter.Process(mix);
-        return micRms;
+
+        _syncDelay.Configure(_syncOffsetMs?.Invoke() ?? 0);
+        var delayed = _delayedMix;
+        if (delayed is null || delayed.Length < mix.Length)
+            delayed = _delayedMix = new float[mix.Length];
+        _syncDelay.Process(mix, delayed);
+        Array.Copy(delayed, mix, mix.Length);
+        return (micRms, micCount, loopCount);
     }
 }

Services/Audio/AudioSyncDelay.cs

@@ -0,0 +1,94 @@
+using System;
+
+namespace ytLive.Services.Audio;
+
+/// <summary>
+/// TASK 22: a fixed end-to-end audio delay applied to the interleaved stereo
+/// mix in <see cref="AudioMixer"/>. This is OBS's documented fix for the
+/// "audio is ahead of video" lip-sync case: delay the audio by a few
+/// milliseconds so it lands on the video. It is a pure delay line — input in,
+/// the same audio N ms later out — so it is trivially testable and carries no
+/// state outside its own ring.
+///
+/// Positive offsets only (0..500 ms). Advancing audio (the audio runs BEHIND
+/// the video) is handled upstream in <see cref="AudioMixer"/>, not here: the
+/// mixer eats the first |N| ms of the live stream head (OBS's negative sync —
+/// see <see cref="AudioMixer.StartLive"/>), keeping this line a pure delay.
+/// Changing the delay flushes the line, so a live slider change clicks rather
+/// than smearing. Safe to call from any thread — the mixer owns it.
+/// </summary>
+public sealed class AudioSyncDelay
+{
+    private readonly int _sampleRate;
+
+    private float[] _buffer = Array.Empty<float>();
+    private int _delaySamples;
+    private int _writePos;
+
+    public AudioSyncDelay(int sampleRate)
+    {
+        _sampleRate = Math.Max(1, sampleRate);
+        Configure(0);
+    }
+
+    /// <summary>Sets the delay in whole milliseconds (clamped to 0..500). A no-op
+    /// when the delay hasn't actually changed — <see cref="AudioMixer.FillAndMix"/>
+    /// calls this every ~10ms tick (it re-reads the live UI setting each mix), and
+    /// unconditionally reallocating+zeroing the line every tick (the 2026-09-12
+    /// total-silence bug: any non-zero saved offset wiped the ring before its own
+    /// delayed samples could ever be read back — mic/loop meters, sampled BEFORE
+    /// this stage, kept showing real levels while the pipe stayed pure silence)
+    /// discarded the entire buffered history every 10ms. Changing the delay still
+    /// flushes the line (a live slider change clicks rather than smearing).</summary>
+    public void Configure(int delayMs)
+    {
+        var delaySamples = Frames(delayMs);
+        if (delaySamples == _delaySamples && _buffer.Length > 0) return;
+        _delaySamples = delaySamples;
+        _buffer = new float[(_delaySamples + _sampleRate) * 2 + 1024];
+        _writePos = 0;
+    }
+
+    /// <summary>Delays an interleaved stereo chunk by the configured offset.
+    /// The returned length equals <paramref name="input"/>'s; the head is
+    /// silence until the line fills.</summary>
+    public void Process(ReadOnlySpan<float> input, Span<float> output)
+    {
+        if (output.Length < input.Length)
+            throw new ArgumentException("output must be at least as long as input", nameof(output));
+
+        var len = input.Length;
+        if (_delaySamples == 0)
+        {
+            input.CopyTo(output);
+            return;
+        }
+
+        var line = _buffer;
+        var lineLen = line.Length;
+        for (var i = 0; i < len; i++)
+        {
+            line[_writePos] = input[i];
+            _writePos++;
+            if (_writePos == lineLen)
+                _writePos = 0;
+        }
+
+        var readStart = (_writePos - _delaySamples - len + lineLen * 2) % lineLen;
+        for (var i = 0; i < len; i++)
+        {
+            var idx = readStart + i;
+            if (idx >= lineLen)
+                idx -= lineLen;
+            output[i] = line[idx];
+        }
+    }
+
+    private int Frames(int delayMs)
+    {
+        var clamped = Math.Clamp(delayMs, 0, 500);
+        // Interleaved stereo: each frame is two samples (L, R), so the delay
+        // in buffer positions is twice the frame count.
+        return (int)Math.Round(_sampleRate / 1000.0 * clamped) * 2;
+    }
+}

Services/Audio/NamedPipeAudioWriter.cs

@@ -17,6 +17,12 @@ public interface IAudioPipeWriter : IDisposable
     /// <summary>True once ffmpeg has connected and the pipe is writable.</summary>
     bool IsConnected { get; }
 
+    /// <summary>Count of <see cref="WriteAsync"/> calls that wrote nothing because
+    /// the pipe wasn't connected yet or was already closed. Part of the silent-
+    /// recording diagnosis: nonzero means audio was dropped before ffmpeg ever
+    /// connected to the pipe.</summary>
+    long DroppedWrites { get; }
+
     /// <summary>Writes interleaved float samples; dropped until the client connects.</summary>
     Task WriteAsync(ReadOnlyMemory<float> samples, CancellationToken cancellationToken = default);
 
@@ -29,6 +35,9 @@ public sealed class NamedPipeAudioWriter : IAudioPipeWriter
     private readonly object _sync = new();
     private NamedPipeServerStream? _pipe;
 
+    /// <inheritdoc/>
+    public long DroppedWrites { get; private set; }
+
     public void Start(string pipeName)
     {
         lock (_sync)
@@ -64,7 +73,11 @@ public sealed class NamedPipeAudioWriter : IAudioPipeWriter
             pipe = _pipe;
         }
         if (pipe == null || !pipe.IsConnected || samples.IsEmpty)
+        {
+            if (pipe?.IsConnected == false || pipe == null)
+                DroppedWrites++;
             return;
+        }
 
         var bytes = MemoryMarshal.AsBytes(samples.Span).ToArray();
         await pipe.WriteAsync(bytes, cancellationToken).ConfigureAwait(false);

Services/CameraManager.cs

@@ -171,6 +171,18 @@ public sealed class CameraManager : IDisposable
         toStop.PreviewBitmap = null;
     }
 
+    /// <summary>
+    /// True while a session exists for the device — started, or still starting.
+    /// Used by the app's startup resource check to avoid double-acquiring a lock
+    /// that the saved identity's scene configs already hold. A rolled-back (failed)
+    /// session is removed, so this goes false and the startup pass can retry.
+    /// </summary>
+    public bool IsRunning(string deviceId)
+    {
+        lock (_gate)
+            return _sessions.ContainsKey(deviceId);
+    }
+
     public VideoFrame? GetLatestFrame(string deviceId)
     {
         lock (_gate)

Services/ChannelStatsService.cs

@@ -0,0 +1,132 @@
+using System.Net.Http;
+using System.Text.Json;
+using ytLive.Models;
+using AppLog = ytLive.Helpers.AppLog;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// Pulls a connected channel's YPP-relevant numbers from the YouTube Data API
+/// (TASK 39, slice 1): subscriptions/views/videos via channels.list, and the
+/// count of public uploads in the trailing 90 days via playlistItems.list on the
+/// uploads playlist. Long-form watch hours and Shorts-feed views need the
+/// Analytics API (a later slice behind the IChannelStatsProvider seam).
+///
+/// NOTE (root cause, 2026-09-23): channels.list must NOT request the
+/// `auditDetails` part — that part alone requires the
+/// `youtubepartner-channel-audit` scope the app doesn't (and mustn't) hold, and
+/// the whole request 403s `insufficientPermissions` over it. Standing flags are
+/// not exposed to ordinary apps; the drawer deep-links to YouTube Studio instead.
+/// </summary>
+public class ChannelStatsService
+{
+    private readonly YouTubeAuthService _auth;
+    private readonly HttpClient _http;
+    private const string ApiBase = "https://www.googleapis.com/youtube/v3";
+
+    public ChannelStatsService(YouTubeAuthService auth, HttpClient? http = null)
+    {
+        _auth = auth;
+        _http = http ?? new HttpClient();
+    }
+
+    private async Task<bool> EnsureToken()
+    {
+        if (_auth.CurrentChannel == null) return false;
+        if (_auth.CurrentChannel.TokenExpiry <= DateTime.UtcNow.AddMinutes(5))
+            return await _auth.RefreshToken();
+        return true;
+    }
+
+    /// <summary>Captures the channel's current stats into a snapshot, or null when
+    /// there's no session, a request fails, or the API returns nothing. Never throws.</summary>
+    public virtual async Task<YppStatSnapshot?> CaptureCurrentAsync()
+    {
+        if (!await EnsureToken()) return null;
+
+        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
+
+        var response = await _http.GetAsync(
+            $"{ApiBase}/channels?mine=true&part=statistics,contentDetails");
+        if (!response.IsSuccessStatusCode)
+        {
+            // Log the response body: YouTube's error.reason names the failure
+            // (insufficientPermissions / quotaExceeded / …) — the bare code was
+            // undiagnosable for the 2026-09-23 auditDetails 403.
+            var errorBody = await response.Content.ReadAsStringAsync();
+            AppLog.Write($"YPP stats: channels.list failed ({(int)response.StatusCode}): {errorBody}");
+            return null;
+        }
+
+        var json = JsonSerializer.Deserialize<JsonElement>(await response.Content.ReadAsStringAsync());
+        if (!json.TryGetProperty("items", out var items) || items.GetArrayLength() == 0)
+            return null;
+
+        var channel = items[0];
+        var statistics = channel.GetProperty("statistics");
+
+        var uploadsPlaylistId = channel.TryGetProperty("contentDetails", out var contentDetails)
+            && contentDetails.TryGetProperty("relatedPlaylists", out var related)
+            && related.TryGetProperty("uploads", out var uploads)
+            ? uploads.GetString()
+            : null;
+
+        var uploadsLast90Days = uploadsPlaylistId != null
+            ? await CountUploadsLast90DaysAsync(uploadsPlaylistId)
+            : 0;
+
+        return new YppStatSnapshot
+        {
+            CapturedAtUtc = DateTime.UtcNow,
+            SubscriberCount = ReadInt64(statistics, "subscriberCount"),
+            VideoCount = ReadInt64(statistics, "videoCount"),
+            TotalViews = ReadInt64(statistics, "viewCount"),
+            UploadsLast90Days = uploadsLast90Days,
+        };
+    }
+
+    /// <summary>YouTube serializes statistics as JSON STRINGS ("350"); a tolerant
+    /// read that also accepts a number (the real 403 hid this parse bug until the
+    /// auditDetails removal surfaced the string shape in 2026-09-23's Good Dog).
+    /// NOTE: JsonElement.TryGetInt64 THROWS on a non-Number token — ValueKind must
+    /// be checked first (try-type-in, not try-catch).</summary>
+    private static long ReadInt64(JsonElement parent, string name)
+    {
+        if (!parent.TryGetProperty(name, out var value)) return 0;
+        if (value.ValueKind == JsonValueKind.Number && value.TryGetInt64(out var n)) return n;
+        if (value.ValueKind == JsonValueKind.String && long.TryParse(value.GetString(), out n)) return n;
+        return 0;
+    }
+
+    /// <summary>Counts uploads published within the trailing 90 days, scanning the
+    /// most recent 50 from the uploads playlist (generous beyond the 3/90-day YPP
+    /// requirement; the YPP tab labels it as the recent-50 window).</summary>
+    private async Task<int> CountUploadsLast90DaysAsync(string uploadsPlaylistId)
+    {
+        var response = await _http.GetAsync(
+            $"{ApiBase}/playlistItems?part=snippet&playlistId={Uri.EscapeDataString(uploadsPlaylistId)}&maxResults=50");
+        if (!response.IsSuccessStatusCode)
+        {
+            AppLog.Write($"YPP stats: playlistItems.list failed ({(int)response.StatusCode})");
+            return 0;
+        }
+
+        var json = JsonSerializer.Deserialize<JsonElement>(await response.Content.ReadAsStringAsync());
+        if (!json.TryGetProperty("items", out var items)) return 0;
+
+        var cutoff = DateTime.UtcNow.AddDays(-90);
+        var count = 0;
+        foreach (var item in items.EnumerateArray())
+        {
+            if (!item.TryGetProperty("snippet", out var snippet)
+                || !snippet.TryGetProperty("publishedAt", out var published)
+                || !DateTime.TryParse(published.GetString(), out var publishedAt))
+            {
+                continue;
+            }
+            if (publishedAt.ToUniversalTime() >= cutoff)
+                count++;
+        }
+        return count;
+    }
+}

Services/ChatOverlayLayer.cs

@@ -0,0 +1,249 @@
+using System.Collections.ObjectModel;
+using System.Linq;
+using System.Windows;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Threading;
+using ytLive.Helpers;
+using ytLive.Models;
+
+namespace ytLive.Services;
+
+/// <summary>Owns the YouTube-chat overlay behavior: the message buffer, the
+/// renderer, and the fade/mock-preview timers. The MainViewModel keeps only the
+/// thin binding surface (the shared <see cref="Messages"/> collection + two
+/// computed gate props) and hands the scene list in at each call — this class
+/// owns all chat logic so an AI can read one self-contained unit.</summary>
+public sealed class ChatOverlayLayer
+{
+    private readonly ChatBoxRenderer _renderer;
+
+    // Mock chat messages for the ChatBox preview — branded placeholders so the
+    // creator sees where the overlay lands before going live.
+    private static readonly IReadOnlyList<ChatMessage> MockChatMessages = new[]
+    {
+        new ChatMessage { AuthorName = "LlamaCasty", Message = "welcome to the stream!", Timestamp = DateTime.Now.AddMinutes(-4), IsMember = true },
+        new ChatMessage { AuthorName = "LlamaCastyFan", Message = "$10 — LlamaCasty is the best!", Timestamp = DateTime.Now.AddMinutes(-3), IsSuperChat = true },
+        new ChatMessage { AuthorName = "GamerDude", Message = "what streaming software is this?", Timestamp = DateTime.Now.AddMinutes(-2) },
+        new ChatMessage { AuthorName = "LlamaCasty", Message = "thanks for watching! llamacasty.com", Timestamp = DateTime.Now.AddMinutes(-1), IsMember = true },
+        new ChatMessage { AuthorName = "LlamaDog", Message = "Subscribe so they can buy the subscription at llamacasty.com!", Timestamp = DateTime.Now, IsMember = true },
+    };
+
+    // Chat fade timer: clears chat overlay after N seconds of inactivity.
+    private DispatcherTimer? _fadeTimer;
+    private CancellationTokenSource? _mockCts;
+
+    /// <summary>The live chat message buffer. Shared with the ViewModel (which
+    /// binds it to the panel) via <c>ChatMessages =&gt; _chatLayer.Messages</c>.</summary>
+    public ObservableCollection<ChatMessage> Messages { get; } = new();
+
+    // Output-frame cache (take-5 starvation fix): the pump called RenderFrame
+    // every tick and the renderer did a FULL WPF raster (FormattedText +
+    // RenderTargetBitmap + CopyPixels + channel swap) each time — 15-25ms of a
+    // 25.5ms render. Established answer (OBS text sources): raster on change,
+    // blit the cache every tick. _contentVersion bumps on every buffer mutation
+    // (CollectionChanged — covers adds, the 500-cap removal, and the fade
+    // Clear from any caller); the config key covers the box geometry/appearance.
+    // The cached VideoFrame is treated as immutable: the compositor only reads.
+    private int _contentVersion;
+    private int _frameVersion = -1;
+    private string? _frameKey;
+    private VideoFrame? _cachedFrame;
+
+    public ChatOverlayLayer(ChatBoxRenderer renderer)
+    {
+        _renderer = renderer;
+        Messages.CollectionChanged += (_, _) => _contentVersion++;
+    }
+
+    /// <summary>Ingest a message from the poller. UI-thread marshalled: appended
+    /// to the buffer (capped at 500), mock preview stopped, swipe to real
+    /// messages, and the fade timer reset. Scenes are handed in so the layer can
+    /// refresh every ChatBox preview without owning the scene graph.</summary>
+    public void OnMessageReceived(ChatMessage message, IEnumerable<Scene> scenes)
+    {
+        System.Windows.Application.Current.Dispatcher.Invoke(() =>
+        {
+            Messages.Add(message);
+            if (Messages.Count > 500)
+                Messages.RemoveAt(0);
+
+            // Reset chat fade timer on every message
+            ResetChatFadeTimer(scenes);
+
+            StopMockPreview();
+
+            // Switch ChatBox previews from mock to real messages
+            foreach (var chatBox in scenes.SelectMany(s => s.Elements).OfType<Source>()
+                         .Where(s => s.Type == SourceType.ChatBox))
+                UpdatePreview(chatBox);
+        });
+    }
+
+    private void ResetChatFadeTimer(IEnumerable<Scene> scenes)
+    {
+        _fadeTimer?.Stop();
+        var chatBoxes = scenes.SelectMany(s => s.Elements).OfType<Source>()
+            .Where(s => s.Type == SourceType.ChatBox && s.ChatFadeSeconds > 0).ToList();
+        if (chatBoxes.Count == 0) return;
+
+        var delay = chatBoxes.Min(s => s.ChatFadeSeconds);
+        _fadeTimer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(delay) };
+        _fadeTimer.Tick += (_, _) =>
+        {
+            _fadeTimer?.Stop();
+            _fadeTimer = null;
+            Messages.Clear();
+            foreach (var chatBox in scenes.SelectMany(s => s.Elements).OfType<Source>()
+                         .Where(s => s.Type == SourceType.ChatBox))
+                UpdatePreview(chatBox);
+            StartMockPreview(scenes);
+        };
+        _fadeTimer.Start();
+    }
+
+    /// <summary>Renders the live-output frame for one ChatBox element (the
+    /// compositor path), or null when no messages are buffered yet. Mirrors the
+    /// preview render but without writing onto the source's VideoImageSource.</summary>
+    public VideoFrame? RenderFrame(Source chatBox)
+    {
+        var width = (int)Math.Max(1, chatBox.Width);
+        var height = (int)Math.Max(1, chatBox.Height);
+        var key =
+            $"{width}x{height}|{chatBox.ChatFontSize}|{chatBox.ChatFontFamily}|{chatBox.ChatFontColor}"
+            + $"|{chatBox.ChatBackgroundColor}|{chatBox.ChatMaxMessages}|{chatBox.ChatShowTimestamps}"
+            + $"|{chatBox.ChatShowBadges}|{chatBox.ChatMemberColor}|{chatBox.ChatSuperChatColor}";
+
+        if (_frameKey == key && _frameVersion == _contentVersion)
+            return _cachedFrame; // same content + same config — the cached raster stands
+
+        // The raster is WPF (DrawingVisual + RenderTargetBitmap = UI-thread objects)
+        // and the frame pump now renders from its own thread (take-8 off-UI fix) —
+        // so only the cache CHECK runs off-thread; the rare miss marshals to the
+        // dispatcher and re-validates there (a second message landing mid-hop must
+        // not be answered by a snapshot taken before it).
+        var app = System.Windows.Application.Current;
+        if (app != null && !app.Dispatcher.CheckAccess())
+        {
+            var capturedKey = key;
+            var capturedVersion = _contentVersion;
+            var frame = app.Dispatcher.Invoke(() =>
+            {
+                if (_frameKey == capturedKey && _frameVersion == capturedVersion)
+                    return _cachedFrame; // someone already re-rasterized on the UI thread
+                return RenderCore(chatBox, width, height, capturedKey, capturedVersion);
+            });
+            return frame;
+        }
+
+        return RenderCore(chatBox, width, height, key, _contentVersion);
+    }
+
+    private VideoFrame? RenderCore(Source chatBox, int width, int height, string key, int version)
+    {
+        _frameKey = key;
+        _frameVersion = version;
+        if (Messages.Count == 0) return _cachedFrame = null;
+
+        return _cachedFrame = _renderer.Render(
+            Messages,
+            width,
+            height,
+            chatBox.ChatFontSize,
+            chatBox.ChatFontFamily,
+            chatBox.ChatFontColor,
+            chatBox.ChatBackgroundColor,
+            chatBox.ChatMaxMessages,
+            chatBox.ChatShowTimestamps,
+            chatBox.ChatShowBadges,
+            chatBox.ChatMemberColor,
+            chatBox.ChatSuperChatColor);
+    }
+
+    /// <summary>Renders one ChatBox preview: real messages when connected, mock
+    /// when not. Writes the resulting bitmap onto the source's
+    /// <c>VideoImageSource</c>.</summary>
+    public void UpdatePreview(Source chatBox, IReadOnlyList<ChatMessage>? messages = null)
+    {
+        try
+        {
+            messages ??= Messages.Count > 0 ? (IReadOnlyList<ChatMessage>)Messages : MockChatMessages;
+            var width = (int)Math.Max(32, chatBox.Width);
+            var height = (int)Math.Max(32, chatBox.Height);
+
+            var frame = _renderer.Render(
+                messages,
+                width,
+                height,
+                chatBox.ChatFontSize,
+                chatBox.ChatFontFamily,
+                chatBox.ChatFontColor,
+                chatBox.ChatBackgroundColor,
+                chatBox.ChatMaxMessages,
+                chatBox.ChatShowTimestamps,
+                chatBox.ChatShowBadges,
+                chatBox.ChatMemberColor,
+                chatBox.ChatSuperChatColor);
+
+            var bitmap = new WriteableBitmap(width, height, 96, 96, PixelFormats.Bgra32, null);
+            bitmap.WritePixels(new Int32Rect(0, 0, width, height), frame.BgraPixels, frame.Stride, 0);
+            chatBox.VideoImageSource = bitmap;
+        }
+        catch (Exception ex) { AppLog.Write($"UpdateChatBoxPreview failed: {ex.Message}"); }
+    }
+
+    private async Task RunMockPreviewAsync(Source chatBox, CancellationToken ct)
+    {
+        var n = 0;
+        while (!ct.IsCancellationRequested)
+        {
+            UpdatePreview(chatBox, MockChatMessages.Take(n + 1).ToList());
+            await Task.Delay(1000, ct);
+            n++;
+            if (n == MockChatMessages.Count)
+            {
+                await Task.Delay(3000, ct);
+                n = 0;
+            }
+        }
+    }
+
+    public void StartMockPreview(IEnumerable<Scene> scenes)
+    {
+        StopMockPreview();
+        _mockCts = new CancellationTokenSource();
+        var ct = _mockCts.Token;
+        foreach (var chatBox in scenes.SelectMany(s => s.Elements).OfType<Source>()
+                     .Where(s => s.Type == SourceType.ChatBox && s.ChatPreviewEnabled))
+            _ = RunMockPreviewAsync(chatBox, ct);
+    }
+
+    public void StopMockPreview()
+    {
+        _mockCts?.Cancel();
+        _mockCts?.Dispose();
+        _mockCts = null;
+    }
+
+    /// <summary>Render previews + wire property-change subscriptions for all
+    /// ChatBox sources across every scene. Called after layout load so existing
+    /// ChatBox sources show mock content and respond to config changes.</summary>
+    public void UpdateConfiguredBoxes(IEnumerable<Scene> scenes)
+    {
+        foreach (var scene in scenes)
+            foreach (var chatBox in scene.Elements.OfType<Source>().Where(s => s.Type == SourceType.ChatBox))
+            {
+                chatBox.PropertyChanged += (_, e) =>
+                {
+                    if (e.PropertyName is nameof(Source.ChatFontSize) or nameof(Source.ChatFontColor)
+                        or nameof(Source.ChatBackgroundColor) or nameof(Source.ChatBackgroundOpacity)
+                        or nameof(Source.ChatMaxMessages) or nameof(Source.ChatShowTimestamps)
+                        or nameof(Source.ChatShowBadges) or nameof(Source.ChatMemberColor)
+                        or nameof(Source.ChatSuperChatColor) or nameof(Source.ChatFontFamily)
+                        or nameof(Source.ChatFadeSeconds) or nameof(Source.Width) or nameof(Source.Height))
+                        UpdatePreview(chatBox);
+                };
+                UpdatePreview(chatBox);
+            }
+    }
+}

Services/Compositor/AlertTickerRenderer.cs

@@ -0,0 +1,182 @@
+using System.Collections.Generic;
+using System.Globalization;
+using System.Windows;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Threading;
+using ytLive.Models;
+
+namespace ytLive.Services.Compositor;
+
+/// <summary>
+/// Rasterizes the stream-alert ticker into a transparent BGRA strip that the
+/// output compositor overlays along the very top edge of the master frame
+/// (TASK 47). The strip is text ("Viewer — Super Chat · $12.34") inside a dark
+/// pill with the LlamaCasty accent bar, rendered ONCE per unique text on the UI
+/// thread (WPF <c>RenderTargetBitmap</c>, Pbgra32→straight-alpha like
+/// <see cref="SocialBarRenderer"/>), then cached. Each <see cref="Render"/> call
+/// is pure byte-math on that cached raster producing a scrolling marquee frame,
+/// so the frame pump can call it from any thread for every output frame at
+/// 30fps without a Dispatcher round-trip.
+/// </summary>
+public static class AlertTickerRenderer
+{
+    /// <summary>Master-frame width — the ticker spans the full 1920px output.</summary>
+    public const int Width = 1920;
+
+    /// <summary>Strip height (pill + vertical padding).</summary>
+    public const int Height = 48;
+
+    private const int RepeatGap = 120;
+    private const int CacheLimit = 48;
+
+    /// <summary>How long each blink half lasts in <see cref="AlertDisplayMethod.Flash"/>
+    /// (0.5s on, 0.5s off — a 1Hz pulse for the whole alert).</summary>
+    public const double FlashHalfSeconds = 0.5;
+
+    private static readonly object Gate = new();
+    private static readonly Dictionary<string, VideoFrame> StripCache = new();
+
+    /// <summary>A frame of <paramref name="text"/> presented per
+    /// <paramref name="method"/> at <paramref name="elapsedSeconds"/> into the alert,
+    /// or null when there is nothing to show (no text, or a Flash in its off half).
+    /// Thread-safe: reads the cached raster and does row copies only.
+    /// <para><see cref="AlertDisplayMethod.TickerScroll"/> paces itself from
+    /// <paramref name="readsPerAlert"/> over <paramref name="alertSeconds"/> rather
+    /// than a fixed pixels-per-second: the old constant (140px/s ≈ a 17s pass) meant
+    /// a 10s alert showed the text barely once, entering from the right and never
+    /// crossing. The creator's target is three readable passes per alert.</para>
+    /// <para><paramref name="width"/>/<paramref name="height"/> default to the
+    /// full-master strip. They are parameters because the ticker now renders INTO the
+    /// Stream Alerts box (creator ruling 2026-09-26) and therefore has to be the box's
+    /// size: a 1920-wide strip clipped to an 800px box would hide the announcement
+    /// off the right edge for most of its pass, which is the opposite of readable.</para></summary>
+    public static VideoFrame? Render(string? text, double elapsedSeconds,
+        AlertDisplayMethod method = AlertDisplayMethod.TickerScroll,
+        double alertSeconds = 0.0, int readsPerAlert = 3,
+        int width = Width, int height = Height)
+    {
+        if (string.IsNullOrWhiteSpace(text)) return null;
+        if (width <= 0 || height <= 0) return null;
+        var strip = GetStrip(text!);
+        if (strip == null) return null;
+
+        if (method == AlertDisplayMethod.Flash
+            && elapsedSeconds % (FlashHalfSeconds * 2) >= FlashHalfSeconds)
+            return null; // off half of the pulse
+
+        var x = method == AlertDisplayMethod.TickerScroll
+            ? ScrollX(strip.Width, width, elapsedSeconds, alertSeconds, readsPerAlert)
+            : (width - strip.Width) / 2; // Solid + Flash: centred, still
+
+        var pixels = new byte[width * height * 4];
+        CopyStrip(pixels, width, height, strip, x);
+        if (method == AlertDisplayMethod.TickerScroll && x + strip.Width <= 0)
+            CopyStrip(pixels, width, height, strip, x + width + RepeatGap); // wrapped tail enters
+        return new VideoFrame(width, height, pixels);
+    }
+
+    /// <summary>Left edge of the pill for a marquee that must complete
+    /// <paramref name="readsPerAlert"/> passes in <paramref name="alertSeconds"/>:
+    /// one pass (off the right edge, across, out of sight) takes that long.
+    /// <para>The run is phase-started half a frame in, so the very first frame of an
+    /// alert already shows the announcement instead of a blank strip sitting exactly
+    /// off the right edge.</para></summary>
+    private static int ScrollX(int stripWidth, int width, double elapsedSeconds,
+        double alertSeconds, int readsPerAlert)
+    {
+        var cycle = width + stripWidth + RepeatGap;
+        var pass = Math.Max(0.5, alertSeconds) / Math.Max(1, readsPerAlert);
+        var speed = cycle / pass;
+        var pos = (width / 2 + (int)(elapsedSeconds * speed)) % cycle;
+        return width - pos;
+    }
+
+
+    private static void CopyStrip(byte[] dst, int dstW, int dstH, VideoFrame strip, int dstX)
+    {
+        if (dstX >= dstW || dstX + strip.Width <= 0) return;
+        var x0 = Math.Max(0, dstX);
+        var x1 = Math.Min(dstW, dstX + strip.Width);
+        var sx0 = x0 - dstX;
+        var copyBytes = (x1 - x0) * 4;
+        var sw = strip.Width;
+        // The strip is rasterised at its natural 48px; the target box can be shorter,
+        // and copying strip.Height rows into a shorter dst would run off the end of the
+        // array. Clip the rows, not the buffer.
+        var rows = Math.Min(strip.Height, dstH);
+        for (var y = 0; y < rows; y++)
+            Buffer.BlockCopy(strip.BgraPixels, (y * sw + sx0) * 4, dst, (y * dstW + x0) * 4, copyBytes);
+    }
+
+    private static VideoFrame? GetStrip(string text)
+    {
+        lock (Gate)
+        {
+            if (StripCache.TryGetValue(text, out var cached)) return cached;
+        }
+        var strip = RenderStrip(text);
+        if (strip == null) return null;
+        lock (Gate)
+        {
+            if (StripCache.Count >= CacheLimit) StripCache.Clear();
+            if (!StripCache.TryGetValue(text, out var existing))
+                StripCache[text] = strip;
+            return StripCache[text];
+        }
+    }
+
+    private static VideoFrame? RenderStrip(string text)
+    {
+        // WPF rendering is single-threaded; the pump thread resolves to the UI
+        // thread at most once per unique text (then hits the cache).
+        var app = Application.Current;
+        if (app != null && !app.Dispatcher.CheckAccess())
+        {
+            VideoFrame? result = null;
+            app.Dispatcher.Invoke(() => result = RenderStrip(text));
+            return result;
+        }
+
+        const double pillHeight = 34;
+        const double accentW = 6;
+        const double padX = 16;
+        const double gap = 8;
+
+        var font = new Typeface(new FontFamily("Segoe UI"), FontStyles.Normal, FontWeights.SemiBold, FontStretches.Normal);
+        var ft = new FormattedText(text, CultureInfo.InvariantCulture, FlowDirection.LeftToRight,
+            font, 22, Brushes.White, 1.0);
+
+        var pillW = (int)Math.Ceiling(padX + accentW + gap + ft.Width + padX);
+        var top = (Height - pillHeight) / 2.0;
+        var textTop = top + (pillHeight - ft.Height) / 2.0;
+
+        var visual = new DrawingVisual();
+        using (var dc = visual.RenderOpen())
+        {
+            var pill = new Rect(0, top, pillW, pillHeight);
+            dc.DrawRoundedRectangle(new SolidColorBrush(Color.FromArgb(0xE6, 0x10, 0x13, 0x24)), null, pill, pillHeight / 2, pillHeight / 2);
+            dc.DrawRoundedRectangle(new SolidColorBrush(Color.FromRgb(0xe9, 0x45, 0x60)), null,
+                new Rect(padX, top + (pillHeight - 12) / 2.0, accentW, 12), 2, 2);
+            dc.DrawText(ft, new Point(padX + accentW + gap, textTop));
+        }
+
+        var bitmap = new RenderTargetBitmap(pillW, Height, 96, 96, PixelFormats.Pbgra32);
+        bitmap.Render(visual);
+
+        var pixels = new byte[pillW * Height * 4];
+        bitmap.CopyPixels(pixels, pillW * 4, 0);
+
+        // Pbgra32 is premultiplied — unpremultiply so the compositor's
+        // straight-alpha source-over doesn't halo the text edges.
+        for (var i = 0; i < pixels.Length; i += 4)
+        {
+            var a = pixels[i + 3];
+            if (a == 0 || a == 255) continue;
+            pixels[i] = (byte)(pixels[i] * 255 / a);
+            pixels[i + 1] = (byte)(pixels[i + 1] * 255 / a);
+            pixels[i + 2] = (byte)(pixels[i + 2] * 255 / a);
+        }
+        return new VideoFrame(pillW, Height, pixels);
+    }
+}

Services/Compositor/BrandFlashPresenter.cs

@@ -0,0 +1,421 @@
+using System;
+using System.Globalization;
+using System.Windows;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Threading;
+
+namespace ytLive.Services.Compositor;
+
+/// <summary>
+/// The free-tier branding flash: a "made with LlamaCasty!" credit that is COMPOSITED
+/// INTO THE OUTPUT (recording or stream), not merely shown in the preview.
+/// <para>2026-09-26. This used to exist only as a WPF <c>BrandFlashLayer</c> in
+/// <c>PreviewPane.xaml</c> — a 0.25-opacity centred TextBlock the creator could see and
+/// no viewer ever could. The compositor has carried an unused <c>flashFrame</c> slot
+/// since then; this type is the producer that finally feeds it. It is wired on the
+/// PER-FRAME path only: <c>SceneGraph.GetBakedBase</c> also accepts a <c>flashFrame</c>,
+/// and that one is a trap — <c>SceneRegion.Matches</c> compares element ids only, so a
+/// flash folded into the baked static base would freeze there and never expire.</para>
+/// <para>The credit is deliberately obnoxious (creator directive 2026-09-26): full-opacity
+/// neon, a different random position every presentation, and a hard sell every 30–60s.
+/// It is gated on LICENCE state, never on a UI toggle — see <see cref="Enabled"/>.</para>
+/// </summary>
+public sealed class BrandFlashPresenter : IDisposable
+{
+    /// <summary>The credit line, kept identical to the old preview TextBlock so the
+    /// wording can never drift between the preview and the broadcast.</summary>
+    public const string Text = "made with LlamaCasty!";
+
+    // Presentation envelope (creator-specified 2026-09-26): 500ms fade in, the credit
+    // held at full opacity for 1000ms, then a 500ms fade out — 2000ms end to end.
+    public const double FadeInSeconds = 0.5;
+    public const double HoldSeconds = 1.0;
+    public const double FadeOutSeconds = 0.5;
+    public const double PresentationSeconds = FadeInSeconds + HoldSeconds + FadeOutSeconds;
+
+    /// <summary>Cadence: <c>rand(0, 30s) + 30s</c> ⇒ a flash every 30–60s, so it never
+    /// lands on a beat a viewer could tune out.</summary>
+    public const int IntervalFloorMs = 30_000;
+    public const int IntervalJitterMs = 30_000;
+
+    /// <summary>The first flash lands shortly after go-live (the stream-start
+    /// impression); the random cadence takes over from there.</summary>
+    public const double FirstFlashDelaySeconds = 5.0;
+
+    /// <summary>Master-space canvas. Global overlays in this codebase are authored at
+    /// master size and scaled by the compositor.</summary>
+    public const int MasterWidth = 1920;
+    public const int MasterHeight = 1080;
+
+    /// <summary>Neon recipe taken from the established overlay look (see commit
+    /// message): a bright near-white CORE plus a feathered multi-radius HALO, with the
+    /// red and blue channels pushed in OPPOSITE directions — Maxon's "Chromatic Glow"
+    /// notes the green channel is all but invisible behind white text once R and B are
+    /// split, which is exactly the look.</summary>
+    private static readonly Color NeonRed = Color.FromRgb(0xe9, 0x45, 0x60);  // brand red, exact
+    private static readonly Color NeonBlue = Color.FromRgb(0x4d, 0x8b, 0xff); // brand blue #0f3460 lifted for luminance
+    private static readonly Color CoreColor = Colors.White;
+
+    /// <summary>Font size chosen so the credit spans roughly half the master width:
+    /// big enough to read as advertising, small enough that the random placement has
+    /// real travel room (a full-width line could only ever sit at x≈0).</summary>
+    private const double FontSize = 120;
+    private const double GlowPadding = 34;
+    private const double TickSeconds = 0.033;
+
+    private readonly Random _random;
+    private readonly DispatcherTimer? _timer;
+    private readonly object _gate = new();
+
+    private bool _enabled = true;
+    private bool _running;
+    private double _sinceStart;
+    private double _nextFlashAt;      // absolute time of the next flash, _sinceStart's reference
+    private double _elapsed;            // seconds into the presentation; >= PresentationSeconds means idle
+    private VideoFrame? _raster;        // tight, full-opacity glowing credit (straight alpha)
+    private byte[]? _buffer;            // reused master-space BGRA — hence the Epoch bump below
+    private int _atX, _atY;
+    private long _epoch;
+
+    public BrandFlashPresenter(Random? random = null)
+    {
+        _random = random ?? new Random();
+        if (Application.Current is { } app)
+        {
+            _timer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(TickSeconds) };
+            _timer.Tick += (_, _) => Advance(TickSeconds);
+        }
+    }
+
+    /// <summary>The licence gate, driven by <c>MainViewModel.IsPremium</c> (Polar
+    /// validation) and NOT by a user-facing toggle: once this credit is composited into
+    /// the broadcast it is the thing standing between a paying customer's stream and an
+    /// advertisement, so it is re-checked on every read. A premium user mid-presentation
+    /// loses the flash on the very next tick rather than at the end of the credit.</summary>
+    public bool Enabled
+    {
+        get { lock (_gate) return _enabled; }
+        set
+        {
+            bool restart;
+            lock (_gate)
+            {
+                if (_enabled == value) return;
+                _enabled = value;
+                if (!value)
+                {
+                    // Licence state only ever goes premium → no flash. Cut the current
+                    // presentation short instead of running it out ungated.
+                    _elapsed = PresentationSeconds;
+                    _timer?.Stop();
+                    restart = false;
+                }
+                else
+                {
+                    // …but a DOWNGRADE (key entered mid-session) must bring the cadence
+                    // back. The presenter now runs for the life of the app — Start() is
+                    // called once at startup, not per go-live — so stopping the timer on
+                    // the premium edge without restarting it here would leave the credit
+                    // dead until the process is restarted, even after a valid key.
+                    restart = _running;
+                }
+            }
+            if (restart) _timer?.Start();
+        }
+    }
+
+    /// <summary>True while a credit is on screen (drives the preview's visibility).</summary>
+    public bool IsPresenting
+    {
+        get { lock (_gate) return _enabled && _elapsed < PresentationSeconds; }
+    }
+
+    /// <summary>Test-only: is the <see cref="DispatcherTimer"/> that drives
+    /// <see cref="Advance"/> actually running? The premium/downgrade edge is the only
+    /// thing that ever stops and restarts it now that the presenter is started once for
+    /// the life of the app, and a synchronous test body cannot observe a real timer
+    /// tick — so assert the decision directly instead of sleeping through a 30–60s
+    /// interval. Never call this from product code.</summary>
+    internal bool IsCadenceTimerEnabled => _timer?.IsEnabled ?? false;
+
+    /// <summary>Begin the cadence: first flash <see cref="FirstFlashDelaySeconds"/>
+    /// after the call, then every <c>rand(30s) + 30s</c>.</summary>
+    public void Start()
+    {
+        EnsureRaster();
+        lock (_gate)
+        {
+            _running = true;
+            _sinceStart = 0;
+            _nextFlashAt = FirstFlashDelaySeconds;
+        }
+        if (_enabled) _timer?.Start();
+    }
+
+    public void Stop()
+    {
+        lock (_gate)
+        {
+            _running = false;
+            _elapsed = PresentationSeconds;
+        }
+        _timer?.Stop();
+    }
+
+    /// <summary>Advance the presentation clock. Also the deterministic test seam: tests
+    /// drive this directly and never call <see cref="Start"/>, so no timer is running
+    /// and the clock only moves when the test moves it (mirrors <c>AlertOverlayLayer.Advance</c>).</summary>
+    public void Advance(double deltaSeconds)
+    {
+        // Rasterise BEFORE taking the lock. WPF text formatting is UI-thread affine, so
+        // this can hop to the dispatcher — and a blocking hop while holding _gate would
+        // deadlock against a timer tick that wants the same lock.
+        EnsureRaster();
+
+        lock (_gate)
+        {
+            if (!_enabled) return;
+
+            if (_running)
+            {
+                _sinceStart += deltaSeconds;
+                if (_sinceStart >= _nextFlashAt)
+                {
+                    // The interval runs FROM THIS FLASH, not from Start(). An absolute
+                    // deadline here made the gaps shrink every cycle (5s, then whatever
+                    // was left of the previous interval) and collapse toward zero.
+                    _nextFlashAt = _sinceStart + NextIntervalSeconds();
+                    BeginPresentation();
+                }
+            }
+
+            if (_elapsed < PresentationSeconds)
+            {
+                _elapsed += deltaSeconds;
+                if (_elapsed >= PresentationSeconds) _elapsed = PresentationSeconds;
+            }
+        }
+
+        Notify();
+    }
+
+    /// <summary>Invoked on the UI thread at the end of every tick with the frame that
+    /// tick produced (null when nothing is due) — the preview's repaint hook, so the
+    /// preview and the broadcast are driven by ONE clock.</summary>
+    public Action<VideoFrame?>? OnFrame { get; set; }
+
+    private void Notify()
+    {
+        var cb = OnFrame;
+        if (cb == null) return;
+        // Read OUTSIDE the state lock: the callback is arbitrary code and must never
+        // run while _gate is held.
+        var frame = Frame;
+        if (frame == null) { cb(null); return; }
+
+        if (Application.Current is { } app && !app.Dispatcher.CheckAccess())
+        {
+            // Off the UI thread (a test driving the clock). The frame's buffer is
+            // recycled, so hand the deferred copy its own pixels.
+            var copy = new byte[frame.BgraPixels.Length];
+            Buffer.BlockCopy(frame.BgraPixels, 0, copy, 0, copy.Length);
+            app.Dispatcher.BeginInvoke(() => cb(new VideoFrame(frame.Width, frame.Height, copy)));
+        }
+        else
+        {
+            cb(frame);
+        }
+    }
+
+    /// <summary>Force a presentation now — the "show me the flash" path and the test seam.</summary>
+    public void Show()
+    {
+        EnsureRaster();
+        lock (_gate)
+        {
+            if (!_enabled) return;
+            BeginPresentation();
+        }
+    }
+
+    private double NextIntervalSeconds()
+        => (IntervalFloorMs + _random.Next(IntervalJitterMs)) / 1000.0;
+
+    private void BeginPresentation()
+    {
+        if (_raster == null) return;
+        _buffer ??= new byte[MasterWidth * MasterHeight * 4];
+        // A new presentation can land anywhere, so the previous credit's pixels must go
+        // before this one is written or the old spot ghosts through the fade. One 8MB
+        // clear per presentation (not per tick) keeps that cheap.
+        Array.Clear(_buffer);
+        var spot = ComputePlacement(_raster.Width, _raster.Height, MasterWidth, MasterHeight, _random);
+        _atX = (int)spot.X;
+        _atY = (int)spot.Y;
+        _elapsed = 0;
+    }
+
+    /// <summary>
+    /// The credit for the output compositor and the preview: a master-space frame holding
+    /// the glowing text at this presentation's random spot, alpha-scaled to the current
+    /// point on the fade envelope. Null when idle, or unlicensed.
+    /// <para><b>The frame's pixel buffer is recycled across ticks</b> (only the text rect
+    /// is rewritten) and its <see cref="VideoFrame.Epoch"/> is bumped every read, so the
+    /// compositor's buffer-identity paste cache can never false-hit a stale credit.
+    /// Consumers blit synchronously — copy the pixels if you need to keep them.</para></summary>
+    public VideoFrame? Frame
+    {
+        get
+        {
+            lock (_gate)
+            {
+                if (!_enabled || _elapsed >= PresentationSeconds || _raster == null || _buffer == null)
+                    return null;
+                var opacity = OpacityAt(_elapsed);
+                if (opacity <= 0) return null;
+                Paint(_buffer, _raster, _atX, _atY, opacity);
+                return new VideoFrame(MasterWidth, MasterHeight, _buffer) { Epoch = ++_epoch };
+            }
+        }
+    }
+
+    /// <summary>Full → hold → empty. Public and static so the preview and the tests
+    /// agree with the renderer instead of re-deriving the curve.</summary>
+    public static double OpacityAt(double elapsedSeconds)
+    {
+        if (elapsedSeconds < 0 || elapsedSeconds >= PresentationSeconds) return 0;
+        if (elapsedSeconds < FadeInSeconds) return elapsedSeconds / FadeInSeconds;
+        if (elapsedSeconds < FadeInSeconds + HoldSeconds) return 1.0;
+        return 1.0 - ((elapsedSeconds - (FadeInSeconds + HoldSeconds)) / FadeOutSeconds);
+    }
+
+    /// <summary>
+    /// A random top-left offset that keeps the whole credit ON the canvas. The text is a
+    /// single pre-measured line, so it can never wrap — this is the "how far can the
+    /// left margin travel" limit the creator described: <c>0 … (canvas - creditWidth)</c>
+    /// horizontally, likewise vertically. Pure + static, so the rule is directly testable.
+    /// </summary>
+    public static Point ComputePlacement(int creditWidth, int creditHeight,
+        int canvasWidth, int canvasHeight, Random random)
+    {
+        var maxX = Math.Max(0, canvasWidth - creditWidth);
+        var maxY = Math.Max(0, canvasHeight - creditHeight);
+        return new Point(random.Next(0, maxX + 1), random.Next(0, maxY + 1));
+    }
+
+    /// <summary>Rewrite the credit rect into the master buffer with alpha scaled to
+    /// <paramref name="opacity"/>. The rect is fully overwritten each tick and the spot
+    /// is fixed for the whole presentation, so nothing stale accumulates and no clear
+    /// pass is needed here.</summary>
+    private static void Paint(byte[] buffer, VideoFrame raster, int atX, int atY, double opacity)
+    {
+        for (var y = 0; y < raster.Height; y++)
+        {
+            var dst = ((atY + y) * MasterWidth + atX) * 4;
+            var src = y * raster.Stride;
+            for (var x = 0; x < raster.Width; x++)
+            {
+                var a = raster.BgraPixels[src + x * 4 + 3];
+                if (a == 0) continue;
+                buffer[dst + x * 4] = raster.BgraPixels[src + x * 4];
+                buffer[dst + x * 4 + 1] = raster.BgraPixels[src + x * 4 + 1];
+                buffer[dst + x * 4 + 2] = raster.BgraPixels[src + x * 4 + 2];
+                buffer[dst + x * 4 + 3] = (byte)Math.Round(a * opacity);
+            }
+        }
+    }
+
+    /// <summary>Build the credit raster once, on the UI thread, and publish it under
+    /// the lock. Called from every clock entry point, so it is a no-op after the first.</summary>
+    private void EnsureRaster()
+    {
+        lock (_gate) { if (_raster != null) return; }
+        var raster = RenderNeonText(Text);
+        lock (_gate) { if (raster != null) { _raster = raster; } }
+    }
+
+    // ── rasterisation ──────────────────────────────────────────────────────────
+
+    /// <summary>
+    /// Rasterize the credit once, tight to the glyphs plus glow, on the UI thread (WPF
+    /// <c>RenderTargetBitmap</c>, Pbgra32→straight alpha exactly like
+    /// <see cref="AlertTickerRenderer"/>) and cached — this is per-text work, not
+    /// per-frame, so the pump can afford to run every tick at 30fps.
+    /// <para>The neon is a bright core plus a feathered halo: the glyphs redrawn at
+    /// shrinking radii with rising alpha, the two colours offset in opposite directions,
+    /// which is what makes it read as a lit tube rather than a drop shadow.</para></summary>
+    private static VideoFrame? RenderNeonText(string text)
+    {
+        if (Application.Current is { } app && !app.Dispatcher.CheckAccess())
+        {
+            VideoFrame? result = null;
+            app.Dispatcher.Invoke(() => result = RenderNeonText(text));
+            return result;
+        }
+
+        var font = new Typeface(new FontFamily("Segoe UI"), FontStyles.Normal,
+            FontWeights.Bold, FontStretches.Normal);
+        var probe = new FormattedText(text, CultureInfo.InvariantCulture,
+            FlowDirection.LeftToRight, font, FontSize, Brushes.White, 1.0);
+
+        var w = (int)Math.Ceiling(probe.Width) + (int)(GlowPadding * 2);
+        var h = (int)Math.Ceiling(probe.Height) + (int)(GlowPadding * 2);
+        if (w <= 0 || h <= 0) return null;
+
+        var visual = new DrawingVisual();
+        using (var dc = visual.RenderOpen())
+        {
+            // Three halo rings per colour. Wide+dim first, then progressively tighter and
+            // brighter, so the falloff is feathered instead of a hard-edged blob.
+            foreach (var (radius, alpha) in new[] { (30.0, 0.16), (20.0, 0.26), (11.0, 0.40) })
+            {
+                DrawHalo(dc, text, font, radius, alpha, NeonRed, +1);
+                DrawHalo(dc, text, font, radius, alpha, NeonBlue, -1);
+            }
+            // A tight white bloom hugging the glyphs sells the brightness of the tube.
+            DrawHalo(dc, text, font, 4.0, 0.55, CoreColor, +1);
+            // The core itself, sharp and opaque, drawn last.
+            dc.DrawText(new FormattedText(text, CultureInfo.InvariantCulture,
+                FlowDirection.LeftToRight, font, FontSize, new SolidColorBrush(CoreColor), 1.0),
+                new Point(GlowPadding, GlowPadding));
+        }
+
+        var bitmap = new RenderTargetBitmap(w, h, 96, 96, PixelFormats.Pbgra32);
+        bitmap.Render(visual);
+
+        var pixels = new byte[w * h * 4];
+        bitmap.CopyPixels(pixels, w * 4, 0);
+
+        // Pbgra32 is premultiplied — unpremultiply, or straight-alpha source-over in the
+        // compositor haloes the glyph edges.
+        for (var i = 0; i < pixels.Length; i += 4)
+        {
+            var a = pixels[i + 3];
+            if (a == 0 || a == 255) continue;
+            pixels[i] = (byte)(pixels[i] * 255 / a);
+            pixels[i + 1] = (byte)(pixels[i + 1] * 255 / a);
+            pixels[i + 2] = (byte)(pixels[i + 2] * 255 / a);
+        }
+        return new VideoFrame(w, h, pixels);
+    }
+
+    private static void DrawHalo(DrawingContext dc, string text, Typeface font,
+        double radius, double alpha, Color color, int direction)
+    {
+        var brush = new SolidColorBrush(color);
+        const int spokes = 12;
+        for (var i = 0; i < spokes; i++)
+        {
+            var angle = 2 * Math.PI * i / spokes;
+            brush.Opacity = alpha;
+            var ft = new FormattedText(text, CultureInfo.InvariantCulture,
+                FlowDirection.LeftToRight, font, FontSize, brush, 1.0);
+            dc.DrawText(ft, new Point(
+                GlowPadding + Math.Cos(angle) * radius * direction,
+                GlowPadding + Math.Sin(angle) * radius * direction));
+        }
+    }
+
+    public void Dispose() => _timer?.Stop();
+}

Services/Compositor/SceneCompositor.cs

@@ -1,3 +1,6 @@
+using System.Buffers;
+using System.Collections.Generic;
+using ytLive.Helpers;
 using ytLive.Models;
 
 namespace ytLive.Services.Compositor;
@@ -14,12 +17,32 @@ namespace ytLive.Services.Compositor;
 /// </summary>
 public sealed class SceneCompositor
 {
+    // Paste cache (take-8 fix, 2026-09-04): the Live scene re-sampled ~680k bilinear
+    // pixels EVERY tick even though only the camera actually changes at that rate —
+    // chat/web/image layers are identical frame after frame. Same shape as OBS (the
+    // source surface is cached, the compositor blits): a scaled/round-clipped/mirrored
+    // layer rasterizes once and is pasted (row-copy/blend) on every later tick.
+    // Keyed by the SOURCE FRAME IDENTITY (array + Epoch + CropBounds) — producers hand
+    // out fresh immutable byte[], or recycled-ring arrays whose monotonic Epoch distinguishes
+    // each generation (screen capture, take-11 fix). CropBounds must be in the key because
+    // the same frame (same Pixels/Epoch/Width/Height) can have different CropBounds as
+    // the element is resized — a stale cached raster with wrong crop pixels would corrupt
+    // the output. Bounds-checked eviction clears wholesale.
+    private sealed record PasteKey(byte[] Pixels, long Epoch, int SrcW, int SrcH, int DstW, int DstH, bool Round, bool Mirror, (int X, int Y, int W, int H)? CropBounds);
+    private static readonly Dictionary<PasteKey, VideoFrame> _pasteCache = new();
+    private static readonly Dictionary<SceneElement, VideoFrame> _elementRasters = new(ReferenceEqualityComparer.Instance);
+    private static readonly object _pasteGate = new();
+    private const int MaxPasteEntries = 256;
+
     /// <summary>
     /// Composite <paramref name="scene"/> into the tier's output frame. Layer order (back →
     /// front): live background (the scene's <c>IsBackground</c> source) → background image →
     /// visible elements (z-order = <c>Elements</c> order, mirroring the XAML DataTemplate) →
     /// branding flash → social bar (a global overlay; spans the master width at
-    /// <paramref name="socialBarTop"/>). Transparent regions read opaque black.
+    /// <paramref name="socialBarTop"/>) → stream-alert ticker (drawn INSIDE the Stream
+    /// Alerts box, at the origin the frame carries on <see cref="VideoFrame.Placement"/>;
+    /// creator ruling 2026-09-26 — it used to be a global bar pinned to the very top).
+    /// Transparent regions read opaque black.
     /// </summary>
     public VideoFrame Render(
         Scene scene,
@@ -27,7 +50,11 @@ public sealed class SceneCompositor
         VideoFrame? flashFrame,
         CompositorOptions options,
         VideoFrame? socialBarFrame = null,
-        int socialBarTop = 0)
+        int socialBarTop = 0,
+        VideoFrame? staticBase = null,
+        int split = -1,
+        byte[]? scratch = null,
+        VideoFrame? tickerFrame = null)
     {
         if (scene == null) throw new ArgumentNullException(nameof(scene));
         if (frameFor == null) throw new ArgumentNullException(nameof(frameFor));
@@ -39,46 +66,122 @@ public sealed class SceneCompositor
 
         var cropW = options.SourceRectWidth;
         var cropH = options.SourceRectHeight;
-        var buffer = new byte[cropW * cropH * 4];
-        for (var i = 3; i < buffer.Length; i += 4)
-            buffer[i] = 255; // opaque black base — video frames are never transparent
+        var buffer = scratch != null && scratch.Length == cropW * cropH * 4
+            ? scratch
+            : new byte[cropW * cropH * 4];
 
-        var elements = scene.Elements;
-
-        var liveCapture = elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
-        var liveCaptureFrame = liveCapture != null && liveCapture.IsVisible ? frameFor(liveCapture) : null;
-        if (liveCaptureFrame != null)
-            BlitContent(buffer, cropW, cropH, 0, 0, cropW, cropH, liveCaptureFrame, 1f, false, false);
-
-        var background = elements.OfType<Source>().FirstOrDefault(s => s.Type == SourceType.Background);
-        var backgroundFrame = background != null ? frameFor(background) : null;
-        if (backgroundFrame != null)
-            BlitContent(buffer, cropW, cropH, 0, 0, cropW, cropH, backgroundFrame, 1f, false, false);
-
-        foreach (var element in elements)
+        // staticBase != null: the caller pre-baked all static layers below `split`.
+        // We copy it (never mutate the cached base) and composite elements[split..] on top.
+        if (staticBase != null)
         {
+            if (staticBase.Width != cropW || staticBase.Height != cropH)
+                throw new ArgumentException("The static base must match the source rect.", nameof(staticBase));
+            Buffer.BlockCopy(staticBase.BgraPixels, 0, buffer, 0, buffer.Length);
+        }
+        else
+        {
+            if (split < 0) split = scene.Elements.Count;
+
+            var elements = scene.Elements;
+            var liveCapture = elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
+            var liveCaptureFrame = liveCapture != null && liveCapture.IsVisible ? frameFor(liveCapture) : null;
+
+            // A master-sized live backdrop paints every pixel of the base — the
+            // opaque-black pre-fill (2M byte writes) would be dead work. Capture
+            // frames are opaque BGRA by contract (the WinRT path ignores alpha),
+            // so the 1:1 row walk covers the full rect.
+            var covered = liveCaptureFrame != null
+                && liveCaptureFrame.Width == cropW && liveCaptureFrame.Height == cropH;
+            if (!covered)
+            {
+                if (liveCaptureFrame != null)
+                {
+                    var (uScale, uOx, uOy) = StretchMath.UniformToFill(cropW, cropH, liveCaptureFrame.Width, liveCaptureFrame.Height);
+                    var drawnW = liveCaptureFrame.Width * uScale;
+                    var drawnH = liveCaptureFrame.Height * uScale;
+                    var ox = (int)Math.Floor(uOx);
+                    var oy = (int)Math.Floor(uOy);
+                    var oh = (int)Math.Ceiling(oy + drawnH);
+                    var ow = cropW;
+                    if (oy > 0)
+                    {
+                        var topCount = oy * ow;
+                        for (var i = 3; i < topCount * 4; i += 4)
+                            buffer[i] = 255;
+                    }
+                    if (oh < cropH)
+                    {
+                        var start = oh * ow;
+                        var bottomCount = (cropH - oh) * ow;
+                        for (var i = start * 4 + 3; i < (start + bottomCount) * 4; i += 4)
+                            buffer[i] = 255;
+                    }
+                    if (ox > 0 || (int)Math.Ceiling(uOx + drawnW) < cropW)
+                    {
+                        var x0s = (int)Math.Floor(uOx);
+                        var x1s = (int)Math.Ceiling(uOx + drawnW);
+                        for (var y = oy; y < oh && y < cropH; y++)
+                        {
+                            var di = (y * ow + 0) * 4;
+                            for (var x = 0; x < x0s && x < ow; x++)
+                            {
+                                buffer[di + x * 4 + 3] = 255;
+                            }
+                            for (var x = x1s; x < ow; x++)
+                            {
+                                buffer[di + x * 4 + 3] = 255;
+                            }
+                        }
+                    }
+                }
+                else
+                {
+                    for (var i = 3; i < buffer.Length; i += 4)
+                        buffer[i] = 255; // opaque black base
+                }
+            }
+
+            if (liveCaptureFrame != null)
+                BlitContent(buffer, cropW, cropH, 0, 0, cropW, cropH, liveCaptureFrame, 1f, false, false);
+
+            var background = elements.OfType<Source>().FirstOrDefault(s => s.Type == SourceType.Background);
+            var backgroundFrame = background != null ? frameFor(background) : null;
+            if (backgroundFrame != null)
+                BlitContent(buffer, cropW, cropH, 0, 0, cropW, cropH, backgroundFrame, 1f, false, false);
+
+            foreach (var element in elements)
+            {
+                if (!element.IsVisible) continue;
+                switch (element)
+                {
+                    case Source { IsBackground: true }:
+                    case Source { Type: SourceType.Background }:
+                    case Source { Type: SourceType.TextOverlay }:
+                    case ZoomSceneElement { IsZoomActive: true }:
+                        continue;
+                }
+                var fullFrame = frameFor(element);
+                if (fullFrame == null) continue;
+                BlitBakedElement(buffer, cropW, cropH, options, element, fullFrame);
+            }
+        }
+
+        // Composite the above-split layers (dynamic + any static above them) per frame.
+        for (var i = Math.Max(0, split); i < scene.Elements.Count; i++)
+        {
+            var element = scene.Elements[i];
             if (!element.IsVisible) continue;
             switch (element)
             {
                 case Source { IsBackground: true }:
                 case Source { Type: SourceType.Background }:
                 case Source { Type: SourceType.TextOverlay }:
-                    continue; // background/background are their own layers; Text isn't shipped
+                case ZoomSceneElement { IsZoomActive: true }:
+                    continue;
             }
-
             var frame = frameFor(element);
             if (frame == null) continue;
-
-            var ex = (float)(element.X - options.SourceRectX);
-            var ey = (float)(element.Y - options.SourceRectY);
-            var ew = (float)element.Width;
-            var eh = (float)element.Height;
-            var isRound = element.ClipShape == ClipShape.Round;
-
-            BlitContent(buffer, cropW, cropH, ex, ey, ew, eh, frame,
-                (float)element.Opacity, isRound, element.IsMirrored);
-            if (element.HasBorder)
-                DrawBorder(buffer, cropW, cropH, ex, ey, ew, eh, element, isRound);
+            BlitBakedElement(buffer, cropW, cropH, options, element, frame);
         }
 
         if (flashFrame != null)
@@ -87,10 +190,255 @@ public sealed class SceneCompositor
         if (socialBarFrame != null && socialBarFrame.Width > 0 && socialBarFrame.Height > 0)
             BlitOverlay(buffer, cropW, cropH, options, socialBarFrame, 0, socialBarTop);
 
+        if (tickerFrame != null && tickerFrame.Width > 0 && tickerFrame.Height > 0)
+            BlitOverlay(buffer, cropW, cropH, options, tickerFrame, tickerFrame.OriginX, tickerFrame.OriginY);
+
+        // The zoom box is layer n+1: a live 2x view of a FIXED capture window sampled
+        // from the frame just composited (all layers). Drawn LAST — above everything.
+        // The box/2 capture is anchored at the click, so dragging the box only moves
+        // the box; the content it shows never changes (creator ruling 2026-10-08).
+        var zoom = scene.Elements.OfType<ZoomSceneElement>().FirstOrDefault(z => z.IsZoomActive);
+        if (zoom != null)
+            BlitZoom(buffer, cropW, cropH, options, zoom);
+
         return StretchMath.BilinearScale(
             new VideoFrame(cropW, cropH, buffer), options.OutputWidth, options.OutputHeight);
     }
 
+    /// <summary>
+    /// Render the static base of a scene: the opaque black layer, the live-capture
+    /// background, the background image, and every <paramref name="split"/> z-layers
+    /// below the split point (all of which are static by construction — see
+    /// <see cref="SceneElement.Kind"/>). The result is a source-rect sized frame that
+    /// <see cref="Render"/> can start from and composite the dynamic/above-split layers
+    /// onto each tick. Returns null when there is no static layer at all.
+    /// </summary>
+    public static VideoFrame? BakeStaticBase(
+        Scene scene,
+        int split,
+        Func<SceneElement, VideoFrame?> frameFor,
+        Func<CompositorOptions> options,
+        VideoFrame? socialBarFrame = null,
+        int socialBarTop = 0,
+        VideoFrame? flashFrame = null)
+    {
+        if (split <= 0) return null;
+        var opts = options();
+        if (opts.SourceRectWidth <= 0 || opts.SourceRectHeight <= 0) return null;
+
+        var cropW = opts.SourceRectWidth;
+        var cropH = opts.SourceRectHeight;
+        var buffer = new byte[cropW * cropH * 4];
+        for (var i = 3; i < buffer.Length; i += 4)
+            buffer[i] = 255;
+
+        var elements = scene.Elements;
+
+        var liveCapture = elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
+        if (liveCapture != null)
+        {
+            var liveCaptureFrame = liveCapture.IsVisible ? frameFor(liveCapture) : null;
+            if (liveCaptureFrame != null && split > elements.IndexOf(liveCapture))
+                BlitContent(buffer, cropW, cropH, 0, 0, cropW, cropH, liveCaptureFrame, 1f, false, false);
+        }
+
+        var background = elements.OfType<Source>().FirstOrDefault(s => s.Type == SourceType.Background);
+        if (background != null)
+        {
+            var backgroundFrame = frameFor(background);
+            if (backgroundFrame != null && split > elements.IndexOf(background))
+                BlitContent(buffer, cropW, cropH, 0, 0, cropW, cropH, backgroundFrame, 1f, false, false);
+        }
+
+        for (var i = 0; i < split; i++)
+        {
+            var element = scene.Elements[i];
+            if (!element.IsVisible) continue;
+            switch (element)
+            {
+                case Source { IsBackground: true }:
+                case Source { Type: SourceType.Background }:
+                case Source { Type: SourceType.TextOverlay }:
+                case ZoomSceneElement:
+                    continue;
+            }
+            var frame = frameFor(element);
+            if (frame == null) continue;
+            BlitBakedElement(buffer, cropW, cropH, opts, element, frame);
+        }
+
+        var baked = new VideoFrame(cropW, cropH, buffer);
+        if (flashFrame != null)
+            baked = Overlay(baked, opts, flashFrame, 0, 0);
+        if (socialBarFrame != null && socialBarFrame.Width > 0 && socialBarFrame.Height > 0)
+            baked = Overlay(baked, opts, socialBarFrame, 0, socialBarTop);
+        return baked;
+    }
+
+    /// <summary>The compositor's dynamic/above-split path: start from an existing frame
+    /// buffer and composite the z-layers from <paramref name="split"/> onward on top.
+    /// When <paramref name="baseFrame"/> is null the caller must fall back to full render.
+    /// The social bar never reaches here (it IS baked into the static base) but the alert
+    /// ticker must: it is dynamic by construction — only ever present while an alert plays —
+    /// so it overlays LAST, pinned to the very top (TASK 47).</summary>
+    public static VideoFrame CompositeLayers(
+        VideoFrame baseFrame,
+        Scene scene,
+        int split,
+        Func<SceneElement, VideoFrame?> frameFor,
+        CompositorOptions options,
+        VideoFrame? socialBarFrame = null,
+        int socialBarTop = 0,
+        VideoFrame? flashFrame = null,
+        byte[]? scratch = null,
+        VideoFrame? tickerFrame = null)
+    {
+        var cropW = options.SourceRectWidth;
+        var cropH = options.SourceRectHeight;
+        // We must not mutate the cached base: copy it into a fresh (or pooled) buffer.
+        var buffer = scratch != null && scratch.Length == baseFrame.BgraPixels.Length
+            ? scratch
+            : new byte[baseFrame.BgraPixels.Length];
+        Buffer.BlockCopy(baseFrame.BgraPixels, 0, buffer, 0, baseFrame.BgraPixels.Length);
+
+        for (var i = split; i < scene.Elements.Count; i++)
+        {
+            var element = scene.Elements[i];
+            if (!element.IsVisible) continue;
+            switch (element)
+            {
+                case Source { IsBackground: true }:
+                case Source { Type: SourceType.Background }:
+                case Source { Type: SourceType.TextOverlay }:
+                case ZoomSceneElement { IsZoomActive: true }:
+                    continue;
+            }
+            var frame = frameFor(element);
+            if (frame == null) continue;
+            BlitBakedElement(buffer, cropW, cropH, options, element, frame);
+        }
+
+        if (tickerFrame != null && tickerFrame.Width > 0 && tickerFrame.Height > 0)
+            BlitOverlay(buffer, cropW, cropH, options, tickerFrame, tickerFrame.OriginX, tickerFrame.OriginY);
+
+        var zoom = scene.Elements.OfType<ZoomSceneElement>().FirstOrDefault(z => z.IsZoomActive);
+        if (zoom != null)
+            BlitZoom(buffer, cropW, cropH, options, zoom);
+
+        return StretchMath.BilinearScale(new VideoFrame(cropW, cropH, buffer), options.OutputWidth, options.OutputHeight);
+    }
+
+    private static void BlitBakedElement(
+        byte[] buffer, int cropW, int cropH, CompositorOptions options, SceneElement element, VideoFrame frame)
+    {
+        var ex = (float)(element.X - options.SourceRectX);
+        var ey = (float)(element.Y - options.SourceRectY);
+        var ew = (float)element.Width;
+        var eh = (float)element.Height;
+        var isRound = element.ClipShape == ClipShape.Round;
+
+        // All rect-placed elements route through the paste cache (take-9 lesson): the
+        // IsOpaque bypass kept re-sampling the webcam (~156k px) EVERY tick even when
+        // the device frame had not changed; an opaque source rasterizes to an opaque
+        // raster whose paste is a per-pixel copy branch, so hits beat the sampler and
+        // misses cost exactly what the bypass cost.
+        BlitCachedLayer(buffer, cropW, cropH, ex, ey, ew, eh, frame, element, isRound);
+        if (element.HasBorder)
+            DrawBorder(buffer, cropW, cropH, ex, ey, ew, eh, element, isRound);
+    }
+
+    /// <summary>Non-opaque layer blit through the paste cache: the element-space raster
+    /// (scaled to the element rect, round-clipped, mirrored) depends only on the source
+    /// frame + rect + shape/mirror — NOT on position or opacity. Static content (chat,
+    /// web overlays, images, the media frame between updates) is sampled ONCE and pasted
+    /// at integer position with per-tixel blend; only layers whose source frame actually
+    /// changed (webcam at device fps) pay resampling.</summary>
+    private static void BlitCachedLayer(
+        byte[] buffer, int cropW, int cropH,
+        float ex, float ey, float ew, float eh,
+        VideoFrame frame, SceneElement element, bool isRound)
+    {
+        if (ew <= 0 || eh <= 0) return;
+        var dw = (int)System.Math.Ceiling(ew);
+        var dh = (int)System.Math.Ceiling(eh);
+        if (dw <= 0 || dh <= 0) return;
+        var mirror = element.IsMirrored;
+
+        PasteKey? key = null;
+        VideoFrame? raster = null;
+        lock (_pasteGate)
+        {
+            key = new PasteKey(frame.BgraPixels, frame.Epoch, frame.Width, frame.Height, dw, dh, isRound, mirror, frame.CropBounds);
+            _pasteCache.TryGetValue(key, out raster);
+        }
+
+        if (raster == null)
+        {
+            // Rasterize in ELEMENT space on a TRANSPARENT base: the sampler writes 255
+            // alpha only where it actually draws, so untouched margins (outside the
+            // round clip, past the UniformToFill edges) stay alpha 0 and the paste
+            // reveals the master beneath instead of black. The ARRAY is reused per
+            // element (see _elementRasters note) — new source generations re-raster
+            // in place, so the steady state allocates nothing.
+            lock (_pasteGate)
+            {
+                if (_elementRasters.TryGetValue(element, out var existing)
+                    && existing.Width == dw && existing.Height == dh)
+                    raster = existing;
+            }
+            if (raster == null) raster = new VideoFrame(dw, dh, new byte[dw * dh * 4]);
+            Array.Clear(raster.BgraPixels);
+            BlitContentRaw(raster.BgraPixels, dw, dh, 0, 0, ew, eh, frame, 1f, isRound, mirror, transparentDst: true);
+            lock (_pasteGate)
+            {
+                // Only the SOURCE frame's identity is a real key owner; drop any older
+                // entry that shared this element's reused raster so a stale key can never
+                // paste a mid-update array.
+                if (_pasteCache.Count >= MaxPasteEntries) _pasteCache.Clear();
+                _pasteCache[key!] = raster;
+                _elementRasters[element] = raster;
+            }
+        }
+
+        // Paste at integer position; opacity blends. The raster is never flagged
+        // IsOpaque — round clips/margins carry alpha 0 — so the row blend always runs.
+        var op = (int)(System.Math.Clamp(element.Opacity, 0f, 1f) * 256);
+        if (op <= 0) return;
+        var px = (int)System.Math.Floor(ex);
+        var py = (int)System.Math.Floor(ey);
+        var x0 = System.Math.Max(0, px);
+        var y0 = System.Math.Max(0, py);
+        var x1 = System.Math.Min(cropW, px + dw);
+        var y1 = System.Math.Min(cropH, py + dh);
+        if (x0 >= x1 || y0 >= y1) return;
+        var s = raster.BgraPixels;
+        StripPool.For(y0, y1, y =>
+        {
+            var si = ((y - py) * dw + (x0 - px)) * 4;
+            var len = x1 - x0;
+            if (op == 256)
+                BlendRowOpaque(buffer, (y * cropW + x0) * 4, s, si, len);
+            else
+                BlendRowWeighted(buffer, (y * cropW + x0) * 4, s, si, len, op);
+        });
+    }
+
+    /// <summary>Copy <paramref name="frame"/> and blit a global overlay onto the copy
+    /// at (sx0, sy0) in crop space. internal (not private) because the frame pump's
+    /// fully-static path needs it: that path stretches the cached bake straight to the
+    /// output, so any per-frame overlay — social bar, alert ticker, brand flash — has to
+    /// be composited here first. Copying is the whole point: the bake is cached, and a
+    /// flash written straight into it would freeze there and never expire.</summary>
+    internal static VideoFrame Overlay(VideoFrame frame, CompositorOptions options, VideoFrame overlay, int sx0, int sy0)
+    {
+        var cropW = options.SourceRectWidth;
+        var cropH = options.SourceRectHeight;
+        var buffer = new byte[frame.BgraPixels.Length];
+        Buffer.BlockCopy(frame.BgraPixels, 0, buffer, 0, buffer.Length);
+        BlitOverlay(buffer, cropW, cropH, options, overlay, sx0, sy0);
+        return new VideoFrame(cropW, cropH, buffer);
+    }
+
     /// <summary>
     /// Render a cross-fade blend between two scenes. Used by <see cref="TransitionService"/>
     /// during fade/move transitions: the caller renders each scene individually, then blends
@@ -131,26 +479,144 @@ public sealed class SceneCompositor
     {
         if (ew <= 0 || eh <= 0) return;
 
+        var (scale, ox, oy) = StretchMath.UniformToFill(ew, eh, src.Width, src.Height);
+
+        // 1:1 aligned fast path (the full-frame backdrop, master-sized overlays):
+        // bilinear sampling at scale 1 with integer offsets is the identity, so the
+        // blit is a row walk, not 2M float samples + rounds. Research-first (2026-09-03,
+        // take-3 fix; libyuv's row-based BLEND_NONE pattern —
+        // https://chromium.googlesource.com/libyuv/libyuv/): the 258ms/frame render
+        // that time-lapsed take 3 lived in the general loop below.
+        if (!isRound && !isMirror && scale == 1f && ox == 0f && oy == 0f
+            && ex == MathF.Floor(ex) && ey == MathF.Floor(ey))
+        {
+            Blit1To1Rows(dst, dstW, dstH, (int)ex, (int)ey, src, opacity);
+            return;
+        }
+
+        BlitContentRaw(dst, dstW, dstH, ex, ey, ew, eh, src, opacity, isRound, isMirror);
+    }
+
+    /// <summary>The general scaled/clipped/mirrored sampler (integer fixed-point
+    /// bilinear + source-over). Also rasterizes paste-cache entries in ELEMENT space
+    /// onto a TRANSPARENT base (alpha 0) so pasting over the master keeps the round
+    /// clip and transparency of the untouched margins.</summary>
+    private static void BlitContentRaw(
+        byte[] dst, int dstW, int dstH,
+        float ex, float ey, float ew, float eh,
+        VideoFrame src, float opacity, bool isRound, bool isMirror,
+        bool transparentDst = false)
+    {
+        if (ew <= 0 || eh <= 0) return;
+
+        float scale, ox, oy, invScale;
+        float drawnW, drawnH;
+        // No CropBounds means "the whole source canvas is the crop region" — cbW/cbH
+        // MUST default to the full source dims, not 0. A zero cbW/cbH makes every
+        // sxCrop/syCrop below evaluate to 0 regardless of position, collapsing the
+        // entire sampled rect to source pixel (0,0) (the webcam gray-block regression,
+        // 2026-09-12: introduced by the CropBounds Fill-style scaling work the same
+        // day — CropBounds-bearing sources, i.e. the web widget, were never affected).
+        var cbX = 0;
+        var cbY = 0;
+        var cbW = src.Width;
+        var cbH = src.Height;
+
+        if (src.CropBounds is { } cb)
+        {
+            cbX = cb.X;
+            cbY = cb.Y;
+            cbW = cb.W;
+            cbH = cb.H;
+            scale = Math.Max(ew / cbW, eh / cbH);
+            invScale = 1f / scale;
+            drawnW = cbW * scale;
+            drawnH = cbH * scale;
+            ox = (ew - drawnW) / 2f;
+            oy = (eh - drawnH) / 2f;
+        }
+        else
+        {
+            var (uScale, uOx, uOy) = StretchMath.UniformToFill(ew, eh, src.Width, src.Height);
+            scale = uScale;
+            invScale = 1f / uScale;
+            ox = uOx;
+            oy = uOy;
+            drawnW = src.Width * uScale;
+            drawnH = src.Height * uScale;
+        }
+
+        var radius = Math.Min(ew, eh) / 2f;
+        var cx = ew / 2f;
+        var cy = eh / 2f;
+
         var x0 = Math.Max(0, (int)Math.Floor(ex));
         var y0 = Math.Max(0, (int)Math.Floor(ey));
         var x1 = Math.Min(dstW - 1, (int)Math.Ceiling(ex + ew));
         var y1 = Math.Min(dstH - 1, (int)Math.Ceiling(ey + eh));
         if (x0 > x1 || y0 > y1) return;
 
-        var (scale, ox, oy) = StretchMath.UniformToFill(ew, eh, src.Width, src.Height);
-        var drawnW = src.Width * scale;
-        var drawnH = src.Height * scale;
-        var radius = Math.Min(ew, eh) / 2f;
-        var cx = ew / 2f;
-        var cy = eh / 2f;
+        var op = (int)(Math.Clamp(opacity, 0f, 1f) * 256);
+        if (op <= 0) return;
+        var s = src.BgraPixels;
+        var srcStride = src.Width; // canvas stride in pixels (not bytes)
 
-        for (var y = y0; y <= y1; y++)
+        // Build horizontal LUT for scaled blit to reduce per-pixel divides. The table is
+        // READ by the strip workers while it is being sampled, so it must not be shared
+        // mutable state: it comes from the thread-safe ArrayPool and goes back in a finally
+        // (the static single-buffer version raced the moment the strips went parallel).
+        var lutCount = x1 - x0 + 1;
+        var sxLut = ArrayPool<float>.Shared.Rent(lutCount);
+        try
         {
-            for (var x = x0; x <= x1; x++)
+            var pxBase = x0 - ex;
+            for (var xi = 0; xi < lutCount; xi++)
             {
-                var px = x - ex; // element space
-                var py = y - ey;
-                if (px < ox || px > ox + drawnW || py < oy || py > oy + drawnH) continue;
+                var px = pxBase + xi;
+                float sxCanvas;
+                if (px < ox || px > ox + drawnW)
+                {
+                    sxCanvas = float.NaN;
+                }
+                else
+                {
+                    var sxNorm = (px - ox) / drawnW;
+                    sxNorm = sxNorm < 0f ? 0f : sxNorm > 1f ? 1f : sxNorm;
+                    var sxCrop = sxNorm * cbW;
+                    sxCanvas = cbX + sxCrop;
+                    if (sxCanvas < 0f) sxCanvas = 0f;
+                    if (sxCanvas > src.Width - 1f) sxCanvas = src.Width - 1f;
+                    if (isMirror) sxCanvas = src.Width - 1f - sxCanvas;
+                }
+                sxLut[xi] = sxCanvas;
+            }
+
+            StripPool.For(y0, y1 + 1, y =>
+        {
+            var py = y - ey;
+            if (py < oy || py > oy + drawnH) return;
+
+            // syNorm: normalized [0,1] position within the drawn content (vertically)
+            var syNorm = (py - oy) / drawnH;
+            if (syNorm < 0f) syNorm = 0f;
+            if (syNorm > 1f) syNorm = 1f;
+            // syCrop: pixel position within the crop region
+            var syCrop = syNorm * cbH;
+            // syCanvas: canvas pixel row (for buffer indexing)
+            var syCanvas = cbY + syCrop;
+            if (syCanvas < 0f) syCanvas = 0f;
+            if (syCanvas > src.Height - 1f) syCanvas = src.Height - 1f;
+            var syi = (int)syCanvas;
+            var sy1i = Math.Min(syi + 1, src.Height - 1);
+            var fy8 = (int)((syCanvas - syi) * 256);
+            var fyInv = 256 - fy8;
+
+            var di = (y * dstW + x0) * 4;
+            for (var xi = 0; xi < lutCount; xi++, di += 4)
+            {
+                var sxCanvas = sxLut[xi];
+                if (float.IsNaN(sxCanvas)) continue;
+                var px = pxBase + xi;
                 if (isRound)
                 {
                     var dx = px - cx;
@@ -158,12 +624,176 @@ public sealed class SceneCompositor
                     if (dx * dx + dy * dy > radius * radius) continue;
                 }
 
-                var sx = (px - ox) / scale;
-                var sy = (py - oy) / scale;
-                if (isMirror) sx = src.Width - 1 - sx;
-                var sample = StretchMath.SampleBgra(src.BgraPixels, src.Width, src.Height, sx, sy);
-                BlendPixel(dst, (y * dstW + x) * 4, sample, opacity);
+                var sxi = (int)sxCanvas;
+                var sx1i = Math.Min(sxi + 1, src.Width - 1);
+                var fx8 = (int)((sxCanvas - sxi) * 256);
+                var fxInv = 256 - fx8;
+
+                // ALL pixel indexing uses srcStride (canvas stride), NOT crop width
+                var p00 = (syi * srcStride + sxi) * 4;
+                var p10 = (syi * srcStride + sx1i) * 4;
+                var p01 = (sy1i * srcStride + sxi) * 4;
+                var p11 = (sy1i * srcStride + sx1i) * 4;
+                var sb = Bilinear(s[p00], s[p10], s[p01], s[p11], fx8, fxInv, fy8, fyInv);
+                var sg = Bilinear(s[p00 + 1], s[p10 + 1], s[p01 + 1], s[p11 + 1], fx8, fxInv, fy8, fyInv);
+                var sr = Bilinear(s[p00 + 2], s[p10 + 2], s[p01 + 2], s[p11 + 2], fx8, fxInv, fy8, fyInv);
+                var saFull = Bilinear(s[p00 + 3], s[p10 + 3], s[p01 + 3], s[p11 + 3], fx8, fxInv, fy8, fyInv);
+
+                var sa = saFull * op >> 8;
+                if (sa >= 255)
+                {
+                    dst[di] = (byte)sb;
+                    dst[di + 1] = (byte)sg;
+                    dst[di + 2] = (byte)sr;
+                    dst[di + 3] = 255;
+                }
+                else if (sa > 0)
+                {
+                    if (transparentDst)
+                    {
+                        // Element-raster pass on a TRANSPARENT base (the paste cache):
+                        // keep straight color + straight alpha so the paste rows can
+                        // source-over onto the opaque master. Premultiplying here (the
+                        // opaque-dst blend) stamped alpha 255 onto already-alpha-scaled
+                        // color — the paste over-wrote the scene with darkened ink, the
+                        // web widget's "black box" in recordings.
+                        dst[di] = (byte)sb;
+                        dst[di + 1] = (byte)sg;
+                        dst[di + 2] = (byte)sr;
+                        dst[di + 3] = (byte)sa;
+                    }
+                    else
+                    {
+                        var inv = 255 - sa;
+                        dst[di] = (byte)((sb * sa + dst[di] * inv + 127) / 255);
+                        dst[di + 1] = (byte)((sg * sa + dst[di + 1] * inv + 127) / 255);
+                        dst[di + 2] = (byte)((sr * sa + dst[di + 2] * inv + 127) / 255);
+                        dst[di + 3] = 255;
+                    }
+                }
             }
+            });
+        }
+        finally
+        {
+            ArrayPool<float>.Shared.Return(sxLut);
+        }
+    }
+
+    /// <summary>Two-stage bilinear in 8.8 fixed point; result within ±1 of the
+    /// float StretchMath.SampleBgra (well inside every pixel test's ±2 tolerance).
+    /// The first stage must NOT shift back to 8 bits — shifting twice collapsed
+    /// every solid-255 sample to 1 (green overwrites silently degraded to no-ops;
+    /// caught by the SceneCompositor/SceneGraph pixel probes 2026-09-04).</summary>
+    private static int Bilinear(int tl, int tr, int bl, int br, int fx8, int fxInv, int fy8, int fyInv)
+    {
+        // Both stages in one 16.8 scale: top/bot ≤ 65280, ×256 + round ≤ 16.8M — int-safe.
+        var top = tl * fxInv + tr * fx8;
+        var bot = bl * fxInv + br * fx8;
+        return (top * fyInv + bot * fy8 + 32768) >> 16;
+    }
+
+    /// <summary>Row walk for a 1:1 aligned blit at integer offset (ex, ey): per-pixel
+    /// branch on source alpha — opaque rows copy straight, transparent pixels are
+    /// skipped, partial alpha blends in integer fixed-point (libyuv's pattern). The
+    /// master buffer's destination alpha is always opaque (black base paints 255 and
+    /// every blend writes 255), so dst alpha is never read — matching BlendPixel's
+    /// source-over result for opaque dst within ±1.</summary>
+    private static void Blit1To1Rows(byte[] dst, int dstW, int dstH, int ex, int ey, VideoFrame src, float opacity)
+    {
+        var op = (int)(Math.Clamp(opacity, 0f, 1f) * 256);
+        if (op <= 0) return;
+
+        var x0 = Math.Max(0, ex);
+        var y0 = Math.Max(0, ey);
+        var x1 = Math.Min(dstW, ex + src.Width);
+        var y1 = Math.Min(dstH, ey + src.Height);
+        if (x0 >= x1 || y0 >= y1) return;
+
+        // The take-4 fix: a full-canvas opaque capture (the Live backdrop) is ONE
+        // memcpy, not 2.07M managed loop iterations — the row walk below still cost
+        // ~58ms/frame dominated by bounds-check arithmetic and GC of the per-pixel
+        // loop's slowness, i.e. the same starvation shape as take 3, one floor lower.
+        if (op == 256 && src.IsOpaque && x0 == 0 && y0 == 0 && x1 == dstW && y1 == dstH)
+        {
+            Buffer.BlockCopy(src.BgraPixels, 0, dst, 0, dstW * dstH * 4);
+            return;
+        }
+        // Opaque source with 1:1 aligned region covering full canvas
+        if (op == 256 && src.IsOpaque && ex == 0 && ey == 0 && src.Width == dstW && src.Height == dstH)
+        {
+            Buffer.BlockCopy(src.BgraPixels, 0, dst, 0, dstW * dstH * 4);
+            return;
+        }
+
+        var d = dst.AsSpan();
+        var s = src.BgraPixels.AsSpan();
+        var rowLen = x1 - x0;
+        if (op == 256)
+        {
+            for (var y = y0; y < y1; y++)
+            {
+                var si = ((y - ey) * src.Width + (x0 - ex)) * 4;
+                BlendRowOpaque(d, (y * dstW + x0) * 4, s, si, rowLen);
+            }
+        }
+        else
+        {
+            for (var y = y0; y < y1; y++)
+            {
+                var si = ((y - ey) * src.Width + (x0 - ex)) * 4;
+                BlendRowWeighted(d, (y * dstW + x0) * 4, s, si, rowLen, op);
+            }
+        }
+    }
+
+    private static void BlendRowOpaque(Span<byte> dst, int di, ReadOnlySpan<byte> src, int si, int count)
+    {
+        for (var n = 0; n < count; n++)
+        {
+            var a = src[si + 3];
+            if (a == 255)
+            {
+                dst[di] = src[si];
+                dst[di + 1] = src[si + 1];
+                dst[di + 2] = src[si + 2];
+                dst[di + 3] = 255;
+            }
+            else if (a != 0)
+            {
+                var inv = 255 - a;
+                dst[di] = (byte)((src[si] * a + dst[di] * inv + 127) / 255);
+                dst[di + 1] = (byte)((src[si + 1] * a + dst[di + 1] * inv + 127) / 255);
+                dst[di + 2] = (byte)((src[si + 2] * a + dst[di + 2] * inv + 127) / 255);
+                dst[di + 3] = 255;
+            }
+            si += 4;
+            di += 4;
+        }
+    }
+
+    private static void BlendRowWeighted(Span<byte> dst, int di, ReadOnlySpan<byte> src, int si, int count, int op)
+    {
+        for (var n = 0; n < count; n++)
+        {
+            var a = src[si + 3] * op >> 8;
+            if (a >= 255)
+            {
+                dst[di] = src[si];
+                dst[di + 1] = src[si + 1];
+                dst[di + 2] = src[si + 2];
+                dst[di + 3] = 255;
+            }
+            else if (a > 0)
+            {
+                var inv = 255 - a;
+                dst[di] = (byte)((src[si] * a + dst[di] * inv + 127) / 255);
+                dst[di + 1] = (byte)((src[si + 1] * a + dst[di + 1] * inv + 127) / 255);
+                dst[di + 2] = (byte)((src[si + 2] * a + dst[di + 2] * inv + 127) / 255);
+                dst[di + 3] = 255;
+            }
+            si += 4;
+            di += 4;
         }
     }
 
@@ -201,22 +831,40 @@ public sealed class SceneCompositor
     }
 
     /// <summary>1:1 copy of a master-sized overlay (flash, social bar) cropped to the
-    /// active source rect. The overlay is positioned in master space by (sx0, sy0).</summary>
+    /// active source rect. The overlay is positioned in master space by (sx0, sy0).
+    /// Iterates only the intersection rect — the old loop walked every destination
+    /// pixel to blit a ~64px strip (2M iterations of bounds checks per overlay).</summary>
     private static void BlitOverlay(
         byte[] dst, int dstW, int dstH, CompositorOptions options,
         VideoFrame overlay, int sx0, int sy0)
     {
-        for (var y = 0; y < dstH; y++)
+        var dx0 = Math.Max(0, sx0 - options.SourceRectX);
+        var dy0 = Math.Max(0, sy0 - options.SourceRectY);
+        var dx1 = Math.Min(dstW, sx0 - options.SourceRectX + overlay.Width);
+        var dy1 = Math.Min(dstH, sy0 - options.SourceRectY + overlay.Height);
+        StripPool.For(dy0, dy1, y =>
         {
-            for (var x = 0; x < dstW; x++)
-            {
-                var sx = x + options.SourceRectX - sx0;
-                var sy = y + options.SourceRectY - sy0;
-                if (sx < 0 || sy < 0 || sx >= overlay.Width || sy >= overlay.Height) continue;
-                var sample = StretchMath.SampleBgra(overlay.BgraPixels, overlay.Width, overlay.Height, sx, sy);
-                BlendPixel(dst, (y * dstW + x) * 4, sample, 1f);
-            }
-        }
+            var si = ((y + options.SourceRectY - sy0) * overlay.Width
+                + dx0 + options.SourceRectX - sx0) * 4;
+            BlendRowOpaque(dst, (y * dstW + dx0) * 4, overlay.BgraPixels, si, dx1 - dx0);
+        });
+    }
+
+    /// <summary>
+    /// The zoom box layer (n+1): map the element's master-space box and capture to
+    /// crop space and 2x-magnify the capture onto the box from the composed frame.
+    /// The active zoom element is never blitted by the normal layer loops — the
+    /// switch skips it and this pass draws it above everything, last.
+    /// </summary>
+    private static void BlitZoom(
+        byte[] dst, int cropW, int cropH, CompositorOptions options, ZoomSceneElement zoom)
+    {
+        ZoomMagnifier.MagnifyInto(
+            dst, cropW, cropH,
+            zoom.X - options.SourceRectX, zoom.Y - options.SourceRectY,
+            zoom.Width, zoom.Height,
+            zoom.CaptureX - options.SourceRectX, zoom.CaptureY - options.SourceRectY,
+            zoom.ClipShape == ClipShape.Round);
     }
 
     /// <summary>Straight-alpha source-over blend; the frame's alpha (and the layer opacity) drives coverage.</summary>

Services/Compositor/StaticPixelCache.cs

@@ -16,14 +16,19 @@ public static class StaticPixelCache
     public static VideoFrame? Get(string assetId)
     {
         if (string.IsNullOrWhiteSpace(assetId)) return null;
-        if (Cache.TryGetValue(assetId, out var frame)) return frame;
+        // Locked: the frame pump decodes from its own thread now (take-8 off-UI fix),
+        // so the dictionary genuinely races with UI-path callers (snapshots, heals).
+        lock (Cache)
+        {
+            if (Cache.TryGetValue(assetId, out var frame)) return frame;
 
-        var bytes = LayoutStore.Instance?.GetAssetBytes(assetId);
-        if (bytes == null || bytes.Length == 0) return null;
+            var bytes = LayoutStore.Instance?.GetAssetBytes(assetId);
+            if (bytes == null || bytes.Length == 0) return null;
 
-        var decoded = Decode(bytes);
-        if (decoded != null) Cache[assetId] = decoded;
-        return decoded;
+            var decoded = Decode(bytes);
+            if (decoded != null) Cache[assetId] = decoded;
+            return decoded;
+        }
     }
 
     public static VideoFrame? Decode(byte[] bytes)

Services/Compositor/ZoomMagnifier.cs

@@ -0,0 +1,116 @@
+using System;
+using System.Buffers;
+
+namespace ytLive.Services.Compositor;
+
+/// <summary>
+/// The zoom box's magnifier (creator-corrected model, 2026-10-08): the box is a
+/// detached 2x view of a FIXED capture window — the box/2 region centred on the
+/// spot the creator clicked — sampled from the ALREADY-COMPOSITED frame (every
+/// layer: live backdrop, art, webcam, sources, alerts). Moving the box relocates
+/// it on screen without changing the capture; the box is painted LAST (layer n+1)
+/// so it sits above everything. The capture snapshot is taken before the box is
+/// drawn, so a box overlapping its own source never recurses.
+/// </summary>
+internal static class ZoomMagnifier
+{
+    /// <summary>
+    /// Magnify a box/2 capture window onto a box/2&#x2009;² box in <paramref name="dst"/>
+    /// (an opaque, already-composited crop-space buffer). dst pixel centres map to
+    /// capture coords as <c>cap + (dstLocal + 0.5) / 2</c> — the exact 2x the preview's
+    /// VisualBrush shows via a box/2 Viewbox with Stretch=Fill. <paramref name="round"/>
+    /// clips the box to a true circle (zoom shape Circle).
+    /// </summary>
+    internal static void MagnifyInto(
+        byte[] dst, int dstW, int dstH,
+        double boxX, double boxY, double boxW, double boxH,
+        double capX, double capY,
+        bool round)
+    {
+        if (boxW <= 0 || boxH <= 0) return;
+        if (dstW <= 0 || dstH <= 0) return;
+
+        // Integer box draw bounds (clamped to the buffer).
+        var bx0 = Math.Max(0, (int)Math.Floor(boxX));
+        var by0 = Math.Max(0, (int)Math.Floor(boxY));
+        var bx1 = Math.Min(dstW, (int)Math.Ceiling(boxX + boxW));
+        var by1 = Math.Min(dstH, (int)Math.Ceiling(boxY + boxH));
+        if (bx0 >= bx1 || by0 >= by1) return;
+        var bw = bx1 - bx0;
+        var bh = by1 - by0;
+
+        // Integer capture-window read bounds (the 2x window is box/2, clamped).
+        var rx0 = Math.Max(0, (int)Math.Floor(capX));
+        var ry0 = Math.Max(0, (int)Math.Floor(capY));
+        var rx1 = Math.Min(dstW, (int)Math.Ceiling(capX + boxW / 2.0));
+        var ry1 = Math.Min(dstH, (int)Math.Ceiling(capY + boxH / 2.0));
+        var rw = rx1 - rx0;
+        var rh = ry1 - ry0;
+        if (rw <= 0 || rh <= 0) return;
+
+        // Snapshot the capture first: the box may overlap its own source region.
+        var src = ArrayPool<byte>.Shared.Rent(rw * rh * 4);
+        try
+        {
+            for (var y = 0; y < rh; y++)
+                Buffer.BlockCopy(dst, ((ry0 + y) * dstW + rx0) * 4, src, y * rw * 4, rw * 4);
+
+            var radius = Math.Min(boxW, boxH) / 2.0;
+            var ccx = boxX + boxW / 2.0;
+            var ccy = boxY + boxH / 2.0;
+
+            for (var y = 0; y < bh; y++)
+            {
+                var dy = by0 + y;
+                var sy = capY + (dy + 0.5 - boxY) * 0.5 - ry0;
+                if (sy < 0.0) sy = 0.0;
+                if (sy > rh - 1.0) sy = rh - 1.0;
+                var syi = (int)sy;
+                var syInv = Math.Min(syi + 1, rh - 1);
+                var fy8 = (int)((sy - syi) * 256);
+                var fyInv = 256 - fy8;
+
+                var di = (dy * dstW + bx0) * 4;
+                for (var x = 0; x < bw; x++, di += 4)
+                {
+                    var dx = bx0 + x;
+                    if (round)
+                    {
+                        var ox = dx - ccx;
+                        var oy = dy - ccy;
+                        if (ox * ox + oy * oy > radius * radius) continue;
+                    }
+                    var sx = capX + (dx + 0.5 - boxX) * 0.5 - rx0;
+                    if (sx < 0.0) sx = 0.0;
+                    if (sx > rw - 1.0) sx = rw - 1.0;
+                    var sxi = (int)sx;
+                    var sxInv = Math.Min(sxi + 1, rw - 1);
+                    var fx8 = (int)((sx - sxi) * 256);
+                    var fxInv = 256 - fx8;
+
+                    var p00 = (syi * rw + sxi) * 4;
+                    var p10 = (syi * rw + sxInv) * 4;
+                    var p01 = (syInv * rw + sxi) * 4;
+                    var p11 = (syInv * rw + sxInv) * 4;
+                    dst[di] = (byte)Bilinear(src[p00], src[p10], src[p01], src[p11], fx8, fxInv, fy8, fyInv);
+                    dst[di + 1] = (byte)Bilinear(src[p00 + 1], src[p10 + 1], src[p01 + 1], src[p11 + 1], fx8, fxInv, fy8, fyInv);
+                    dst[di + 2] = (byte)Bilinear(src[p00 + 2], src[p10 + 2], src[p01 + 2], src[p11 + 2], fx8, fxInv, fy8, fyInv);
+                    dst[di + 3] = 255;
+                }
+            }
+        }
+        finally
+        {
+            ArrayPool<byte>.Shared.Return(src);
+        }
+    }
+
+    /// <summary>Two-stage bilinear in 8.8 fixed point (same precision as
+    /// <see cref="SceneCompositor"/>'s sampler).</summary>
+    private static int Bilinear(int tl, int tr, int bl, int br, int fx8, int fxInv, int fy8, int fyInv)
+    {
+        var top = tl * fxInv + tr * fx8;
+        var bot = bl * fxInv + br * fx8;
+        return (top * fyInv + bot * fy8 + 32768) >> 16;
+    }
+}

Services/Encoder/FfmpegArgs.cs

@@ -2,7 +2,9 @@ namespace ytLive.Services.Encoder;
 
 /// <summary>
 /// Builds the FFmpeg command line for a live RTMP push (TASK 4 ship step 3):
-/// raw BGRA frames via stdin (paced <c>-re</c>), real audio via the named pipe
+/// raw BGRA frames via stdin (paced by the frame pump — the pump holds a strict
+/// CFR cadence, so <c>-re</c> would only add a second, fighting pacer), real
+/// audio via the named pipe
 /// (TASK 9 — the mixer streams f32le at 48 kHz stereo into <c>\\.\pipe\&lt;name&gt;</c>;
 /// WASAPI loopback + the mic ride the pipe instead of the old anullsrc silence),
 /// H.264 + AAC encoding, FLV muxing to the ingestion URL. Pure — the encoder
@@ -16,7 +18,6 @@ public static class FfmpegArgs
         {
             "-hide_banner", "-loglevel", "info",
             "-stats", "-stats_period", "0.5",
-            "-re",
             "-f", "rawvideo", "-pix_fmt", "bgra",
             "-video_size", $"{options.Width}x{options.Height}",
             "-framerate", options.Fps.ToString(),

Services/Encoder/FfmpegEncoder.cs

@@ -1,4 +1,6 @@
+using System.Buffers;
 using System.Diagnostics;
+using System.Threading.Channels;
 using ytLive.Helpers;
 using ytLive.Models;
 
@@ -30,6 +32,21 @@ public sealed class FfmpegEncoder : IFfmpegEncoder
     private Task? _stderrLoop;
     private bool _stopRequested;
 
+    // Pipe decoupling (slice 10, 2026-09-10): a bounded pending-frame queue drained
+    // by its own task (the OBS video-thread → encoder-queue model — the encoder's
+    // thread never couples back into the video thread; libobs obs-encoder.c). The
+    // pump's SubmitFrameAsync now ENQUEUES (copying into a pooled buffer) instead of
+    // blocking on WriteAsync when ffmpeg lags the pipe; overflow DROPS the newest
+    // frame (skip-newest) and counts it. BoundedChannelFullMode.Wait + TryWrite gives
+    // exactly that: when full, TryWrite returns false and the caller drops the item.
+    private const int QueueCapacity = 120; // ~2s at the tier's 60fps
+    private readonly Channel<PendingWrite> _frames = Channel.CreateBounded<PendingWrite>(
+        new BoundedChannelOptions(QueueCapacity) { SingleReader = true });
+    private Task? _drainTask;
+    private int _droppedBackpressure;
+
+    private readonly record struct PendingWrite(byte[] Buffer, int Length);
+
     public FfmpegEncoder(
         IFfmpegLocator locator,
         Func<IEncoderProcess>? processFactory = null)
@@ -40,6 +57,13 @@ public sealed class FfmpegEncoder : IFfmpegEncoder
 
     public bool IsRunning { get; private set; }
 
+    /// <summary>Frames dropped by the bounded queue because the drain task couldn't
+    /// keep the pipe fed (the encoder lagging the real-time capture rate). The pump
+    /// reports this in its stats; the burned-in frame counter in the recording
+    /// shows the identical jumps. Distinct from <see cref="StreamHealth.DroppedFrames"/>
+    /// (ffmpeg's own progress-derived estimate).</summary>
+    public int DroppedFrames => Volatile.Read(ref _droppedBackpressure);
+
     public async Task StartAsync(EncoderOptions options, CancellationToken cancellationToken = default)
     {
         if (options == null) throw new ArgumentNullException(nameof(options));
@@ -93,26 +117,40 @@ public sealed class FfmpegEncoder : IFfmpegEncoder
 
         _stopRequested = false;
         _stderrLoop = RunStderrLoopAsync(process);
+        StartDrainLoop(process);
     }
 
     /// <summary>
-    /// Write one raw BGRA frame to ffmpeg's stdin. Serialized internally; callers
-    /// (the compositor pump) may race freely. Frames are written as-is — the caller
-    /// paces to capture rate (the compositor's job, ship step 5).
+    /// Enqueue one raw BGRA frame for ffmpeg's stdin (slice 10). The caller races
+    /// freely (the compositor pump); this never blocks on the pipe. The pixels are
+    /// copied into a pooled buffer first because — unlike the old direct write — the
+    /// write happens later on the drain thread, so the caller may (and does) recycle
+    /// its scratch buffer the moment this returns. When the bounded queue is full the
+    /// NEWEST frame is dropped and counted (freshness over coverage; the encoder is
+    /// already behind, so the stale-content failure mode never encodes).
     /// </summary>
-    public async Task SubmitFrameAsync(VideoFrame frame, CancellationToken cancellationToken = default)
+    public Task SubmitFrameAsync(VideoFrame frame, CancellationToken cancellationToken = default)
     {
         if (frame == null) throw new ArgumentNullException(nameof(frame));
-        IEncoderProcess? process;
         lock (_gate)
         {
             if (!IsRunning) throw new InvalidOperationException("The encoder is not running.");
-            process = _process;
         }
 
-        var bytes = frame.BgraPixels;
-        await process!.StandardInput.WriteAsync(bytes, cancellationToken).ConfigureAwait(false);
-        await process.StandardInput.FlushAsync(cancellationToken).ConfigureAwait(false);
+        if (cancellationToken.IsCancellationRequested)
+            return Task.FromCanceled(cancellationToken);
+
+        var pooled = ArrayPool<byte>.Shared.Rent(frame.BgraPixels.Length);
+        Buffer.BlockCopy(frame.BgraPixels, 0, pooled, 0, frame.BgraPixels.Length);
+        if (_frames.Writer.TryWrite(new PendingWrite(pooled, frame.BgraPixels.Length)))
+            return Task.CompletedTask;
+
+        // Queue full (encoder lagging) or the channel completed during stop — drop the
+        // newest and count it. The caller never blocks; the encoder catches up or the
+        // session ends with a (reported) short gap instead of a frozen stall.
+        ArrayPool<byte>.Shared.Return(pooled);
+        Interlocked.Increment(ref _droppedBackpressure);
+        return Task.CompletedTask;
     }
 
     public async Task StopAsync(CancellationToken cancellationToken = default)
@@ -127,13 +165,17 @@ public sealed class FfmpegEncoder : IFfmpegEncoder
             loop = _stderrLoop;
         }
 
+        // Flush every queued frame, then EOF: TryComplete lets the drain task write
+        // the buffered frames, close stdin → ffmpeg finalizes and exits by itself
+        // (the "did not exit after EOF" kill below is only the backstop).
         try
         {
-            process!.StandardInput.Dispose(); // EOF → ffmpeg finalizes + exits
+            _frames.Writer.TryComplete();
+            if (_drainTask != null) await _drainTask.ConfigureAwait(false);
         }
         catch (Exception ex)
         {
-            AppLog.Write(ex, "FFmpeg encoder: closing stdin failed");
+            AppLog.Write(ex, "FFmpeg encoder: drain loop faulted during stop");
         }
 
         try
@@ -178,6 +220,7 @@ public sealed class FfmpegEncoder : IFfmpegEncoder
 
     public void Dispose()
     {
+        _frames.Writer.TryComplete(); // unblock a stuck drain loop alongside the kill
         lock (_gate)
         {
             if (!IsRunning) return;
@@ -188,6 +231,54 @@ public sealed class FfmpegEncoder : IFfmpegEncoder
         }
     }
 
+    /// <summary>
+    /// The drain task (slice 10): owns every stdin write, so pipe backpressure — the
+    /// pump's old stall — lives HERE, on a thread the pump never touches. Frames are
+    /// written exactly as queued (the pooled array through its recorded length —
+    /// ArrayPool may return a larger buffer), returned to the pool after the write
+    /// copies into the pipe, and stdin is closed (EOF) once the queue drains.
+    /// </summary>
+    private void StartDrainLoop(IEncoderProcess process)
+    {
+        _drainTask = Task.Run(async () =>
+        {
+            try
+            {
+                try
+                {
+                    while (await _frames.Reader.WaitToReadAsync().ConfigureAwait(false))
+                    {
+                        while (_frames.Reader.TryRead(out var pending))
+                        {
+                            await process.StandardInput.WriteAsync(pending.Buffer, 0, pending.Length)
+                                .ConfigureAwait(false);
+                            await process.StandardInput.FlushAsync().ConfigureAwait(false);
+                            ArrayPool<byte>.Shared.Return(pending.Buffer);
+                        }
+                    }
+                }
+                catch (ChannelClosedException)
+                {
+                    // channel completed while waiting — fall through to EOF
+                }
+                catch (Exception ex)
+                {
+                    AppLog.Write(ex, "FFmpeg encoder: drain loop write faulted");
+                }
+                finally
+                {
+                    // EOF on every path — a byte that sits in the pool when the pipe
+                    // breaks is garbage anyway, and ffmpeg MUST see the close to finalize.
+                    process.StandardInput.Dispose();
+                }
+            }
+            catch (Exception ex)
+            {
+                AppLog.Write(ex, "FFmpeg encoder: drain loop faulted");
+            }
+        });
+    }
+
     private async Task<string> ProbeEncoderAsync(string ffmpegPath, CancellationToken cancellationToken)
     {
         try
@@ -230,14 +321,35 @@ public sealed class FfmpegEncoder : IFfmpegEncoder
                     OnStderrLine(process, line);
                 }
 
-                var code = process.ExitCode;
-                var stillRunning = false;
-                lock (_gate) stillRunning = IsRunning;
-                if (stillRunning && !_stopRequested && code != 0)
+                // Read the exit code defensively: the stop path disposes the process
+                // while this loop may still be waking (2026-09-01 "No process is
+                // associated with this object" — a cosmetic race that poisoned the log).
+                int exitCode;
+                try
                 {
-                    AppLog.Write($"FFmpeg encoder: subprocess exited unexpectedly ({code})");
-                    _health.LastError = $"FFmpeg exited with code {code}";
-                    ProcessFailed?.Invoke(this, $"FFmpeg exited with code {code}");
+                    exitCode = process.ExitCode;
+                }
+                catch (Exception)
+                {
+                    exitCode = -1;
+                }
+
+                var stillRunning = false;
+                var stopping = false;
+                lock (_gate)
+                {
+                    stillRunning = IsRunning;
+                    stopping = _stopRequested;
+                }
+                if (stillRunning && !stopping)
+                {
+                    // ANY exit we did not ask for is a failure — including code 0.
+                    // The old `code != 0` gate let ffmpeg's clean early exit vanish
+                    // without a word while the pump kept feeding a corpse
+                    // (2026-09-01 first real recording: died at ~0.9s, zero logs).
+                    AppLog.Write($"FFmpeg encoder: subprocess exited unexpectedly (code {exitCode})");
+                    _health.LastError = $"FFmpeg exited with code {exitCode}";
+                    ProcessFailed?.Invoke(this, $"FFmpeg exited with code {exitCode}");
                 }
             }
             catch (Exception ex)
@@ -250,7 +362,17 @@ public sealed class FfmpegEncoder : IFfmpegEncoder
     private void OnStderrLine(IEncoderProcess process, string line)
     {
         var progress = FfmpegProgressParser.TryParse(line);
-        if (progress == null) return;
+        if (progress == null)
+        {
+            // THE EYES: everything ffmpeg says that isn't a progress line — startup
+            // config, warnings, the real reason it quit. Was silently discarded
+            // (2026-09-01: encoder died at ~0.9s, log silent). Truncated so a
+            // \r-choked stats blob can't flood; noise now beats blindness.
+            var text = line.Trim('\r', ' ', '\t');
+            if (text.Length > 0)
+                AppLog.Write($"ffmpeg: {(text.Length > 400 ? text[..400] + "…" : text)}");
+            return;
+        }
 
         var dropped = Math.Max(0, (long)Math.Round(progress.Value.Fps * progress.Value.Duration.TotalSeconds) - progress.Value.Frame);
 

Services/Encoder/FfmpegLocator.cs

@@ -1,125 +1,81 @@
 using System.IO;
-using System.IO.Compression;
-using System.Net.Http;
 using ytLive.Helpers;
 
 namespace ytLive.Services.Encoder;
 
 /// <summary>
-/// The default <see cref="IFfmpegLocator"/>: probe PATH first (the user's own
-/// install wins), then the cache in <c>%APPDATA%\ytLlive\tools</c>, then pull the
-/// pinned BtbN **lgpl-shared** build (TASK 4 ship step 2). The shared variant is a
-/// deliberate licensing choice: dynamic linking means LGPL compliance is "license
-/// text + source offer", with no static-relink (LGPL §6) material required. The
-/// shared zip puts <c>ffmpeg.exe</c> plus the <c>libav*.dll</c> family in <c>bin/</c>,
-/// so both are extracted — Windows resolves the DLLs from the exe's own directory.
-/// Search dirs, tools dir, and the downloader are constructor-injected so tests
-/// fake the network and stay on a temp directory.
+/// The default <see cref="IFfmpegLocator"/>: resolve the <b>bundled</b> FFmpeg that ships
+/// next to the app, falling back to PATH for anyone who deliberately installed their own.
+///
+/// <para><b>Nothing is downloaded.</b> This type used to pin a BtbN release URL, download
+/// the zip on first run, and execute it — which is Windows Store policy 10.2.2 (dynamic
+/// code inclusion, cited in <c>TASKS/research-store-certification.md</c> §4) and already
+/// cost a real failure: the pin aged out of BtbN's 14-day retention and the download
+/// <b>404'd on the creator's first real recording attempt</b> (2026-09-01). The binaries
+/// are now fetched at BUILD time by <c>scripts/fetch-ffmpeg.sh</c> (pinned URL + SHA-256)
+/// and copied into <c>ffmpeg/</c> beside the executable.</para>
+///
+/// <para><b>Order is bundled-first, deliberately.</b> The old code probed PATH first
+/// ("the user's own install wins"). With a bundle in the package that is the wrong way
+/// round: a random PATH <c>ffmpeg</c> may be a different major version or a GPL build, and
+/// the bundle is the one we pinned, license-vetted, and tested against. PATH stays as the
+/// escape hatch, which is what it is actually good for.</para>
+///
+/// <para>The lgpl-<b>shared</b> variant is a licensing choice, not a packaging one: dynamic
+/// linking makes LGPL compliance "license text + source offer" with no static-relink
+/// (LGPL §6) material required. That means the <c>libav*.dll</c> family must sit in the
+/// same folder as the exe — Windows resolves them from the executable's own directory.</para>
 /// </summary>
 public sealed class FfmpegLocator : IFfmpegLocator
 {
     public const string FileName = "ffmpeg.exe";
 
-    /// <summary>Pinned BtbN LGPL-shared win64 build (immutable autobuild tag; see TASKS.md).</summary>
-    public const string PinnedUrl =
-        "https://github.com/BtbN/FFmpeg-Builds/releases/download/autobuild-2026-08-09-13-03/ffmpeg-master-latest-win64-lgpl-shared.zip";
+    /// <summary>Sibling probe binary — bundled alongside ffmpeg so the media
+    /// frame-rate probe (<see cref="ytLive.Services.FfmpegFrameRateProbe"/>) can
+    /// derive its path from the located ffmpeg directory.</summary>
+    public const string ProbeFileName = "ffprobe.exe";
+
+    /// <summary>Folder, relative to the app base directory, that the build copies the
+    /// bundled build into. One folder for the exe and every DLL.</summary>
+    public const string BundleFolderName = "ffmpeg";
+
+    /// <summary>Base directory the bundle is resolved against. Injectable so tests can
+    /// point at a temp tree; defaults to the running app's base directory.</summary>
+    private readonly string _bundleRoot;
 
     private readonly string[] _searchDirs;
-    private readonly string _toolsDir;
-    private readonly Func<string, CancellationToken, Task<byte[]>> _downloader;
 
-    public FfmpegLocator(
-        string[]? searchDirs = null,
-        string? toolsDir = null,
-        Func<string, CancellationToken, Task<byte[]>>? downloader = null)
+    public FfmpegLocator(string[]? searchDirs = null, string? bundleRoot = null)
     {
         _searchDirs = searchDirs ?? ParsePath();
-        _toolsDir = toolsDir ?? Path.Combine(
-            Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "ytLlive", "tools");
-        _downloader = downloader ?? DefaultDownload;
+        _bundleRoot = bundleRoot ?? AppContext.BaseDirectory;
     }
 
-    public async Task<string> LocateAsync(CancellationToken cancellationToken = default)
+    public Task<string> LocateAsync(CancellationToken cancellationToken = default)
     {
+        var bundled = Path.Combine(_bundleRoot, BundleFolderName, FileName);
+        if (IsUsable(bundled)) return Task.FromResult(bundled);
+
         foreach (var dir in _searchDirs)
         {
             if (string.IsNullOrEmpty(dir)) continue;
             var candidate = Path.Combine(dir, FileName);
-            if (File.Exists(candidate)) return candidate;
+            if (IsUsable(candidate)) return Task.FromResult(candidate);
         }
 
-        var cached = Path.Combine(_toolsDir, FileName);
-        if (File.Exists(cached) && new FileInfo(cached).Length > 0) return cached;
-
-        try
-        {
-            var zip = await _downloader(PinnedUrl, cancellationToken).ConfigureAwait(false);
-            if (zip.Length == 0)
-                throw new IOException($"FFmpeg download from {PinnedUrl} returned an empty payload.");
-            Directory.CreateDirectory(_toolsDir);
-            ExtractBinaries(zip, _toolsDir);
-            return cached;
-        }
-        catch (Exception ex) when (ex is IOException or InvalidDataException or NotSupportedException)
-        {
-            AppLog.Write(ex, "FFmpeg locator: download/extract failed");
-            throw;
-        }
+        // Deliberately loud. The previous cache-then-download ladder had a "found
+        // something on disk" path that could satisfy a missing bundle with a stale copy,
+        // which is exactly the silent-drift a certification-gated dependency must not
+        // have. If the package forgot ffmpeg/, the app says so and stops.
+        throw new IOException(
+            $"FFmpeg was not found. The bundled copy is missing from " +
+            $"'{Path.Combine(_bundleRoot, BundleFolderName)}' — this build is incomplete " +
+            "(reinstall or re-fetch with scripts/fetch-ffmpeg.sh). Installing an LGPL-shared " +
+            "FFmpeg and putting 'ffmpeg' on PATH also works.");
     }
 
-    /// <summary>
-    /// Extract <c>ffmpeg.exe</c> and every <c>*.dll</c> into <c>toolsDir</c> via a
-    /// staging directory, so a failed extract never leaves a partially-populated
-    /// cache behind (the previous good cache stays until every move succeeds).
-    /// </summary>
-    private static void ExtractBinaries(byte[] zip, string toolsDir)
-    {
-        var staging = toolsDir + ".stage";
-        if (Directory.Exists(staging)) Directory.Delete(staging, recursive: true);
-        Directory.CreateDirectory(staging);
-        try
-        {
-            using var stream = new MemoryStream(zip, writable: false);
-            using var archive = new ZipArchive(stream, ZipArchiveMode.Read);
-            var exe = archive.Entries.FirstOrDefault(
-                    e => e.FullName.EndsWith("/" + FileName, StringComparison.OrdinalIgnoreCase))
-                ?? throw new InvalidDataException($"The pinned FFmpeg archive does not contain {FileName}.");
-            ExtractOne(exe, Path.Combine(staging, FileName));
-            foreach (var entry in archive.Entries)
-            {
-                if (entry.FullName.EndsWith(".dll", StringComparison.OrdinalIgnoreCase))
-                    ExtractOne(entry, Path.Combine(staging, Path.GetFileName(entry.FullName)));
-            }
-            foreach (var file in Directory.GetFiles(staging))
-                File.Move(file, Path.Combine(toolsDir, Path.GetFileName(file)), overwrite: true);
-        }
-        finally
-        {
-            if (Directory.Exists(staging)) Directory.Delete(staging, recursive: true);
-        }
-    }
-
-    private static void ExtractOne(ZipArchiveEntry entry, string destination)
-    {
-        var temp = destination + ".tmp";
-        try
-        {
-            using (var source = entry.Open())
-            using (var target = File.Create(temp))
-                source.CopyTo(target);
-            File.Move(temp, destination);
-        }
-        finally
-        {
-            if (File.Exists(temp)) File.Delete(temp);
-        }
-    }
-
-    private static async Task<byte[]> DefaultDownload(string url, CancellationToken ct)
-    {
-        using var http = new HttpClient { Timeout = TimeSpan.FromMinutes(10) };
-        return await http.GetByteArrayAsync(url, ct).ConfigureAwait(false);
-    }
+    private static bool IsUsable(string path) =>
+        File.Exists(path) && new FileInfo(path).Length > 0;
 
     private static string[] ParsePath()
     {

Services/Encoder/FramePump.cs

@@ -29,15 +29,92 @@ public sealed class FramePump : IDisposable
     private readonly Action<string>? _log;
     private readonly Func<TimeSpan, CancellationToken, Task> _pacingDelay;
     private readonly Func<(VideoFrame? Frame, SocialBarPosition Position)>? _socialBar;
+    private readonly Func<VideoFrame?>? _alertTicker;
+    private readonly Func<VideoFrame?>? _brandFlash;
     private readonly TransitionService? _transition;
-    private readonly Func<Scene?>? _fromSceneProvider;
+    private readonly SceneGraph? _sceneGraph;
     private readonly SceneCompositor _compositor = new();
 
+    // Master-buffer scratch pool (take-4 starvation fix, slice 2 of 2): a fresh
+    // 8.3MB byte[] every tick is ~500MB/s of LOH churn — GC stalls masquerading
+    // as render cost. The pump pools ONLY buffers it handed out (reference-equality
+    // set), so bake-cache / social-bar / static-cache frames are never touched;
+    // SubmitFrameAsync copies the bytes to the encoder's stdin before returning,
+    // so recycling after submit is safe (MyMistakes recipe).
+    private readonly HashSet<byte[]> _ownedScratch = new(ReferenceEqualityComparer.Instance);
+    private readonly List<byte[]> _freeScratch = new();
+    private const int MaxScratchPooled = 4;
+
+    private byte[] AcquireScratch(int size)
+    {
+        for (var i = _freeScratch.Count - 1; i >= 0; i--)
+        {
+            if (_freeScratch[i].Length != size) continue;
+            var buffer = _freeScratch[i];
+            _freeScratch.RemoveAt(i);
+            return buffer;
+        }
+        var fresh = new byte[size];
+        _ownedScratch.Add(fresh);
+        return fresh;
+    }
+
+    private void ReleaseScratch(byte[]? buffer)
+    {
+        if (buffer == null || !_ownedScratch.Contains(buffer)) return;
+        if (_freeScratch.Count >= MaxScratchPooled || _freeScratch.Contains(buffer)) return;
+        _freeScratch.Add(buffer);
+    }
+
+    // Windows sleep quantum (take-9 finding, 2026-09-04): Task.Delay rounds every
+    // request up to the system clock tick (~15.6ms default — learn.microsoft.com/en-us/
+    // dotnet/api/system.threading.tasks.task.delay: "approximately 15 milliseconds on
+    // Windows systems"), so a pacer requesting 3-15ms actually sleeps 15.6ms. Takes
+    // 5-9 measured work ~25ms but period ~37ms: one padded wait per frame hid every
+    // compositor improvement. Established media-app practice (game-loop/OBS canon —
+    // stackoverflow.com/questions/5441464; and raise the resolution for the session —
+    // learn.microsoft.com/en-us/windows/win32/api/timeapi/nf-timeapi-timebeginperiod):
+    // timeBeginPeriod(1) while the pump runs, sleep only the BULK of the remainder,
+    // and spin the last ~2ms across the deadline.
+    [System.Runtime.InteropServices.DllImport("winmm.dll")]
+    private static extern uint timeBeginPeriod(uint uMilliseconds);
+    [System.Runtime.InteropServices.DllImport("winmm.dll")]
+    private static extern uint timeEndPeriod(uint uMilliseconds);
+    private static readonly long SpinTailTicks = System.Diagnostics.Stopwatch.Frequency * 2 / 1000; // 2ms
+
     private readonly object _gate = new();
     private IFfmpegEncoder? _encoder;
     private CancellationTokenSource? _cts;
     private Task? _pumpTask;
     private bool _started;
+    private long _outputIndex;
+
+    /// <summary>Captured by <see cref="ProbeRender"/> when a render exceeds ~20ms —
+    /// the 2026-09-12 half-speed-render probe. Appended (once) to the next stats or
+    /// stall line, then cleared.</summary>
+    private string _renderDetail = "";
+
+    /// <summary>C4 blit-on-change cache (2026-09-15): the FULL-render path (split=0
+    /// when the live-capture backdrop sits at element 0, or no SceneGraph) re-composites
+    /// the ENTIRE frame every tick even when no input changed — the ty-1841 take logged
+    /// a render stall on EVERY iteration (totalMs 21-44, one composite per ~30ms while
+    /// the content moved ~20 updates/s). The SceneGraph split can never help here: the
+    /// backdrop is element 0 and must stay dynamic (a baked capture goes stale), so the
+    /// cache lives at the pump: the last full-render output plus the input identity that
+    /// produced it. Unchanged identity → ONE BlockCopy (~3ms) reuses the composite;
+    /// changed identity → re-composite. The cache buffer is a SEPARATE long-lived array,
+    /// never the scratch pool — the caller burns the frame counter and recycles the
+    /// scratch AFTER RenderScene returns, so the cache is written from the rendered
+    /// scratch BEFORE returning (pre-burn, pre-recycle). The identity mirror is
+    /// <see cref="BuildFullRenderSignature"/>: it resolves the same frames the compositor
+    /// will (same resolver seam), so a changed frame (new capture, new webcam, new chat
+    /// raster) forces a re-render and an unchanged one never serves stale bytes. Internal
+    /// counters feed the Good Dog test + the 5s cache detail in the stats line.</summary>
+    private byte[]? _fullCachePixels;
+    private bool _fullCacheValid;
+    private ulong _lastFullSignature;
+    internal long CacheHits;
+    internal long CacheRenders;
 
     /// <summary>Forwards the encoder's parsed health — ship step 6 binds this to the bottom bar.</summary>
     public event EventHandler<StreamHealth>? HealthUpdated;
@@ -54,8 +131,10 @@ public sealed class FramePump : IDisposable
         Action<string>? log = null,
         Func<TimeSpan, CancellationToken, Task>? pacingDelay = null,
         Func<(VideoFrame? Frame, SocialBarPosition Position)>? socialBar = null,
+        Func<VideoFrame?>? alertTicker = null,
+        Func<VideoFrame?>? brandFlash = null,
         TransitionService? transition = null,
-        Func<Scene?>? fromSceneProvider = null)
+        SceneGraph? sceneGraph = null)
     {
         _sceneProvider = sceneProvider ?? throw new ArgumentNullException(nameof(sceneProvider));
         _frameResolver = frameResolver ?? throw new ArgumentNullException(nameof(frameResolver));
@@ -65,12 +144,19 @@ public sealed class FramePump : IDisposable
         _log = log;
         _pacingDelay = pacingDelay ?? ((delay, ct) => Task.Delay(delay, ct));
         _socialBar = socialBar;
+        _alertTicker = alertTicker;
+        _brandFlash = brandFlash;
         _transition = transition;
-        _fromSceneProvider = fromSceneProvider;
+        _sceneGraph = sceneGraph;
     }
 
     public bool IsRunning { get; private set; }
 
+    /// <summary>The burned counter of the LAST frame submitted to the encoder. Stable
+    /// across a tick's multiple resolver passes (it advances only at burn/submit, which
+    /// happens AFTER render) — tests key per-tick content on it.</summary>
+    internal long OutputIndex => _outputIndex;
+
     /// <summary>Never throws: failures are logged and surfaced via <see cref="Failed"/>,
     /// so the VM can fire-and-forget it from a sync command handler.</summary>
     public async Task StartAsync(CancellationToken cancellationToken = default)
@@ -107,8 +193,20 @@ public sealed class FramePump : IDisposable
             // synchronously on this thread before PumpAsync even returns.
             IsRunning = true;
             _cts = new CancellationTokenSource();
-            _pumpTask = PumpAsync(options, _cts.Token);
-            _log?.Invoke($"FramePump started ({options.Width}×{options.Height} @ {options.Fps} fps)");
+            // The loop runs on the thread pool ON PURPOSE (take-8 finding, 2026-09-04):
+            // Task.Run installs no SynchronizationContext, so every await continuation
+            // stays off the UI dispatcher. Before this, the pump inherited the UI
+            // thread's sync context (StartAsync is fired from a command handler), so
+            // "render 22ms, wait 10ms" was the producer sitting in the dispatcher
+            // queue behind the live preview it is meant to be independent of — the
+            // stats quantum fix made the wait VISIBLE; this removes its cause.
+            // OBS's video threads are dedicated for exactly this reason.
+            _pumpTask = Task.Run(() => PumpAsync(options, _cts.Token));
+            var scene = _sceneProvider();
+            var comp = _compositorOptions();
+            _log?.Invoke($"FramePump started ({options.Width}×{options.Height} @ {options.Fps} fps)" +
+                         (scene != null ? $" scene='{scene.Name}'" : "") +
+                         $" comp={comp.SourceRectWidth}x{comp.SourceRectHeight}");
         }
         catch (Exception ex)
         {
@@ -208,6 +306,8 @@ public sealed class FramePump : IDisposable
         {
             _log?.Invoke($"FramePump: dispose failed: {ex.Message}");
         }
+        _freeScratch.Clear();
+        _ownedScratch.Clear();
     }
 
     private async Task PumpAsync(EncoderOptions options, CancellationToken ct)
@@ -215,6 +315,121 @@ public sealed class FramePump : IDisposable
         var interval = TimeSpan.FromSeconds(1d / Math.Max(1, options.Fps));
         var lastTick = System.Diagnostics.Stopwatch.StartNew();
 
+        // Deadline pacing (2026-09-03, take-3 fix): the frame interval is a DEADLINE,
+        // not an afterthought sleep — the OBS libobs video-io.c pattern (researched
+        // before coding; see https://github.com/obsproject/obs-studio/blob/master/
+        // libobs/media-io/video-io.c). The old loop slept the FULL interval after
+        // each render, so period = render + submit + interval: at take-3's 258ms
+        // render that was 3.6fps stamped into a 60fps container — rawvideo stamps by
+        // arrival, so 30 wall-seconds muxed as a 2.1s time-lapse, no error anywhere.
+        var intervalTicks = Math.Max(1, (long)Math.Round(interval.TotalSeconds * System.Diagnostics.Stopwatch.Frequency));
+        var nextTick = System.Diagnostics.Stopwatch.GetTimestamp();
+
+        // Stage timing (2026-09-01, take two): rawvideo carries no per-frame
+        // timestamps — ffmpeg stamps frames by ARRIVAL at the declared fps. A producer
+        // slower than the declared rate yields a time-lapsed, short file (observed:
+        // 39 frames in 27 wall-seconds ≈ 30x at 60fps) with no error anywhere.
+        // Log the render/submit split every 5s so the next take names the stage.
+        var renderSw = new System.Diagnostics.Stopwatch();
+        var submitSw = new System.Diagnostics.Stopwatch();
+        var waitSw = new System.Diagnostics.Stopwatch();
+        // Resolve-vs-composite split (2026-09-04, take-6 ambiguity): "render" was a
+        // black box — the stats line now reports resolver time separately so a take
+        // names the stage (get-frame vs blit) instead of feeding another guess.
+        var resolveSw = new System.Diagnostics.Stopwatch();
+        long renderTicks = 0, submitTicks = 0, resolveTicks = 0, waitTicks = 0;
+        long socialBarTicks = 0, tickerTicks = 0, flashTicks = 0, acquireTicks = 0;
+        long worstRender = 0, worstSubmit = 0;
+        int statFrames = 0;
+        int stalls = 0;
+        long lastCacheHits = 0, lastCacheRenders = 0;
+        var statsNext = DateTime.UtcNow + TimeSpan.FromSeconds(5);
+        // bool _loggedStartDetail = false;
+
+        // Real-render accounting (UNIT 0, 2026-10-05): every average above was
+        // divided by statFrames — the number of frames SUBMITTED, which deadline
+        // padding always fills to the full target even when the renderer only
+        // produced a fifth of them. A 60fps container therefore reported "300/300
+        // frames, avg render 12ms" while the source actually fed it 60 distinct
+        // images. Render cost is now divided by the render count, and the render
+        // count is reported beside the submit count — the two numbers side by side
+        // ARE the duplicate-on-lag ratio, which is the only honest reading of how
+        // much of the stream is a repeat.
+        int statRenders = 0;
+
+        // Webcam cadence (UNIT 0, 2026-10-05): the pump sees each element's resolved
+        // frame, and VideoFrame.Epoch is the webcam ring's monotonic generation — so a
+        // NEW epoch means the webcam actually delivered something new between two of
+        // our ticks. This is the counterpart to MediaCaptureFrameSource's arrivals
+        // line: it measures what reached the OUTPUT, not what the camera produced. If
+        // the camera reports 30/s and this reports 25/s, the loss is between them.
+        var webcamCadence = new Helpers.FrameCadence();
+        var seenWebcamEpochs = new HashSet<long>();
+
+        void ReportStats()
+        {
+            if (DateTime.UtcNow < statsNext) return;
+            var target = 5d / interval.TotalSeconds; // frames expected per window
+            IFfmpegEncoder? encoder;
+            lock (_gate) encoder = _encoder;
+            var dropped = encoder == null ? 0 : encoder.DroppedFrames;
+            var detail = _renderDetail;
+            _renderDetail = "";
+            var cacheDetail = "";
+            if (statFrames > 0)
+            {
+                // C4 window detail: rendered composites (R) vs cache reuses (H) since the
+                // last report — hard numeric proof the blit-on-change cache engaged.
+                var hits = CacheHits - lastCacheHits;
+                var renders = CacheRenders - lastCacheRenders;
+                lastCacheHits = CacheHits;
+                lastCacheRenders = CacheRenders;
+                if (hits > 0 || renders > 0) cacheDetail = $", cache {renders}R/{hits}H";
+            }
+            double freq = System.Diagnostics.Stopwatch.Frequency;
+            _log?.Invoke(statFrames == 0
+                ? "FramePump stats: NO frames produced in 5s (loop stalled?)" + (detail.Length > 0 ? " | " + detail : "")
+                : $"FramePump stats: {statFrames}/{target:F0} frames per 5s from {statRenders} renders, " +
+                  $"avg render {renderTicks / freq * 1000 / Math.Max(1, statRenders):F1}ms " +
+                  $"(resolve {resolveTicks / freq * 1000 / Math.Max(1, statRenders):F1}, " +
+                  $"social {socialBarTicks / freq * 1000 / Math.Max(1, statRenders):F2}ms, " +
+                  $"ticker {tickerTicks / freq * 1000 / Math.Max(1, statRenders):F2}ms, " +
+                  $"flash {flashTicks / freq * 1000 / Math.Max(1, statRenders):F2}ms, " +
+                  $"acq {acquireTicks / freq * 1000 / Math.Max(1, statRenders):F2}ms), " +
+                  $"avg submit {submitTicks / freq * 1000 / statFrames:F1}ms, "
+                  + $"avg wait {waitTicks / freq * 1000 / Math.Max(1, statRenders):F1}ms, "
+                  + $"worst render {worstRender / freq * 1000:F1}ms, "
+                  + $"worst submit {worstSubmit / freq * 1000:F1}ms, "
+                  + $"dropped {dropped}, stalls {stalls}{cacheDetail}, {webcamCadence.Summarize().Describe("webcam")}"
+                  + (detail.Length > 0 ? " | " + detail : ""));
+            worstRender = 0;
+            worstSubmit = 0;
+            renderTicks = submitTicks = resolveTicks = waitTicks = 0;
+            socialBarTicks = tickerTicks = flashTicks = acquireTicks = 0;
+            statFrames = 0;
+            statRenders = 0;
+            stalls = 0;
+            webcamCadence.Reset();
+            seenWebcamEpochs.Clear();
+            statsNext = DateTime.UtcNow + TimeSpan.FromSeconds(5);
+        }
+
+        // One wrapper shared by every render of the run — resolve time accumulates
+        // inside the render measurement, and the stats line reports the split.
+        timeBeginPeriod(1); // pairs with timeEndPeriod in the finally — see field note
+        var previousGcMode = System.Runtime.GCSettings.LatencyMode;
+        System.Runtime.GCSettings.LatencyMode = System.Runtime.GCLatencyMode.SustainedLowLatency;
+        VideoFrame? TimedResolver(SceneElement element)
+        {
+            resolveSw.Restart();
+            var frame = _frameResolver(element);
+            resolveSw.Stop();
+            resolveTicks += resolveSw.ElapsedTicks;
+            if (element.IsWebcam && frame != null && seenWebcamEpochs.Add(frame.Epoch))
+                webcamCadence.Add(System.Diagnostics.Stopwatch.GetTimestamp());
+            return frame;
+        }
+
         try
         {
             while (!ct.IsCancellationRequested)
@@ -222,6 +437,7 @@ public sealed class FramePump : IDisposable
                 var scene = _sceneProvider();
                 if (scene != null)
                 {
+                    var iterStart = System.Diagnostics.Stopwatch.GetTimestamp();
                     var compositorOptions = _compositorOptions();
                     VideoFrame? socialBarFrame = null;
                     var socialBarTop = 0;
@@ -235,30 +451,125 @@ public sealed class FramePump : IDisposable
                                 : compositorOptions.SourceRectHeight - barFrame.Height;
                     }
 
+                    var sw = System.Diagnostics.Stopwatch.StartNew();
+                    VideoFrame? tickerFrame = _alertTicker?.Invoke();
+                    tickerTicks += sw.ElapsedTicks;
+                    sw.Restart();
+                    VideoFrame? flashFrame = _brandFlash?.Invoke();
+                    flashTicks += sw.ElapsedTicks;
+                    sw.Restart();
+                    var (barFrame2, position2) = (_socialBar == null ? (null, SocialBarPosition.Bottom) : _socialBar());
+                    socialBarFrame = barFrame2;
+                    socialBarTop = barFrame2 == null ? 0 : (position2 == SocialBarPosition.Top ? 0 : compositorOptions.SourceRectHeight - barFrame2.Height);
+                    socialBarTicks += sw.ElapsedTicks;
+
                     VideoFrame frame;
-                    if (_transition is { Active: true } transition && _fromSceneProvider != null)
+                    var scratchSize = compositorOptions.SourceRectWidth
+                        * compositorOptions.SourceRectHeight * 4;
+                    renderSw.Restart();
+                    sw.Restart();
+                    var scratch = AcquireScratch(scratchSize);
+                    acquireTicks += sw.ElapsedTicks;
+                    frame = RenderScene(scene, compositorOptions, socialBarFrame, socialBarTop, tickerFrame, flashFrame, scratch, TimedResolver);
+                    if (_transition is { Active: true } transition)
                     {
-                        var fromScene = _fromSceneProvider();
-                        var fromFrame = fromScene != null
-                            ? _compositor.Render(fromScene, _frameResolver, null, compositorOptions, socialBarFrame, socialBarTop)
-                            : _compositor.Render(scene, _frameResolver, null, compositorOptions, socialBarFrame, socialBarTop);
-                        var toFrame = _compositor.Render(scene, _frameResolver, null, compositorOptions, socialBarFrame, socialBarTop);
-                        frame = transition.BlendFrame(toFrame);
+                        frame = transition.BlendFrame(frame);
                         transition.Tick(lastTick.Elapsed.TotalMilliseconds);
-                        lastTick.Restart();
-                    }
-                    else
-                    {
-                        frame = _compositor.Render(scene, _frameResolver, null, compositorOptions, socialBarFrame, socialBarTop);
-                        lastTick.Restart();
                     }
+                    // Restarted EVERY frame (transition or not): a transition begun
+                    // after idle must not inherit a giant ElapsedMs and complete
+                    // instantly on its first Tick.
+                    lastTick.Restart();
+                    renderSw.Stop();
+                    renderTicks += renderSw.ElapsedTicks;
+                    if (renderSw.ElapsedTicks > worstRender) worstRender = renderSw.ElapsedTicks;
+                    statRenders++;
 
                     IFfmpegEncoder? encoder;
                     lock (_gate) encoder = _encoder;
                     if (encoder == null) break;
-                    await encoder.SubmitFrameAsync(frame, ct);
+
+                    // Deadline pacing, OBS duplicate-on-lag (slice 15): emit ONE frame per
+                    // deadline slot — a fresh composite when the render kept up, a REPEAT
+                    // of this iteration's latest composite for every slot the render
+                    // overran. The OBS model never leaves a wall-time hole: libobs
+                    // media-io/video-io.c runs on its own clock and duplicates the latest
+                    // frame when the video thread lags, logging "lagged frames due to
+                    // rendering lag/stalls" — never skipped time (docs.obsproject.com/
+                    // backend-design: "If the video frame queue is full, it will duplicate
+                    // the last frame"). Slice 10 chose the opposite for freshness: an
+                    // overrun SKIPPED the missed slots, so a 60fps-authoring pump emitting
+                    // one frame per 35ms overrun authored ~1.7x playback (ty-1726: 163
+                    // video frames for 2.93s of audio) and ended the video 0.22s before the
+                    // audio tail. Counting duplicates instead of skips keeps recording
+                    // duration == wall duration (no acceleration, no audio tail cut) at the
+                    // cost of a short judder during a stall — the accepted trade. The burst
+                    // is microseconds (the enqueue never blocks, and the loop is clamped to
+                    // deadlineNow) so it can't smear the way the take-9 blocking burst did.
+                    var deadlineNow = System.Diagnostics.Stopwatch.GetTimestamp();
+                    while (!ct.IsCancellationRequested && deadlineNow >= nextTick)
+                    {
+                        // Burned-in frame counter (slice 10 judge): a clock-independent
+                        // pacing witness burned literally into the composite. Decode the
+                        // recording and read the bottom-right strip: the number must
+                        // advance +1 per authored frame and jump only by counted drops
+                        // (queue overflow). Burned here — on the buffer finally submitted,
+                        // which the enqueue's snapshot copies before the next iteration
+                        // rewrites it — so every file frame carries its own index and a
+                        // fast-render iteration that submitted nothing leaves no phantom
+                        // gap (the slice-10 unconditional bump before the gate could).
+                        _outputIndex++;
+                        BurnFrameIndex(frame.BgraPixels, frame.Width, frame.Height, _outputIndex);
+
+                        submitSw.Restart();
+                        await encoder.SubmitFrameAsync(frame, ct);
+                        submitSw.Stop();
+                        statFrames++;
+                        submitTicks += submitSw.ElapsedTicks;
+                        if (submitSw.ElapsedTicks > worstSubmit) worstSubmit = submitSw.ElapsedTicks;
+                        nextTick += intervalTicks;
+                    }
+
+                    // SubmitFrameAsync copied the bytes into the encoder's queue — the
+                    // tick's buffers are recyclable once the enqueue snapshot them.
+                    // The free-list Contains guard keeps the Cut path (BlendFrame
+                    // returns toFrame itself, aliasing scratch) safe.
+                    ReleaseScratch(frame.BgraPixels);
+                    ReleaseScratch(scratch);
+
+                    // Sleep the BULK of the remainder, SPIN the 2ms tail — never hand
+                    // a sub-tick remainder to the sleep quantum (the timeBeginPeriod
+                    // note). If the renderer already ate the budget there is nothing
+                    // left to sleep and the loop renders the next frame straight away.
+                    waitSw.Restart();
+                    var ahead = nextTick - System.Diagnostics.Stopwatch.GetTimestamp();
+                    if (ahead > SpinTailTicks)
+                        await _pacingDelay(TimeSpan.FromSeconds(
+                            (ahead - SpinTailTicks) / (double)System.Diagnostics.Stopwatch.Frequency), ct);
+                    while (!ct.IsCancellationRequested
+                           && System.Diagnostics.Stopwatch.GetTimestamp() < nextTick)
+                        Thread.SpinWait(400);
+                    waitSw.Stop();
+                    waitTicks += waitSw.ElapsedTicks;
+
+                    // Stall logger (slice 10): an iteration spanning more than two full
+                    // intervals is the old bug's fingerprint — name the stage instead of
+                    // guessing. With the queue, submit should be ~1ms, so a stall here
+                    // means RENDER or RESOLVE (the stage terms of the last take).
+                    var iterWall = System.Diagnostics.Stopwatch.GetTimestamp() - iterStart;
+                    if (iterWall > 2 * intervalTicks)
+                    {
+                        stalls++;
+                        var detail = _renderDetail;
+                        _renderDetail = "";
+                        _log?.Invoke($"FramePump stall: iteration {iterWall / (double)System.Diagnostics.Stopwatch.Frequency * 1000:F0}ms " +
+                            $"(> 2× the {interval.TotalMilliseconds:F0}ms interval): worst render " +
+                            $"{worstRender / (double)System.Diagnostics.Stopwatch.Frequency * 1000:F0}ms, worst submit " +
+                            $"{worstSubmit / (double)System.Diagnostics.Stopwatch.Frequency * 1000:F0}ms, dropped {encoder.DroppedFrames}" +
+                            (detail.Length > 0 ? " | " + detail : ""));
+                    }
+                    ReportStats();
                 }
-                await _pacingDelay(interval, ct);
             }
         }
         catch (OperationCanceledException)
@@ -281,12 +592,310 @@ public sealed class FramePump : IDisposable
         }
         finally
         {
+            System.Runtime.GCSettings.LatencyMode = previousGcMode;
+            timeEndPeriod(1);
             lock (_gate) IsRunning = false;
         }
     }
 
     private void OnHealthUpdated(object? sender, StreamHealth health) => HealthUpdated?.Invoke(this, health);
 
+    /// <summary>Render a scene, using the baked-crust optimization when a <see cref="SceneGraph"/>
+    /// is wired in: bake/cache the static layers below the split point, then composite the
+    /// dynamic/above-split layers per frame. Without a SceneGraph, falls back to a full render
+    /// (identical output — see SceneCompositorTests). <paramref name="scratch"/> is a pooled
+    /// master buffer when supplied; the fully-static path returns the bake-cache frame itself
+    /// (never pooled — the release side checks owned-by-reference).</summary>
+    private VideoFrame RenderScene(
+        Scene scene,
+        CompositorOptions options,
+        VideoFrame? socialBarFrame,
+        int socialBarTop,
+        VideoFrame? tickerFrame,
+        VideoFrame? flashFrame,
+        byte[]? scratch = null,
+        Func<SceneElement, VideoFrame?>? resolver = null)
+    {
+        resolver ??= _frameResolver;
+        if (_sceneGraph == null)
+        {
+            var sw = System.Diagnostics.Stopwatch.StartNew();
+            var frame = RenderFull(scene, options, socialBarFrame, socialBarTop, tickerFrame, flashFrame, scratch, resolver);
+            ProbeRender("full-no-graph", scene, -1, sw.ElapsedMilliseconds, 0);
+            return frame;
+        }
+
+        var split = _sceneGraph.GetSplitPoint(scene);
+        if (split == scene.Elements.Count)
+        {
+            // Fully static scene: bake once, reuse.
+            var sw = System.Diagnostics.Stopwatch.StartNew();
+            var baked = _sceneGraph.GetBakedBase(scene, _frameResolver, _compositorOptions);
+            if (baked != null)
+            {
+                // BUG (pre-existing, found while wiring the branding credit 2026-09-26):
+                // this path returned the stretched bake and silently DROPPED the social
+                // bar and the alert ticker. Overlay() copies before blitting, so the
+                // cached bake is not mutated and the flash still cannot get sticky in it.
+                if (socialBarFrame != null || tickerFrame != null || flashFrame != null)
+                {
+                    var withOverlays = baked;
+                    if (flashFrame != null) withOverlays = SceneCompositor.Overlay(withOverlays, options, flashFrame, 0, 0);
+                    if (tickerFrame != null) withOverlays = SceneCompositor.Overlay(withOverlays, options, tickerFrame, tickerFrame.OriginX, tickerFrame.OriginY);
+                    if (socialBarFrame != null) withOverlays = SceneCompositor.Overlay(withOverlays, options, socialBarFrame, socialBarTop, 0);
+                    baked = withOverlays;
+                }
+                var stretched = StretchMath.BilinearScale(baked, options.OutputWidth, options.OutputHeight);
+                ProbeRender("fully-static", scene, split, sw.ElapsedMilliseconds, (int)sw.ElapsedMilliseconds);
+                return stretched;
+            }
+        }
+
+        var swBase = System.Diagnostics.Stopwatch.StartNew();
+        var baseFrame = _sceneGraph.GetBakedBase(scene, _frameResolver, _compositorOptions);
+        if (baseFrame != null)
+        {
+            var frame = SceneCompositor.CompositeLayers(
+                baseFrame, scene, split, resolver, options, socialBarFrame, socialBarTop, flashFrame: flashFrame, tickerFrame: tickerFrame, scratch: scratch);
+            ProbeRender("base+layers", scene, split, swBase.ElapsedMilliseconds, 0);
+            return frame;
+        }
+
+        // No static base (first layer is dynamic or empty scene) — full render.
+        var swFull = System.Diagnostics.Stopwatch.StartNew();
+        var frame2 = RenderFull(scene, options, socialBarFrame, socialBarTop, tickerFrame, flashFrame, scratch, resolver);
+        ProbeRender("full-render", scene, split, swFull.ElapsedMilliseconds, 0);
+        return frame2;
+    }
+
+    /// <summary>The full-render path (no SceneGraph, or no static base) wrapped in the
+    /// C4 blit-on-change cache: when every resolved input plus every element's
+    /// layout/visual bits match the last composite, reuse it with one BlockCopy instead
+    /// of re-compositing. Mirror the compositor's resolution <i>before</i> deciding so a
+    /// hit costs ~3ms of pure copy and a miss costs exactly the old full render.</summary>
+    private VideoFrame RenderFull(
+        Scene scene, CompositorOptions options, VideoFrame? socialBarFrame, int socialBarTop,
+        VideoFrame? tickerFrame, VideoFrame? flashFrame,
+        byte[]? scratch, Func<SceneElement, VideoFrame?> resolver)
+    {
+        // 1:1 guard: the cache stores the OUTPUT bytes and scratch is source-sized —
+        // at 1:1 they are the same buffer size. Off-size tiers (a vertical 1080×1920
+        // tier, an H264-1080p tier) fall back to a per-tick full render; the deployed
+        // config is master-sized and caching a per-tick fresh scale buffer is the known
+        // vertical-tier follow-up (see ai.md), not silently baked here.
+        var useCache = scratch != null && options.SourceRectWidth == options.OutputWidth
+            && options.SourceRectHeight == options.OutputHeight;
+        var signature = useCache
+            ? BuildFullRenderSignature(scene, options, socialBarFrame, socialBarTop, tickerFrame, flashFrame, resolver)
+            : 0UL;
+
+        if (useCache && _fullCacheValid && signature == _lastFullSignature
+            && _fullCachePixels!.Length == scratch!.Length)
+        {
+            Buffer.BlockCopy(_fullCachePixels, 0, scratch, 0, scratch.Length);
+            CacheHits++;
+            return new VideoFrame(options.SourceRectWidth, options.SourceRectHeight, scratch);
+        }
+
+        var rendered = _compositor.Render(scene, resolver, flashFrame, options, socialBarFrame, socialBarTop, scratch: scratch, tickerFrame: tickerFrame);
+        CacheRenders++;
+        if (useCache)
+        {
+            var pixels = rendered.BgraPixels;
+            if (_fullCachePixels == null || _fullCachePixels.Length != pixels.Length)
+                _fullCachePixels = new byte[pixels.Length];
+            // PRE-burn / PRE-recycle: the caller burns the counter and recycles this
+            // scratch after RenderScene returns — the cache keeps a clean copy, and the
+            // burn on the next hit writes to a FRESH scratch copy, never the cache.
+            Buffer.BlockCopy(pixels, 0, _fullCachePixels, 0, pixels.Length);
+            _lastFullSignature = signature;
+            _fullCacheValid = true;
+        }
+        else
+        {
+            _fullCacheValid = false; // size changed — never reuse a wrong-size buffer
+        }
+        return rendered;
+    }
+
+    /// <summary>Hash the complete set of inputs the compositor's FULL render consumes:
+    /// the crop/output dimensions, the social bar, and — in element order, mirroring
+    /// <c>SceneCompositor.Render</c>'s iteration — every element's layout/visual fields
+    /// plus the frame each one resolves (through the SAME resolver seam the render will
+    /// use). A changed frame (new capture, new webcam Epoch, new chat raster) changes the
+    /// hash → re-composite; an unchanged one reuses the cache. Buffer-array identity +
+    /// Epoch + CropBounds is the compositor's own paste-key shape — producers hand out
+    /// fresh immutable arrays, or recycled-ring arrays whose monotonic Epoch
+    /// distinguishes generations (the capture take-11 fix), so address-identity alone is
+    /// never trusted to key recycled content.</summary>
+    private static ulong BuildFullRenderSignature(
+        Scene scene, CompositorOptions options, VideoFrame? socialBarFrame, int socialBarTop,
+        VideoFrame? tickerFrame,
+        VideoFrame? flashFrame,
+        Func<SceneElement, VideoFrame?> resolver)
+    {
+        var h = 14695981039346656037UL; // FNV-1a offset basis
+        h = Mix(h, (ulong)options.SourceRectX);
+        h = Mix(h, (ulong)options.SourceRectY);
+        h = Mix(h, (ulong)options.SourceRectWidth);
+        h = Mix(h, (ulong)options.SourceRectHeight);
+        h = Mix(h, (ulong)options.OutputWidth);
+        h = Mix(h, (ulong)options.OutputHeight);
+        h = Mix(h, (ulong)socialBarTop);
+        if (socialBarFrame != null) h = MixFrame(h, socialBarFrame);
+        else h = Mix(h, 0xFFFFFFFFFFFFFFFFUL);
+        if (tickerFrame != null) h = MixFrame(h, tickerFrame);
+        else h = Mix(h, 0xFFFFFFFFFFFFFFFFUL);
+        // BrandFlashPresenter recycles one buffer and bumps Epoch every read, so this
+        // invalidates the cache on every tick of a credit — a cached frame would freeze
+        // the fade and pin a stale spot.
+        if (flashFrame != null) h = MixFrame(h, flashFrame);
+        else h = Mix(h, 0xFFFFFFFFFFFFFFFFUL);
+
+        var backdropResolved = false;
+        foreach (var element in scene.Elements)
+        {
+            h = Mix(h, (ulong)System.Runtime.CompilerServices.RuntimeHelpers.GetHashCode(element));
+            h = Mix(h, element.IsVisible ? 1UL : 0UL);
+            h = MixDouble(h, element.X);
+            h = MixDouble(h, element.Y);
+            h = MixDouble(h, element.Width);
+            h = MixDouble(h, element.Height);
+            h = MixDouble(h, element.Opacity);
+            h = Mix(h, (ulong)element.ClipShape);
+            h = Mix(h, element.IsMirrored ? 1UL : 0UL);
+            h = Mix(h, (ulong)element.BorderWidth);
+            h = MixDouble(h, element.BorderOpacity);
+            if (element.TryGetBorderColor(out var bcR, out var bcG, out var bcB))
+                h = Mix(h, (ulong)((bcR << 16) | (bcG << 8) | bcB));
+            else
+                h = Mix(h, 0UL);
+
+            // Mirror the compositor's per-element frame resolution EXACTLY, so the hash
+            // reacts to the same frames a render uses and never to a frame a render
+            // ignores (a false-positive change only wastes one render; a false NEGATIVE
+            // would serve stale bytes — that is what this mirror prevents).
+            VideoFrame? frame = null;
+            if (element is Source { IsBackground: true })
+            {
+                h = Mix(h, 1UL); // the live backdrop — first visible one is resolved, once
+                if (element.IsVisible && !backdropResolved)
+                {
+                    frame = resolver(element);
+                    backdropResolved = true;
+                }
+            }
+            else if (element is Source { Type: SourceType.TextOverlay })
+            {
+                h = Mix(h, 2UL); // skipped kind — never resolved by the compositor
+            }
+            else if (element is Source { Type: SourceType.Background })
+            {
+                h = Mix(h, 3UL); // background image — resolved even when invisible (Render does)
+                frame = resolver(element);
+            }
+            else
+            {
+                h = Mix(h, 4UL); // regular layer — resolved only when visible
+                if (element.IsVisible) frame = resolver(element);
+            }
+            if (frame != null) h = MixFrame(h, frame);
+            else h = Mix(h, 0UL);
+        }
+        return h;
+    }
+
+    private static ulong Mix(ulong h, ulong v) => (h ^ v) * 0x9E3779B97F4A7C15UL;
+
+    private static ulong MixDouble(ulong h, double v)
+        => Mix(h, unchecked((ulong)BitConverter.DoubleToInt64Bits(v)));
+
+    private static ulong MixFrame(ulong h, VideoFrame frame)
+    {
+        h = Mix(h, (ulong)System.Runtime.CompilerServices.RuntimeHelpers.GetHashCode(frame.BgraPixels));
+        h = Mix(h, (ulong)frame.Epoch);
+        h = Mix(h, (ulong)frame.Width);
+        h = Mix(h, (ulong)frame.Height);
+        if (frame.CropBounds is { } cb)
+        {
+            h = Mix(h, (ulong)cb.X);
+            h = Mix(h, (ulong)cb.Y);
+            h = Mix(h, (ulong)cb.W);
+            h = Mix(h, (ulong)cb.H);
+        }
+        else
+        {
+            h = Mix(h, 0xFFFFFFFFFFFFFFFFUL);
+        }
+        return h;
+    }
+
+    /// <summary>2026-09-12 half-speed-render probe: the pump only produces ~27fps
+    /// (render ~35ms vs the 16.7ms deadline), and rawvideo muxes at the DECLARED fps,
+    /// so every take muxes at ~half its wall length (the truncation complaint). This
+    /// names WHICH compositor path ate the slow frame so the fix targets the real
+    /// stage. Records only when a frame takes ≥20ms (or carries the previous detail).</summary>
+    private void ProbeRender(string path, Scene scene, int split, long totalMs, int bakeMs)
+    {
+        if (totalMs < 20 && _renderDetail.Length == 0) return;
+        var dynamics = 0;
+        foreach (var e in scene.Elements)
+            if (e.Kind == ElementKind.Dynamic) dynamics++;
+        _renderDetail = $"render={path} split={split} elements={scene.Elements.Count} dynamic={dynamics}" +
+                        (bakeMs > 0 ? $" bakeMs={bakeMs}" : "") + $" totalMs={totalMs}";
+    }
+
+    // Dot-matrix digits (5×7, one row per raster line, '1' = lit) burned into the
+    // bottom-right of every composite. Basic OCR-safe shapes, sized so the strip is
+    // a 36×8 white box in the corner of a 1920×1080 frame — readable with a zoomed
+    // player, invisible at normal size.
+    private static readonly string[][] DigitGlyphs =
+    {
+        new[] { "01110","10001","10001","10001","10001","10001","01110" }, // 0
+        new[] { "00100","01100","00100","00100","00100","00100","01110" }, // 1
+        new[] { "01110","10001","00001","00010","00100","01000","11111" }, // 2
+        new[] { "11111","00001","00010","00110","00001","10001","01110" }, // 3
+        new[] { "00010","00110","01010","10010","11111","00010","00010" }, // 4
+        new[] { "11111","10000","11110","00001","00001","10001","01110" }, // 5
+        new[] { "01110","10001","10000","11110","10001","10001","01110" }, // 6
+        new[] { "11111","00001","00010","00100","01000","01000","01000" }, // 7
+        new[] { "01110","10001","10001","01110","10001","10001","01110" }, // 8
+        new[] { "01110","10001","10001","01111","00001","10001","01110" }, // 9
+    };
+
+    private static void BurnFrameIndex(byte[] bgra, int width, int height, long index)
+    {
+        const int digitW = 5, digitH = 7, gap = 1, margin = 2, digitCount = 6;
+        var stripW = digitCount * (digitW + gap) - gap;
+        var left = width - margin - stripW;
+        var top = height - margin - digitH;
+
+        // Solid white box under the digits — the underlying scene can be anything.
+        for (var y = top; y < top + digitH; y++)
+            for (var x = left; x < left + stripW; x++)
+            {
+                var i = (y * width + x) * 4;
+                bgra[i] = 255;
+                bgra[i + 1] = 255;
+                bgra[i + 2] = 255;
+            }
+
+        var text = index.ToString("D6");
+        for (var d = 0; d < digitCount; d++)
+        {
+            var glyph = DigitGlyphs[text[d] - '0'];
+            for (var row = 0; row < digitH; row++)
+                for (var col = 0; col < digitW; col++)
+                {
+                    if (glyph[row][col] != '1') continue;
+                    var i = ((top + row) * width + (left + d * (digitW + gap) + col)) * 4;
+                    bgra[i] = 0;
+                    bgra[i + 1] = 0;
+                    bgra[i + 2] = 0;
+                }
+        }
+    }
+
     private void OnProcessFailed(object? sender, string message)
     {
         _log?.Invoke($"FramePump: encoder process failed: {message}");

Services/Encoder/IFfmpegEncoder.cs

@@ -22,4 +22,9 @@ public interface IFfmpegEncoder : IDisposable
     Task StartAsync(EncoderOptions options, CancellationToken cancellationToken = default);
     Task SubmitFrameAsync(VideoFrame frame, CancellationToken cancellationToken = default);
     Task StopAsync(CancellationToken cancellationToken = default);
+
+    /// <summary>Frames dropped by the encoder's bounded queue since start (the encoder
+    /// lagging the real-time capture rate). Zero in a healthy session; fed to the pump's
+    /// stats and mirrored by gaps in the burned-in frame counter of the recording.</summary>
+    int DroppedFrames { get; }
 }

Services/FfmpegDecodeProcess.cs

@@ -0,0 +1,36 @@
+using System.Diagnostics;
+using System.IO;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// The real <see cref="IDecodeProcess"/>: a <see cref="Process"/> with stdout
+/// redirected as raw bytes for reading <c>rawvideo</c> frames. Constructed by
+/// <see cref="MediaVideoSource"/> for the media-file decoder subprocess.
+/// </summary>
+public sealed class FfmpegDecodeProcess : IDecodeProcess
+{
+    private readonly Process _process;
+
+    public FfmpegDecodeProcess() => _process = new Process { EnableRaisingEvents = true };
+
+    public void Start(ProcessStartInfo startInfo)
+    {
+        _process.StartInfo = startInfo;
+        _process.Start();
+    }
+
+    public Stream StandardOutput => _process.StandardOutput.BaseStream;
+
+    public bool HasExited => _process.HasExited;
+    public int ExitCode => _process.ExitCode;
+    public void Kill()
+    {
+        if (!_process.HasExited) _process.Kill();
+    }
+
+    public Task WaitForExitAsync(CancellationToken cancellationToken = default)
+        => _process.WaitForExitAsync(cancellationToken);
+
+    public void Dispose() => _process.Dispose();
+}

Services/FfmpegFrameRateParser.cs

@@ -0,0 +1,53 @@
+using System.Globalization;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// TASK 21 (slice 2): parses the native frame rate of a video from ffprobe
+/// <c>-show_entries stream=avg_frame_rate,r_frame_rate</c> output, which reports
+/// each as a rational like <c>30/1</c> or <c>60000/1001</c> (or <c>0/0</c> when
+/// unknown). Prefers <c>avg_frame_rate</c> (the true display rate over the whole
+/// file, correct for VFR) and falls back to <c>r_frame_rate</c> (the container/
+/// codec rate). Pure: no ffprobe, no I/O, unit-testable.
+/// </summary>
+public static class FfmpegFrameRateParser
+{
+    public static double? ParseFrameRate(string probeOutput)
+    {
+        foreach (var key in new[] { "avg_frame_rate=", "r_frame_rate=" })
+        {
+            var value = FindValue(probeOutput, key);
+            if (value is not null && TryParseRational(value, out var fps))
+                return fps;
+        }
+        return null;
+    }
+
+    /// <summary>The trimmed value of the first line beginning with <paramref name="key"/>.</summary>
+    private static string? FindValue(string text, string key)
+    {
+        foreach (var line in text.Split('\n'))
+        {
+            var trimmed = line.Trim();
+            if (trimmed.StartsWith(key, StringComparison.Ordinal))
+                return trimmed.Substring(key.Length).Trim();
+        }
+        return null;
+    }
+
+    /// <summary>Parses <c>v</c> as <c>N</c> (integer) or <c>N/M</c> (rational) into
+    /// a frames-per-second double. <c>0</c> and <c>0/M</c> count as unknown.</summary>
+    private static bool TryParseRational(string value, out double fps)
+    {
+        fps = 0;
+        var parts = value.Split('/');
+        if (parts.Length == 0 || !int.TryParse(parts[0], NumberStyles.None, CultureInfo.InvariantCulture, out var num))
+            return false;
+        var den = 1;
+        if (parts.Length > 1 && !int.TryParse(parts[1], NumberStyles.None, CultureInfo.InvariantCulture, out den))
+            return false;
+        if (num <= 0 || den <= 0) return false;
+        fps = (double)num / den;
+        return true;
+    }
+}

Services/FrameRateProbe.cs

@@ -0,0 +1,67 @@
+using System.Diagnostics;
+using System.IO;
+using ytLive.Services.Encoder;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// TASK 21 (slice 2): resolves the native frame rate of a media file so the
+/// decoder can pace frames to real time. Seam so <see cref="MediaVideoSource"/>
+/// never touches ffprobe directly and tests can fake the whole probe.
+/// </summary>
+public interface IFrameRateProbe
+{
+    /// <summary>Native video FPS for <paramref name="path"/>, or null when unknown
+    /// (no video stream, ffprobe unavailable, unparsable).</summary>
+    Task<double?> ProbeAsync(string path, CancellationToken cancellationToken = default);
+}
+
+/// <summary>
+/// Default probe: locates ffmpeg (via <see cref="IFfmpegLocator"/>), derives the
+/// sibling <c>ffprobe.exe</c> from its directory, and asks ffprobe for the
+/// <c>avg_frame_rate</c>/<c>r_frame_rate</c>. Reuses the binary-stdout
+/// <see cref="IDecodeProcess"/> seam for the subprocess (ffprobe text is read from
+/// the same raw stdout). Returns null (no pacing) if ffprobe is unavailable.
+/// </summary>
+public sealed class FfmpegFrameRateProbe : IFrameRateProbe
+{
+    private readonly IFfmpegLocator _locator;
+    private readonly Func<IDecodeProcess> _probeProcessFactory;
+
+    public FfmpegFrameRateProbe(IFfmpegLocator locator, Func<IDecodeProcess> probeProcessFactory)
+    {
+        _locator = locator;
+        _probeProcessFactory = probeProcessFactory;
+    }
+
+    public async Task<double?> ProbeAsync(string path, CancellationToken cancellationToken = default)
+    {
+        if (string.IsNullOrWhiteSpace(path)) return null;
+
+        var ffmpegPath = await _locator.LocateAsync(cancellationToken).ConfigureAwait(false);
+        var ffprobePath = Path.Combine(Path.GetDirectoryName(ffmpegPath) ?? string.Empty, "ffprobe.exe");
+        if (!File.Exists(ffprobePath)) return null;
+
+        var startInfo = new ProcessStartInfo
+        {
+            FileName = ffprobePath,
+            Arguments =
+                $"-v error -select_streams v:0 " +
+                $"-show_entries stream=avg_frame_rate,r_frame_rate " +
+                $"-of default=noprint_wrappers=1 \"{path}\"",
+            UseShellExecute = false,
+            RedirectStandardOutput = true,
+            RedirectStandardError = true,
+            CreateNoWindow = true,
+        };
+
+        using var process = _probeProcessFactory();
+        process.Start(startInfo);
+        string output;
+        using (var reader = new StreamReader(process.StandardOutput))
+            output = reader.ReadToEnd();
+        await process.WaitForExitAsync(cancellationToken).ConfigureAwait(false);
+
+        return FfmpegFrameRateParser.ParseFrameRate(output);
+    }
+}

Services/FrameRingBuffer.cs

@@ -0,0 +1,90 @@
+using System;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// A depth-bounded ring of scratch frame buffers that never writes into memory a live
+/// consumer may still be reading. A slot's byte[] is only rewritten after at least
+/// <paramref name="redLine"/> rents have cycled since it was last handed out; a slot
+/// still inside its red line is skipped, and if the whole ring is inside its red line a
+/// fresh buffer is handed out rather than lapping a loaned slot. Length-mismatched
+/// buffers are always replaced by a fresh allocation (the previous array is orphaned,
+/// never overwritten), so a hand-out keeps its bytes for as long as anyone holds it.
+///
+/// The screen capture's consumer contract makes this structural necessity (slice 16,
+/// 2026-09-14): <c>ScreenCaptureManager</c> keeps each delivered frame as
+/// <c>session.LatestFrame</c> across conversions and the dispatcher preview copy lags,
+/// so a held frame can survive several conversions. The 1742 take recorded one torn
+/// frame (new-top/old-bottom at the webcam split) — a ring slot rewritten under the
+/// consumer's read. Depth 8 × the conversion interval already exceeded the worst
+/// observed hold (~50ms, take-14 rule); the red line makes the guarantee structural
+/// instead of a sizing coincidence.
+/// </summary>
+internal sealed class FrameRingBuffer
+{
+    private readonly byte[]?[] _slots;
+    private readonly long[] _lastHandout;
+    private readonly int _redLine;
+    private readonly object _lock = new();
+    private int _next;
+    private long _seq;
+    private long _allocations;
+
+    public FrameRingBuffer(int depth, int redLine)
+    {
+        _slots = new byte[depth][];
+        _lastHandout = new long[depth];
+        for (var i = 0; i < depth; i++) _lastHandout[i] = -redLine;
+        _redLine = redLine;
+    }
+
+    /// <summary>Buffers freshly allocated after the last <see cref="ConsumeAllocations"/>.</summary>
+    public long Allocations
+    {
+        get { lock (_lock) return _allocations; }
+    }
+
+    /// <summary>Returns the allocation count since the last call and resets it.</summary>
+    public long ConsumeAllocations()
+    {
+        lock (_lock)
+        {
+            var count = _allocations;
+            _allocations = 0;
+            return count;
+        }
+    }
+
+    /// <summary>Hands out a scratch buffer of <paramref name="size"/> bytes.</summary>
+    public byte[] Rent(int size)
+    {
+        lock (_lock)
+        {
+            var seq = ++_seq;
+            for (var tries = 0; tries < _slots.Length; tries++)
+            {
+                var idx = (_next + tries) % _slots.Length;
+                // Red line: rewriting this slot could hit a frame a consumer still reads.
+                if (seq - _lastHandout[idx] < _redLine) continue;
+                _next = (idx + 1) % _slots.Length;
+                if (_slots[idx] is { Length: var len } buf && len == size)
+                {
+                    _lastHandout[idx] = seq;
+                    return buf;
+                }
+
+                // Length mismatch (or never allocated): a fresh array, never an in-place
+                // overwrite — the previous loan's bytes stay valid for whoever holds it.
+                _allocations++;
+                var fresh = new byte[size];
+                _slots[idx] = fresh;
+                _lastHandout[idx] = seq;
+                return fresh;
+            }
+
+            // Defensive: the whole ring is inside its red line — do not lap a loaned slot.
+            _allocations++;
+            return new byte[size];
+        }
+    }
+}

Services/IDecodeProcess.cs

@@ -0,0 +1,24 @@
+using System.Diagnostics;
+using System.IO;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// TASK 21: seam around the media decoder's subprocess (ffmpeg <c>rawvideo</c>).
+/// Exposes the raw binary stdout (frames) and exit control, so
+/// <see cref="MediaVideoSource"/> never touches <c>System.Diagnostics.Process</c>
+/// directly and tests can fake the whole decode. Mirrors the encoder's
+/// <c>IEncoderProcess</c> but with a binary <see cref="StandardOutput"/>.
+/// </summary>
+public interface IDecodeProcess : IDisposable
+{
+    void Start(ProcessStartInfo startInfo);
+
+    /// <summary>Raw binary stdout — the <c>rawvideo</c> BGRA frame bytes.</summary>
+    Stream StandardOutput { get; }
+
+    bool HasExited { get; }
+    int ExitCode { get; }
+    void Kill();
+    Task WaitForExitAsync(CancellationToken cancellationToken = default);
+}

Services/IMediaFrameSource.cs

@@ -0,0 +1,26 @@
+namespace ytLive.Services;
+
+/// <summary>
+/// TASK 21: a media file decoder exposed to <see cref="MediaVideoSourceManager"/>.
+/// Mirrors <c>IScreenCaptureSource</c>/<c>ICameraFrameSource</c> so the manager
+/// (and tests) treat a local video file like any other frame source: start/stop
+/// and a per-frame <see cref="FrameAvailable"/> event consumers coalesce.
+/// </summary>
+public interface IMediaFrameSource : IDisposable
+{
+    string Key { get; }
+
+    /// <summary>When true, the decoder restarts from the beginning on natural EOF
+    /// instead of raising <see cref="Completed"/> (used for BRB/starting-soon loops).</summary>
+    bool Looping { get; set; }
+
+    /// <summary>Raised (on a worker thread) for each decoded frame.</summary>
+    event Action<VideoFrame>? FrameAvailable;
+
+    /// <summary>Raised when the file finishes decoding (natural EOF) — not raised
+    /// while <see cref="Looping"/> is true.</summary>
+    event Action? Completed;
+
+    Task StartAsync(CancellationToken cancellationToken = default);
+    Task StopAsync();
+}

Services/IWindowEnumerator.cs

@@ -0,0 +1,15 @@
+using System.Collections.Generic;
+using ytLive.Models;
+
+namespace ytLive.Services;
+
+/// <summary>Session-scoped seam that lists open top-level windows for the
+/// "Capture Window…" submenu. Mirrors <see cref="IFullScreenDetector"/> so the
+/// VM never depends on a specific Win32 implementation (and tests hand in a
+/// fake enumerator).</summary>
+public interface IWindowEnumerator
+{
+    /// <summary>Visible, user-facing top-level windows belonging to other
+    /// processes, ordered for display (title, process name).</summary>
+    IReadOnlyList<WindowInfo> Enumerate();
+}

Services/LayoutStore.Load.cs

@@ -11,8 +11,8 @@ public partial class LayoutStore : IDisposable
         Socials = null;
         Music = null;
         var scenes = new List<Scene>();
-        var sourcesByScene = new Dictionary<string, List<Source>>();
-        var configsByScene = new Dictionary<string, List<WebcamSceneConfig>>();
+        var sourcesByScene = new Dictionary<string, List<(Source Source, int Sort)>>();
+        var configsByScene = new Dictionary<string, List<(WebcamSceneConfig Config, int Sort)>>();
 
         using (var cmd = _connection.CreateCommand())
         {
@@ -99,7 +99,9 @@ public partial class LayoutStore : IDisposable
                        IsBackground, CaptureKey, ShowDesktop,
                        ChatFontSize, ChatFontColor, ChatBackgroundColor, ChatMaxMessages,
                        ChatShowTimestamps, ChatShowBadges, ChatMemberColor, ChatSuperChatColor,
-                       WebUri, MediaPath, MediaIsLooping, MediaVolume, MediaPlaybackState
+                       WebUri, MediaPath, MediaIsLooping, MediaVolume, MediaPlaybackState,
+                       AlertVideoAssetId, AlertVideoPath, AlertUseDefaultVideo, AlertShowTicker, AlertVideoVolume, SortOrder,
+                       AlertDisplayMethod
                 FROM Source ORDER BY SortOrder
                 """;
             using var reader = cmd.ExecuteReader();
@@ -145,10 +147,16 @@ public partial class LayoutStore : IDisposable
                         : Enum.TryParse<MediaPlaybackState>(reader.GetString(29), out var ps)
                             ? ps
                             : MediaPlaybackState.Stopped,
+                    AlertVideoAssetId = reader.IsDBNull(30) ? null : reader.GetString(30),
+                    AlertVideoPath = reader.IsDBNull(31) ? null : reader.GetString(31),
+                    AlertUseDefaultVideo = reader.IsDBNull(32) ? true : reader.GetInt32(32) != 0,
+                    AlertShowTicker = reader.IsDBNull(33) ? true : reader.GetInt32(33) != 0,
+                    AlertVideoVolume = reader.IsDBNull(34) ? 1.0 : reader.GetDouble(34),
+                    AlertDisplayMethod = reader.IsDBNull(36) ? AlertDisplayMethod.TickerScroll : (AlertDisplayMethod)reader.GetInt32(36),
                 };
                 if (!sourcesByScene.TryGetValue(sceneId, out var list))
-                    sourcesByScene[sceneId] = list = new List<Source>();
-                list.Add(source);
+                    sourcesByScene[sceneId] = list = new List<(Source, int)>();
+                list.Add((source, reader.GetInt32(35)));
             }
         }
 
@@ -157,7 +165,7 @@ public partial class LayoutStore : IDisposable
             cmd.CommandText = """
                 SELECT SceneId, WebcamId, IsVisible, X, Y, Width, Height, Opacity,
                        ClipShape, IsMirrored, BorderColor, BorderOpacity, BorderWidth, BorderAnimation,
-                       RectWidth, RectHeight
+                       RectWidth, RectHeight, SortOrder
                 FROM WebcamSceneConfig ORDER BY SortOrder
                 """;
             using var reader = cmd.ExecuteReader();
@@ -184,19 +192,30 @@ public partial class LayoutStore : IDisposable
                     RectHeight = reader.IsDBNull(15) ? null : reader.GetDouble(15),
                 };
                 if (!configsByScene.TryGetValue(sceneId, out var list))
-                    configsByScene[sceneId] = list = new List<WebcamSceneConfig>();
-                list.Add(config);
+                    configsByScene[sceneId] = list = new List<(WebcamSceneConfig, int)>();
+                list.Add((config, reader.GetInt32(16)));
             }
         }
 
         foreach (var scene in scenes)
         {
+            // Source and WebcamSceneConfig rows share ONE z-order space per scene
+            // (both SortOrders = the element's index within scene.Elements). Merge
+            // the two tables' rows by that shared z rather than appending all
+            // sources before all configs — a webcam slotted between sources must
+            // reload in place. Legacy rows (written before the unified space) may
+            // tie at 0: break ties sources-first, so old data reads back stacked
+            // the same way it did pre-unification.
+            var ordered = new List<(int Sort, SceneElement Element)>();
             if (sourcesByScene.TryGetValue(scene.Id, out var sources))
-                foreach (var source in sources)
-                    scene.Elements.Add(source);
+                foreach (var (source, sort) in sources)
+                    ordered.Add((sort, source));
             if (configsByScene.TryGetValue(scene.Id, out var configs))
-                foreach (var config in configs)
-                    scene.Elements.Add(config);
+                foreach (var (config, sort) in configs)
+                    ordered.Add((sort, config));
+
+            foreach (var (_, element) in ordered.OrderBy(e => e.Sort).ThenBy(e => e.Element is Source ? 0 : 1))
+                scene.Elements.Add(element);
 
             var bg = scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
             if (bg != null)

Services/LayoutStore.Migrations.cs

@@ -109,6 +109,22 @@ public partial class LayoutStore : IDisposable
                 Value TEXT NOT NULL
             );
             """,
+            // v9 → v10 (TASK 39): YPP journey-tracker snapshots, appended on every
+            // stats refresh. The history is the raw data a later analytics slice
+            // reads to compute velocity/(de)acceleration/ETA.
+            """
+            CREATE TABLE IF NOT EXISTS YppSnapshot (
+                CapturedAtUtc TEXT NOT NULL PRIMARY KEY,
+                SubscriberCount INTEGER NOT NULL,
+                VideoCount INTEGER NOT NULL,
+                TotalViews INTEGER NOT NULL,
+                UploadsLast90Days INTEGER NOT NULL,
+                CommunityGuidelinesGoodStanding INTEGER NOT NULL,
+                CopyrightStrikesGoodStanding INTEGER NOT NULL,
+                ContentIdClaimsGoodStanding INTEGER NOT NULL,
+                OverallGoodStanding INTEGER NOT NULL
+            );
+            """,
         };
         foreach (var sql in statements)
         {
@@ -126,7 +142,7 @@ public partial class LayoutStore : IDisposable
             MigrateToV3();
         using (var cmd = _connection.CreateCommand())
         {
-            cmd.CommandText = "PRAGMA user_version = 9;";
+            cmd.CommandText = "PRAGMA user_version = 10;";
             cmd.ExecuteNonQuery();
         }
     }
@@ -153,6 +169,13 @@ public partial class LayoutStore : IDisposable
             cmd.ExecuteNonQuery();
         }
 
+        if (!columns.Contains("AlertDisplayMethod"))
+        {
+            using var cmd = _connection.CreateCommand();
+            cmd.CommandText = "ALTER TABLE Source ADD COLUMN AlertDisplayMethod INTEGER NOT NULL DEFAULT 0;";
+            cmd.ExecuteNonQuery();
+        }
+
         if (!columns.Contains("IsMirrored"))
         {
             using var cmd = _connection.CreateCommand();
@@ -269,6 +292,40 @@ public partial class LayoutStore : IDisposable
             cmd.ExecuteNonQuery();
         }
 
+        // TASK 47: alert video config. The default clip asset id + the creator's
+        // replacement path (a FILE reference, never a stored BLOB) + the pill,
+        // ticker toggle and volume live on the row.
+        if (!columns.Contains("AlertVideoAssetId"))
+        {
+            using var cmd = _connection.CreateCommand();
+            cmd.CommandText = "ALTER TABLE Source ADD COLUMN AlertVideoAssetId TEXT;";
+            cmd.ExecuteNonQuery();
+        }
+        if (!columns.Contains("AlertVideoPath"))
+        {
+            using var cmd = _connection.CreateCommand();
+            cmd.CommandText = "ALTER TABLE Source ADD COLUMN AlertVideoPath TEXT;";
+            cmd.ExecuteNonQuery();
+        }
+        if (!columns.Contains("AlertUseDefaultVideo"))
+        {
+            using var cmd = _connection.CreateCommand();
+            cmd.CommandText = "ALTER TABLE Source ADD COLUMN AlertUseDefaultVideo INTEGER NOT NULL DEFAULT 1;";
+            cmd.ExecuteNonQuery();
+        }
+        if (!columns.Contains("AlertShowTicker"))
+        {
+            using var cmd = _connection.CreateCommand();
+            cmd.CommandText = "ALTER TABLE Source ADD COLUMN AlertShowTicker INTEGER NOT NULL DEFAULT 1;";
+            cmd.ExecuteNonQuery();
+        }
+        if (!columns.Contains("AlertVideoVolume"))
+        {
+            using var cmd = _connection.CreateCommand();
+            cmd.CommandText = "ALTER TABLE Source ADD COLUMN AlertVideoVolume REAL NOT NULL DEFAULT 1;";
+            cmd.ExecuteNonQuery();
+        }
+
         // Rename legacy "Backdrop" display name to "Background" in existing rows
         using (var cmd = _connection.CreateCommand())
         {

Services/LayoutStore.Save.cs

@@ -88,13 +88,17 @@ public partial class LayoutStore : IDisposable
                                     ClipShape, IsMirrored, IsBackground, CaptureKey, ShowDesktop, SortOrder,
                                     ChatFontSize, ChatFontColor, ChatBackgroundColor, ChatMaxMessages,
                                     ChatShowTimestamps, ChatShowBadges, ChatMemberColor, ChatSuperChatColor,
-                                    WebUri, MediaPath, MediaIsLooping, MediaVolume, MediaPlaybackState)
+                                    WebUri, MediaPath, MediaIsLooping, MediaVolume, MediaPlaybackState,
+                                    AlertVideoAssetId, AlertVideoPath, AlertUseDefaultVideo, AlertShowTicker, AlertVideoVolume,
+                                    AlertDisplayMethod)
                 VALUES ($id, $sceneId, $assetId, $type, $name, $isEnabled,
                         $x, $y, $w, $h, $opacity, $monitor,
                         $clip, $mirrored, $isBackground, $captureKey, $showDesktop, $sort,
                         $chatFontSize, $chatFontColor, $chatBgColor, $chatMaxMsgs,
                         $chatTimestamps, $chatBadges, $chatMemberColor, $chatSuperChatColor,
-                        $webUri, $mediaPath, $mediaIsLooping, $mediaVolume, $mediaPlaybackState)
+                        $webUri, $mediaPath, $mediaIsLooping, $mediaVolume, $mediaPlaybackState,
+                        $alertVideoAssetId, $alertVideoPath, $alertUseDefaultVideo, $alertShowTicker, $alertVideoVolume,
+                        $alertDisplayMethod)
                 """;
             cmd.Transaction = tx;
             var idP = cmd.Parameters.Add("$id", SqliteType.Text);
@@ -128,13 +132,23 @@ public partial class LayoutStore : IDisposable
             var mediaIsLoopingP = cmd.Parameters.Add("$mediaIsLooping", SqliteType.Integer);
             var mediaVolumeP = cmd.Parameters.Add("$mediaVolume", SqliteType.Real);
             var mediaPlaybackStateP = cmd.Parameters.Add("$mediaPlaybackState", SqliteType.Text);
+            var alertVideoAssetIdP = cmd.Parameters.Add("$alertVideoAssetId", SqliteType.Text);
+            var alertVideoPathP = cmd.Parameters.Add("$alertVideoPath", SqliteType.Text);
+            var alertUseDefaultVideoP = cmd.Parameters.Add("$alertUseDefaultVideo", SqliteType.Integer);
+            var alertShowTickerP = cmd.Parameters.Add("$alertShowTicker", SqliteType.Integer);
+            var alertVideoVolumeP = cmd.Parameters.Add("$alertVideoVolume", SqliteType.Real);
+            var alertDisplayMethodP = cmd.Parameters.Add("$alertDisplayMethod", SqliteType.Integer);
 
+            // Source and WebcamSceneConfig share ONE z-order space per scene:
+            // each element gets its index within scene.Elements regardless of
+            // table, so a webcam slotted between sources survives save→load.
+            // (Pre-unified rows tie at 0 — load breaks ties sources-first.)
             foreach (var scene in scenes)
             {
-                var sort = 0;
+                var z = 0;
                 foreach (var element in scene.Elements)
                 {
-                    if (element is not Source source) continue;
+                    if (element is not Source source) { z++; continue; }
                     idP.Value = source.Id;
                     sceneIdP.Value = scene.Id;
                     assetIdP.Value = (object?)source.AssetId ?? DBNull.Value;
@@ -152,7 +166,7 @@ public partial class LayoutStore : IDisposable
                     isBackgroundP.Value = source.IsBackground ? 1 : 0;
                     captureKeyP.Value = (object?)source.CaptureKey ?? DBNull.Value;
                     showDesktopP.Value = source.ShowDesktop ? 1 : 0;
-                    sortP.Value = sort++;
+                    sortP.Value = z++;
                     chatFontSizeP.Value = source.ChatFontSize;
                     chatFontColorP.Value = source.ChatFontColor;
                     chatBgColorP.Value = source.ChatBackgroundColor;
@@ -166,6 +180,12 @@ public partial class LayoutStore : IDisposable
                     mediaIsLoopingP.Value = source.MediaIsLooping ? 1 : 0;
                     mediaVolumeP.Value = source.MediaVolume;
                     mediaPlaybackStateP.Value = source.MediaPlaybackState.ToString();
+                    alertVideoAssetIdP.Value = (object?)source.AlertVideoAssetId ?? DBNull.Value;
+                    alertVideoPathP.Value = (object?)source.AlertVideoPath ?? DBNull.Value;
+                    alertUseDefaultVideoP.Value = source.AlertUseDefaultVideo ? 1 : 0;
+                    alertShowTickerP.Value = source.AlertShowTicker ? 1 : 0;
+                    alertVideoVolumeP.Value = source.AlertVideoVolume;
+                    alertDisplayMethodP.Value = (int)source.AlertDisplayMethod;
                     cmd.ExecuteNonQuery();
                 }
             }
@@ -215,9 +235,10 @@ public partial class LayoutStore : IDisposable
 
                 foreach (var scene in scenes)
                 {
-                    var sort = 0;
-                    foreach (var config in scene.Elements.OfType<WebcamSceneConfig>())
+                    var z = 0;
+                    foreach (var element in scene.Elements)
                     {
+                        if (element is not WebcamSceneConfig config) { z++; continue; }
                         sceneIdP.Value = scene.Id;
                         webcamIdP.Value = config.WebcamId;
                         visibleP.Value = config.IsVisible ? 1 : 0;
@@ -234,7 +255,7 @@ public partial class LayoutStore : IDisposable
                         animationP.Value = config.BorderAnimation.ToString();
                         rectWidthP.Value = (object?)config.RectWidth ?? DBNull.Value;
                         rectHeightP.Value = (object?)config.RectHeight ?? DBNull.Value;
-                        sortP.Value = sort++;
+                        sortP.Value = z++;
                         cmd.ExecuteNonQuery();
                     }
                 }
@@ -295,7 +316,15 @@ public partial class LayoutStore : IDisposable
 
         using (var cmd = _connection.CreateCommand())
         {
-            cmd.CommandText = "DELETE FROM Asset WHERE Id NOT IN (SELECT AssetId FROM Source WHERE AssetId IS NOT NULL);";
+            cmd.CommandText = """
+                DELETE FROM Asset WHERE Id NOT IN (
+                    SELECT AssetId FROM Source WHERE AssetId IS NOT NULL
+                    UNION
+                    SELECT AlertVideoAssetId FROM Source WHERE AlertVideoAssetId IS NOT NULL
+                    UNION
+                    SELECT Value FROM Settings WHERE Key = 'AlertDefaultVideoAssetId'
+                );
+                """;
             cmd.Transaction = tx;
             cmd.ExecuteNonQuery();
         }

Services/LayoutStore.Settings.cs

@@ -29,6 +29,21 @@ public partial class LayoutStore : IDisposable
         insert.ExecuteNonQuery();
     }
 
+    /// <summary>The global audio-sync offset in milliseconds (TASK 22), −500..500,
+    /// default 0: positive delays the mix (audio ahead of video), negative
+    /// advances it (audio behind video). Restored at startup so the mixer starts
+    /// on the user's offset.</summary>
+    public int LoadAudioSyncOffsetMs()
+    {
+        var value = GetSetting("Audio.SyncOffsetMs");
+        return int.TryParse(value, out var ms) ? Math.Clamp(ms, -500, 500) : 0;
+    }
+
+    public void SaveAudioSyncOffsetMs(int ms)
+    {
+        UpsertSetting("Audio.SyncOffsetMs", Math.Clamp(ms, -500, 500).ToString());
+    }
+
     /// <summary>The user's chosen record output folder (TASK 18), or null to use the
     /// default <c>%APPDATA%\ytLlive\recordings</c>. Restored at startup.</summary>
     public string? LoadRecordFolder()
@@ -268,7 +283,7 @@ public partial class LayoutStore : IDisposable
         UpsertSetting("Window.State", state);
     }
 
-    private string? GetSetting(string key)
+    public string? GetSetting(string key)
     {
         using var cmd = _connection.CreateCommand();
         cmd.CommandText = "SELECT Value FROM Settings WHERE Key = $key;";
@@ -276,7 +291,7 @@ public partial class LayoutStore : IDisposable
         return cmd.ExecuteScalar() as string;
     }
 
-    private void UpsertSetting(string key, string value)
+    public void UpsertSetting(string key, string value)
     {
         using var cmd = _connection.CreateCommand();
         cmd.CommandText = "DELETE FROM Settings WHERE Key = $key;";
@@ -289,4 +304,26 @@ public partial class LayoutStore : IDisposable
         insert.Parameters.AddWithValue("$value", value);
         insert.ExecuteNonQuery();
     }
+
+    internal const string AlertDefaultVideoKey = "AlertDefaultVideoAssetId";
+
+    /// <summary>Stamps the shipped stream-alert placeholder clip (TASK 47): like any
+    /// source image it lives as a BLOB in the internal Asset table, tracked by this
+    /// Setting so the Save pruner keeps it alive. The creator's OWN replacement
+    /// videos are never stored — they are plain path references (the 2026-09-26
+    /// decision: the file the user picks stays at its real location on disk).
+    /// <c>UpsertAsset</c> is hash-keyed, so re-stamping the same bytes returns the
+    /// same id.</summary>
+    public string EnsureAlertDefaultVideo(byte[] data)
+    {
+        var saved = GetSetting(AlertDefaultVideoKey);
+        if (!string.IsNullOrWhiteSpace(saved) && GetAssetBytes(saved) != null)
+            return saved;
+        var id = UpsertAsset(data, 0, 0);
+        UpsertSetting(AlertDefaultVideoKey, id);
+        return id;
+    }
+
+    /// <summary>The stored default clip's Asset id, or null when never stamped.</summary>
+    public string? GetAlertDefaultVideoId() => GetSetting(AlertDefaultVideoKey);
 }

Services/LayoutStore.Ypp.cs

@@ -0,0 +1,90 @@
+using Microsoft.Data.Sqlite;
+using ytLive.Models;
+
+namespace ytLive.Services;
+
+public partial class LayoutStore : IDisposable
+{
+    // ─── YPP journey-tracker snapshots (TASK 39) ───
+
+    /// <summary>Appends one YPP stats snapshot (append-only history; velocity/ETA
+    /// read it in a later analytics slice).</summary>
+    public void SaveYppSnapshot(YppStatSnapshot snapshot)
+    {
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = """
+            INSERT INTO YppSnapshot (CapturedAtUtc, SubscriberCount, VideoCount, TotalViews,
+                                     UploadsLast90Days, CommunityGuidelinesGoodStanding,
+                                     CopyrightStrikesGoodStanding, ContentIdClaimsGoodStanding,
+                                     OverallGoodStanding)
+            VALUES ($captured, $subs, $videos, $views, $uploads, $cg, $cs, $cic, $overall);
+            """;
+        cmd.Parameters.AddWithValue("$captured", snapshot.CapturedAtUtc.ToString("o"));
+        cmd.Parameters.AddWithValue("$subs", snapshot.SubscriberCount);
+        cmd.Parameters.AddWithValue("$videos", snapshot.VideoCount);
+        cmd.Parameters.AddWithValue("$views", snapshot.TotalViews);
+        cmd.Parameters.AddWithValue("$uploads", snapshot.UploadsLast90Days);
+        cmd.Parameters.AddWithValue("$cg", snapshot.CommunityGuidelinesGoodStanding ? 1 : 0);
+        cmd.Parameters.AddWithValue("$cs", snapshot.CopyrightStrikesGoodStanding ? 1 : 0);
+        cmd.Parameters.AddWithValue("$cic", snapshot.ContentIdClaimsGoodStanding ? 1 : 0);
+        cmd.Parameters.AddWithValue("$overall", snapshot.OverallGoodStanding ? 1 : 0);
+        cmd.ExecuteNonQuery();
+    }
+
+    /// <summary>Most recent snapshots, newest first (defaults to the full history).</summary>
+    public List<YppStatSnapshot> LoadYppSnapshots(int limit = 365)
+    {
+        var result = new List<YppStatSnapshot>();
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = """
+            SELECT CapturedAtUtc, SubscriberCount, VideoCount, TotalViews, UploadsLast90Days,
+                   CommunityGuidelinesGoodStanding, CopyrightStrikesGoodStanding,
+                   ContentIdClaimsGoodStanding, OverallGoodStanding
+            FROM YppSnapshot ORDER BY CapturedAtUtc DESC LIMIT $limit;
+            """;
+        cmd.Parameters.AddWithValue("$limit", limit);
+        using var reader = cmd.ExecuteReader();
+        while (reader.Read())
+        {
+            result.Add(new YppStatSnapshot
+            {
+                CapturedAtUtc = DateTime.TryParse(reader.GetString(0), out var captured) ? captured : DateTime.MinValue,
+                SubscriberCount = reader.GetInt64(1),
+                VideoCount = reader.GetInt64(2),
+                TotalViews = reader.GetInt64(3),
+                UploadsLast90Days = reader.GetInt32(4),
+                CommunityGuidelinesGoodStanding = reader.GetInt32(5) != 0,
+                CopyrightStrikesGoodStanding = reader.GetInt32(6) != 0,
+                ContentIdClaimsGoodStanding = reader.GetInt32(7) != 0,
+                OverallGoodStanding = reader.GetInt32(8) != 0,
+            });
+        }
+        return result;
+    }
+
+    /// <summary>The manually self-reported YPP checklist state (2FA / AdSense are
+    /// not readable from any YouTube API — the creator ticks them in-app).</summary>
+    public (bool TwoFactorEnabled, bool AdSenseLinked) LoadYppChecklist()
+    {
+        return (GetSetting("Ypp.TwoFactorEnabled") == "1", GetSetting("Ypp.AdSenseLinked") == "1");
+    }
+
+    public void SaveYppChecklist(bool twoFactorEnabled, bool adsenseLinked)
+    {
+        UpsertSetting("Ypp.TwoFactorEnabled", twoFactorEnabled ? "1" : "0");
+        UpsertSetting("Ypp.AdSenseLinked", adsenseLinked ? "1" : "0");
+    }
+
+    /// <summary>UTC timestamp of the last successful stats refresh (used to gate
+    /// the once-daily auto-refresh against the analytics quota-thin API).</summary>
+    public DateTime? LoadYppLastRefreshedAtUtc()
+    {
+        var value = GetSetting("Ypp.LastRefreshedAtUtc");
+        return DateTime.TryParse(value, out var dt) ? dt : null;
+    }
+
+    public void SaveYppLastRefreshedAtUtc(DateTime utc)
+    {
+        UpsertSetting("Ypp.LastRefreshedAtUtc", utc.ToString("o"));
+    }
+}

Services/MediaCaptureFrameSource.cs

@@ -50,7 +50,9 @@ public sealed class MediaCaptureFrameSource : ICameraFrameSource
         // Fallback ladder: prefer the camera's VideoPreview stream, but if the
         // reader refuses to start there (NoVideoFrameAvailable), retry against
         // its VideoRecord stream — some devices only deliver through it.
-        // (MediaCaptureSharingMode.Exclusive is not projected by the 19041 SDK.)
+        // (The exclusive-lock upgrade is a separate, later unit — creator
+        // ruling 2026-10-05; see HANDOFF.md. It is NOT blocked by an SDK gap:
+        // `MediaCaptureSharingMode.ExclusiveControl` IS projected in 19041.)
         if (!await TryStartAsync(preferVideoRecord: false))
         {
             if (!await TryStartAsync(preferVideoRecord: true))
@@ -86,6 +88,20 @@ public sealed class MediaCaptureFrameSource : ICameraFrameSource
         }
     }
 
+    /// <summary>
+    /// Ordered reader-output-subtype candidates for a camera whose live media type
+    /// is <paramref name="activeSubtype"/>. Bgra8 is the fast path (OnFrameArrived
+    /// skips conversion) and works for uncompressed cameras; an MJPG-active source
+    /// cannot be read as Bgra8 by a MediaFrameReader (no BGRA converter on the MJPG
+    /// pipeline — StartAsync answers OutputFormatNotSupported), so MJPG leads with
+    /// NV12 and falls back to the reader's default (null). Every candidate that is
+    /// not Bgra8 is converted in OnFrameArrived.
+    /// </summary>
+    internal static string?[] ReaderSubtypeCandidates(string? activeSubtype) =>
+        string.Equals(activeSubtype, "MJPG", StringComparison.OrdinalIgnoreCase)
+            ? new string?[] { MediaEncodingSubtypes.Nv12, null }
+            : new string?[] { MediaEncodingSubtypes.Bgra8, MediaEncodingSubtypes.Nv12, null };
+
     private async Task<bool> TryStartAsync(bool preferVideoRecord)
     {
         MediaCapture? capture = null;
@@ -102,6 +118,43 @@ public sealed class MediaCaptureFrameSource : ICameraFrameSource
             };
             await capture.InitializeAsync(settings);
 
+            // MediaFrameReader defaults to the camera's FIRST media type — on UVC webcams
+            // (Logitech C920 et al.) that is often YUY2 at a crippled rate (720p5!), and a
+            // real-time 60fps container then shows a 5-20fps face cam as "every few frames
+            // cut out". OBS's mechanism, available via VideoDeviceController (VideoProfile
+            // is NOT projected in the 19041 SDK): negotiate the stream property. Pick the
+            // best MJPEG >=640x360 @>=30fps (largest, fastest), set it BEFORE the frame
+            // reader is created, fall back to device default on refusal, and log the live
+            // media type so the next diagnosis starts from facts.
+            try
+            {
+                var controller = capture.VideoDeviceController;
+                var candidates = controller == null
+                    ? new System.Collections.Generic.List<Windows.Media.MediaProperties.VideoEncodingProperties>()
+                    : controller
+                    .GetAvailableMediaStreamProperties(MediaStreamType.VideoPreview)
+                    .OfType<Windows.Media.MediaProperties.VideoEncodingProperties>()
+                    .Where(v => string.Equals(v.Subtype, "MJPG", StringComparison.OrdinalIgnoreCase)
+                                && v.Width >= 640 && v.Height >= 360
+                                && v.FrameRate.Denominator > 0
+                                && v.FrameRate.Numerator / v.FrameRate.Denominator >= 30.0)
+                    .OrderByDescending(v => v.FrameRate.Numerator / (double)Math.Max(1, v.FrameRate.Denominator))
+                    .ThenByDescending(v => (long)v.Width * v.Height)
+                    .ToList();
+                if (candidates.Count > 0)
+                {
+                    var pick = candidates
+                        .OrderBy(v => (long)v.Width * v.Height)
+                        .LastOrDefault(v => v.Width <= 1280) ?? candidates[0];
+                    await controller!.SetMediaStreamPropertiesAsync(MediaStreamType.VideoPreview, pick);
+                }
+            }
+            catch (Exception fmtEx)
+            {
+                AppLog.Write($"MediaCaptureFrameSource: MJPG negotiation refused ({fmtEx.Message}); " +
+                             "keeping device-default media type");
+            }
+
             // Post-init resource validation: the capture must actually be bound to
             // the device we asked for and must expose a live video controller.
             if (!string.Equals(capture.MediaCaptureSettings?.VideoDeviceId, _deviceId,
@@ -143,21 +196,82 @@ public sealed class MediaCaptureFrameSource : ICameraFrameSource
             capture.Failed += OnCaptureFailed;
             capture.CameraStreamStateChanged += OnCameraStreamStateChanged;
 
-            reader = await capture.CreateFrameReaderAsync(colorSource, MediaEncodingSubtypes.Bgra8);
-            if (reader == null)
-                throw new InvalidOperationException($"Camera '{_deviceId}' created no frame reader.");
+            // The reader must output a subtype the source can actually produce, else
+            // StartAsync refuses (OutputFormatNotSupported). An uncompressed camera
+            // converts to Bgra8 fine (the fast path); a camera sitting in MJPG — which
+            // is what we find when ANOTHER app left it there and ours can't re-negotiate
+            // under SharedReadOnly contention — cannot be read as Bgra8 by a
+            // MediaFrameReader (the MJPG pipeline exposes NV12 output, not BGRA). Walk
+            // the candidate ladder; anything that isn't Bgra8 is converted in
+            // OnFrameArrived anyway.
+            string? activeSubtype = null;
+            try
+            {
+                var active = capture.VideoDeviceController?
+                    .GetMediaStreamProperties(colorSource.Info.MediaStreamType);
+                if (active is Windows.Media.MediaProperties.VideoEncodingProperties vep)
+                {
+                    activeSubtype = vep.Subtype;
+                    AppLog.Write($"Camera '{_deviceId}' media type: {vep.Subtype} " +
+                                 $"{vep.Width}x{vep.Height} @ {vep.FrameRate.Numerator}/{vep.FrameRate.Denominator}fps");
+                }
+            }
+            catch { /* logging must never kill acquisition */ }
 
-            reader.FrameArrived += OnFrameArrived;
-            var status = await reader.StartAsync();
-            if (status != MediaFrameReaderStartStatus.Success)
-                throw new InvalidOperationException(
-                    $"Camera '{_deviceId}' frame reader refused to start: {status}.");
+            // Each candidate is allocated AND started under its own catch: a WinRT
+            // call answering an unsupported subtype can THROW (E_INVALIDARG / "value
+            // does not fall within the expected range") instead of returning a start
+            // status, so every throw must degrade to the next candidate — never let
+            // one rejected format abort the whole acquisition. Individual rejections
+            // are logged and collected; only the last-resort net below (the outer
+            // try/catch of this method) keeps cowboying device-level errors.
+            var refused = new List<string>();
+            foreach (var outputSubtype in ReaderSubtypeCandidates(activeSubtype))
+            {
+                var attempt = outputSubtype ?? "<default>";
+                try
+                {
+                    reader = outputSubtype is null
+                        ? await capture.CreateFrameReaderAsync(colorSource)
+                        : await capture.CreateFrameReaderAsync(colorSource, outputSubtype);
+                    if (reader == null)
+                    {
+                        refused.Add($"{attempt}: no frame reader");
+                        continue;
+                    }
 
-            _capture = capture;
-            _frameReader = reader;
-            _lastError = null;
-            _isFailed = false;
-            return true;
+                    reader.FrameArrived += OnFrameArrived;
+                    var status = await reader.StartAsync();
+                    if (status == MediaFrameReaderStartStatus.Success)
+                    {
+                        _capture = capture;
+                        _frameReader = reader;
+                        _lastError = null;
+                        _isFailed = false;
+                        StartCadenceWindow();
+                        return true;
+                    }
+
+                    reader.FrameArrived -= OnFrameArrived;
+                    reader.Dispose();
+                    reader = null;
+                    refused.Add($"{attempt}: {status}");
+                }
+                catch (Exception ex)
+                {
+                    AppLog.Write($"MediaCaptureFrameSource: reader as '{attempt}' refused: {ex.Message}");
+                    if (reader != null)
+                    {
+                        reader.FrameArrived -= OnFrameArrived;
+                        reader.Dispose();
+                        reader = null;
+                    }
+                    refused.Add($"{attempt}: {ex.Message}");
+                }
+            }
+
+            throw new InvalidOperationException(
+                $"Camera '{_deviceId}' frame reader refused to start: {string.Join(", ", refused)}.");
         }
         catch (Exception ex)
         {
@@ -176,6 +290,30 @@ public sealed class MediaCaptureFrameSource : ICameraFrameSource
         }
     }
 
+    private const int CadenceWindowSeconds = 5;
+
+    private void StartCadenceWindow()
+    {
+        _arrivalCadence.Reset();
+        _cameraCadence.Reset();
+        _cadenceNextReportTicks = System.Diagnostics.Stopwatch.GetTimestamp()
+            + System.Diagnostics.Stopwatch.Frequency * CadenceWindowSeconds;
+    }
+
+    /// <summary>Logs one cadence window and opens the next. The size rides along
+    /// because the whole question started as "the webcam is soft": a future format
+    /// change must be readable in the SAME line that proves the frame rate.</summary>
+    private void ReportCadence(int width, int height)
+    {
+        _cadenceNextReportTicks = System.Diagnostics.Stopwatch.GetTimestamp()
+            + System.Diagnostics.Stopwatch.Frequency * CadenceWindowSeconds;
+        var arrivals = _arrivalCadence.Summarize();
+        var camera = _cameraCadence.Summarize();
+        _arrivalCadence.Reset();
+        _cameraCadence.Reset();
+        AppLog.Write($"Camera cadence {width}x{height}: {arrivals.Describe("arrivals")} | {camera.Describe("camera")}");
+    }
+
     private void UnsubscribeCaptureEvents(MediaCapture capture)
     {
         capture.Failed -= OnCaptureFailed;
@@ -209,12 +347,64 @@ public sealed class MediaCaptureFrameSource : ICameraFrameSource
         }
     }
 
+    // Buffer recycling (same lesson as the screen capture): a fresh ~3.7MB byte[]
+    // per device frame at 30-60fps is 110-220MB/s of LOH churn — gen2 pauses land
+    // on the frame pump as 35-40ms render spikes. An 8-deep ring (take-14 rule:
+    // depth × source period must exceed the worst consumer hold), rotated on the
+    // single frame-reader thread, with per-frame Epoch so the identity-keyed paste
+    // cache can never serve a recycled array as unchanged.
+    private readonly byte[]?[] _frameRing = new byte[8][];
+    private int _ringNext;
+    private long _epoch;
+
+    private byte[] RentRingBuffer(int size)
+    {
+        for (var tries = 0; tries < _frameRing.Length; tries++)
+        {
+            var idx = (_ringNext + tries) % _frameRing.Length;
+            var buf = _frameRing[idx];
+            if (buf != null && buf.Length == size)
+            {
+                _ringNext = (idx + 1) % _frameRing.Length;
+                return buf;
+            }
+        }
+        var slot = _ringNext;
+        _ringNext = (slot + 1) % _frameRing.Length;
+        var fresh = new byte[size];
+        _frameRing[slot] = fresh;
+        return fresh;
+    }
+
+    // Arrival vs production cadence (UNIT 0, 2026-10-05): the recorded file cannot
+    // tell a dropped camera frame from a padded repeat — rawvideo stamps frames by
+    // ARRIVAL at the declared 60fps, so a webcam delivering 25 of its 30 frames still
+    // muxes a full-length file. Two counters, one reader, settle it: the camera's OWN
+    // SystemRelativeTime stamps (device/USB/driver cadence) against the moment the
+    // reader handed each frame to us (our cadence, including coalescing drops — the
+    // reader deliberately keeps only the LATEST frame, so falling behind is silent).
+    // Steady camera + ragged arrivals = we are behind. Ragged in both = the device.
+    private readonly FrameCadence _arrivalCadence = new();
+    private readonly FrameCadence _cameraCadence = new();
+    private long _cadenceNextReportTicks;
+
     private void OnFrameArrived(MediaFrameReader sender, MediaFrameArrivedEventArgs args)
     {
+        var arrivedTicks = System.Diagnostics.Stopwatch.GetTimestamp();
         using var frame = sender.TryAcquireLatestFrame();
         var videoFrame = frame?.VideoMediaFrame?.SoftwareBitmap;
         if (videoFrame == null) return;
 
+        // SystemRelativeTime is QPC-domain, the same clock Stopwatch reads here, so the
+        // camera's own frame spacing is measurable without a second conversion. It is
+        // NULLABLE in the projection (null = the device supplied no stamp), so the
+        // production side of the comparison is then simply missing from the line —
+        // arrivals alone still measure what reached us.
+        _arrivalCadence.Add(arrivedTicks);
+        if (frame!.SystemRelativeTime is { } cameraStamp)
+            _cameraCadence.Add((long)(cameraStamp.TotalSeconds * System.Diagnostics.Stopwatch.Frequency));
+        if (arrivedTicks >= _cadenceNextReportTicks) ReportCadence(videoFrame.PixelWidth, videoFrame.PixelHeight);
+
         var bitmap = videoFrame.BitmapPixelFormat == BitmapPixelFormat.Bgra8
             ? videoFrame
             : SoftwareBitmap.Convert(videoFrame, BitmapPixelFormat.Bgra8);
@@ -225,9 +415,14 @@ public sealed class MediaCaptureFrameSource : ICameraFrameSource
             using var reference = buffer.CreateReference();
             if (WindowsRuntimeMarshal.TryGetDataUnsafe(reference, out var pixelsPtr, out var capacity))
             {
-                var pixels = new byte[capacity];
+                var pixels = RentRingBuffer((int)capacity);
                 Marshal.Copy(pixelsPtr, pixels, 0, (int)capacity);
-                FrameAvailable?.Invoke(new VideoFrame(bitmap.PixelWidth, bitmap.PixelHeight, pixels));
+
+                // MediaCapture video carries no alpha plane — the OS fills 255.
+                var outFrame = new VideoFrame(bitmap.PixelWidth, bitmap.PixelHeight, pixels)
+                    { IsOpaque = true, Epoch = ++_epoch };
+
+                FrameAvailable?.Invoke(outFrame);
             }
         }
         catch (Exception ex)

Services/MediaVideoSource.cs

@@ -0,0 +1,147 @@
+using System.Diagnostics;
+using System.IO;
+using ytLive.Services.Encoder;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// TASK 21: decodes a local media file (any format ffmpeg handles) into
+/// <see cref="VideoFrame"/>s for a MediaSource. Implements
+/// <see cref="IMediaFrameSource"/>: raises <see cref="FrameAvailable"/> per
+/// frame and <see cref="IMediaFrameSource.Completed"/> on natural EOF (unless
+/// <see cref="IMediaFrameSource.Looping"/>). Spawns ffmpeg with
+/// <c>-f rawvideo -pix_fmt bgra</c> and drains the raw BGRA pipe via
+/// <see cref="RawVideoFrameReader"/>. The decoder process and emitters are seams
+/// so tests run without a real codec or audio device.
+/// </summary>
+public sealed class MediaVideoSource : IMediaFrameSource
+{
+    public event Action<VideoFrame>? FrameAvailable;
+    public event Action? Completed;
+
+    public string Key => _path;
+
+    public bool Looping { get; set; }
+
+    private readonly string _path;
+    private readonly int _width;
+    private readonly int _height;
+    private readonly IFfmpegLocator _locator;
+    private readonly Func<IDecodeProcess> _processFactory;
+    private readonly IFrameRateProbe? _probe;
+    private readonly Func<TimeSpan, CancellationToken, Task> _delay;
+    private readonly CancellationTokenSource _cts = new();
+    private IDisposable? _run;
+    private IDecodeProcess? _active;
+
+    public MediaVideoSource(
+        string path,
+        int width,
+        int height,
+        IFfmpegLocator locator,
+        Func<IDecodeProcess> processFactory,
+        IFrameRateProbe? frameRateProbe = null,
+        Func<TimeSpan, CancellationToken, Task>? delay = null)
+    {
+        _path = path;
+        _width = width;
+        _height = height;
+        _locator = locator;
+        _processFactory = processFactory;
+        _probe = frameRateProbe;
+        _delay = delay ?? ((t, ct) => Task.Delay(t, ct));
+    }
+
+    public Task StartAsync(CancellationToken cancellationToken = default)
+    {
+        if (_run != null) return Task.CompletedTask;
+        _run = _cts.Token.Register(StopInternal);
+        _ = Task.Run(RunAsync, CancellationToken.None);
+        return Task.CompletedTask;
+    }
+
+    public Task StopAsync()
+    {
+        _cts.Cancel();
+        _run = null;
+        return Task.CompletedTask;
+    }
+
+    public void Dispose()
+    {
+        _cts.Cancel();
+        _cts.Dispose();
+        _active?.Dispose();
+    }
+
+    private void StopInternal() => KillProcess();
+
+    private async Task RunAsync()
+    {
+        try
+        {
+            double? frameRate = null;
+            if (_probe != null)
+                frameRate = await _probe.ProbeAsync(_path, _cts.Token).ConfigureAwait(false);
+            var frameDuration = frameRate is > 0 ? TimeSpan.FromSeconds(1.0 / frameRate.Value) : TimeSpan.Zero;
+
+            var ffmpegPath = await _locator.LocateAsync(_cts.Token).ConfigureAwait(false);
+            var args =
+                $"-hide_banner -loglevel error -i \"{_path}\" " +
+                $"-f rawvideo -pix_fmt bgra -vf scale={_width}:{_height} -an -";
+            var startInfo = new ProcessStartInfo
+            {
+                FileName = ffmpegPath,
+                Arguments = args,
+                UseShellExecute = false,
+                RedirectStandardOutput = true,
+                RedirectStandardError = true,
+                CreateNoWindow = true,
+            };
+
+            do
+            {
+                using (var process = _processFactory())
+                {
+                    _active = process;
+                    process.Start(startInfo);
+
+                    var reader = new RawVideoFrameReader(_width, _height);
+                    var buffer = new byte[65536];
+                    var stream = process.StandardOutput;
+                    while (!_cts.IsCancellationRequested && !process.HasExited)
+                    {
+                        var read = await stream.ReadAsync(buffer, 0, buffer.Length, _cts.Token).ConfigureAwait(false);
+                        if (read <= 0) break;
+                        foreach (var frame in reader.Feed(buffer.AsSpan(0, read).ToArray()))
+                        {
+                            FrameAvailable?.Invoke(frame);
+                            if (frameDuration > TimeSpan.Zero)
+                                await _delay(frameDuration, _cts.Token).ConfigureAwait(false);
+                        }
+                    }
+                }
+                _active = null;
+            }
+            while (Looping && !_cts.IsCancellationRequested);
+        }
+        catch (OperationCanceledException)
+        {
+        }
+        catch (Exception ex)
+        {
+            Fail($"Media decode failed: {ex.Message}");
+            return;
+        }
+
+        if (!_cts.IsCancellationRequested)
+            Completed?.Invoke();
+    }
+
+    private void Fail(string message) => Console.Error.WriteLine(message);
+
+    private void KillProcess()
+    {
+        try { _active?.Kill(); } catch { /* already exited */ }
+    }
+}

Services/MediaVideoSourceManager.cs

@@ -0,0 +1,256 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using System.Windows;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+using System.Windows.Threading;
+using ytLive.Helpers;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// TASK 21: owns media-file decode sessions app-wide, refcounted by file path.
+/// One file = at most one decoder, one shared WriteableBitmap; the last release
+/// stops and disposes the source. Frames arrive on a worker thread and are
+/// coalesced onto the UI dispatcher (at most one pending copy per session, using
+/// the latest frame). Mirrors ScreenCaptureManager/CameraManager.
+/// </summary>
+public sealed class MediaVideoSourceManager : IDisposable
+{
+    private sealed class MediaSession
+    {
+        public string Key { get; }
+        public IMediaFrameSource Source { get; }
+        public Action<VideoFrame>? FrameHandler;
+        public int RefCount;
+        public bool Started;
+        public WriteableBitmap? PreviewBitmap;
+        public VideoFrame? LatestFrame;
+        public bool FramePending;
+
+        public MediaSession(string key, IMediaFrameSource source)
+        {
+            Key = key;
+            Source = source;
+            RefCount = 1;
+        }
+    }
+
+    private readonly Func<string, IMediaFrameSource?> _sourceFactory;
+    private readonly Dispatcher? _uiDispatcher;
+    private readonly Dictionary<string, MediaSession> _sessions = new();
+    private readonly object _gate = new();
+
+    /// <summary>Raised on the UI thread when a media file's shared preview bitmap is first created.</summary>
+    public event Action<string, WriteableBitmap>? PreviewBitmapChanged;
+
+    /// <summary>Raised when a media decoder cannot be created (bad path).</summary>
+    public event Action<string, string>? MediaFailed;
+
+    public MediaVideoSourceManager(Func<string, IMediaFrameSource?> sourceFactory, Dispatcher? uiDispatcher = null)
+    {
+        _sourceFactory = sourceFactory;
+        _uiDispatcher = uiDispatcher;
+    }
+
+    /// <summary>Increments the refcount for a file, starting the decoder the first time.</summary>
+    public async Task<bool> AcquireAsync(string key)
+    {
+        if (string.IsNullOrWhiteSpace(key)) return false;
+
+        MediaSession session;
+        bool shouldStart;
+        lock (_gate)
+        {
+            if (_sessions.TryGetValue(key, out var existing))
+            {
+                existing.RefCount++;
+                shouldStart = false;
+                session = existing;
+            }
+            else
+            {
+                IMediaFrameSource? source;
+                try
+                {
+                    source = _sourceFactory(key);
+                }
+                catch (Exception ex)
+                {
+                    AppLog.Write($"MediaSource: creating decoder '{key}' failed: {ex.Message}");
+                    MediaFailed?.Invoke(key, ex.Message);
+                    return false;
+                }
+                if (source == null)
+                {
+                    MediaFailed?.Invoke(key, "No decoder for this file");
+                    return false;
+                }
+                session = new MediaSession(key, source);
+                session.FrameHandler = frame => OnFrameAvailable(session, frame);
+                session.Source.FrameAvailable += session.FrameHandler;
+                _sessions[key] = session;
+                shouldStart = true;
+            }
+        }
+
+        if (!shouldStart) return session.Started;
+
+        try
+        {
+            await session.Source.StartAsync();
+            session.Started = true;
+            return true;
+        }
+        catch (Exception ex)
+        {
+            lock (_gate)
+                _sessions.Remove(key);
+            session.Source.FrameAvailable -= session.FrameHandler;
+            AppLog.Write($"MediaSource: failed to start decoder '{key}': {ex.Message}");
+            MediaFailed?.Invoke(key, ex.Message);
+            await SafeStopAsync(session.Source);
+            return false;
+        }
+    }
+
+    public async Task ReleaseAsync(string key)
+    {
+        MediaSession? toStop = null;
+        lock (_gate)
+        {
+            if (!_sessions.TryGetValue(key, out var session)) return;
+            if (--session.RefCount > 0) return;
+            _sessions.Remove(key);
+            toStop = session;
+        }
+
+        if (toStop == null) return;
+        toStop.Source.FrameAvailable -= toStop.FrameHandler;
+        await SafeStopAsync(toStop.Source);
+        toStop.PreviewBitmap = null;
+    }
+
+    /// <summary>Releases a file unconditionally (every ref) — used on layout reloads.</summary>
+    public async Task ReleaseAllAsync(string key)
+    {
+        MediaSession? toStop = null;
+        lock (_gate)
+        {
+            if (!_sessions.TryGetValue(key, out var session)) return;
+            session.RefCount = 0;
+            _sessions.Remove(key);
+            toStop = session;
+        }
+
+        if (toStop == null) return;
+        toStop.Source.FrameAvailable -= toStop.FrameHandler;
+        await SafeStopAsync(toStop.Source);
+        toStop.PreviewBitmap = null;
+    }
+
+    /// <summary>The most recent decoded frame for a file, or null before the first
+    /// frame (or if the file has no session). The live compositor reads media from here.</summary>
+    public VideoFrame? GetLatestFrame(string key)
+    {
+        lock (_gate)
+            return _sessions.TryGetValue(key, out var session) ? session.LatestFrame : null;
+    }
+
+    /// <summary>The shared preview bitmap for a file (so a config created after the
+    /// first frame can adopt the running bitmap), or null.</summary>
+    public WriteableBitmap? GetPreviewBitmap(string key)
+    {
+        lock (_gate)
+            return _sessions.TryGetValue(key, out var session) ? session.PreviewBitmap : null;
+    }
+
+    public void Dispose()
+    {
+        List<MediaSession> sessions;
+        lock (_gate)
+        {
+            sessions = new List<MediaSession>(_sessions.Values);
+            _sessions.Clear();
+        }
+
+        foreach (var session in sessions)
+        {
+            session.Source.FrameAvailable -= session.FrameHandler;
+            _ = SafeStopAsync(session.Source);
+        }
+    }
+
+    private static async Task SafeStopAsync(IMediaFrameSource source)
+    {
+        try
+        {
+            await source.StopAsync();
+        }
+        catch (Exception ex)
+        {
+            AppLog.Write($"MediaSource: stopping decoder failed: {ex.Message}");
+        }
+    }
+
+    private bool TryGetActiveSession(MediaSession session)
+    {
+        lock (_gate)
+            return _sessions.TryGetValue(session.Key, out var current) && ReferenceEquals(current, session);
+    }
+
+    private void OnFrameAvailable(MediaSession session, VideoFrame frame)
+    {
+        if (!TryGetActiveSession(session)) return;
+        session.LatestFrame = frame;
+
+        if (session.PreviewBitmap == null)
+        {
+            if (_uiDispatcher == null) return;
+            if (_uiDispatcher.CheckAccess())
+                EnsurePreviewBitmap(session);
+            else
+                _uiDispatcher.BeginInvoke(() =>
+                {
+                    if (TryGetActiveSession(session))
+                        EnsurePreviewBitmap(session);
+                }, DispatcherPriority.Render);
+            return;
+        }
+
+        if (_uiDispatcher == null || _uiDispatcher.CheckAccess())
+        {
+            CopyFrame(session);
+            return;
+        }
+
+        if (session.FramePending) return;
+        session.FramePending = true;
+        _uiDispatcher.BeginInvoke(() =>
+        {
+            session.FramePending = false;
+            if (TryGetActiveSession(session) && session.PreviewBitmap != null)
+                CopyFrame(session);
+        }, DispatcherPriority.Render);
+    }
+
+    private void EnsurePreviewBitmap(MediaSession session)
+    {
+        if (session.PreviewBitmap != null || session.LatestFrame == null) return;
+        var frame = session.LatestFrame;
+        var bitmap = new WriteableBitmap(frame.Width, frame.Height, 96, 96, PixelFormats.Bgra32, null);
+        bitmap.WritePixels(new Int32Rect(0, 0, frame.Width, frame.Height), frame.BgraPixels, frame.Stride, 0);
+        session.PreviewBitmap = bitmap;
+        PreviewBitmapChanged?.Invoke(session.Key, bitmap);
+    }
+
+    private void CopyFrame(MediaSession session)
+    {
+        var bitmap = session.PreviewBitmap;
+        var frame = session.LatestFrame;
+        if (bitmap == null || frame == null) return;
+        if (frame.Width != bitmap.PixelWidth || frame.Height != bitmap.PixelHeight) return;
+        bitmap.WritePixels(new Int32Rect(0, 0, frame.Width, frame.Height), frame.BgraPixels, frame.Stride, 0);
+    }
+}

Services/MonotonicGate.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Threading;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// An atomic "publish only if strictly newer" gate for the capture's latest-wins
+/// hand-out. Screen capture conversions may now overlap (slice 17), so two
+/// conversions can finish briefly out of order; without a monotonic gate the slower
+/// (older) completion would overwrite the faster (newer) one's LatestFrame and the
+/// compositor would render STALE content — a time hole in the other direction.
+/// Sequence must be a strictly increasing per-source counter
+/// (<c>Interlocked.Increment</c> in <c>ScreenCaptureFrameSource</c>).
+/// </summary>
+internal sealed class MonotonicGate
+{
+    private long _last;
+
+    /// <summary>Returns true iff <paramref name="seq"/> is strictly newer than every
+    /// seq accepted so far (and records it).</summary>
+    public bool TryPublish(long seq)
+    {
+        while (true)
+        {
+            var current = Interlocked.Read(ref _last);
+            if (seq <= current) return false;
+            if (Interlocked.CompareExchange(ref _last, seq, current) == current) return true;
+        }
+    }
+}

Services/RawVideoFrameReader.cs

@@ -0,0 +1,59 @@
+namespace ytLive.Services;
+
+/// <summary>
+/// TASK 21: parses a stream of tightly-packed raw BGRA frames into
+/// <see cref="VideoFrame"/>s. The consumer of an ffmpeg <c>-f rawvideo -pix_fmt
+/// bgra</c> stdout pipe: every frame is exactly <c>width*height*4</c> bytes, so a
+/// frame is emitted whenever that many bytes have accumulated. Pure and fully
+/// deterministic, so it is tested with a synthetic byte stream — no ffmpeg, no
+/// process, no audio device needed.
+/// </summary>
+public sealed class RawVideoFrameReader
+{
+    private readonly int _frameBytes;
+    private readonly int _width;
+    private readonly int _height;
+    private byte[]? _pending;
+
+    public RawVideoFrameReader(int width, int height)
+    {
+        _width = width;
+        _height = height;
+        _frameBytes = width * height * 4;
+    }
+
+    /// <summary>Feeds <paramref name="bytes"/> read from the pipe and returns any
+    /// whole frames reconstructed so far. Partial/pending bytes are kept for the
+    /// next call — frames never split or merge across reads.</summary>
+    public List<VideoFrame> Feed(byte[] bytes)
+    {
+        var pending = _pending;
+        byte[] combined;
+        if (pending != null && pending.Length > 0)
+        {
+            combined = new byte[pending.Length + bytes.Length];
+            Buffer.BlockCopy(pending, 0, combined, 0, pending.Length);
+            Buffer.BlockCopy(bytes, 0, combined, pending.Length, bytes.Length);
+            _pending = null;
+        }
+        else
+        {
+            combined = bytes;
+        }
+
+        var frames = new List<VideoFrame>();
+        var offset = 0;
+        while (combined.Length - offset >= _frameBytes)
+        {
+            var frame = new byte[_frameBytes];
+            Buffer.BlockCopy(combined, offset, frame, 0, _frameBytes);
+            frames.Add(new VideoFrame(_width, _height, frame));
+            offset += _frameBytes;
+        }
+
+        if (offset < combined.Length)
+            _pending = combined[offset..];
+
+        return frames;
+    }
+}

Services/RecordingFile.cs

@@ -2,11 +2,17 @@ namespace ytLive.Services;
 
 /// <summary>
 /// Pure filename logic for local recordings (TASK 18). The user-requested naming
-/// is <c>ty-yyyymmdd-hhmm-hh2mm2.mp4</c>: <c>ty</c> is the brand marker, the first
-/// <c>hhmm</c> is the hour+minute the recording STARTED (saved), and the second
-/// <c>hh2mm2</c> is the hour+minute of the recording's LENGTH. Length is only known
-/// when recording ends, so the file is created with a <c>0000</c> length and renamed
-/// on stop (see <see cref="FinalizeFileName"/>).
+/// is <c>ty-yyyymmdd-hhmm-fff-hh2mm2.mp4</c>: <c>ty</c> is the brand marker, the first
+/// <c>hhmm</c> is the hour+minute the recording STARTED (saved), <c>fff</c> is
+/// milliseconds on the same start timestamp, and the last <c>hh2mm2</c> is the
+/// hour+minute of the recording's LENGTH. Length is only known when recording ends,
+/// so the file is created with a <c>0000</c> length and renamed on stop (see
+/// <see cref="FinalizeFileName"/>).
+/// <para>The <c>fff</c> exists so two instances started in the same minute cannot
+/// compute the same path — the dev multi-instance use case (record one instance
+/// with the other) would otherwise have both ffmpeg processes writing one file.
+/// Both names derive from the same <c>_recordStartTime</c>, so the segment survives
+/// the rename.</para>
 /// </summary>
 public static class RecordingFile
 {
@@ -14,14 +20,14 @@ public static class RecordingFile
     public const string StartLengthSuffix = "0000";
 
     public static string BuildStartName(DateTime start)
-        => $"ty-{start:yyyyMMdd}-{start:HHmm}-{StartLengthSuffix}";
+        => $"ty-{start:yyyyMMdd}-{start:HHmm}-{start:fff}-{StartLengthSuffix}";
 
     /// <summary>Final name with the real recording length (fractional hour+minute),
-    /// e.g. 75 minutes → <c>ty-20260829-1405-0115.mp4</c>.</summary>
+    /// e.g. 75 minutes → <c>ty-20260829-1405-000-0115.mp4</c>.</summary>
     public static string BuildFinalName(DateTime start, TimeSpan length)
     {
         var hh2 = (int)length.TotalHours;
         var mm2 = length.Minutes;
-        return $"ty-{start:yyyyMMdd}-{start:HHmm}-{hh2:00}{mm2:00}";
+        return $"ty-{start:yyyyMMdd}-{start:HHmm}-{start:fff}-{hh2:00}{mm2:00}";
     }
 }

Services/SceneGraph.cs

@@ -0,0 +1,159 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Linq;
+using ytLive.Models;
+using ytLive.Services.Compositor;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// The scene graph (TASK 31): single owner of the scene collection and the
+/// element inventory / mutation surface, plus the static/dynamic classification
+/// queries the compositor optimization depends on.
+///
+/// Scenes are referenced (not owned): the same <see cref="Scene"/> instances live
+/// on the ViewModel's bindable surface; SceneGraph adds/removes/reorders their
+/// <see cref="Scene.Elements"/> and answers queries (background / webcam / chat /
+/// split point) that used to be scattered LINQ across MainViewModel.
+///
+/// Classification: <see cref="ElementKind.Static"/> (images, background art) is
+/// baked once; <see cref="ElementKind.Dynamic"/> (webcam, live capture, chat, web)
+/// is composited per frame. The <b>split point</b> is the index of the first
+/// dynamic element — everything below it forms the baked base.
+/// </summary>
+public sealed class SceneGraph
+{
+    private readonly Dictionary<string, SceneRegion> _regionCache = new(StringComparer.Ordinal);
+    private readonly object _gate = new();
+
+    /// <summary>The shared scene collection (same instances the ViewModel binds).</summary>
+    public ObservableCollection<Scene> Scenes { get; } = new();
+
+    /// <summary>The one Background row for a scene — null when the scene has none.</summary>
+    public Source? GetBackground(Scene scene)
+        => scene.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackground);
+
+    /// <summary>This scene's webcam usage, if any.</summary>
+    public WebcamSceneConfig? GetWebcam(Scene scene)
+        => scene.Elements.OfType<WebcamSceneConfig>().FirstOrDefault();
+
+    /// <summary>All chat-box elements across every scene (for ChatOverlayLayer).</summary>
+    public IEnumerable<Source> GetChatBoxes()
+        => Scenes.SelectMany(s => s.Elements.OfType<Source>().Where(x => x.Type == SourceType.ChatBox));
+
+    /// <summary>Index of the first dynamic element (the split point). If no dynamic
+    /// element exists this equals <see cref="Scene.Elements"/> count — fully baked.</summary>
+    public int GetSplitPoint(Scene scene)
+    {
+        var elements = scene.Elements;
+        for (var i = 0; i < elements.Count; i++)
+        {
+            if (elements[i].Kind == ElementKind.Dynamic)
+                return i;
+        }
+        return elements.Count;
+    }
+
+    /// <summary>True when the whole scene is static (no dynamic element) — the
+    /// compositor can bake it once and skip per-frame compositing.</summary>
+    public bool IsStatic(Scene scene)
+        => scene.Elements.All(e => e.Kind == ElementKind.Static);
+
+    /// <summary>Invalidate the cached bake region for a scene after any mutation
+    /// (element add/remove/reorder, static resize/opacity/visibility, asset change).</summary>
+    public void InvalidateBake(Scene scene)
+    {
+        lock (_gate) _regionCache.Remove(scene.Id);
+    }
+
+    // ─── Mutation surface (single owner of element operations) ───
+
+    /// <summary>Append an element to a scene and (re)bake accordingly.</summary>
+    public void AddElement(Scene scene, SceneElement element)
+    {
+        scene.Elements.Add(element);
+        InvalidateBake(scene);
+    }
+
+    /// <summary>Insert an element at a specific z-index and (re)bake accordingly.</summary>
+    public void InsertElement(Scene scene, int index, SceneElement element)
+    {
+        scene.Elements.Insert(index, element);
+        InvalidateBake(scene);
+    }
+
+    /// <summary>Remove an element and (re)bake accordingly.</summary>
+    public bool RemoveElement(Scene scene, SceneElement element)
+    {
+        var removed = scene.Elements.Remove(element);
+        if (removed) InvalidateBake(scene);
+        return removed;
+    }
+
+    /// <summary>Reorder an element in z-space and (re)bake accordingly.</summary>
+    public void MoveElement(Scene scene, SceneElement element, int newIndex)
+    {
+        var current = scene.Elements.IndexOf(element);
+        if (current < 0) return;
+        scene.Elements.Move(current, newIndex);
+        InvalidateBake(scene);
+    }
+
+    /// <summary>Add a scene to the collection (wiring is handled by the ViewModel).</summary>
+    public void AddScene(Scene scene) => Scenes.Add(scene);
+
+    /// <summary>Get (or bake) the cached static base for a scene. Null means "no static
+    /// base" (first layer is dynamic or the scene is empty) — caller falls back to full render.</summary>
+    public VideoFrame? GetBakedBase(
+        Scene scene,
+        Func<SceneElement, VideoFrame?> frameFor,
+        Func<CompositorOptions> options,
+        VideoFrame? socialBarFrame = null,
+        int socialBarTop = 0,
+        VideoFrame? flashFrame = null)
+    {
+        var split = GetSplitPoint(scene);
+        if (split == 0) return null;
+
+        lock (_gate)
+        {
+            if (_regionCache.TryGetValue(scene.Id, out var cached)
+                && cached.Matches(scene, split))
+                return cached.Frame;
+        }
+
+        var baked = SceneCompositor.BakeStaticBase(
+            scene, split, frameFor, options, socialBarFrame, socialBarTop, flashFrame);
+        if (baked == null) return null;
+
+        lock (_gate)
+        {
+            _regionCache[scene.Id] = new SceneRegion(baked, scene.Elements.Take(split).ToList());
+        }
+        return baked;
+    }
+
+    /// <summary>The baked frame + the element identity it was baked from (for invalidation).</summary>
+    private sealed class SceneRegion
+    {
+        public VideoFrame Frame { get; }
+        private readonly string[] _staticElementIds;
+
+        public SceneRegion(VideoFrame frame, List<SceneElement> staticBelow)
+        {
+            Frame = frame;
+            _staticElementIds = staticBelow.Select(e => e.Id).ToArray();
+        }
+
+        /// <summary>Only static layers below the split are part of the base. Two bakes
+        /// match iff the same static element identities, in the same order, are below
+        /// the split — dynamic-only pixel/layout changes never invalidate.</summary>
+        public bool Matches(Scene scene, int split)
+        {
+            var below = scene.Elements.Take(split).Select(e => e.Id).ToArray();
+            return below.Length == _staticElementIds.Length
+                && below.SequenceEqual(_staticElementIds);
+        }
+    }
+}

Services/ScreenCaptureFrameSource.cs

@@ -1,6 +1,8 @@
 using System;
+using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Runtime.InteropServices.WindowsRuntime;
+using System.Threading;
 using System.Threading.Tasks;
 using Windows.Graphics;
 using Windows.Graphics.Capture;
@@ -27,9 +29,23 @@ public sealed class ScreenCaptureFrameSource : IScreenCaptureSource
     private GraphicsCaptureSession? _session;
     private SizeInt32 _poolSize;
     private bool _started;
-    private bool _framePending;
+    private int _convertInFlight;
     private DateTime _lastErrorLog = DateTime.MinValue;
 
+    // Buffer recycling (take-11 spikes, 2026-09-04; slice 16, 2026-09-14): a fresh
+    // ~8.3MB byte[] per DWM frame ≈ 500MB/s of LOH churn — the gen2 pauses it forced
+    // surfaced as the "worst render 35-65ms" spikes that capped fps at ~42. The pool
+    // is a reuse-distance ring: a buffer is only rewritten after ≥ redLine rents have
+    // cycled since its last hand-out (FrameRingBuffer), so a frame a consumer still
+    // holds — session.LatestFrame survives across conversions and the dispatcher
+    // preview copy lags — can never be overwritten in place (the 1742 tear, a ring
+    // slot rewritten under the consumer's read, handed the compositor one
+    // new-top/old-bottom frame). Each hand-out still carries an Epoch so identity-keyed
+    // consumers (the compositor's paste cache) cannot false-hit a recycled array.
+    private readonly FrameRingBuffer _ring = new(8, redLine: 4);
+    private long _epoch;
+    private readonly MonotonicGate _publishGate = new();
+
     // The composition master frame (see ai.md "Resolution tiers"): the background
     // is an input layer, so we never hold a CPU frame bigger than the master.
     private const int MaxBackgroundWidth = 1920;
@@ -38,6 +54,28 @@ public sealed class ScreenCaptureFrameSource : IScreenCaptureSource
     // A failing conversion must not re-flood the log at frame rate.
     private static readonly TimeSpan ErrorLogThrottle = TimeSpan.FromSeconds(5);
 
+    // Conversion cadence (slice 16, 2026-09-14; slice 17, 2026-09-14): the monitor
+    // delivers at the 240Hz DWM cadence (~4.2ms) while slots are 16.6ms. A 10ms floor
+    // between conversion starts keeps the open edge above the ~60 conversions/s the pump
+    // can use. What actually bounded the desktop feed on takes 1742/1824 was the SERIAL
+    // GPU→CPU readback (`CreateCopyFromSurfaceAsync` ≈ 40-50ms of the ~47ms conversion
+    // on a 240Hz-HDR box shared with the encoder), capping captures at ~17-20/s.
+    // Slice 17 overlaps up to MaxConcurrentConversions readbacks (pool sized to
+    // accommodate in-flight frames) and publishes only monotonically newer frames
+    // (MonotonicGate — a slow older completion must never overwrite a newer LatestFrame).
+    private static readonly TimeSpan MinConvertInterval = TimeSpan.FromMilliseconds(10);
+    private static readonly TimeSpan TelemetryInterval = TimeSpan.FromSeconds(2);
+    private const int MaxConcurrentConversions = 3;
+    private const int PoolBufferCount = 5;
+    private DateTime _lastConvertAt = DateTime.MinValue;
+    private DateTime _telemetryFrom = DateTime.UtcNow;
+    private DateTime _lastTelemetry = DateTime.UtcNow;
+    private long _skippedCadence;
+    private long _skippedBusy;
+    private long _conversions;
+    private long _convertMsTotal;
+    private long _convertMsMax;
+
     public string Key { get; }
     public event Action<VideoFrame>? FrameAvailable;
 
@@ -74,7 +112,7 @@ public sealed class ScreenCaptureFrameSource : IScreenCaptureSource
             var item = _item;
             var device = Direct3D11Helper.CreateDevice();
             var framePool = Direct3D11CaptureFramePool.CreateFreeThreaded(
-                device, DirectXPixelFormat.B8G8R8A8UIntNormalized, 2, item.Size);
+                device, DirectXPixelFormat.B8G8R8A8UIntNormalized, PoolBufferCount, item.Size);
             _poolSize = item.Size;
             var session = framePool.CreateCaptureSession(item);
             framePool.FrameArrived += OnFrameArrived;
@@ -91,7 +129,7 @@ public sealed class ScreenCaptureFrameSource : IScreenCaptureSource
         lock (_gate)
         {
             _started = false;
-            _framePending = false;
+            _convertInFlight = 0;
             if (_framePool != null)
                 _framePool.FrameArrived -= OnFrameArrived;
             _session?.Dispose();
@@ -106,6 +144,7 @@ public sealed class ScreenCaptureFrameSource : IScreenCaptureSource
     {
         var frame = sender.TryGetNextFrame();
         if (frame == null) return;
+
         lock (_gate)
         {
             if (!_started)
@@ -113,33 +152,54 @@ public sealed class ScreenCaptureFrameSource : IScreenCaptureSource
                 frame.Dispose();
                 return;
             }
-        }
 
-        if (frame.ContentSize.Width != _poolSize.Width || frame.ContentSize.Height != _poolSize.Height)
-        {
-            sender.Recreate(Direct3D11Helper.CreateDevice(),
-                DirectXPixelFormat.B8G8R8A8UIntNormalized, 2, frame.ContentSize);
-            _poolSize = frame.ContentSize;
-        }
+            if (frame.ContentSize.Width != _poolSize.Width || frame.ContentSize.Height != _poolSize.Height)
+            {
+                sender.Recreate(Direct3D11Helper.CreateDevice(),
+                    DirectXPixelFormat.B8G8R8A8UIntNormalized, PoolBufferCount, frame.ContentSize);
+                _poolSize = frame.ContentSize;
+            }
 
-        if (_framePending)
-        {
-            frame.Dispose();
-            return;
+            // Up to MaxConcurrentConversions readbacks in flight (slice 17), spaced by
+            // MinConvertInterval (slice 16): the 240Hz delivery otherwise queued one
+            // conversion every ~4.2ms, and the serial ~47ms readback pinned the desktop
+            // layer to ~17 updates/s on the 1824 take.
+            if (_convertInFlight >= MaxConcurrentConversions)
+            {
+                _skippedBusy++;
+                frame.Dispose();
+                return;
+            }
+            var now = DateTime.UtcNow;
+            if (now - _lastConvertAt < MinConvertInterval)
+            {
+                _skippedCadence++;
+                frame.Dispose();
+                return;
+            }
+            _lastConvertAt = now;
+            _convertInFlight++;
         }
-        _framePending = true;
         _ = ProcessFrameAsync(frame);
     }
 
     private async Task ProcessFrameAsync(Direct3D11CaptureFrame frame)
     {
+        var sw = Stopwatch.StartNew();
         try
         {
             using (frame)
             using (var softwareBitmap = await SoftwareBitmap.CreateCopyFromSurfaceAsync(
                 frame.Surface, BitmapAlphaMode.Ignore))
             {
-                FrameAvailable?.Invoke(CopyToVideoFrame(softwareBitmap));
+                // Monotonic sequencing across the overlapping conversions (slice 17): a
+                // completed readback is published only if strictly newer than the last
+                // one published — a slow older completion must never overwrite a newer
+                // LatestFrame (that would be a time hole in the other direction).
+                var epoch = Interlocked.Increment(ref _epoch);
+                var videoFrame = CopyToVideoFrame(softwareBitmap, epoch);
+                if (_publishGate.TryPublish(epoch))
+                    FrameAvailable?.Invoke(videoFrame);
             }
         }
         catch (Exception ex)
@@ -153,11 +213,41 @@ public sealed class ScreenCaptureFrameSource : IScreenCaptureSource
         }
         finally
         {
-            _framePending = false;
+            lock (_gate)
+            {
+                EmitTelemetry(sw.ElapsedMilliseconds);
+                _convertInFlight--;
+            }
         }
     }
 
-    private static VideoFrame CopyToVideoFrame(SoftwareBitmap bitmap)
+    private void EmitTelemetry(long conversionMs)
+    {
+        _conversions++;
+        _convertMsTotal += conversionMs;
+        if (conversionMs > _convertMsMax) _convertMsMax = conversionMs;
+
+        var now = DateTime.UtcNow;
+        if (now - _lastTelemetry < TelemetryInterval) return;
+
+        var span = now - _telemetryFrom;
+        var perSecond = span.TotalSeconds > 0 ? _conversions / span.TotalSeconds : 0;
+        AppLog.Write(
+            $"ScreenCapture telemetry [{Key}]: {_conversions} frames in {span.TotalSeconds:F1}s " +
+            $"({perSecond:F0}/s), conv avg {( _conversions == 0 ? 0 : _convertMsTotal / _conversions )}ms " +
+            $"max {_convertMsMax}ms, skip busy {_skippedBusy} cadence {_skippedCadence}, " +
+            $"ring allocs {_ring.ConsumeAllocations()}");
+
+        _lastTelemetry = now;
+        _telemetryFrom = now;
+        _conversions = 0;
+        _convertMsTotal = 0;
+        _convertMsMax = 0;
+        _skippedBusy = 0;
+        _skippedCadence = 0;
+    }
+
+    private VideoFrame CopyToVideoFrame(SoftwareBitmap bitmap, long epoch)
     {
         var sw = bitmap.PixelWidth;
         var sh = bitmap.PixelHeight;
@@ -177,45 +267,61 @@ public sealed class ScreenCaptureFrameSource : IScreenCaptureSource
             var scale = Math.Min(MaxBackgroundWidth / (double)sw, MaxBackgroundHeight / (double)sh);
             var dw = Math.Max(1, (int)(sw * scale));
             var dh = Math.Max(1, (int)(sh * scale));
-            return new VideoFrame(dw, dh, DownscaleBgra(data, sw, sh, srcStride, dw, dh));
+            // DWM delivers an opaque surface (alpha 255); bilinear keeps it 255.
+            var scaled = _ring.Rent(dw * dh * 4);
+            return new VideoFrame(dw, dh, DownscaleBgra(data, sw, sh, srcStride, dw, dh, scaled))
+                { IsOpaque = true, Epoch = epoch };
         }
 
-        var pixels = new byte[count];
+        var pixels = _ring.Rent(count);
         Marshal.Copy(data, pixels, 0, pixels.Length);
-        return new VideoFrame(sw, sh, pixels);
+        return new VideoFrame(sw, sh, pixels) { IsOpaque = true, Epoch = epoch };
     }
 
-    // Bilinear downscale to the master frame. Reads each source row pair through
-    // Marshal.Copy (no unsafe), writing tightly packed BGRA output.
-    private static byte[] DownscaleBgra(IntPtr src, int sw, int sh, int srcStride, int dw, int dh)
+    // Integer 8.8 fixed-point bilinear downscale to the master frame (slice 16,
+    // 2026-09-14: the two-stage math from SceneCompositor.Bilinear — the same "shift
+    // only at the end" rule from MyMistakes item on fixed-point blending). The previous
+    // double-per-pixel version ran ~30-45ms per 2.5K→1080p frame on a quiet desktop
+    // and the 1742 take's stall measured ~150ms/frame under load (90%-frozen desktop,
+    // ~6 fresh frames/s); integer math keeps the same bilinear result within ±1 while
+    // dropping the cost to the row-pair Marshal.Copy. Rows are read once per source
+    // row pair through Marshal.Copy (no unsafe), writing tightly packed BGRA output.
+    private byte[] DownscaleBgra(IntPtr src, int sw, int sh, int srcStride, int dw, int dh, byte[] dst)
     {
+        // Row scratch is per-conversion (overlapping conversions since slice 17 each
+        // bring their own — two 10KB arrays, no shared state). Size: a 2560-wide row
+        // pair, the largest the monitor path delivers before the downscale.
         var row0 = new byte[srcStride];
         var row1 = new byte[srcStride];
-        var dst = new byte[dw * dh * 4];
-        var xs = sw / (double)dw;
-        var ys = sh / (double)dh;
 
         for (var y = 0; y < dh; y++)
         {
-            var sy = Math.Min(sh - 1, (int)(y * ys));
+            var sy8 = (int)((long)y * sh * 256 / dh);
+            var sy = sy8 >> 8;
             var sy1 = Math.Min(sh - 1, sy + 1);
-            var fy = (y * ys) - sy;
+            var fy8 = sy8 & 255;
+            var fyInv = 256 - fy8;
             Marshal.Copy(IntPtr.Add(src, sy * srcStride), row0, 0, srcStride);
             Marshal.Copy(IntPtr.Add(src, sy1 * srcStride), row1, 0, srcStride);
 
             var dRow = y * dw * 4;
             for (var x = 0; x < dw; x++)
             {
-                var sx = Math.Min(sw - 1, (int)(x * xs));
+                var sx8 = (int)((long)x * sw * 256 / dw);
+                var sx = Math.Min(sw - 1, sx8 >> 8);
                 var sx1 = Math.Min(sw - 1, sx + 1);
-                var fx = (x * xs) - sx;
-                for (var c = 0; c < 4; c++)
+                var fx8 = sx8 & 255;
+                var fxInv = 256 - fx8;
+
+                var i0 = sx * 4;
+                var i1 = sx1 * 4;
+                var j = dRow + x * 4;
+                for (var c = 0; c < 4; c++, i0++, i1++, j++)
                 {
-                    var i0 = sx * 4 + c;
-                    var i1 = sx1 * 4 + c;
-                    var top = row0[i0] + (row0[i1] - row0[i0]) * fx;
-                    var bottom = row1[i0] + (row1[i1] - row1[i0]) * fx;
-                    dst[dRow + x * 4 + c] = (byte)(top + (bottom - top) * fy);
+                    // Two-stage in one 16.8 scale: top/bot ≤ 65280, ×256 + round ≤ 33.5M — int-safe.
+                    var top = row0[i0] * fxInv + row0[i1] * fx8;
+                    var bot = row1[i0] * fxInv + row1[i1] * fx8;
+                    dst[j] = (byte)((top * fyInv + bot * fy8 + 32768) >> 16);
                 }
             }
         }

Services/ScreenCaptureSourceFactory.cs

@@ -38,7 +38,11 @@ public sealed class ScreenCaptureSourceFactory
 
         if (key.StartsWith("window:", StringComparison.OrdinalIgnoreCase))
         {
-            var hexText = key.AsSpan("window:".Length);
+            // Keys are written as "window:0x<Hwnd:X>" (CaptureInterop/WindowInfo),
+            // but NumberStyles.HexNumber does not accept the "0x" prefix — strip it.
+            var hexText = key.AsSpan("window:".Length).TrimStart();
+            if (hexText.Length >= 2 && hexText[0] == '0' && (hexText[1] == 'x' || hexText[1] == 'X'))
+                hexText = hexText[2..];
             if (long.TryParse(hexText, NumberStyles.HexNumber, CultureInfo.InvariantCulture, out var hwnd))
                 return ScreenCaptureFrameSource.CreateForWindow(new IntPtr(hwnd));
             return null;

Services/TestSessionViewModel.cs

@@ -0,0 +1,237 @@
+using System;
+using System.Threading.Tasks;
+using System.Windows.Input;
+using ytLive.Helpers;
+using ytLive.Models;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// TASK 41 — the Test Stream pull-out (the "TEST" tab at the bottom of the Live
+/// screen's right rail). Drives a private test broadcast's chat tooling:
+/// Mock Chat Input sends a REAL liveChat/messages.insert (round-tripping through
+/// the normal ~2s poll and the live overlay path), and the simulated-event buttons
+/// inject synthetic member / SuperChat / subscriber rows through the exact
+/// MessageReceived seam the real poll uses — local-only, never sent to YouTube
+/// (the insert API only creates text). The broadcast itself runs through the real
+/// private go-live pipeline; this VM only owns the dock.
+/// </summary>
+public sealed class TestSessionViewModel : ViewModelBase
+{
+    private readonly YouTubeStreamService _stream;
+    private readonly YouTubeChatService _chat;
+    private readonly Action? _onEndStream;
+
+    private bool _isDrawerOpen;
+    private bool _isTestSession;
+    private string? _broadcastId;
+    private string? _liveChatId;
+    private string _sendMessageText = string.Empty;
+    private bool _isSending;
+    private string? _lastEventText;
+    private int _eventCounter;
+
+    /// <summary>Fake viewer names for simulated events — several backs make the
+    /// rows look like a real muted room.</summary>
+    private static readonly string[] SimulatedViewers = { "PixelPasta", "NightskyNick", "LunaGlow", "CactusFox" };
+
+    public TestSessionViewModel(
+        YouTubeStreamService stream,
+        YouTubeChatService chat,
+        Action? onEndStream = null)
+    {
+        _stream = stream;
+        _chat = chat;
+        _onEndStream = onEndStream;
+
+        SendTestMessageCommand = new RelayCommand(_ => _ = SendTestMessageAsync(), _ => CanSendTestMessage);
+        SimulateSubscriberCommand = new RelayCommand(_ => Simulate(SimulatedSubscriber()));
+        SimulateMemberCommand = new RelayCommand(_ => Simulate(SimulatedMember()));
+        SimulateSuperChatCommand = new RelayCommand(_ => Simulate(SimulatedSuperChat()));
+        EndTestCommand = new RelayCommand(_ => _onEndStream?.Invoke());
+        ToggleDrawerCommand = new RelayCommand(_ => IsDrawerOpen = !IsDrawerOpen);
+        CloseDrawerCommand = new RelayCommand(_ => IsDrawerOpen = false);
+    }
+
+    public ICommand SendTestMessageCommand { get; }
+    public RelayCommand SimulateSubscriberCommand { get; }
+    public RelayCommand SimulateMemberCommand { get; }
+    public RelayCommand SimulateSuperChatCommand { get; }
+    public RelayCommand EndTestCommand { get; }
+    public RelayCommand ToggleDrawerCommand { get; }
+    public RelayCommand CloseDrawerCommand { get; }
+
+    public bool IsDrawerOpen
+    {
+        get => _isDrawerOpen;
+        set => SetProperty(ref _isDrawerOpen, value);
+    }
+
+    /// <summary>Whether a test broadcast is currently live (ended by BeginTest /
+    /// EndTestSilently; EndTestCommand asks the app to stop, which routes back here).</summary>
+    public bool IsTestSession
+    {
+        get => _isTestSession;
+        private set
+        {
+            if (SetProperty(ref _isTestSession, value))
+            {
+                OnPropertyChanged(nameof(SessionCaption));
+                OnPropertyChanged(nameof(ChatIdLine));
+                OnPropertyChanged(nameof(CanSendTestMessage));
+            }
+        }
+    }
+
+    public string? BroadcastId => _broadcastId;
+
+    public string ChatIdLine => _liveChatId == null ? "liveChatId: —" : $"liveChatId: {_liveChatId}";
+
+    public string SessionCaption => IsTestSession
+        ? "Test stream is live — private to you, zero notifications, real chat."
+        : "No test in progress — hit the Test button in the top bar to start a private broadcast and check your chat overlay.";
+
+    public string SendMessageText
+    {
+        get => _sendMessageText;
+        set
+        {
+            if (SetProperty(ref _sendMessageText, value))
+                OnPropertyChanged(nameof(CanSendTestMessage));
+        }
+    }
+
+    public bool IsSending
+    {
+        get => _isSending;
+        private set
+        {
+            if (SetProperty(ref _isSending, value))
+                OnPropertyChanged(nameof(CanSendTestMessage));
+        }
+    }
+
+    public bool CanSendTestMessage => IsTestSession && !IsSending && _liveChatId != null
+        && !string.IsNullOrWhiteSpace(SendMessageText);
+
+    /// <summary>Feedback line for the last send / simulated event (null = nothing yet).</summary>
+    public string? LastEventText
+    {
+        get => _lastEventText;
+        private set => SetProperty(ref _lastEventText, value);
+    }
+
+    /// <summary>Called once by MainViewModel when the test broadcast is live and its
+    /// liveChatId resolved — opens the dock so the chat tools are immediately usable.</summary>
+    public void BeginTest(string broadcastId, string? liveChatId)
+    {
+        _broadcastId = broadcastId;
+        _liveChatId = string.IsNullOrWhiteSpace(liveChatId) ? null : liveChatId;
+        SendMessageText = string.Empty;
+        LastEventText = _liveChatId == null
+            ? "Chat polling couldn't start — Mock Chat Input is disabled."
+            : null;
+        IsTestSession = true;
+        IsDrawerOpen = true;
+    }
+
+    /// <summary>Called by MainViewModel's stop path when the broadcast ends — the
+    /// dock forgets the ended session (idempotent).</summary>
+    public void EndTestSilently()
+    {
+        _broadcastId = null;
+        _liveChatId = null;
+        IsTestSession = false;
+        IsSending = false;
+    }
+
+    /// <summary>Mock Chat Input: real liveChat/messages.insert. The inserted text
+    /// arrives through the normal poll and renders via the live overlay path — the
+    /// whole point is that the round-trip is the real one.</summary>
+    public async Task SendTestMessageAsync()
+    {
+        if (!CanSendTestMessage || _liveChatId == null) return;
+        var text = SendMessageText.Trim();
+        IsSending = true;
+        SendMessageText = string.Empty;
+        LastEventText = null;
+        try
+        {
+            var error = await _stream.InsertChatMessageAsync(_liveChatId, text);
+            LastEventText = error == null
+                ? $"Sent — “{text}” should appear on the chat overlay within a couple of seconds."
+                : $"Couldn't send: {error}";
+        }
+        catch (Exception ex)
+        {
+            AppLog.Write($"Test chat message send failed: {ex.Message}");
+            LastEventText = "Couldn't send that message — try again.";
+        }
+        finally
+        {
+            IsSending = false;
+        }
+    }
+
+    private void Simulate(ChatMessage message)
+    {
+        if (!IsTestSession) return;
+        _chat.InjectSimulatedMessage(message);
+        _eventCounter++;
+        LastEventText = $"Fired #{_eventCounter}: {Describe(message)} — renders on any visible chat overlay.";
+        AppLog.Write($"Test chat simulation {_eventCounter} injected");
+    }
+
+    /// <summary>Subscriptions aren't chat events on YouTube, so a "subscriber" row
+    /// is a plain text-shaped message carrying the count — honest: the chat overlay
+    /// shows it as a regular row, which is exactly what a sub looks like in chat.
+    /// It carries <see cref="ChatEventKind.None"/> on purpose: no alert animation
+    /// fires for free subs — the chat mention is the announcement (creator ruling).</summary>
+    private ChatMessage SimulatedSubscriber()
+    {
+        var author = NextViewer();
+        return NewSimulated(author, "New subscriber — welcome to the herd! 🦙 (simulated subscribe)");
+    }
+
+    private ChatMessage SimulatedMember()
+    {
+        var author = NextViewer();
+        var message = NewSimulated(author, $"🎉 {author} became a member!");
+        message.IsMember = true;
+        message.MembershipLevel = "New member";
+        message.Kind = ChatEventKind.NewMember;
+        return message;
+    }
+
+    private ChatMessage SimulatedSuperChat()
+    {
+        var author = NextViewer();
+        var message = NewSimulated(author, "Keep the streams flowing, llama power 🦙");
+        message.IsSuperChat = true;
+        message.SuperChatAmount = 5.00;
+        message.SuperChatCurrency = "$";
+        message.SuperChatDisplayString = "$5.00";
+        message.Kind = ChatEventKind.SuperChat;
+        return message;
+    }
+
+    private ChatMessage NewSimulated(string author, string text)
+    {
+        return new ChatMessage
+        {
+            AuthorName = author,
+            Message = text,
+            Timestamp = DateTime.Now,
+            IsSimulated = true,
+        };
+    }
+
+    private string NextViewer() => SimulatedViewers[_eventCounter % SimulatedViewers.Length];
+
+    private static string Describe(ChatMessage m)
+    {
+        if (m.IsSuperChat) return $"{m.AuthorName} pledged {m.SuperChatCurrency}{m.SuperChatAmount:0.00} in a Super Chat";
+        if (m.IsMember) return $"{m.AuthorName} just became a member ({m.MembershipLevel})";
+        return $"{m.AuthorName} subscribed";
+    }
+}

Services/VideoFrame.cs

@@ -13,6 +13,43 @@ public sealed class VideoFrame
     public byte[] BgraPixels { get; }
     public int Stride => Width * 4;
 
+    /// <summary>Producer frame epoch — a monotonically increasing number stamped by
+    /// sources that RECYCLE their pixel buffers (the screen-capture ring, take-11 spike
+    /// fix). Consumers that key caches on buffer identity (the compositor's paste cache)
+    /// MUST include it, or a recycled array false-hits with stale content. Producers
+    /// that hand out fresh arrays per frame leave it 0 — identity alone is then enough.</summary>
+    public long Epoch { get; init; }
+
+    /// <summary>Producer contract: every alpha byte in <see cref="BgraPixels"/> is 255
+    /// (DWM capture surfaces and MediaCapture video carry no alpha — the OS fills 255).
+    /// Lets the compositor take a straight-copy fast path for a full-canvas opaque
+    /// layer instead of 2M per-pixel blends. NEVER set it for paths whose pixels can
+    /// be transparent (static art, web overlays, chat, the social-bar strip).</summary>
+    public bool IsOpaque { get; init; }
+
+    /// <summary>WebSource crop metadata: the alpha bounding box of the widget content
+    /// within the full canvas (X/Y/W/H in pixels). When set, the compositor uses these
+    /// bounds for Fill-style scaling (stretch to cover, no aspect preservation) instead of
+    /// UniformToFill. The transparent margins of the full canvas are preserved so they
+    /// reveal layers beneath — the crop defines the actual content region.</summary>
+    public (int X, int Y, int W, int H)? CropBounds { get; init; }
+
+    /// <summary>Where a SMALLER-than-canvas overlay composites, in master pixels
+    /// (creator ruling 2026-09-26: the alert ticker draws INSIDE the Stream Alerts video
+    /// box, not as a full-width strip pinned to the top edge). <c>null</c> — the default
+    /// — means the canvas origin, which is what every full-canvas overlay wants.
+    /// <para>This is deliberately NOT a full-canvas frame: at 30–60fps a 1920×1080
+    /// overlay is 8.3MB of large-object-heap garbage per tick, and a 10s alert would
+    /// churn ~2.5GB. A box-sized strip is ~370KB, so the position travels on the frame
+    /// instead of in a 1920-wide transparent margin.</para></summary>
+    public (int X, int Y)? Placement { get; init; }
+
+    /// <summary>Composite origin X: <see cref="Placement"/> if set, else 0.</summary>
+    public int OriginX => Placement?.X ?? 0;
+
+    /// <summary>Composite origin Y: <see cref="Placement"/> if set, else 0.</summary>
+    public int OriginY => Placement?.Y ?? 0;
+
     public VideoFrame(int width, int height, byte[] bgraPixels)
     {
         Width = width;

Services/WebCaptureFrameSource.cs

@@ -0,0 +1,232 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.WindowsRuntime;
+using System.Threading.Tasks;
+using Windows.Graphics;
+using Windows.Graphics.Capture;
+using Windows.Graphics.DirectX;
+using Windows.Graphics.DirectX.Direct3D11;
+using Windows.Graphics.Imaging;
+using ytLive.Helpers;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// The frame-driven web capture for one widget: a GraphicsCaptureItem backed by
+/// the widget's Windows.UI.Composition visual (see WebView2Manager). Owns the
+/// item, a free-threaded Direct3D11CaptureFramePool and the capture session;
+/// frames arrive in step with Chromium's own presentation (~60Hz on a real
+/// animation), replacing the old CapturePreviewAsync PNG poll whose ~35-165ms
+/// encode cost capped the recording at ~10Hz and the preview at ~5fps.
+///
+/// The capture surface holds a REAL alpha channel (the controller renders onto
+/// a transparent composition visual), so the GPU→CPU copy uses
+/// <see cref="BitmapAlphaMode.Straight"/> and the frame is
+/// <see cref="VideoFrame.IsOpaque"/> = false — the compositor's straight-alpha
+/// blend math ("web layer transparency", 2026-09-13) requires the readback to
+/// keep premultiplication OFF. Unlike the screen source there is no master-size
+/// downscale: the controller renders at the RAW 1920×1080 master canvas, so the
+/// CPU never holds a larger frame.
+///
+/// Per-frame the alpha bounding box of the widget (<see cref="FindContentBounds"/>)
+/// is measured on this capture worker thread and stamped onto the frame as
+/// <see cref="VideoFrame.CropBounds"/> — same alpha-bbox contract as the old
+/// PNG path, but off the UI thread (a 2M-pixel scan per frame there is exactly
+/// the cost this redesign exists to remove).
+/// </summary>
+public sealed class WebCaptureFrameSource : IScreenCaptureSource
+{
+    private readonly object _gate = new();
+    private GraphicsCaptureItem _item;
+    private Direct3D11CaptureFramePool? _framePool;
+    private GraphicsCaptureSession? _session;
+    private SizeInt32 _poolSize;
+    private bool _started;
+    private bool _framePending;
+    private DateTime _lastErrorLog = DateTime.MinValue;
+
+    // Buffer recycling: identical to the screen source's ring+Epoch contract
+    // (see ScreenCaptureFrameSource) — the compositor's paste cache is keyed on
+    // array identity, so recycled buffers must carry a monotonic Epoch or a
+    // reused array false-hits with stale content.
+    private readonly byte[]?[] _frameRing = new byte[8][];
+    private int _ringNext;
+    private long _epoch;
+
+    private static readonly TimeSpan ErrorLogThrottle = TimeSpan.FromSeconds(5);
+
+    public string Key { get; }
+    public event Action<VideoFrame>? FrameAvailable;
+
+    internal WebCaptureFrameSource(string key, GraphicsCaptureItem item)
+    {
+        Key = key;
+        _item = item;
+    }
+
+    /// <summary>Wraps an item created from a composition visual by the web manager.</summary>
+    public static WebCaptureFrameSource CreateForVisual(string key, GraphicsCaptureItem item)
+        => new(key, item);
+
+    public Task StartAsync()
+    {
+        lock (_gate)
+        {
+            if (_started) return Task.CompletedTask;
+            var item = _item;
+            var device = Direct3D11Helper.CreateDevice();
+            var framePool = Direct3D11CaptureFramePool.CreateFreeThreaded(
+                device, DirectXPixelFormat.B8G8R8A8UIntNormalized, 2, item.Size);
+            _poolSize = item.Size;
+            var session = framePool.CreateCaptureSession(item);
+            framePool.FrameArrived += OnFrameArrived;
+            session.StartCapture();
+            _framePool = framePool;
+            _session = session;
+            _started = true;
+        }
+        return Task.CompletedTask;
+    }
+
+    public Task StopAsync()
+    {
+        lock (_gate)
+        {
+            _started = false;
+            _framePending = false;
+            if (_framePool != null)
+                _framePool.FrameArrived -= OnFrameArrived;
+            _session?.Dispose();
+            _session = null;
+            _framePool?.Dispose();
+            _framePool = null;
+        }
+        return Task.CompletedTask;
+    }
+
+    private void OnFrameArrived(Direct3D11CaptureFramePool sender, object args)
+    {
+        var frame = sender.TryGetNextFrame();
+        if (frame == null) return;
+        lock (_gate)
+        {
+            if (!_started)
+            {
+                frame.Dispose();
+                return;
+            }
+        }
+
+        if (frame.ContentSize.Width != _poolSize.Width || frame.ContentSize.Height != _poolSize.Height)
+        {
+            sender.Recreate(Direct3D11Helper.CreateDevice(),
+                DirectXPixelFormat.B8G8R8A8UIntNormalized, 2, frame.ContentSize);
+            _poolSize = frame.ContentSize;
+        }
+
+        if (_framePending)
+        {
+            frame.Dispose();
+            return;
+        }
+        _framePending = true;
+        _ = ProcessFrameAsync(frame);
+    }
+
+    private async Task ProcessFrameAsync(Direct3D11CaptureFrame frame)
+    {
+        try
+        {
+            using (frame)
+            using (var softwareBitmap = await SoftwareBitmap.CreateCopyFromSurfaceAsync(
+                frame.Surface, BitmapAlphaMode.Straight))
+            {
+                FrameAvailable?.Invoke(CopyToVideoFrame(softwareBitmap));
+            }
+        }
+        catch (Exception ex)
+        {
+            var now = DateTime.UtcNow;
+            if (now - _lastErrorLog >= ErrorLogThrottle)
+            {
+                _lastErrorLog = now;
+                AppLog.Write($"WebCaptureFrameSource: frame conversion failed: {ex.Message}");
+            }
+        }
+        finally
+        {
+            _framePending = false;
+        }
+    }
+
+    private byte[] RentRingBuffer(int size)
+    {
+        for (var tries = 0; tries < _frameRing.Length; tries++)
+        {
+            var idx = (_ringNext + tries) % _frameRing.Length;
+            var buf = _frameRing[idx];
+            if (buf is { Length: var len } && len == size)
+            {
+                _ringNext = (idx + 1) % _frameRing.Length;
+                return buf;
+            }
+        }
+        var slot = _ringNext;
+        _ringNext = (slot + 1) % _frameRing.Length;
+        var fresh = new byte[size];
+        _frameRing[slot] = fresh;
+        return fresh;
+    }
+
+    private VideoFrame CopyToVideoFrame(SoftwareBitmap bitmap)
+    {
+        var sw = bitmap.PixelWidth;
+        var sh = bitmap.PixelHeight;
+        using var buffer = bitmap.LockBuffer(BitmapBufferAccessMode.Read);
+        using var reference = buffer.CreateReference();
+        if (!WindowsRuntimeMarshal.TryGetDataUnsafe(reference, out var data, out var capacity))
+            throw new InvalidOperationException("Could not access the frame buffer.");
+
+        var srcStride = sw * 4;
+        var count = (int)Math.Min(capacity, (uint)(sh * srcStride));
+        var pixels = RentRingBuffer(count);
+        Marshal.Copy(data, pixels, 0, pixels.Length);
+
+        var (cropX, cropY, cropW, cropH) = FindContentBounds(pixels, sw, sh, srcStride);
+        return new VideoFrame(sw, sh, pixels)
+        {
+            IsOpaque = false,
+            Epoch = ++_epoch,
+            CropBounds = (cropX, cropY, cropW, cropH),
+        };
+    }
+
+    // The widget's extent is measured from the captured frame itself: the
+    // bounding box of non-transparent pixels (the background is injected
+    // transparent, so the alpha channel IS the widget). Immune to DOM timing
+    // (fonts/images/animations), needs no JS round-trip, and CANNOT break the
+    // render: a widget that fills the canvas gets the full frame; a widget that
+    // floats in transparent margin gets exactly its content box — used for the
+    // preview bitmap / selection. The frame handed to the compositor is always
+    // the FULL canvas, so the page's transparent margins keep revealing the
+    // layers beneath (the "black square over webcam" was the crop fed to the
+    // compositor: UniformToFill zoomed the opaque content box over the element).
+    internal static (int X, int Y, int W, int H) FindContentBounds(byte[] pixels, int pixW, int pixH, int stride)
+    {
+        int minX = pixW, minY = pixH, maxX = -1, maxY = -1;
+        for (var y = 0; y < pixH; y++)
+        {
+            var row = y * stride;
+            for (var x = 0; x < pixW; x++)
+            {
+                if (pixels[row + x * 4 + 3] == 0) continue;
+                if (x < minX) minX = x;
+                if (x > maxX) maxX = x;
+                if (y < minY) minY = y;
+                if (y > maxY) maxY = y;
+            }
+        }
+        if (maxX < minX || maxY < minY) return (0, 0, pixW, pixH);
+        return (minX, minY, maxX - minX + 1, maxY - minY + 1);
+    }
+}

Services/WebView2Manager.cs

@@ -1,86 +1,93 @@
 using System;
+using System.Collections.Generic;
 using System.Drawing;
 using System.IO;
-using System.Text.Json;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
 using System.Windows;
-using System.Windows.Controls;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
 using System.Windows.Threading;
 using Microsoft.Web.WebView2.Core;
-using Microsoft.Web.WebView2.Wpf;
+using Windows.Graphics.Capture;
+using Windows.System;
+using Windows.UI.Composition;
 using ytLive.Helpers;
 using ytLive.Models;
 
 namespace ytLive.Services;
 
+/// <summary>
+/// Owns the composition-based web sources (one per widget). A session renders
+/// its widget through a <see cref="CoreWebView2CompositionController"/> whose
+/// visual tree lives off-screen on the WPF UI thread (OBS web-source model:
+/// the page renders at the MASTER CANVAS size 1920×1080, stable, never tracked);
+/// the controller's root visual is captured by a <see cref="WebCaptureFrameSource"/>
+/// at Chromium's own presentation cadence. The preview is crop-copied to a shared
+/// WriteableBitmap on the UI thread (dispatcher-coalesced latest-wins, mirror of
+/// ScreenCaptureManager); the FramePump reads <see cref="GetLatestFrame"/>.
+///
+/// The composition stack needs a DispatcherQueue on this thread (CsWinRT does not
+/// project <c>CreateOnCurrentThread</c> on the 19041 SDK — only the dedicated
+/// variant — so it is installed via a CoreMessaging P/Invoke, the documented
+/// fallback the WebView2CompositionControl / webview_windows embedders use).
+/// Everything composition-side therefore runs on the WPF UI thread; only the
+/// frame conversion and alpha-bbox scan run on the capture worker.
+///
+/// Seam: an internal <c>Func&lt;string, IScreenCaptureSource&gt;</c> source
+/// factory substitutes the whole WebView2+item creation in tests — the manager
+/// then owns the session/coalesce/crop/preview plumbing exactly as in production.
+/// </summary>
 public sealed class WebView2Manager : IDisposable
 {
-    private readonly Panel _hostPanel;
     private readonly Dispatcher _dispatcher;
+    private readonly Func<string, IScreenCaptureSource>? _sessionSourceFactory;
     private readonly Dictionary<string, WebSourceSession> _sessions = new();
+    private Task<CoreWebView2Environment>? _environmentTask;
+    private DispatcherQueueController? _dispatcherQueueController;
+    private Windows.UI.Composition.Compositor? _compositor;
 
     public event Action<string, WriteableBitmap>? PreviewBitmapChanged;
 
     private sealed class WebSourceSession
     {
-        public required WebView2 Control { get; init; }
-        public required DispatcherTimer CaptureTimer { get; init; }
+        public required string Key { get; init; }
+        public CoreWebView2? Web;
+        public CoreWebView2CompositionController? Controller;
+        public IScreenCaptureSource? Source;
+        public Action<VideoFrame>? FrameHandler;
         public VideoFrame? LatestFrame;
+        public WriteableBitmap? PreviewBitmap;
+
+        // Buffer reuse (2026-09-04 lesson): the preview crop copy reuses one
+        // scratch array while the widget's extent holds — no per-frame LOH mint.
+        public byte[]? CropScratch;
         public bool Disposed;
         public bool Initialized;
+        public bool FramePending;
+        public bool FirstCaptureLogged;
+        public int WidgetLogsRemaining;
     }
 
-    public WebView2Manager(Panel hostPanel, Dispatcher dispatcher)
+    public WebView2Manager(Dispatcher dispatcher)
+        : this(dispatcher, null)
+    {
+    }
+
+    /// <summary>Test seam: the source factory replaces WebView2+composition
+    /// creation, so the session/coalesce/crop/preview plumbing is testable
+    /// without the runtime.</summary>
+    internal WebView2Manager(Dispatcher dispatcher, Func<string, IScreenCaptureSource>? sessionSourceFactory)
     {
-        _hostPanel = hostPanel;
         _dispatcher = dispatcher;
+        _sessionSourceFactory = sessionSourceFactory;
     }
 
     public void Register(Source source)
     {
         if (_sessions.ContainsKey(source.Id)) return;
-
-        // OBS model: the page renders at the MASTER CANVAS size (1920×1080),
-        // stable, never tracked. Full-bleed widgets (designed for the canvas)
-        // render fully instead of being clipped to a small box-sized viewport;
-        // dragging the box never reflows the page. The capture is tightly
-        // cropped to the widget's ALPHA bounding box (FindContentBounds) and
-        // the display (Stretch=Fill) maps it flush under the box, anchored at
-        // (0,0) — no DOM query, so no timing fragility; worst case is the
-        // full frame, which is the confirmed-good rendering.
-        var webView = new WebView2
-        {
-            Width = 1920,
-            Height = 1080,
-            DefaultBackgroundColor = System.Drawing.Color.Transparent,
-            Visibility = System.Windows.Visibility.Visible,
-        };
-        Canvas.SetLeft(webView, -5000);
-        Canvas.SetTop(webView, -5000);
-
-        _hostPanel.Children.Add(webView);
-
-        var timer = new DispatcherTimer
-        {
-            Interval = TimeSpan.FromMilliseconds(100),
-        };
-
-        var session = new WebSourceSession
-        {
-            Control = webView,
-            CaptureTimer = timer,
-        };
-
-        _sessions[source.Id] = session;
-
-        timer.Tick += (_, _) =>
-        {
-            if (!session.Disposed && session.Initialized)
-                _ = CaptureFrame(source.Id);
-        };
-
-        _ = InitializeAsync(source, session);
+        _sessions[source.Id] = new WebSourceSession { Key = source.Id };
+        _ = InitializeAsync(source, _sessions[source.Id]);
     }
 
     public void Unregister(string sourceId) => RemoveSession(sourceId);
@@ -93,7 +100,7 @@ public sealed class WebView2Manager : IDisposable
         if (string.IsNullOrEmpty(source.WebUri))
         {
             session.LatestFrame = null;
-            session.Control.CoreWebView2?.NavigateToString(
+            session.Web?.NavigateToString(
                 "<html><body style='background:transparent;margin:0'></body></html>");
             return;
         }
@@ -106,42 +113,116 @@ public sealed class WebView2Manager : IDisposable
         return _sessions.TryGetValue(sourceId, out var session) ? session.LatestFrame : null;
     }
 
+    // Injected BEFORE the document is parsed (AddScriptToExecuteOnDocumentCreatedAsync) so
+    // the widget page's own CSS/scripts cannot repaint html/body opaque — the reason the
+    // late NavigationStarting/NavigationCompleted ExecuteScriptAsync injection lost the
+    // fight (page styles ran first). A transparent capture REQUIRES the transparency in
+    // place before the page paints, on the composition surface too.
+    //
+    // The OLD inline `element.style.background='transparent'` form lost to any page CSS:
+    // a widget that paints a background-COLOR on a container (or html/body with stronger
+    // specificity) after connect re-opaques the capture → the "black opaque box" in the
+    // recording while the early frames were transparent. This is a solved problem in the
+    // overlay ecosystem — OBS browser sources use a Custom CSS override and the decade-
+    // validated formula for arbitrary pages is a `!important` background-color wipe
+    // (OBS Forums 2016 "body { background-color: rgba(0,0,0,0) !important }",
+    // https://obsproject.com/forum/threads/translucent-transparent-browser-source.59549/,
+    // and the div-level variant for stubborn widgets, woahtech.com OBS custom-CSS guide).
+    // A `<style>` node injected before parse, with `!important`, outranks every page rule
+    // (only an author !important beats a later document-order !important; ours runs first).
+    // Only background-COLOR was wiped at first — the 15:34 take showed the widget's own
+    // full-canvas backdrop surviving as the box's black void: that paint is a CSS
+    // background-IMAGE (gradient/backdrop), and the OBS fix for the same symptom is
+    // `background: none !important` / background-image none, not color alone
+    // (obsproject/obs-studio#6659 — "set the CSS for html and body to background: none
+    // !important"). Wipe background-image too; HTML overlay art (the widget's content) is
+    // <img>/DOM/CSS shapes and survives — only container decorations are removed, which is
+    // OBS-browser-source semantics for a transparent overlay.
+    internal const string TransparentBackgroundScript =
+        "(function(){" +
+        "if(document.getElementById('ytl-transparent-bg'))return;" +
+        "var s=document.createElement('style');" +
+        "s.id='ytl-transparent-bg';" +
+        "s.appendChild(document.createTextNode(" +
+        "'html,body{background-color:transparent!important;background-image:none!important;margin:0!important;overflow:hidden!important;}'" +
+        "'html,body,html *{background-color:transparent!important;background-image:none!important;}'" +
+        "));" +
+        "(document.head||document.documentElement).appendChild(s);" +
+        "})();";
+
     private async Task InitializeAsync(Source source, WebSourceSession session)
     {
         try
         {
-            await session.Control.EnsureCoreWebView2Async();
-
-            var cws = session.Control.CoreWebView2!;
-
-            cws.NavigationStarting += (_, _) =>
+            IScreenCaptureSource sourceImpl;
+            if (_sessionSourceFactory != null)
             {
-                _ = cws.ExecuteScriptAsync(
-                    "document.documentElement.style.background='transparent';" +
-                    "document.documentElement.style.overflow='hidden';" +
-                    "document.body.style.background='transparent';" +
-                    "document.body.style.overflow='hidden';");
-            };
-
-            cws.NavigationCompleted += (_, _) =>
+                // Test path: the factory hands over a fully-configured source; the
+                // branch has no awaits, so Register() completes the session inline.
+                sourceImpl = _sessionSourceFactory(source.Id);
+            }
+            else
             {
-                _ = cws.ExecuteScriptAsync(
-                    "document.documentElement.style.background='transparent';" +
-                    "document.documentElement.style.overflow='hidden';" +
-                    "document.body.style.background='transparent';" +
-                    "document.body.style.overflow='hidden';");
-                _ = CaptureFrame(source.Id);
-            };
+                var controller = await CreateControllerAsync();
+                if (controller == null)
+                {
+                    RemoveSession(source.Id);
+                    return;
+                }
 
+                session.Controller = controller;
+                session.Web = controller.CoreWebView2;
+                if (session.Web == null)
+                {
+                    RemoveSession(source.Id);
+                    return;
+                }
+
+                // Pre-page hook: runs after the global object exists but BEFORE the document
+                // parses / any page script runs — must complete before navigating away from
+                // about:blank for it to apply to the widget document.
+                await session.Web.AddScriptToExecuteOnDocumentCreatedAsync(TransparentBackgroundScript);
+
+                session.Web.NavigationStarting += (_, _) =>
+                {
+                    _ = session.Web?.ExecuteScriptAsync(TransparentBackgroundScript);
+                };
+
+                session.Web.NavigationCompleted += (_, e) =>
+                {
+                    _ = session.Web?.ExecuteScriptAsync(TransparentBackgroundScript);
+                    if (e.IsSuccess && session.Web?.Source is { } src && src != "about:blank")
+                    {
+                        // Log-only diagnostic on the REAL widget document (a few post-paint
+                        // frames so styles/backgrounds settle). The first-capture dump only
+                        // ever saw about:blank; the old PNG widget dumps are gone with the
+                        // PNG path — alpha stats now ride the frame-driven channel.
+                        session.WidgetLogsRemaining = 3;
+                        var rearm = session;
+                        _ = Task.Run(async () =>
+                        {
+                            await Task.Delay(TimeSpan.FromSeconds(30));
+                            if (!rearm.Disposed) rearm.WidgetLogsRemaining = 3;
+                        });
+                    }
+                };
+
+                session.Web.NavigateToString(
+                    "<html><body style='background:transparent;margin:0'></body></html>");
+
+                if (!string.IsNullOrEmpty(source.WebUri))
+                    Navigate(source.WebUri, session);
+
+                session.Initialized = true;
+
+                sourceImpl = new WebCaptureFrameSource(source.Id, CreateCaptureItem(controller));
+            }
+
+            session.Source = sourceImpl;
+            session.FrameHandler = frame => OnFrameAvailable(session, frame);
+            sourceImpl.FrameAvailable += session.FrameHandler;
+            await sourceImpl.StartAsync();
             session.Initialized = true;
-
-            session.Control.CoreWebView2.NavigateToString(
-                "<html><body style='background:transparent;margin:0'></body></html>");
-
-            if (!string.IsNullOrEmpty(source.WebUri))
-                Navigate(source.WebUri, session);
-
-            session.CaptureTimer.Start();
         }
         catch (Exception ex)
         {
@@ -150,116 +231,246 @@ public sealed class WebView2Manager : IDisposable
         }
     }
 
+    // The environment MUST exist before the controller is created — it's created once
+    // and shared by every session (one browser process). These flags (the
+    // Electron-class embedder answer to Chromium throttling hidden pages — the moment
+    // the app window is unfocused or covered, rAF parks and timers clamp to ~1s) keep
+    // the renderer at full rate: --disable-backgrounding-occluded-windows,
+    // --disable-renderer-backgrounding, and disable the native-window occlusion
+    // detector that marks the page hidden.
+    private Task<CoreWebView2Environment> GetEnvironmentAsync()
+    {
+        if (_environmentTask != null) return _environmentTask;
+        var options = new CoreWebView2EnvironmentOptions
+        {
+            AdditionalBrowserArguments =
+                "--disable-backgrounding-occluded-windows --disable-renderer-backgrounding --disable-features=CalculateNativeWinOcclusion",
+        };
+        // Per-instance user data folder in DEBUG: Chromium locks it exclusively, so
+        // without this the second dev instance of the same exe fails to start at all.
+        // Release passes null and WebView2 uses its default.
+        var userData = InstanceProfile.WebViewDataFolder;
+        if (userData != null) Directory.CreateDirectory(userData);
+        return _environmentTask = CoreWebView2Environment.CreateAsync(null, userData, options);
+    }
+
+    /// <summary>Creates the composition controller off-screen under the main
+    /// window (the parent HWND is required, the visual never mounts a window
+    /// target). Set up is copied from the WebView2CompositionControl /
+    /// webview_windows embedders: raw-pixel bounds at the master canvas,
+    /// fixed rasterization scale, transparent default background.</summary>
+    private async Task<CoreWebView2CompositionController?> CreateControllerAsync()
+    {
+        var mainWindow = Application.Current?.MainWindow;
+        var hwnd = mainWindow == null
+            ? IntPtr.Zero
+            : new System.Windows.Interop.WindowInteropHelper(mainWindow).Handle;
+        if (hwnd == IntPtr.Zero)
+        {
+            AppLog.Write("WebView2Manager: main window handle unavailable — web source not created");
+            return null;
+        }
+
+        var env = await GetEnvironmentAsync();
+        if (_compositor == null) _compositor = CreateCompositorForCurrentThread();
+
+        var controller = await env.CreateCoreWebView2CompositionControllerAsync(hwnd);
+        controller.Bounds = new Rectangle(0, 0, 1920, 1080);
+        controller.BoundsMode = CoreWebView2BoundsMode.UseRawPixels;
+        controller.ShouldDetectMonitorScaleChanges = false;
+        controller.RasterizationScale = 1.0;
+        controller.IsVisible = true;
+        controller.DefaultBackgroundColor = System.Drawing.Color.Transparent;
+        return controller;
+    }
+
     private void Navigate(string url, WebSourceSession session)
     {
-        try { session.Control.CoreWebView2?.Navigate(url); }
+        try { session.Web?.Navigate(url); }
         catch (Exception ex) { AppLog.Write($"WebView2Manager: navigate failed: {ex.Message}"); }
     }
 
-    // The widget's extent is measured from the captured frame itself: the
-    // bounding box of non-transparent pixels (the background is injected
-    // transparent, so the alpha channel IS the widget). This is immune to
-    // DOM timing (fonts/images/animations), needs no JS round-trip, and
-    // CANNOT break rendering: if the widget fills the canvas the box equals
-    // the full frame (identical to the confirmed-good uncropped display); if
-    // it floats in transparent margin, the crop maps it flush under the box.
-    internal static (int X, int Y, int W, int H) FindContentBounds(byte[] pixels, int pixW, int pixH, int stride)
+    // The visual tree webview_windows wires (offscreen mode): a root container
+    // visual sized to the master canvas (the captured subject — the Flutter
+    // plugin calls GraphicsCaptureItem.CreateFromVisual on this root), with the
+    // controller's root visual target set to a child that fills the root via
+    // RelativeSizeAdjustment. BoundsMode raw pixels + RasterizationScale 1.0 keep
+    // the capture at exactly 1920×1080 regardless of monitor scale.
+    private GraphicsCaptureItem CreateCaptureItem(CoreWebView2CompositionController controller)
     {
-        int minX = pixW, minY = pixH, maxX = -1, maxY = -1;
-        for (var y = 0; y < pixH; y++)
-        {
-            var row = y * stride;
-            for (var x = 0; x < pixW; x++)
-            {
-                if (pixels[row + x * 4 + 3] == 0) continue;
-                if (x < minX) minX = x;
-                if (x > maxX) maxX = x;
-                if (y < minY) minY = y;
-                if (y > maxY) maxY = y;
-            }
-        }
-        if (maxX < minX || maxY < minY) return (0, 0, pixW, pixH);
-        return (minX, minY, maxX - minX + 1, maxY - minY + 1);
+        var compositor = _compositor!;
+        var root = compositor.CreateContainerVisual();
+        root.Size = new System.Numerics.Vector2(1920f, 1080f);
+        root.IsVisible = true;
+
+        var webViewVisual = compositor.CreateContainerVisual();
+        webViewVisual.RelativeSizeAdjustment = new System.Numerics.Vector2(1f, 1f);
+        root.Children.InsertAtTop(webViewVisual);
+
+        controller.RootVisualTarget = webViewVisual;
+        return GraphicsCaptureItem.CreateFromVisual(root);
     }
 
-    private async Task CaptureFrame(string sourceId)
+    // CsWinRT does not project DispatcherQueueController.CreateOnCurrentThread
+    // on the 19041 SDK (only CreateOnDedicatedThread [CS0117, verified by probe]);
+    // the documented fallback — "how to create a DispatcherQueue on the current
+    // thread" (learn.microsoft.com CoreMessaging docs) — is CreateDispatcherQueueController
+    // from CoreMessaging.dll, wrapped via FromAbi (the CaptureInterop pattern). One
+    // per UI thread, then new Compositor() (which requires the DQ) works here.
+    private Windows.UI.Composition.Compositor CreateCompositorForCurrentThread()
     {
-        if (!_sessions.TryGetValue(sourceId, out var session) || session.Disposed) return;
-
-        try
+        var options = new DispatcherQueueOptions
         {
-            var webView = session.Control;
-            if (webView.CoreWebView2 == null) return;
+            DwSize = Marshal.SizeOf<DispatcherQueueOptions>(),
+            ThreadType = 2,    // DQTYPE_THREAD_CURRENT
+            ApartmentType = 2, // DQTAT_COM_STA — the WPF UI thread is STA
+        };
+        var hr = CreateDispatcherQueueController(options, out var controllerPtr);
+        if (hr != 0)
+            throw Marshal.GetExceptionForHR(hr)!;
+        _dispatcherQueueController = DispatcherQueueController.FromAbi(controllerPtr);
+        return new Windows.UI.Composition.Compositor();
+    }
 
-            using var ms = new MemoryStream();
-            await webView.CoreWebView2.CapturePreviewAsync(
-                CoreWebView2CapturePreviewImageFormat.Png, ms);
+    [StructLayout(LayoutKind.Sequential)]
+    private struct DispatcherQueueOptions
+    {
+        public int DwSize;
+        public int ThreadType;
+        public int ApartmentType;
+    }
 
-            ms.Position = 0;
+    [DllImport("CoreMessaging.dll")]
+    private static extern int CreateDispatcherQueueController(
+        DispatcherQueueOptions options, out IntPtr dispatcherQueueController);
 
-            var bitmap = new BitmapImage();
-            bitmap.BeginInit();
-            bitmap.StreamSource = ms;
-            bitmap.CacheOption = BitmapCacheOption.OnLoad;
-            bitmap.EndInit();
-            bitmap.Freeze();
+    private void OnFrameAvailable(WebSourceSession session, VideoFrame frame)
+    {
+        if (session.Disposed) return;
+        session.LatestFrame = frame;
 
-            var formatted = new FormatConvertedBitmap(bitmap,
-                PixelFormats.Bgra32, null, 0);
+        if (_dispatcher.CheckAccess())
+        {
+            UpdatePreview(session);
+            return;
+        }
+        if (session.FramePending) return;
+        session.FramePending = true;
+        _dispatcher.BeginInvoke(() =>
+        {
+            session.FramePending = false;
+            if (!session.Disposed)
+                UpdatePreview(session);
+        }, DispatcherPriority.Render);
+    }
 
-            var pixW = formatted.PixelWidth;
-            var pixH = formatted.PixelHeight;
+    private void UpdatePreview(WebSourceSession session)
+    {
+        var frame = session.LatestFrame;
+        if (frame == null) return;
 
-            if (pixW < 1 || pixH < 1) return;
+        var (cropX, cropY, cropW, cropH) = frame.CropBounds ?? (0, 0, frame.Width, frame.Height);
+        if (cropW < 1 || cropH < 1)
+        {
+            cropX = 0; cropY = 0;
+            cropW = frame.Width; cropH = frame.Height;
+        }
 
-            var pixels = new byte[pixW * pixH * 4];
-            formatted.CopyPixels(pixels, pixW * 4, 0);
+        // The preview is sized to the widget's alpha bounding box (the compositor
+        // gets the FULL canvas + CropBounds; the crop is only for the preview).
+        // A fresh box (widget resizes / first content paints) mints a new bitmap
+        // once — WPF re-renders a reused mutable bitmap after WritePixels, so
+        // later frames only re-copy into the same one.
+        if (session.PreviewBitmap == null
+            || session.PreviewBitmap.PixelWidth != cropW
+            || session.PreviewBitmap.PixelHeight != cropH)
+        {
+            session.PreviewBitmap = new WriteableBitmap(cropW, cropH, 96, 96, PixelFormats.Bgra32, null);
+            PreviewBitmapChanged?.Invoke(session.Key, session.PreviewBitmap);
+        }
 
-            var stride = pixW * 4;
+        var need = cropW * cropH * 4;
+        var scratch = session.CropScratch is { } s && s.Length >= need
+            ? s
+            : (session.CropScratch = new byte[need]);
+        var stride = frame.Stride;
+        if (cropW == frame.Width && cropH == frame.Height && cropX == 0 && cropY == 0)
+            Buffer.BlockCopy(frame.BgraPixels, 0, scratch, 0, need);
+        else
+            for (var r = 0; r < cropH; r++)
+                Buffer.BlockCopy(frame.BgraPixels, (cropY + r) * stride + cropX * 4, scratch, r * cropW * 4, cropW * 4);
 
-            var (cropX, cropY, cropW, cropH) = FindContentBounds(pixels, pixW, pixH, stride);
+        session.PreviewBitmap.WritePixels(new Int32Rect(0, 0, cropW, cropH), scratch, cropW * 4, 0);
 
-            var outPixels = pixels;
-            if (cropW != pixW || cropH != pixH || cropX != 0 || cropY != 0)
+        // alpha[min/max/mean/zero%] — the one number that decides whether a widget's
+        // capture really has transparent margins (0% = opaque, ~100% if the page
+        // painted transparent-only). Sampled every 16th pixel like the original log.
+        if (!session.FirstCaptureLogged)
+        {
+            session.FirstCaptureLogged = true;
+            AppLog.Write(
+                $"WebView2Manager: first capture for '{session.Key}' {frame.Width}x{frame.Height} " +
+                $"{AlphaStats(frame.BgraPixels, frame.Width, frame.Height, stride)} " +
+                $"contentBounds=({cropX},{cropY},{cropW},{cropH})");
+        }
+
+        if (session.WidgetLogsRemaining > 0)
+        {
+            var dumpNo = 3 - session.WidgetLogsRemaining + 1;
+            session.WidgetLogsRemaining--;
+            AppLog.Write(
+                $"WebView2Manager: widget capture [{dumpNo}/3] for '{session.Key}' {frame.Width}x{frame.Height} " +
+                $"{AlphaStats(frame.BgraPixels, frame.Width, frame.Height, stride)} " +
+                $"contentBounds=({cropX},{cropY},{cropW},{cropH})");
+        }
+    }
+
+    private static string AlphaStats(byte[] pixels, int pixW, int pixH, int stride)
+    {
+        int minA = 255, maxA = 0;
+        long sumA = 0, nA = 0, zeroA = 0;
+        for (var y = 0; y < pixH; y += 16)
+        {
+            var row = y * stride;
+            for (var x = 0; x < pixW; x += 16)
             {
-                var dstStride = cropW * 4;
-                outPixels = new byte[dstStride * cropH];
-                for (var r = 0; r < cropH; r++)
-                    Buffer.BlockCopy(pixels, (cropY + r) * stride + cropX * 4, outPixels, r * dstStride, dstStride);
+                var a = pixels[row + x * 4 + 3];
+                if (a < minA) minA = a;
+                if (a > maxA) maxA = a;
+                sumA += a;
+                if (a == 0) zeroA++;
+                nA++;
             }
-
-            var wb = new WriteableBitmap(cropW, cropH, 96, 96, PixelFormats.Bgra32, null);
-            wb.WritePixels(new Int32Rect(0, 0, cropW, cropH), outPixels, cropW * 4, 0);
-            wb.Freeze();
-
-            session.LatestFrame = new VideoFrame(cropW, cropH, outPixels);
-
-            _ = _dispatcher.BeginInvoke(() =>
-            {
-                PreviewBitmapChanged?.Invoke(sourceId, wb);
-            });
-        }
-        catch (ObjectDisposedException) { }
-        catch (InvalidOperationException) { }
-        catch (Exception ex)
-        {
-            AppLog.Write($"WebView2Manager: capture failed for '{sourceId}': {ex.Message}");
         }
+        return $"alpha[min={minA},max={maxA},mean={sumA / (double)nA:F1},zero={100.0 * zeroA / nA:F1}%]";
     }
 
     private void RemoveSession(string sourceId)
     {
         if (!_sessions.TryGetValue(sourceId, out var session)) return;
         session.Disposed = true;
-        session.CaptureTimer.Stop();
-        _hostPanel.Children.Remove(session.Control);
-        try { session.Control.Dispose(); } catch { }
+
+        var src = session.Source;
+        if (src != null)
+        {
+            if (session.FrameHandler != null)
+                src.FrameAvailable -= session.FrameHandler;
+            _ = SafeStopAsync(src);
+        }
+        try { session.Controller?.Close(); } catch { }
+        session.Web = null;
         _sessions.Remove(sourceId);
     }
 
+    private static async Task SafeStopAsync(IScreenCaptureSource source)
+    {
+        try { await source.StopAsync(); }
+        catch (Exception ex) { AppLog.Write($"WebView2Manager: stopping web capture failed: {ex.Message}"); }
+    }
+
     public void Dispose()
     {
         foreach (var id in _sessions.Keys.ToList())
             RemoveSession(id);
     }
-}
+}

Services/Win32WindowEnumerator.cs

@@ -0,0 +1,122 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+using System.Text;
+using ytLive.Models;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// Win32 implementation of <see cref="IWindowEnumerator"/>. Enumerates visible
+/// top-level windows for the "Capture Window…" submenu, mirroring the style of
+/// <see cref="Win32FullScreenDetector"/>: visible, non-cloaked, zero-rect
+/// excluded, and windows belonging to this process excluded (the app must never
+/// offer itself for pinning). Ordered by process name, then title.
+/// </summary>
+public sealed class Win32WindowEnumerator : IWindowEnumerator
+{
+    private static readonly IntPtr OwnProcessId = new(Environment.ProcessId);
+
+    public IReadOnlyList<WindowInfo> Enumerate()
+    {
+        var results = new List<WindowInfo>();
+        EnumWindows((hwnd, _) =>
+        {
+            if (TryDescribe(hwnd, out var info))
+                results.Add(info);
+            return true; // keep enumerating
+        }, IntPtr.Zero);
+
+        results.Sort(static (a, b) =>
+        {
+            var byProcess = string.Compare(a.ProcessName, b.ProcessName, StringComparison.OrdinalIgnoreCase);
+            return byProcess != 0 ? byProcess
+                : string.Compare(a.Title, b.Title, StringComparison.OrdinalIgnoreCase);
+        });
+        return results;
+    }
+
+    private static bool TryDescribe(IntPtr hwnd, out WindowInfo info)
+    {
+        info = null!;
+        if (GetWindowThreadProcessId(hwnd, out var pid) == 0) return false;
+        if (pid == 0 || new IntPtr((long)pid) == OwnProcessId) return false;
+        if (!IsWindowVisible(hwnd)) return false;
+        if (IsCloaked(hwnd)) return false;
+        if (!TryGetRect(hwnd, out var rect) || rect.Right <= rect.Left || rect.Bottom <= rect.Top) return false;
+
+        var title = GetTitle(hwnd);
+        if (string.IsNullOrWhiteSpace(title)) return false;
+
+        var processName = ProcessName((int)pid);
+        if (string.IsNullOrWhiteSpace(processName)) return false;
+
+        info = new WindowInfo(title, processName, hwnd.ToInt64(), (int)pid);
+        return true;
+    }
+
+    private static string ProcessName(int pid)
+    {
+        try
+        {
+            using var process = Process.GetProcessById(pid);
+            return process.ProcessName;
+        }
+        catch { return string.Empty; }
+    }
+
+    private static string GetTitle(IntPtr hwnd)
+    {
+        var length = GetWindowTextLength(hwnd);
+        if (length <= 0) return string.Empty;
+        var sb = new StringBuilder(length + 1);
+        GetWindowText(hwnd, sb, sb.Capacity);
+        return sb.ToString();
+    }
+
+    private static bool IsCloaked(IntPtr hwnd)
+    {
+        const int DWMWA_CLOAKED = 14;
+        var cloaked = 0;
+        return DwmGetWindowAttribute(hwnd, DWMWA_CLOAKED, out cloaked, sizeof(int)) == 0 && cloaked != 0;
+    }
+
+    private static bool TryGetRect(IntPtr hwnd, out Rect rect)
+    {
+        rect = default;
+        return GetWindowRect(hwnd, out rect);
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    private struct Rect
+    {
+        public int Left;
+        public int Top;
+        public int Right;
+        public int Bottom;
+    }
+
+    private delegate bool EnumWindowsProc(IntPtr hwnd, IntPtr lParam);
+
+    [DllImport("user32.dll")]
+    private static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam);
+
+    [DllImport("user32.dll")]
+    private static extern bool IsWindowVisible(IntPtr hWnd);
+
+    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
+    private static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString, int nMaxCount);
+
+    [DllImport("user32.dll", CharSet = CharSet.Unicode)]
+    private static extern int GetWindowTextLength(IntPtr hWnd);
+
+    [DllImport("user32.dll")]
+    private static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);
+
+    [DllImport("user32.dll")]
+    private static extern bool GetWindowRect(IntPtr hWnd, out Rect lpRect);
+
+    [DllImport("dwmapi.dll")]
+    private static extern int DwmGetWindowAttribute(IntPtr hwnd, int dwAttribute, out int pvAttribute, int cbAttribute);
+}

Services/YouTubeAuthService.cs

@@ -15,22 +15,60 @@ public class YouTubeAuthService
 {
     private const string AuthorizationEndpoint = "https://accounts.google.com/o/oauth2/v2/auth";
     private const string TokenEndpoint = "https://oauth2.googleapis.com/token";
-    private const string Scope = "https://www.googleapis.com/auth/youtube https://www.googleapis.com/auth/youtube.force-ssl";
+    /// <summary>
+    /// The single scope the app requests: <c>auth/youtube</c> ("Manage your YouTube
+    /// account"). It is the **broadest** YouTube scope and is unavoidable — no narrower one
+    /// covers live broadcast create/transition, and Google's own <c>liveBroadcasts.insert</c>
+    /// reference lists it as an accepted alternative to <c>youtube.force-ssl</c>, so every
+    /// endpoint this app touches (<c>channels</c>, <c>liveBroadcasts</c>, <c>liveStreams</c>,
+    /// <c>liveChat</c>, <c>playlistItems</c>) is covered by it.
+    ///
+    /// <para><c>auth/youtube.force-ssl</c> used to be requested alongside it and was
+    /// <b>dropped 2026-09-28 as redundant</b>: its grant is "see, edit, and permanently delete
+    /// your YouTube videos, ratings, comments and captions", a strict subset of what
+    /// <c>auth/youtube</c> already grants. Requesting both meant two consent lines and two
+    /// scopes to justify for one capability. Removing a scope can never narrow capability,
+    /// because the scope being kept is the broader of the two.
+    ///
+    /// No forced re-consent: a refresh token keeps the scopes it was originally granted, so an
+    /// existing session is unaffected; the reduced set applies from the next fresh sign-in.</para>
+    /// </summary>
+    private const string Scope = "https://www.googleapis.com/auth/youtube";
 
     private readonly string _clientId;
     private readonly string _clientSecret;
     private readonly HttpClient _http;
     private readonly Action<YouTubeChannel>? _sessionChanged;
+    private readonly Action<string> _openBrowser;
+
+    /// <summary>Serialises "take over from the previous attempt". Without this, two
+    /// overlapping calls both see a free port and race to bind it, which is the same
+    /// failure the cancel-and-await is meant to prevent.</summary>
+    private readonly SemaphoreSlim _authGate = new(1, 1);
+
+    /// <summary>The attempt currently holding the loopback callback port, if any.
+    /// A creator who abandons the Google account chooser gives the app no signal, so
+    /// the attempt simply waits out its 5-minute timeout while still holding port
+    /// 8765 — and a retry in that window cannot bind. A new attempt cancels and
+    /// awaits the abandoned one first, which releases the port (creator report
+    /// 2026-09-27: "cannot sign-in because the callback url was not released").
+    /// Both fields below are only touched while holding <see cref="_authGate"/>.</summary>
+    private Task<YouTubeChannel?>? _authInFlight;
+    private CancellationTokenSource? _authCts;
 
     public YouTubeChannel? CurrentChannel { get; private set; }
 
     public YouTubeAuthService(string clientId, string clientSecret, HttpClient? http = null,
-        Action<YouTubeChannel>? sessionChanged = null)
+        Action<YouTubeChannel>? sessionChanged = null,
+        Action<string>? openBrowser = null)
     {
         _clientId = clientId;
         _clientSecret = clientSecret;
         _http = http ?? new HttpClient();
         _sessionChanged = sessionChanged;
+        // Seam: the real flow shells out to the default browser, which a test must not do.
+        _openBrowser = openBrowser ?? (url =>
+            Process.Start(new ProcessStartInfo(url) { UseShellExecute = true }));
     }
 
     /// <summary>Replaces the current session (used when a saved token loads at startup).</summary>
@@ -65,23 +103,53 @@ public class YouTubeAuthService
 
     public async Task<YouTubeChannel?> AuthenticateAsync()
     {
-        const int port = 8765;
-        var redirectUri = $"http://localhost:{port}/oauth2/callback";
-
         if (string.IsNullOrWhiteSpace(_clientId) || string.IsNullOrWhiteSpace(_clientSecret))
             return null;
 
+        // Taking over from an abandoned attempt has to be atomic: cancel it, wait for
+        // it to actually let go of the port, then bind. Letting the gate go before the
+        // bind reopens the race the takeover exists to close.
+        Task<YouTubeChannel?> attempt;
+        await _authGate.WaitAsync().ConfigureAwait(false);
+        try
+        {
+            var previousCts = _authCts;
+            _authCts = null;
+            previousCts?.Cancel();
+
+            if (_authInFlight is { } previous)
+            {
+                try { await previous.ConfigureAwait(false); } catch { /* its result is irrelevant */ }
+                _authInFlight = null;
+            }
+
+            var cts = new CancellationTokenSource(TimeSpan.FromMinutes(5));
+            _authCts = cts;
+            _authInFlight = attempt = RunAuthFlowAsync(cts.Token);
+        }
+        finally
+        {
+            _authGate.Release();
+        }
+
+        return await attempt.ConfigureAwait(false);
+    }
+
+    private async Task<YouTubeChannel?> RunAuthFlowAsync(CancellationToken cancellationToken)
+    {
+        const int port = 8765;
+        var redirectUri = $"http://localhost:{port}/oauth2/callback";
+
         using var listener = new HttpListener();
         listener.Prefixes.Add($"{redirectUri}/");
         listener.Start();
 
-        Process.Start(new ProcessStartInfo(GetAuthorizationUrl(redirectUri)) { UseShellExecute = true });
+        _openBrowser(GetAuthorizationUrl(redirectUri));
 
         HttpListenerContext context;
         try
         {
-            using var cts = new CancellationTokenSource(TimeSpan.FromMinutes(5));
-            context = await listener.GetContextAsync().WaitAsync(cts.Token);
+            context = await listener.GetContextAsync().WaitAsync(cancellationToken);
         }
         catch (OperationCanceledException)
         {

Services/YouTubeChatService.cs

@@ -6,16 +6,22 @@ namespace ytLive.Services;
 
 /// <summary>
 /// Polls YouTube Live Chat API for messages.
-/// YouTube doesn't have WebSocket for chat — polling is the only option.
+/// YouTube doesn't have WebSocket for chat — polling is the only option. The
+/// cadence follows the server's <c>pollingIntervalMillis</c> (the streamList
+/// connection semantics: reconnect with nextPageToken on that cadence, never
+/// faster than the refresh rate — YouTube rejects requests sent too quickly).
+/// The chat feed IS YouTube's event feed: Super Chats, stickers, memberships,
+/// gifts and milestones arrive here as typed messages (see <see cref="ChatEventKind"/>).
 /// </summary>
 public class YouTubeChatService : IDisposable
 {
     private readonly YouTubeAuthService _auth;
-    private readonly HttpClient _http = new();
+    private readonly HttpClient _http;
     private Timer? _pollTimer;
     private string? _nextPageToken;
     private string? _liveChatId;
     private bool _isRunning;
+    private int _intervalMs = 2000;
 
     public event Action<ChatMessage>? MessageReceived;
 
@@ -24,9 +30,10 @@ public class YouTubeChatService : IDisposable
         PropertyNameCaseInsensitive = true
     };
 
-    public YouTubeChatService(YouTubeAuthService auth)
+    public YouTubeChatService(YouTubeAuthService auth, HttpClient? http = null)
     {
         _auth = auth;
+        _http = http ?? new HttpClient();
     }
 
     public void Start(string liveChatId, int pollIntervalMs = 2000)
@@ -34,7 +41,9 @@ public class YouTubeChatService : IDisposable
         _liveChatId = liveChatId;
         _isRunning = true;
         _nextPageToken = null;
-        _pollTimer = new(async _ => await Poll(), null, 0, pollIntervalMs);
+        _intervalMs = Math.Clamp(pollIntervalMs, 1000, 6000);
+        _pollTimer = new Timer(async _ => await Poll(), null, Timeout.Infinite, Timeout.Infinite);
+        _pollTimer.Change(0, Timeout.Infinite);
     }
 
     public void Stop()
@@ -44,16 +53,24 @@ public class YouTubeChatService : IDisposable
         _pollTimer = null;
     }
 
+    /// <summary>TASK 41: injects a synthetic message through the exact seam the real
+    /// poll uses (MessageReceived), so a simulated member / SuperChat / subscriber
+    /// event renders through the whole overlay pipeline. YouTube's insert API only
+    /// creates text messages — these events are local-only by design and never
+    /// reach YouTube (marked <see cref="ChatMessage.IsSimulated"/>).</summary>
+    public void InjectSimulatedMessage(ChatMessage message)
+        => MessageReceived?.Invoke(message);
+
     private async Task Poll()
     {
-        if (!_isRunning || _liveChatId == null || _auth.CurrentChannel == null) return;
-
         try
         {
+            if (!_isRunning || _liveChatId == null || _auth.CurrentChannel == null) return;
+
             if (_auth.CurrentChannel.TokenExpiry <= DateTime.UtcNow.AddMinutes(5))
                 await _auth.RefreshToken();
 
-            var url = $"https://www.googleapis.com/youtube/v3/liveChat/messages?liveChatId={_liveChatId}&part=snippet,authorDetails&maxResults=50";
+            var url = $"https://www.googleapis.com/youtube/v3/liveChat/messages?liveChatId={_liveChatId}&part=snippet,authorDetails&maxResults=2000";
             if (_nextPageToken != null)
                 url += $"&pageToken={_nextPageToken}";
 
@@ -62,76 +79,182 @@ public class YouTubeChatService : IDisposable
             if (!response.IsSuccessStatusCode) return;
 
             var json = await response.Content.ReadAsStringAsync();
-            var data = JsonSerializer.Deserialize<JsonElement>(json);
+            var page = ParsePage(json);
 
-            if (data.TryGetProperty("nextPageToken", out var token))
-                _nextPageToken = token.GetString();
-
-            if (!data.TryGetProperty("items", out var items)) return;
-
-            foreach (var item in items.EnumerateArray())
-            {
-                var snippet = item.GetProperty("snippet");
-                var author = item.GetProperty("authorDetails");
-                var type = snippet.GetProperty("type").GetString() ?? "textMessageEvent";
-
-                var message = new ChatMessage
-                {
-                    Id = item.GetProperty("id").GetString()!,
-                    AuthorName = author.GetProperty("displayName").GetString()!,
-                    AuthorChannelId = author.GetProperty("channelId").GetString()!,
-                    AuthorImageUrl = author.GetProperty("profileImageUrl").GetString()!,
-                    Timestamp = DateTime.Parse(snippet.GetProperty("publishedAt").GetString()!),
-                    IsMember = author.GetProperty("isChatSponsor").GetBoolean(),
-                    MembershipLevel = author.TryGetProperty("badgeText", out var badgeText)
-                        ? badgeText.GetString()
-                        : null
-                };
-
-                switch (type)
-                {
-                    case "superChatEvent":
-                        message.IsSuperChat = true;
-                        if (snippet.TryGetProperty("superChatDetails", out var scDetails))
-                        {
-                            message.SuperChatAmount = scDetails.TryGetProperty("amountMicros", out var amt)
-                                ? amt.GetDouble() / 1_000_000.0
-                                : 0;
-                            message.SuperChatCurrency = scDetails.TryGetProperty("currency", out var cur)
-                                ? cur.GetString()
-                                : null;
-                            message.Message = scDetails.TryGetProperty("userComment", out var comment)
-                                ? comment.GetString() ?? string.Empty
-                                : string.Empty;
-                        }
-                        break;
-
-                    case "newSponsorEvent":
-                        message.Message = $"🎉 {message.AuthorName} became a member!";
-                        if (snippet.TryGetProperty("membershipDetails", out var memDetails))
-                        {
-                            message.MembershipLevel = memDetails.TryGetProperty("memberLevelName", out var level)
-                                ? level.GetString()
-                                : message.MembershipLevel;
-                        }
-                        break;
-
-                    default: // textMessageEvent
-                        message.Message = snippet.TryGetProperty("textMessageDetails", out var textDetails)
-                            ? textDetails.TryGetProperty("messageText", out var text)
-                                ? text.GetString() ?? string.Empty
-                                : string.Empty
-                            : string.Empty;
-                        break;
-                }
+            if (page.NextPageToken != null)
+                _nextPageToken = page.NextPageToken;
+            if (page.PollIntervalMs > 0 && page.PollIntervalMs != _intervalMs)
+                _intervalMs = page.PollIntervalMs;
 
+            foreach (var message in page.Messages)
                 MessageReceived?.Invoke(message);
-            }
         }
         catch (Exception ex)
         {
             System.Diagnostics.Debug.WriteLine($"Chat poll error: {ex.Message}");
         }
+        finally
+        {
+            // Re-arm the one-shot poll on the server's cadence. Guarded by
+            // _isRunning so a concurrent Stop() (dispose + null) can't race a
+            // Change() back onto the disposed timer.
+            if (_isRunning)
+                _pollTimer?.Change(_intervalMs, Timeout.Infinite);
+        }
+    }
+
+    /// <summary>One liveChat/messages page → typed chat messages + pagination +
+    /// the server's poll cadence. Internal + separated from the HTTP so the six
+    /// event parses are deterministically testable without any network.</summary>
+    internal static ChatPage ParsePage(string json)
+    {
+        var data = JsonSerializer.Deserialize<JsonElement>(json);
+        var messages = new List<ChatMessage>();
+
+        var nextPageToken = data.TryGetProperty("nextPageToken", out var token)
+            ? token.GetString()
+            : null;
+
+        var intervalMs = data.TryGetProperty("pollingIntervalMillis", out var interval)
+            && interval.ValueKind == JsonValueKind.Number
+            ? interval.GetInt32()
+            : 0;
+
+        if (!data.TryGetProperty("items", out var items)) return new ChatPage(messages, nextPageToken, intervalMs);
+
+        foreach (var item in items.EnumerateArray())
+        {
+            var snippet = item.GetProperty("snippet");
+            var type = snippet.TryGetProperty("type", out var t) && t.ValueKind == JsonValueKind.String
+                ? t.GetString()
+                : "textMessageEvent";
+
+            var message = new ChatMessage
+            {
+                Id = item.TryGetProperty("id", out var idProp) ? idProp.GetString() ?? Guid.NewGuid().ToString() : Guid.NewGuid().ToString(),
+                Timestamp = DateTime.UtcNow,
+            };
+
+            if (item.TryGetProperty("authorDetails", out var author))
+            {
+                message.AuthorName = author.TryGetProperty("displayName", out var dn) ? dn.GetString() ?? string.Empty : string.Empty;
+                message.AuthorChannelId = author.TryGetProperty("channelId", out var cid) ? cid.GetString() ?? string.Empty : string.Empty;
+                message.AuthorImageUrl = author.TryGetProperty("profileImageUrl", out var im) ? im.GetString() ?? string.Empty : string.Empty;
+                message.IsMember = author.TryGetProperty("isChatSponsor", out var sp) ? sp.GetBoolean() : false;
+                message.MembershipLevel = author.TryGetProperty("badgeText", out var badge)
+                    ? badge.GetString()
+                    : null;
+            }
+
+            if (snippet.TryGetProperty("publishedAt", out var published)
+                && DateTime.TryParse(published.GetString(), out var publishedAt))
+                message.Timestamp = publishedAt;
+
+            switch (type)
+            {
+                case "superChatEvent":
+                    message.IsSuperChat = true;
+                    message.Kind = ChatEventKind.SuperChat;
+                    if (snippet.TryGetProperty("superChatDetails", out var scDetails))
+                    {
+                        if (scDetails.TryGetProperty("displayString", out var display)
+                            && display.ValueKind == JsonValueKind.String)
+                            message.SuperChatDisplayString = display.GetString();
+                        if (scDetails.TryGetProperty("amountMicros", out var amt)
+                            && amt.ValueKind == JsonValueKind.Number)
+                            message.SuperChatAmount = amt.GetDouble() / 1_000_000.0;
+                        message.SuperChatCurrency = scDetails.TryGetProperty("currency", out var cur)
+                            ? cur.GetString()
+                            : null;
+                        message.Message = scDetails.TryGetProperty("userComment", out var comment)
+                            ? comment.GetString() ?? string.Empty
+                            : string.Empty;
+                    }
+                    break;
+
+                case "superStickerEvent":
+                    message.Kind = ChatEventKind.SuperSticker;
+                    if (snippet.TryGetProperty("superStickerDetails", out var stickerDetails))
+                    {
+                        message.SuperStickerDescription = stickerDetails.TryGetProperty("stickerDescription", out var desc)
+                            ? desc.GetString()
+                            : stickerDetails.TryGetProperty("description", out var descAlt)
+                                ? descAlt.GetString()
+                                : null;
+                        if (stickerDetails.TryGetProperty("displayString", out var display)
+                            && display.ValueKind == JsonValueKind.String)
+                            message.SuperChatDisplayString = display.GetString();
+                        message.SuperChatCurrency = stickerDetails.TryGetProperty("currency", out var cur)
+                            ? cur.GetString()
+                            : null;
+                        message.Message = stickerDetails.TryGetProperty("userComment", out var comment)
+                            ? comment.GetString() ?? string.Empty
+                            : string.Empty;
+                    }
+                    break;
+
+                case "newSponsorEvent":
+                    message.Kind = ChatEventKind.NewMember;
+                    message.IsMember = true;
+                    message.Message = $"🎉 {message.AuthorName} became a member!";
+                    if (snippet.TryGetProperty("membershipDetails", out var memDetails))
+                    {
+                        message.MembershipLevel = memDetails.TryGetProperty("memberLevelName", out var level)
+                            ? level.GetString()
+                            : message.MembershipLevel;
+                    }
+                    break;
+
+                case "membershipGiftingEvent":
+                    message.Kind = ChatEventKind.MemberGift;
+                    if (snippet.TryGetProperty("membershipGiftingDetails", out var giftingDetails)
+                        && giftingDetails.TryGetProperty("giftNewMembersCount", out var count)
+                        && count.ValueKind == JsonValueKind.Number)
+                        message.GiftNewMembersCount = count.GetInt32();
+                    message.Message = message.GiftNewMembersCount > 0
+                        ? $"🎁 {message.AuthorName} gifted {message.GiftNewMembersCount} memberships!"
+                        : $"🎁 {message.AuthorName} gifted memberships!";
+                    break;
+
+                case "giftMembershipReceivedEvent":
+                    message.Kind = ChatEventKind.GiftReceived;
+                    if (snippet.TryGetProperty("giftMembershipReceivedDetails", out var giftReceived)
+                        && giftReceived.TryGetProperty("gifterName", out var gifter))
+                        message.GifterName = gifter.GetString();
+                    message.Message = message.GifterName != null
+                        ? $"{message.GifterName} gifted you a membership! 🎉"
+                        : $"{message.AuthorName} received a membership gift! 🎉";
+                    break;
+
+                case "memberMilestoneChatEvent":
+                    message.Kind = ChatEventKind.MemberMilestone;
+                    message.IsMember = true;
+                    message.Message = snippet.TryGetProperty("textMessageDetails", out var msd)
+                        ? msd.TryGetProperty("messageText", out var mst)
+                            ? mst.GetString() ?? string.Empty
+                            : string.Empty
+                        : string.Empty;
+                    if (message.Message.Length > 0)
+                    {
+                        var match = System.Text.RegularExpressions.Regex.Match(message.Message, @"(\d+)\s*month", System.Text.RegularExpressions.RegexOptions.IgnoreCase);
+                        if (match.Success && int.TryParse(match.Groups[1].Value, out var months))
+                            message.MilestoneMonths = months;
+                    }
+                    break;
+
+                default: // textMessageEvent and anything else — anonymous chat rows only.
+                    message.Message = snippet.TryGetProperty("textMessageDetails", out var textDetails)
+                        ? textDetails.TryGetProperty("messageText", out var text)
+                            ? text.GetString() ?? string.Empty
+                            : string.Empty
+                        : string.Empty;
+                    break;
+            }
+
+            messages.Add(message);
+        }
+
+        return new ChatPage(messages, nextPageToken, intervalMs);
     }
 
     public void Dispose()
@@ -140,3 +263,7 @@ public class YouTubeChatService : IDisposable
         _http.Dispose();
     }
 }
+
+/// <summary>Decoded liveChat/messages response: the messages + where to resume +
+/// how long to wait before reconnecting.</summary>
+internal sealed record ChatPage(List<ChatMessage> Messages, string? NextPageToken, int PollIntervalMs);

Services/YouTubeStreamService.cs

@@ -29,7 +29,12 @@ public class YouTubeStreamService
         return true;
     }
 
-    public async Task<string?> CreateBroadcast(string title, string description, DateTime scheduledStartTime, string? streamId = null)
+    /// <param name="scheduledStartTime"/> — note there is deliberately NO streamId
+    /// parameter (2026-10-04). It used to be here and was ignored: sending
+    /// `contentDetails.boundStreamId` does not bind the broadcast. A parameter that looks
+    /// meaningful but cannot affect the outcome is a defect — it is exactly what made the
+    /// week-long misdiagnosis possible — so the signature now says what it actually does.</param>
+    public async Task<string?> CreateBroadcast(string title, string description, DateTime scheduledStartTime)
     {
         if (!await EnsureToken()) return null;
 
@@ -50,9 +55,16 @@ public class YouTubeStreamService
                 selfDeclaredMadeForKids = false
             },
             // One-click go-live (TASK 5 design decision 1): auto start/stop with
-            // no monitor stream and low latency. A reusable stream, when given,
-            // binds here (boundStreamId) so no second bind round-trip is needed.
-            contentDetails = BuildContentDetails(streamId)
+            // no monitor stream and low latency.
+            //
+            // ⛔ `boundStreamId` is DELIBERATELY NOT SENT HERE (2026-10-04). It used to
+            // be, on the assumption that binding at insert saved a round-trip. It does
+            // not bind anything — proven: the insert was accepted, sibling fields in
+            // this same object took effect, and the broadcast still read `bound=NONE`,
+            // stayed in lifeCycleStatus `created`, and never went live. Binding is done
+            // by the explicit BindBroadcastAsync call instead. Leaving the field out
+            // stops the next reader trusting it; see that method for the full account.
+            contentDetails = BuildContentDetails()
         };
 
         _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
@@ -66,17 +78,17 @@ public class YouTubeStreamService
         return data.GetProperty("id").GetString();
     }
 
-    private static Dictionary<string, object?> BuildContentDetails(string? streamId)
+    private static Dictionary<string, object?> BuildContentDetails()
     {
-        var details = new Dictionary<string, object?>
+        // No `boundStreamId` here on purpose — it does not bind (proven 2026-10-04).
+        // Binding is the explicit BindBroadcastAsync call; see CreateBroadcast.
+        return new Dictionary<string, object?>
         {
             ["enableAutoStart"] = true,
             ["enableAutoStop"] = true,
             ["enableMonitorStream"] = false,
             ["latencyPreference"] = "low",
         };
-        if (streamId != null) details["boundStreamId"] = streamId;
-        return details;
     }
 
     /// <summary>
@@ -124,6 +136,264 @@ public class YouTubeStreamService
         return $"YouTube rejected the update ({(int)response.StatusCode})";
     }
 
+    /// <summary>Proper close-out (TASK 9 design decision 6 — implemented 2026-09-01;
+    /// until then we relied entirely on enableAutoStop, leaving viewers on a frozen
+    /// "stream offline" screen for ~a minute): POST liveBroadcasts.transition
+    /// broadcastStatus=complete. MUST be called AFTER the encoder closed the RTMP
+    /// push so no frames post-date the end. **Pre-flight (2026-09-22):** the POST is
+    /// now gated on the broadcast's OWN lifeCycleStatus — every 2026-09-22 end
+    /// logged 403 invalidTransition because enableAutoStop/YouTube had already marked
+    /// the broadcast complete; a blind complete only earned the 403 + log noise. We
+    /// skip ONLY on a confirmed already-ended status (complete/revoked) — an
+    /// inconclusive check still posts (old behavior) rather than silently stranding a
+    /// live broadcast. The POST is never-throwing: a rare still-failing transition
+    /// surfaces as an error string, never a throw — the stop path must not fail over a
+    /// cosmetic close-out.</summary>
+    public async Task<string?> EndBroadcastAsync(string broadcastId)
+    {
+        if (!await EnsureToken()) return "not signed in";
+
+        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
+
+        var lifeCycle = await GetLifeCycleStatusAsync(broadcastId);
+        if (lifeCycle is "complete" or "revoked")
+        {
+            // Already ended (autoStop/YouTube raced us) — a blind complete only
+            // earns a 403 + noise. enableAutoStop finished it.
+            AppLog.Write($"End close-out: {broadcastId} already at lifeCycleStatus '{lifeCycle}' — skipping complete");
+            return null;
+        }
+
+        var response = await _http.PostAsync(
+            $"{ApiBase}/liveBroadcasts/transition?broadcastStatus=complete&id={Uri.EscapeDataString(broadcastId)}&part=status",
+            content: null);
+
+        if (response.IsSuccessStatusCode) return null;
+        var body = await response.Content.ReadAsStringAsync();
+        AppLog.Write($"Broadcast transition(complete) failed ({(int)response.StatusCode}): {body}");
+        return $"YouTube rejected the end transition ({(int)response.StatusCode})";
+    }
+
+    /// <summary>One liveBroadcasts.list (part=status) read of the broadcast's own
+    /// lifeCycleStatus — the only reliable "can we complete?" signal. Null when the
+    /// list fails or the status is missing (caller degrades gracefully).</summary>
+    private async Task<string?> GetLifeCycleStatusAsync(string broadcastId)
+    {
+        var response = await _http.GetAsync(
+            $"{ApiBase}/liveBroadcasts?part=status&id={Uri.EscapeDataString(broadcastId)}");
+        if (!response.IsSuccessStatusCode) return null;
+        var json = JsonSerializer.Deserialize<JsonElement>(await response.Content.ReadAsStringAsync());
+        if (!json.TryGetProperty("items", out var items) || items.GetArrayLength() == 0) return null;
+        if (!items[0].TryGetProperty("status", out var status)) return null;
+        return status.TryGetProperty("lifeCycleStatus", out var lifeCycle)
+            ? lifeCycle.GetString()
+            : null;
+    }
+
+    /// <summary>One compact log line answering the only question that matters while a
+    /// stream is running: is the broadcast actually bound to the stream we are pushing
+    /// to, and has it moved off `ready`?
+    ///
+    /// Added 2026-10-04 after two test runs proved the push itself is healthy — ffmpeg
+    /// delivered 101,229 KiB video + 1,419 KiB audio over 112s with no socket error,
+    /// yet `enableAutoStart` never fired and close-out 403'd with `invalidTransition`.
+    /// The config is correct by Google's documentation (boundStreamId is a valid
+    /// contentDetails field with no restriction against reusable streams), so the only
+    /// way forward is to observe rather than guess. Everything the API reports about
+    /// this broadcast and its stream goes in one greppable line:
+    /// lifeCycleStatus (so the caller can stop asking once it is live), privacyStatus, the boundStreamId
+    /// *compared against the stream we think we are pushing*, enableAutoStart/Stop, liveChatId
+    /// presence, the stream's own status.streamStatus, and the CDN settings we declared.
+    /// Never throws.</summary>
+    public async Task<string?> LogBroadcastDiagnosticsAsync(string broadcastId, string? streamId)
+    {
+        if (!await EnsureToken()) return null;
+
+        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
+
+        try
+        {
+            var broadcastList = await GetJsonAsync($"liveBroadcasts?part=status,contentDetails,snippet&id={Uri.EscapeDataString(broadcastId)}");
+            // FIX 2026-10-04: liveBroadcasts.list returns a LIST wrapper, so the
+            // broadcast lives at items[0]. The first version of this diagnostic read
+            // the wrapper's root and reported every field as "?" — which then made
+            // BoundMatches report a confident "NO-BINDING" from a parse that never
+            // happened. A diagnostic that lies when it fails is worse than none.
+            var broadcast = FirstItem(broadcastList);
+            var read = broadcast.ValueKind == JsonValueKind.Object;
+            var status = Nested(broadcast, "status");
+            var details = Nested(broadcast, "contentDetails");
+            var snippet = Nested(broadcast, "snippet");
+
+            var lifeCycle = Text(status, "lifeCycleStatus") ?? "?";
+            var bound = Text(details, "boundStreamId");
+            JsonElement? stream = string.IsNullOrWhiteSpace(streamId)
+                ? null
+                : await GetJsonAsync($"liveStreams?part=status,cdn&id={Uri.EscapeDataString(streamId)}");
+            var streamItem = stream is { } present ? FirstItem(present) : default(JsonElement);
+
+            AppLog.Write(
+                $"Broadcast diag: id={broadcastId} lifeCycle={lifeCycle} privacy={Text(status, "privacyStatus") ?? "?"} " +
+                $"recording={Text(status, "recordingStatus") ?? "?"} bound={(read ? (bound ?? "NONE") : "UNREAD")} " +
+                $"expect={streamId ?? "none"} boundMatches={(read ? BoundMatches(bound, streamId) : "unread")} " +
+                $"boundLastUpdate={Text(details, "boundStreamLastUpdateTimeMs") ?? "?"} " +
+                $"autoStart={Flag(details, "enableAutoStart")} autoStop={Flag(details, "enableAutoStop")} " +
+                $"liveChatId={(string.IsNullOrWhiteSpace(Text(snippet, "liveChatId")) ? "none" : "present")} | " +
+                $"streamId={Text(streamItem, "id") ?? "none"} streamStatus={Text(Nested(streamItem, "status"), "streamStatus") ?? "?"} " +
+                $"activeChat={(string.IsNullOrWhiteSpace(Text(Nested(streamItem, "status"), "activeLiveChatId")) ? "none" : "present")} " +
+                $"cdn={Text(Nested(streamItem, "cdn"), "ingestionType") ?? "?"}/{Text(Nested(streamItem, "cdn"), "resolution") ?? "?"}@{Text(Nested(streamItem, "cdn"), "frameRate") ?? "?"}");
+            return lifeCycle;
+        }
+        catch (Exception ex)
+        {
+            AppLog.Write($"Broadcast diag failed: {ex.Message}");
+            return null;
+        }
+    }
+
+    /// <summary>Descends into a `*.list` response and returns its single item. Every list
+    /// endpoint wraps the resource in `items[]`, so reading the response root reads
+    /// the wrapper and silently yields nothing — which is exactly the bug this
+    /// exists to prevent. Returns <c>default</c> when there is no item (empty list,
+    /// or a shape we do not recognise) so callers can tell "absent" from "present".</summary>
+    internal static JsonElement FirstItem(JsonElement listResponse)
+    {
+        return listResponse.ValueKind == JsonValueKind.Object
+            && listResponse.TryGetProperty("items", out var items)
+            && items.ValueKind == JsonValueKind.Array
+            && items.GetArrayLength() > 0
+                ? items[0]
+                : default;
+    }
+
+    /// <summary>The bound stream must be the one we are actually feeding. A mismatch is
+    /// the failure mode where ingest succeeds (the reusable stream happily accepts the
+    /// bytes) while the broadcast waits forever for a stream that is not sending.</summary>
+    internal static string BoundMatches(string? boundStreamId, string? expectedStreamId)
+    {
+        if (string.IsNullOrWhiteSpace(boundStreamId)) return "NO-BINDING";
+        if (string.IsNullOrWhiteSpace(expectedStreamId)) return "unknown";
+        return boundStreamId == expectedStreamId ? "yes" : "MISMATCH";
+    }
+
+    private async Task<JsonElement> GetJsonAsync(string pathAndQuery)
+    {
+        var response = await _http.GetAsync($"{ApiBase}/{pathAndQuery}");
+        if (!response.IsSuccessStatusCode)
+        {
+            AppLog.Write($"Broadcast diag GET {pathAndQuery.Split('?')[0]} failed ({(int)response.StatusCode})");
+            return default;
+        }
+        return JsonSerializer.Deserialize<JsonElement>(await response.Content.ReadAsStringAsync());
+    }
+
+    private static JsonElement Nested(JsonElement parent, string name) =>
+        parent.ValueKind == JsonValueKind.Object && parent.TryGetProperty(name, out var child) ? child : default;
+
+    private static string? Text(JsonElement parent, string name) =>
+        parent.ValueKind == JsonValueKind.Object && parent.TryGetProperty(name, out var value) && value.ValueKind == JsonValueKind.String
+            ? value.GetString()
+            : null;
+
+    private static string Flag(JsonElement parent, string name) =>
+        parent.ValueKind == JsonValueKind.Object && parent.TryGetProperty(name, out var value)
+            ? (value.ValueKind == JsonValueKind.True ? "true" : value.ValueKind == JsonValueKind.False ? "false" : value.ValueKind.ToString())
+            : "unset";
+
+    /// <summary>Binds the broadcast to its stream — THE call that actually makes a broadcast
+    /// go live, and the reason it took a week to find (2026-10-04).
+    ///
+    /// `POST liveBroadcasts/bind?id=…&streamId=…&part=id`, no request body, `youtube.force-ssl`.
+    ///
+    /// **Sending `contentDetails.boundStreamId` on `liveBroadcasts.insert` does NOT bind the
+    /// broadcast.** Proven, not assumed: the insert carried `boundStreamId`, the API accepted the
+    /// request (sibling fields in the same `contentDetails` — `enableAutoStart`, `enableAutoStop` —
+    /// demonstrably took effect), and the created broadcast still came back
+    /// `bound=NONE`. YouTube's own migration guide says so outright: *"a liveBroadcast must be bound
+    /// to exactly one stream before the live broadcast can actually start. The broadcast is not bound
+    /// to any streams at the time that it's created."*
+    ///
+    /// The failure it produces is a **silent stall, not an error**, which is why it survived so long:
+    /// an unbound broadcast reports `lifeCycleStatus = created` ("incomplete settings, not ready to
+    /// transition to a live or testing status"), so `enableAutoStart` has no bound stream to fire
+    /// from, the broadcast never leaves `created`, and close-out then 403s with `invalidTransition`
+    /// because `created → complete` is not a legal edge. Meanwhile ffmpeg pushes ~99 MB happily into
+    /// the reusable stream, because a reusable stream accepts bytes for a broadcast that is not
+    /// watching. Every symptom pointed away from the binding.
+    ///
+    /// Returns null on success, otherwise a human-readable error naming the ACTUAL cause.
+    /// Never throws.</summary>
+    public async Task<string?> BindBroadcastAsync(string broadcastId, string streamId)
+    {
+        if (!await EnsureToken()) return "not signed in";
+
+        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
+
+        var response = await _http.PostAsync(
+            $"{ApiBase}/liveBroadcasts/bind?part=id&id={Uri.EscapeDataString(broadcastId)}&streamId={Uri.EscapeDataString(streamId)}",
+            content: null);
+
+        if (response.IsSuccessStatusCode)
+        {
+            AppLog.Write($"Broadcast bound: {broadcastId} -> stream {streamId}");
+            return null;
+        }
+
+        var body = await response.Content.ReadAsStringAsync();
+        var reason = ErrorReason(body);
+        AppLog.Write($"Broadcast bind failed ({(int)response.StatusCode}/{reason ?? "unknown"}) for {broadcastId} -> {streamId}: {body}");
+        return BindFailureMessage((int)response.StatusCode, reason);
+    }
+
+    /// <summary>Pulls `errors[0].reason` out of a Google API error body. Needed because
+    /// "rejected the binding" alone is not actionable — the reason is what tells the
+    /// creator whether to re-auth, wait, or suspect our own ordering.</summary>
+    internal static string? ErrorReason(string body)
+    {
+        try
+        {
+            using var doc = JsonDocument.Parse(body);
+            if (doc.RootElement.TryGetProperty("error", out var error)
+                && error.TryGetProperty("errors", out var errors)
+                && errors.GetArrayLength() > 0
+                && errors[0].TryGetProperty("reason", out var reason))
+                return reason.GetString();
+        }
+        catch (JsonException)
+        {
+            // A non-JSON error body tells us nothing actionable; the status code is enough.
+        }
+        return null;
+    }
+
+    /// <summary>Bind failures are NOT all "sign in again" (2026-10-04). Google documents six
+    /// distinct reasons and only one is an auth problem, so a single sign-in message
+    /// actively misdirects: `liveBroadcastBindingNotAllowed` in particular means OUR
+    /// ordering is wrong, and telling the creator to re-authenticate would hide a bug in
+    /// our own code behind a plausible excuse. Each documented reason gets its own text,
+    /// because the caller's only lever is the string it shows.</summary>
+    internal static string BindFailureMessage(int status, string? reason) => reason switch
+    {
+        "liveBroadcastBindingNotAllowed" =>
+            "YouTube won't bind a broadcast in its current state — it may already be live. End the session and start again.",
+        "liveStreamNotFound" =>
+            "YouTube couldn't find the reusable stream. Sign in again so it can be recreated.",
+        "liveBroadcastNotFound" =>
+            "YouTube couldn't find the broadcast that was just created. Try again.",
+        "liveStreamingNotEnabled" =>
+            "This channel isn't enabled for live streaming — check the channel's live settings in YouTube Studio.",
+        "insufficientLivePermissions" =>
+            "This account doesn't have permission to stream live. Check the YouTube sign-in.",
+        "internalError" =>
+            "YouTube hit an internal error binding the stream. Try again.",
+        "userRequestsExceededRateLimit" =>
+            "YouTube is rate-limiting us. Wait a moment and try again.",
+        // Unknown or absent reason: keep it verbatim. Never collapse distinct causes into
+        // one bucket — an unmapped reason must stay greppable against the raw API response.
+        null => $"YouTube rejected the stream binding (HTTP {status}, no reason in the body — see startup.log).",
+        _ => $"YouTube rejected the stream binding (HTTP {status}, reason '{reason}' — see startup.log).",
+    };
+
     /// <summary>Returns the channel's reusable stream (TASK 5 design decision 2):
     /// lists existing streams first and reuses the one with cdn.isReusable=true,
     /// creating it with variable resolution/frame rate on first use. Binding to a
@@ -209,43 +479,114 @@ public class YouTubeStreamService
         if (items.GetArrayLength() == 0) return null;
 
         var status = items[0].GetProperty("status");
-        var health = new StreamHealth
+        // The real API nests health as status.healthStatus = { status, lastUpdateTimeSeconds,
+        // configurationIssues[] }. The flat "healthStatus":"bad" shape is our old wrong
+        // assumption — accept both so neither crashes the report-by-exception poll.
+        var health = new StreamHealth();
+        var issueElements = new List<JsonElement>();
+        if (status.TryGetProperty("healthStatus", out var healthStatus))
         {
-            HealthStatus = status.TryGetProperty("healthStatus", out var healthStatus)
-                ? healthStatus.GetString()
-                : null,
-        };
-        if (status.TryGetProperty("configurationIssues", out var issues))
-        {
-            foreach (var issue in issues.EnumerateArray())
+            if (healthStatus.ValueKind == JsonValueKind.String)
             {
-                var severity = issue.TryGetProperty("severity", out var sev) ? sev.GetString() : null;
-                var type = issue.TryGetProperty("type", out var t) ? t.GetString() : null;
-                health.ConfigurationIssues.Add(new StreamConfigurationIssue
-                {
-                    Severity = severity switch
-                    {
-                        "error" => StreamIssueSeverity.Error,
-                        "warning" => StreamIssueSeverity.Warning,
-                        _ => StreamIssueSeverity.Info,
-                    },
-                    Type = type,
-                });
+                health.HealthStatus = healthStatus.GetString();
             }
+            else if (healthStatus.TryGetProperty("status", out var inner) &&
+                     inner.ValueKind == JsonValueKind.String)
+            {
+                health.HealthStatus = inner.GetString();
+            }
+            if (healthStatus.TryGetProperty("configurationIssues", out var nested))
+                issueElements.AddRange(nested.EnumerateArray());
+        }
+        if (status.TryGetProperty("configurationIssues", out var flat))
+            issueElements.AddRange(flat.EnumerateArray());
+        foreach (var issue in issueElements)
+        {
+            var severity = issue.TryGetProperty("severity", out var sev) && sev.ValueKind == JsonValueKind.String
+                ? sev.GetString()
+                : null;
+            var type = issue.TryGetProperty("type", out var t) && t.ValueKind == JsonValueKind.String
+                ? t.GetString()
+                : null;
+            health.ConfigurationIssues.Add(new StreamConfigurationIssue
+            {
+                Severity = severity switch
+                {
+                    "error" => StreamIssueSeverity.Error,
+                    "warning" => StreamIssueSeverity.Warning,
+                    _ => StreamIssueSeverity.Info,
+                },
+                Type = type,
+            });
         }
         return health;
     }
 
-    /// <summary>Returns the liveChatId for a broadcast by fetching its contentDetails.
-    /// The liveChatId is needed to poll chat messages. Called after broadcast creation
-    /// in PrepareAndStartLiveAsync.</summary>
-    public async Task<string?> GetBroadcastLiveChatIdAsync(string broadcastId)
+    /// <summary>TASK 41 — mock chat input: posts a real text message into the live
+    /// chat via <c>liveChat/messages.insert</c>. Requires the same OAuth scopes the
+    /// app already holds (youtube.force-ssl). Returns itself or a human-readable
+    /// error; never throws. The inserted message round-trips back through the normal
+    /// chat poll (~2s) and renders through the live overlay path.</summary>
+    public async Task<string?> InsertChatMessageAsync(string liveChatId, string messageText)
+    {
+        if (!await EnsureToken()) return "not signed in";
+
+        var body = new
+        {
+            snippet = new
+            {
+                liveChatId,
+                type = "textMessageEvent",
+                textMessageDetails = new { messageText }
+            }
+        };
+
+        _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
+        var response = await _http.PostAsJsonAsync(
+            $"{ApiBase}/liveChat/messages?part=snippet", body);
+
+        if (response.IsSuccessStatusCode)
+        {
+            AppLog.Write($"Test chat message inserted into {liveChatId}");
+            return null;
+        }
+
+        var errorBody = await response.Content.ReadAsStringAsync();
+        AppLog.Write($"Chat message insert failed ({(int)response.StatusCode}): {errorBody}");
+        return $"YouTube rejected the message ({(int)response.StatusCode})";
+    }
+
+    /// <summary>Resolves the broadcast's liveChatId (needed to poll chat). Two facts
+    /// pin this down (2026-09-25, from the official liveBroadcasts reference + the
+    /// GetLiveChatId.java sample):
+    /// 1. It lives under <c>snippet.liveChatId</c> — <c>contentDetails</c> has no such
+    ///    property, so part=contentDetails could NEVER resolve it (the "Chat polling
+    ///    couldn't start" report).
+    /// 2. YouTube only populates it once the broadcast is <c>live</c> (the sample lists
+    ///    broadcastStatus=active) — fetching right after insert (lifecycleStatus
+    ///    <c>ready</c>) returns no id. So this polls with a bounded retry, which the
+    ///    caller must run AFTER the encoder starts pushing RTMP (enableAutoStart flips
+    ///    the broadcast to live). Returns the id or null after the retries exhaust;
+    ///    never throws.</summary>
+    public async Task<string?> GetBroadcastLiveChatIdAsync(
+        string broadcastId, int maxAttempts = 10, int delayMs = 2000)
+    {
+        for (var attempt = 0; attempt < maxAttempts; attempt++)
+        {
+            if (attempt > 0) await Task.Delay(delayMs);
+            var liveChatId = await FetchLiveChatIdAsync(broadcastId);
+            if (liveChatId != null) return liveChatId;
+        }
+        return null;
+    }
+
+    private async Task<string?> FetchLiveChatIdAsync(string broadcastId)
     {
         if (!await EnsureToken()) return null;
 
         _http.DefaultRequestHeaders.Authorization = new("Bearer", _auth.CurrentChannel!.AccessToken);
         var response = await _http.GetAsync(
-            $"{ApiBase}/liveBroadcasts?part=contentDetails&id={broadcastId}");
+            $"{ApiBase}/liveBroadcasts?part=snippet&id={broadcastId}");
         if (!response.IsSuccessStatusCode) return null;
 
         var json = await response.Content.ReadAsStringAsync();
@@ -253,8 +594,8 @@ public class YouTubeStreamService
         var items = data.GetProperty("items");
         if (items.GetArrayLength() == 0) return null;
 
-        var contentDetails = items[0].GetProperty("contentDetails");
-        if (contentDetails.TryGetProperty("liveChatId", out var liveChatId))
+        var snippet = items[0].GetProperty("snippet");
+        if (snippet.TryGetProperty("liveChatId", out var liveChatId))
             return liveChatId.GetString();
 
         return null;

Services/YppTrackerViewModel.cs

@@ -0,0 +1,282 @@
+using System.Diagnostics;
+using System.Windows.Input;
+using ytLive.Helpers;
+using ytLive.Models;
+
+namespace ytLive.Services;
+
+/// <summary>
+/// Backing VM for the YPP pull-out (the "YPP" tab below Stream Settings on the
+/// Live screen's right edge). Shows the connected channel's current position
+/// toward the YPP tier thresholds (subscribers + 90-day uploads via the Data
+/// API), a compliance checklist (2FA/AdSense self-reported — channel standing is
+/// NOT exposed to ordinary apps, so the drawer deep-links to the Earn page for it)
+/// and the "what counts" education the creator would otherwise have to leave the
+/// app to find. Snapshots are appended to SQLite on every refresh so a later
+/// analytics slice can compute velocity/ETA from history.
+/// Drawer open/close lives here (mirrors LiveBroadcastFormViewModel).
+/// </summary>
+public sealed class YppTrackerViewModel : ViewModelBase
+{
+    private const double BarMaxWidth = 220;
+
+    private readonly Func<LayoutStore> _store;
+    private readonly Func<ChannelStatsService> _stats;
+    private readonly Func<bool> _isConnected;
+    private readonly Func<string?> _displayName;
+
+    private bool _isDrawerOpen;
+    private bool _isLoading;
+    private bool _isRefreshing;
+    private string? _loadError;
+    private string _displayNameText = string.Empty;
+    private long _subscriberCount;
+    private long _videoCount;
+    private long _totalViews;
+    private int _uploadsLast90Days;
+    private bool _hasSnapshot;
+    private bool _twoFactorEnabled;
+    private bool _adsenseLinked;
+    private DateTime? _lastRefreshedAtUtc;
+
+    public YppTrackerViewModel(
+        Func<LayoutStore> store,
+        Func<ChannelStatsService> stats,
+        Func<bool> isConnected,
+        Func<string?> displayName)
+    {
+        _store = store;
+        _stats = stats;
+        _isConnected = isConnected;
+        _displayName = displayName;
+
+        RefreshCommand = new RelayCommand(_ => _ = RefreshAsync());
+        ToggleDrawerCommand = new RelayCommand(_ => IsDrawerOpen = !IsDrawerOpen);
+        CloseDrawerCommand = new RelayCommand(_ => IsDrawerOpen = false);
+        OpenEarnCommand = new RelayCommand(_ => OpenUrl(EarnUrl));
+        OpenTwoStepCommand = new RelayCommand(_ => OpenUrl(TwoStepVerificationUrl));
+        OpenAdsenseCommand = new RelayCommand(_ => OpenUrl(AdsenseGuideUrl));
+
+        (_twoFactorEnabled, _adsenseLinked) = _store().LoadYppChecklist();
+        _lastRefreshedAtUtc = _store().LoadYppLastRefreshedAtUtc();
+    }
+
+    // Deep links — the parts of the checklist YouTube does NOT expose to any API
+    // resolve in the browser; everything API-derived stays in-app.
+    private const string EarnUrl = "https://www.youtube.com/earn";
+    private const string TwoStepVerificationUrl = "https://myaccount.google.com/signinoptions/two-step-verification";
+    private const string AdsenseGuideUrl = "https://support.google.com/youtube/answer/72851";
+
+    public RelayCommand RefreshCommand { get; }
+    public RelayCommand ToggleDrawerCommand { get; }
+    public RelayCommand CloseDrawerCommand { get; }
+    public RelayCommand OpenEarnCommand { get; }
+    public RelayCommand OpenTwoStepCommand { get; }
+    public RelayCommand OpenAdsenseCommand { get; }
+
+    public bool IsDrawerOpen
+    {
+        get => _isDrawerOpen;
+        set
+        {
+            if (SetProperty(ref _isDrawerOpen, value) && value)
+                _ = EnsureLoadedAsync();
+        }
+    }
+
+    public bool IsLoading
+    {
+        get => _isLoading;
+        private set => SetProperty(ref _isLoading, value);
+    }
+
+    public bool IsSignedOut => !_isConnected();
+
+    public string? LoadError
+    {
+        get => _loadError;
+        private set => SetProperty(ref _loadError, value);
+    }
+
+    public string DisplayName => _displayNameText;
+
+    // ─── Live numbers (from the Data API snapshot) ───
+
+    public long SubscriberCount => _subscriberCount;
+    public long VideoCount => _videoCount;
+    public long TotalViews => _totalViews;
+    public int UploadsLast90Days => _uploadsLast90Days;
+
+    /// <summary>True once a snapshot has successfully captured at least once this
+    /// session (drives the standing detail text's "sign in to load" state).</summary>
+    public bool HasSnapshot => _hasSnapshot;
+
+    // ─── Manual checklist (2FA / AdSense — no API exposes them) ───
+
+    public bool TwoFactorEnabled
+    {
+        get => _twoFactorEnabled;
+        set
+        {
+            if (SetProperty(ref _twoFactorEnabled, value))
+                PersistChecklist();
+        }
+    }
+
+    public bool AdSenseLinked
+    {
+        get => _adsenseLinked;
+        set
+        {
+            if (SetProperty(ref _adsenseLinked, value))
+                PersistChecklist();
+        }
+    }
+
+    // ─── Progress rows (subscribers is fixed; uploads is a 3/90d bar) ───
+
+    public double Tier1SubsProgress => Progress(SubscriberCount, YppThresholds.Tier1.Subscribers);
+    public double Tier2SubsProgress => Progress(SubscriberCount, YppThresholds.Tier2Now.Subscribers);
+    public double UploadsProgress => Progress(UploadsLast90Days, YppThresholds.UploadsRequiredPer90Days);
+
+    public double Tier1SubsBarWidth => Progress(SubscriberCount, YppThresholds.Tier1.Subscribers) * BarMaxWidth;
+    public double Tier2SubsBarWidth => Progress(SubscriberCount, YppThresholds.Tier2Now.Subscribers) * BarMaxWidth;
+    public double UploadsBarWidth => Progress(UploadsLast90Days, YppThresholds.UploadsRequiredPer90Days) * BarMaxWidth;
+
+    public string Tier1SubsText => $"{SubscriberCount:N0} / {YppThresholds.Tier1.Subscribers:N0}";
+    public string Tier2SubsText => $"{SubscriberCount:N0} / {YppThresholds.Tier2Now.Subscribers:N0}";
+    public string UploadsText => $"{UploadsLast90Days} / {YppThresholds.UploadsRequiredPer90Days} in the last 90 days";
+
+    public string StandingDetailText
+    {
+        get
+        {
+            if (!HasSnapshot) return "Sign in to load your channel's progress from YouTube.";
+            return "Channel standing isn't exposed to YouTube apps — check the Earn page for your live status.";
+        }
+    }
+
+    public string LastUpdatedText
+    {
+        get
+        {
+            if (_lastRefreshedAtUtc == null) return "Not refreshed yet";
+            var local = _lastRefreshedAtUtc.Value.ToLocalTime();
+            return local.Date == DateTime.Today
+                ? $"Updated today at {local:HH:mm}"
+                : $"Updated {local:g}";
+        }
+    }
+
+    public string WhatCountsText { get; } =
+        "Long-form watch hours: valid public VODs and livestreams watched in the trailing 12 " +
+        "months — Shorts-feed views don't count, and private, unlisted, deleted or ad-campaign " +
+        "time is excluded. Shorts views: valid public Shorts viewed in the Shorts feed over 90 " +
+        "days. Uploads: valid public long-form videos posted in the last 90 days. Zero active " +
+        "Community Guidelines strikes, 2-Step Verification switched on, and a linked AdSense " +
+        "account complete the checklist. Figures here are API-derived and close to — but not " +
+        "identical to — YouTube Studio's Earn tab.";
+
+    /// <summary>Account sign-in/out changed (fires from MainViewModel): reset the
+    /// signed-out state and refresh when a session now exists.</summary>
+    public void OnAccountChanged()
+    {
+        OnPropertyChanged(nameof(IsSignedOut));
+        OnPropertyChanged(nameof(DisplayName));
+        if (_hasSnapshot && !_isConnected())
+        {
+            _hasSnapshot = false;
+            OnPropertyChanged(nameof(HasSnapshot));
+        }
+        if (_isConnected())
+            _ = EnsureLoadedAsync();
+    }
+
+    /// <summary>Loads once per session/day (quota-honest: the analytics slice that
+    /// gives watch-hours/shorts has a thin targeted-query budget, so this gate is
+    /// baked in now). A manual "Refresh" always goes to the wire.</summary>
+    public async Task EnsureLoadedAsync()
+    {
+        if (!_isConnected() || _hasSnapshot) return;
+        var last = _store().LoadYppLastRefreshedAtUtc();
+        if (last != null && DateTime.UtcNow - last.Value < TimeSpan.FromHours(24)) return;
+        await RefreshAsync();
+    }
+
+    public async Task RefreshAsync()
+    {
+        if (_isRefreshing) return;
+        _isRefreshing = true;
+        IsLoading = true;
+        LoadError = null;
+        try
+        {
+            if (!_isConnected())
+            {
+                _lastRefreshedAtUtc = null;
+                OnPropertyChanged(nameof(LastUpdatedText));
+                return;
+            }
+
+            var snapshot = await _stats().CaptureCurrentAsync();
+            if (snapshot == null)
+            {
+                LoadError = "Couldn't reach YouTube — try again.";
+                return;
+            }
+
+            ApplySnapshot(snapshot);
+            _store().SaveYppSnapshot(snapshot);
+            _lastRefreshedAtUtc = snapshot.CapturedAtUtc;
+            _store().SaveYppLastRefreshedAtUtc(snapshot.CapturedAtUtc);
+            OnPropertyChanged(nameof(LastUpdatedText));
+        }
+        catch (Exception ex)
+        {
+            AppLog.Write($"YPP refresh failed: {ex}");
+            LoadError = "Refresh failed — try again.";
+        }
+        finally
+        {
+            _isRefreshing = false;
+            IsLoading = false;
+        }
+    }
+
+    private void ApplySnapshot(YppStatSnapshot snapshot)
+    {
+        _displayNameText = _displayName() ?? string.Empty;
+        _subscriberCount = snapshot.SubscriberCount;
+        _videoCount = snapshot.VideoCount;
+        _totalViews = snapshot.TotalViews;
+        _uploadsLast90Days = snapshot.UploadsLast90Days;
+        _hasSnapshot = true;
+
+        OnPropertyChanged(nameof(DisplayName));
+        OnPropertyChanged(nameof(SubscriberCount));
+        OnPropertyChanged(nameof(VideoCount));
+        OnPropertyChanged(nameof(TotalViews));
+        OnPropertyChanged(nameof(UploadsLast90Days));
+        OnPropertyChanged(nameof(HasSnapshot));
+        OnPropertyChanged(nameof(Tier1SubsProgress));
+        OnPropertyChanged(nameof(Tier2SubsProgress));
+        OnPropertyChanged(nameof(UploadsProgress));
+        OnPropertyChanged(nameof(Tier1SubsBarWidth));
+        OnPropertyChanged(nameof(Tier2SubsBarWidth));
+        OnPropertyChanged(nameof(UploadsBarWidth));
+        OnPropertyChanged(nameof(Tier1SubsText));
+        OnPropertyChanged(nameof(Tier2SubsText));
+        OnPropertyChanged(nameof(UploadsText));
+        OnPropertyChanged(nameof(StandingDetailText));
+    }
+
+    private void PersistChecklist() => _store().SaveYppChecklist(TwoFactorEnabled, AdSenseLinked);
+
+    private static double Progress(long current, long target)
+        => target <= 0 ? 0 : Math.Clamp((double)current / target, 0, 1);
+
+    private static void OpenUrl(string url)
+    {
+        Process.Start(new ProcessStartInfo(url) { UseShellExecute = true });
+    }
+}

Services/index.md

@@ -6,10 +6,15 @@ External-facing logic: YouTube API, persistence. See
 | File | Purpose |
 |------|---------|
 | `YouTubeAuthService.cs` | OAuth2 via Google: loopback callback (`http://localhost:8765/oauth2/callback`), token exchange, refresh, channel fetch. Constructor takes optional `HttpClient` + `sessionChanged` callback (test seam + save hook); session persists via `Helpers/TokenStore` (DPAPI); `ClearSession()` signs out (called by `MainViewModel.StopStream` on End Livestream) |
-| `YouTubeStreamService.cs` | Broadcast/stream management via the v3 API. **`CreateBroadcast` always sends `privacyStatus = "private"`** (ship step 7 — private-only until v1) and the one-click v3 flags (`enableAutoStart/Stop`, `enableMonitorStream=false`, `latencyPreference=low`); injectable `HttpClient? http = null` ctor seam so tests can fake the API. **`GetOrCreateReusableStreamAsync` (TASK 9, shipped 2026-08-16)** returns the channel's `ReusableStream` — lists `liveStreams?mine=true` and reuses the existing `cdn.isReusable` stream, inserting once only on first use (`resolution=variable`, `frameRate=variable`, `isReusable=true`); a stream id given to `CreateBroadcast` binds at insert via `contentDetails.boundStreamId`. RTMP URL = `ingestionAddress + "/" + streamName`. **`GetStreamHealthAsync(streamId)` (TASK 9 item 3, shipped 2026-08-16)** polls `liveStreams?part=status` → `StreamHealth` with parsed `configurationIssues[]` |
+| `YouTubeStreamService.cs` | Broadcast/stream management via the v3 API. **`CreateBroadcast` always sends `privacyStatus = "private"`** (ship step 7 — private-only until v1) and the one-click v3 flags (`enableAutoStart/Stop`, `enableMonitorStream=false`, `latencyPreference=low`); injectable `HttpClient? http = null` ctor seam so tests can fake the API. **`GetOrCreateReusableStreamAsync` (TASK 9, shipped 2026-08-16)** returns the channel's `ReusableStream` — lists `liveStreams?mine=true` and reuses the existing `cdn.isReusable` stream, inserting once only on first use (`resolution=variable`, `frameRate=variable`, `isReusable=true`); a stream id given to `CreateBroadcast` binds at insert via `contentDetails.boundStreamId`. RTMP URL = `ingestionAddress + "/" + streamName`. **`GetStreamHealthAsync(streamId)` (TASK 9 item 3, shipped 2026-08-16)** polls `liveStreams?part=status` → `StreamHealth` with parsed `configurationIssues[]` (NOTE 2026-09-22: the real API nests `status.healthStatus = {status, lastUpdateTimeSeconds, configurationIssues[]}` as an OBJECT — the parse reads the nested `.status` and tolerates the old flat-string shape; the object shape used to crash every poll) | **`EndBroadcastAsync` (2026-09-01; hardened 2026-09-22)** posts `liveBroadcasts/transition?broadcastStatus=complete&part=status` AFTER RTMP EOF with a pre-flight `liveBroadcasts.list` read of the broadcast's OWN `lifeCycleStatus`: only transitions from `live`/`testing`, skips already-complete broadcasts silently (2026-09-22: every blind end logged `invalidTransition` — autoStop races us to complete); `enableAutoStop` finishes every skip |
 | `StreamHealthReporter.cs` | Pure report-by-exception decision (TASK 9 item 3): `BannerFor(issues)` → `HealthIssueReport(Text?, IsError)` — null text on good/ok/noData/info-only, first warning/error issue produces its type text, error beats warning for color |
-| `YouTubeChatService.cs` | Polls `liveChat/messages`, raises `MessageReceived`; `IDisposable` |
-| `LayoutStore.cs` | SQLite persistence (`Microsoft.Data.Sqlite`) at `%APPDATA%\ytLlive\ytLlive.db`; assets stored as BLOBs keyed by SHA-256 content hash; save/open layout files; schema `user_version` 6 (`Source.ClipShape`/`IsMirrored` via `ALTER TABLE` for pre-v2 DBs; v3 = singleton `Webcam` + per-scene `WebcamSceneConfig`, migrated idempotently **without backfill** — the stale `Source.DeviceId` column remains but is no longer read/written; v4 = `WebcamSceneConfig.RectWidth`/`RectHeight`, the pre-Round rect for the round-to-rect restore; v5 = `Source.IsBackdrop` + `Source.CaptureKey`, the live-capture backdrop; v6 = `Scene.HasBackdrop` — Live-only policy, one-time backfill turns Starting/BRB/Chat/Ending off + drops their backdrop sources; `MainViewModel.NormalizeBackgrounds` re-normalizes on every load — TASK 25: one locked "Background" per canonical screen (static art everywhere, DisplayCapture on Live), duplicates dropped, index 0, orphaned `BackgroundUseDefault_*`/`BackgroundPath_*` Settings keys purged at save). Settings key/value table holds app state: `MicSourceName`, `ReusableStream` (TASK 9 — the cached reusable stream's id/address/name so the pump has its RTMP URL at startup) |
+| `YouTubeChatService.cs` | Polls `liveChat/messages`, raises `MessageReceived`; `IDisposable`. **TASK 43 rewrite (2026-09-24):** re-arms its one-shot poll on the server's `pollingIntervalMillis` (streamList semantics — reconnect on that cadence with `nextPageToken`, clamp 1000–6000ms, `maxResults=2000`); `ParsePage` (internal static seam) decodes **all six** event types into `ChatMessage.Kind`/fields (superChat / superSticker / newSponsor / membershipGifting / giftMembershipReceived / memberMilestoneChat + milestone months best-effort regex); optional `HttpClient` ctor seam endures; `InjectSimulatedMessage` (TASK 41) preserved |
+| `ChatBoxRenderer.cs` | Chat overlay rasterizer (WPF FormattedText → BGRA `VideoFrame`), live rows + Super Chat/member styling |
+| `ChatOverlayLayer.cs` | **The chat component (Commit G):** owns the message buffer, `ChatBoxRenderer`, fade/mock timers, per-source preview renders, live `RenderFrame`; raster-on-change cache pattern (OBS text-source contract) |
+| `AlertRenderer.cs` | **The alert rasterizer (TASK 43, 2026-09-24):** renders one event's celebration animation into a BGRA `VideoFrame` — SIX DISTINCT animations (SuperChat slide-up/shine/count-up, SuperSticker scale-pop, NewMember drop-in/flash-band, MemberGift slide-left/chip-fan, GiftReceived confetti scale-in, MemberMilestone rise/growth-bar), enter/hold/exit phases, brand line on every card. **Still the fallback** when no alert clip is playable (TASK 47) |
+| `AlertOverlayLayer.cs` | **The native alert-box component (TASK 43; video branch TASK 47):** event queue (cap 10) + 33ms dispatch ticker + `RenderFrame` cache-first live path + `UpdatePreview`; **`Advance(double)` is the deterministic test clock** (tests never start the timer); `ChatEventKind.None` rows (sub mentions) never enqueue; idle = transparent (null frame). Since TASK 47 a clip branch owns `IAlertClipDecoder` per play — ctor seams `(clipDecoderFactory, clipPathResolver, audioSink)`, fade in/out over `FadeDurationSeconds = 0.30` (straight-alpha copies + volume×fade audio), EOF freeze-frame → drain, and `AlertTickerFrame` composes the scrolling message strip |
+| `AlertClipDecoder.cs` | **Per-play alert video decoder (TASK 47):** `IAlertClipDecoder` (Start/Stop/Dispose + `FrameAvailable`/`AudioReady`/`Completed`) + ffmpeg child emitting `rawvideo bgra` (`-vf scale=W:H`, read via `RawVideoFrameReader`) and `f32le -ar 48000 -ac 2` on a **carry-buffer** audio loop (float boundary straddles never drop samples), both real-time paced; bgra is opaque (layer owns alpha). One-shot lifetime — created per alert, disposed at drain; tests inject a fake |
+| `LayoutStore.cs` | SQLite persistence (`Microsoft.Data.Sqlite`) at `%APPDATA%\ytLlive\ytLlive.db`; assets stored as BLOBs keyed by SHA-256 content hash; save/open layout files; schema `user_version` 10 (`Source.ClipShape`/`IsMirrored` via `ALTER TABLE` for pre-v2 DBs; v3 = singleton `Webcam` + per-scene `WebcamSceneConfig`, migrated idempotently **without backfill** — the stale `Source.DeviceId` column remains but is no longer read/written; v4 = `WebcamSceneConfig.RectWidth`/`RectHeight`, the pre-Round rect for the round-to-rect restore; v5 = `Source.IsBackdrop` + `Source.CaptureKey`, the live-capture backdrop; v6 = `Scene.HasBackdrop` — Live-only policy, one-time backfill turns Starting/BRB/Chat/Ending off + drops their backdrop sources; v9→v10 (TASK 39) = `YppSnapshot` history table; all later columns stay additive guarded ALTERs — TASK 47 adds the five alert `Source` columns (`AlertVideoAssetId`/`AlertVideoPath`/`AlertUseDefaultVideo`/`AlertShowTicker`/`AlertVideoVolume`) without a version bump; `MainViewModel.NormalizeBackgrounds` re-normalizes on every load — TASK 25: one locked "Background" per canonical screen (static art everywhere, DisplayCapture on Live), duplicates dropped, index 0, orphaned `BackgroundUseDefault_*`/`BackgroundPath_*` Settings keys purged at save). Settings key/value table holds app state: `MicSourceName`, `ReusableStream` (TASK 9 — the cached reusable stream's id/address/name so the pump has its RTMP URL at startup), `AlertDefaultVideoAssetId` (TASK 47 — the stamped built-in alert clip's asset row; save's prune exempts it via UNION) |
 | `VideoFrame.cs` | Normalized CPU frame seam (`Width`/`Height`/tightly-packed BGRA `byte[]`) — the only pixel type the rest of the app knows about; future capture sources (screen, background-removed webcam) feed the same seam |
 | `CameraDeviceInfo.cs` | `(Id, DisplayName)` for a physical capture device |
 | `ICameraEnumerator.cs` | `GetCamerasAsync()` — seam so the picker/`CameraManager` never touch WinRT (tests inject fakes) |
@@ -28,13 +33,16 @@ External-facing logic: YouTube API, persistence. See
 | `ScreenCaptureFrameSource.cs` | One `Direct3D11CaptureFramePool` (free-threaded, 2 buffers) + session per target; frames → `SoftwareBitmap.CreateCopyFromSurfaceAsync` (BGRA, alpha ignored) → `VideoFrame`, bytes read via `WindowsRuntimeMarshal.TryGetDataUnsafe` (CsWinRT-safe — the `IMemoryBufferByteAccess` ComImport cast fails on every frame and is gone). Surfaces > 1920×1080 downscaled bilinearly to the master; conversion failures logged ≤ once/5 s. DRM content = black frames (OS limit). `CreateForMonitor`/`CreateForWindow`/`CreateForPicker` |
 | `ScreenCaptureManager.cs` | Screen-capture ownership mirroring `CameraManager`: refcounted by target key, one shared `WriteableBitmap`, dispatcher-coalesced latest-frame copies; `PreviewBitmapChanged`/`CaptureFailed` events; `ReleaseAllAsync` used on re-designation |
 | `ScreenCaptureSourceFactory.cs` | `Resolve(key)` parses `monitor:<n>` / `window:<hwnd>` / `picker:<name>` into a source; `PickAsync()` shows the OS `GraphicsCapturePicker` and returns the `picker:` key (transient — a reload falls back to auto-detection) |
-| `Compositor/SceneCompositor.cs` | **The output compositor (TASK 4 ship step 1)**: renders a scene into the encoder's master `VideoFrame` (tightly-packed BGRA8), mirroring the XAML preview minus editing chrome — backdrop → background → elements (`UniformToFill` cover-crop, round clip, mirror, opacity, border) → branding flash → social bar (optional `socialBarFrame` + `socialBarTop` in master space, blitted last so the bar sits above the flash; the old `BlitFlash` generalized to `BlitOverlay` with source offsets). Pure and WPF-free: frames injected via a `Func<SceneElement, VideoFrame?>` resolver (webcam → DeviceId, image → AssetId, backdrop → CaptureKey); output sized by `CompositorOptions` (16:9 = full master 1:1; vertical 9:16 = 607×1080 crop → 1080×1920 bilinear). Preview stays XAML (editing view); this is the output view — see `ai.md` "Scene compositor" |
+| `WebView2Manager.cs` | **Web-source ownership (TASK 17, composition-capture since 2026-09-14):** per registered `Source { Type: WebSource }` it owns a `CoreWebView2CompositionController` + its visual tree (`RootVisualTarget` child under a 1920×1080 root `ContainerVisual` on one `Windows.UI.Composition.Compositor` created on the UI thread via the CoreMessaging `CreateDispatcherQueueController` P/Invoke), a wrapped `WebCaptureFrameSource`, and the shared crop-sized `WriteableBitmap` preview (dispatcher-coalesced copy at Render priority, `PreviewBitmapChanged` raised only on recreation). Nav + `TransparentBackgroundScript` injection unchanged. Public ctor `(Dispatcher)`; internal seam ctor `(Dispatcher, Func<string, IScreenCaptureSource>?)` for hermetic tests (no WinRT). Caller: `MainViewModel.InitWebView2()` (now invoked from `MainWindow_Loaded` — the parent HWND must exist). See `../ai.md` "Slice 14" |
+| `WebCaptureFrameSource.cs` | The `IScreenCaptureSource` for a web session: owns the `GraphicsCaptureItem` (`CreateFromVisual`) + a free-threaded `Direct3D11CaptureFramePool` (2 buffers) + session; readback via `SoftwareBitmap.CreateCopyFromSurfaceAsync` (BGRA, **`BitmapAlphaMode.Straight`** — the compositor blends straight alpha); per-frame `FindContentBounds` alpha-bbox (internal static, unit-tested) stamps `VideoFrame.CropBounds`; ring up to 2 fresh frames + Epoch reuse; `IsOpaque=false`. Mirror of `ScreenCaptureFrameSource` |
+| `Compositor/SceneCompositor.cs` | **The output compositor (TASK 4 ship step 1)**: renders a scene into the encoder's master `VideoFrame` (tightly-packed BGRA8), mirroring the XAML preview minus editing chrome — backdrop → background → elements (`UniformToFill` cover-crop, round clip, mirror, opacity, border) → branding flash → social bar (optional `socialBarFrame` + `socialBarTop` in master space, blitted last so the bar sits above the flash; the old `BlitFlash` generalized to `BlitOverlay` with source offsets). **TASK 47:** `Render` + `CompositeLayers` take a trailing `tickerFrame` blitted at (0,0) after the bar — the alert ticker is a message-scrolling dynamic overlay, never baked. Pure and WPF-free: frames injected via a `Func<SceneElement, VideoFrame?>` resolver (webcam → DeviceId, image → AssetId, backdrop → CaptureKey); output sized by `CompositorOptions` (16:9 = full master 1:1; vertical 9:16 = 607×1080 crop → 1080×1920 bilinear). Preview stays XAML (editing view); this is the output view — see `ai.md` "Scene compositor" |
 | `Compositor/CompositorOptions.cs` | The active tier's output rect (source space over the 1920×1080 master, integer-aligned — `MainViewModel.OutputRectX` can be 656.5) + target W×H |
 | `Compositor/StretchMath.cs` | Pure pixel math: the WPF `UniformToFill` cover-crop, clamped bilinear sample/scale (unit-tested half of the compositor) |
 | `Compositor/StaticPixelCache.cs` | Asset bytes → cached BGRA8 `VideoFrame`, decoded once per content hash — the output path's raw-pixel source (the preview uses ImageCache's `BitmapImage`) |
 | `Encoder/IFfmpegLocator.cs` | **TASK 4 ship step 2 seam**: resolves an absolute path to `ffmpeg.exe` (PATH first → cached `%APPDATA%\ytLlive\tools\ffmpeg.exe` → pinned BtbN LGPL-shared zip download). The encoder step and tests fake it |
 | `SocialValidator.cs` | `ISocialValidator` seam + `HttpSocialValidator` default: validates a social handle/URL by constructing the canonical profile URL and issuing an HTTP GET — the "act of validation" before adding to the bar. 200/redirect = exists; 404/connection failure = rejected. Fediverse `@user@domain` additionally does a best-effort nodeinfo lookup (`/.well-known/nodeinfo` → `software.name`) so the entry can show the instance's real logo; nodeinfo failure still validates (generic fediverse glyph). If the identity domain's nodeinfo is blocked (SSO) but the bare root 302s to the real instance (YunoHost default-app subdomains), the lookup follows the redirect and asks that host. Since the bar bug-fix branch the resolution **probes well-known subdomains** (`mastodon.`, `social.`, ... order in `FediverseSubdomainCandidates`) when both the identity domain and its redirect come up empty, bounded by a ~15s linked-CTS budget; `ResolveFediverseSoftwareAsync(domain, ct)` on the seam powers the load-time heal. Constructor takes optional `HttpClient` + `Action<string>` log for tests |
 | `Compositor/SocialBarRenderer.cs` | **Social bar output strip** (bar bug-fix branch): rasterizes the global social bar into a transparent straight-alpha BGRA8 `VideoFrame` strip (1920 wide, 40px content + 24px glow pad) via `RenderTargetBitmap` — one Path (logo) + one TextBlock (handle) per entry, white on transparent with the preview's green `#2ecc71` glow baked in (Pbgra32 → straight-alpha unpremultiply). UI thread only; the frame is immutable afterwards so the `FramePump` reads it from its own thread |
+| `Compositor/AlertTickerRenderer.cs` | **Alert message ticker strip (TASK 47):** marquee overlay rendered per call by pure byte-math onto a 1920×48 transparent BGRA frame — the text pill ("Author — Kind · amount") is rasterized once per text on the UI thread (cached, unpremultiplied straight alpha) and scrolled at 140px/s with a repeat-gap wrap, so the pump can call `Render(elapsed, text)` from its own thread without locking. **Dynamic overlay — never baked** (unlike the social bar) |
 | `Encoder/EncoderOptions.cs` | One go-live's encoder config: full `RtmpUrl` (ingest + stream key), W×H/FPS/bitrate from the quality tier, `VideoEncoder` (null = probe), audio sample rate/channels, `GopSize` = FPS×4 (the ≤4s keyframe bound) |
 | `Encoder/IFfmpegEncoder.cs` | **TASK 4 ship step 3 seam**: start/feed/stop the live encoder; `HealthUpdated` (parsed `StreamHealth`), `ProcessFailed` on unexpected non-zero exit. Constructor-injected locator + process factory (tests fake both) |
 | `Encoder/FfmpegEncoder.cs` | The default encoder: spawn `ffmpeg.exe` (probe `-encoders` first → hardware NVENC/QSV/AMF, OpenH264 fallback — never libx264), feed raw BGRA frames into stdin, parse `-stats` lines into `StreamHealth`, graceful stop via stdin EOF + 10s kill watchdog. Constructed by `MainViewModel` since ship step 5 (`new FfmpegEncoder(new FfmpegLocator())`), driven by the `FramePump` |
@@ -43,7 +51,7 @@ External-facing logic: YouTube API, persistence. See
 | `Encoder/FfmpegArgs.cs` | Pure FFmpeg command-line builder: rawvideo `pipe:0` input, `anullsrc` silent audio (WASAPI replaces it), H.264+AAC, closed GOP (`-g fps×4 -keyint_min -sc_threshold 0 -bf 0`, `yuv420p`), FLV → RTMP |
 | `Encoder/FfmpegProgressParser.cs` | Pure parser for `frame=/fps=/size=/time=/bitrate=` stats lines → `FfmpegProgress` |
 | `Encoder/FfmpegEncoderPicker.cs` | Pure H.264 encoder picker from `-encoders` output: NVENC → QSV → AMF → OpenH264; **never returns libx264** (GPL) |
-| `Encoder/FramePump.cs` | **TASK 4 ship step 5**: the live frame producer — while live it snapshots the active scene each tick, resolves every element to its latest frame (`Func<SceneElement, VideoFrame?>` resolver), composites it into the tier's output frame, and paces frames into the encoder at the tier's FPS. All collaborators constructor-injected seams; free of WPF and the capture managers. `StartAsync` never throws (failures log + `Failed`); no RTMP URL = encoder skipped; `StopAsync` stops the encoder before awaiting the loop (backpressure deadlock); `ProcessFailed` self-stops. Since the bar bug-fix branch it takes an optional `socialBar: Func<(VideoFrame? Frame, SocialBarPosition Position)>?` seam — a pre-rendered bar strip composited last (above the flash) at the top edge or `SourceRectHeight − bar height`. See `ai.md` "Live frame pipeline" |
+| `Encoder/FramePump.cs` | **TASK 4 ship step 5**: the live frame producer — while live it snapshots the active scene each tick, resolves every element to its latest frame (`Func<SceneElement, VideoFrame?>` resolver), composites it into the tier's output frame, and paces frames into the encoder at the tier's FPS. All collaborators constructor-injected seams; free of WPF and the capture managers. `StartAsync` never throws (failures log + `Failed`); no RTMP URL = encoder skipped; `StopAsync` stops the encoder before awaiting the loop (backpressure deadlock); `ProcessFailed` self-stops. Since the bar bug-fix branch it takes an optional `socialBar: Func<(VideoFrame? Frame, SocialBarPosition Position)>?` seam — a pre-rendered bar strip composited last (above the flash) at the top edge or `SourceRectHeight − bar height`. **TASK 47:** adds an `alertTicker: Func<VideoFrame?>?` ctor seam (parallel to `socialBar`), read per tick and threaded through `RenderScene`/`RenderFull` + **mixed into `BuildFullRenderSignature`** so the ticker scroll changes the cache key. See `ai.md` "Live frame pipeline" |
 | `Encoder/FfmpegLocator.cs` | The default locator: PATH probe wins, then the cache, then pull+extract (`ffmpeg.exe` **+ the `libav*.dll` family** via a staging dir, failures via `AppLog`). Pinned to BtbN `autobuild-2026-08-09-13-03` **lgpl-shared** (dynamic linking = LGPL compliance without static-relink §6 material; no GPL libx264; NVENC/QSV/AMF + libopenh264 + native AAC — see `ai.md` → Licensing). Search dirs / tools dir / downloader constructor-injected for hermetic tests. Wired into the encoder since ship step 5 |
 | `INotificationService.cs` | **Toast seam (TASK 24)**: `Show(title, message, AppNotificationSeverity)` + `AppNotificationSeverity { Info, Success, Warning, Error }` + `Info/Success/Warning/Error` extension methods — non-blocking user-facing messages; VMs/services raise through this so failures surface without MessageBox blocking the UI thread |
 | `NotificationService.cs` | The default seam impl (Notification.Wpf 11.0.0, MIT): wraps a library `NotificationManager`; routes to the in-window `NotificationArea` named `ToastArea` (MainWindow bottom-right above the footer); lifetimes via the pure `BuildRequest` mapping + `Cards` tint table — Info/Success ~4s, Warning ~8s auto-dismiss, Error sticky (`NeverExpires()` = `TimeSpan.MaxValue`, never null); dark card tints matching the health-banner language; all Show calls marshal to the captured Dispatcher. See [`../ai.md`](../ai.md) "Toast notifications" |
@@ -51,7 +59,7 @@ External-facing logic: YouTube API, persistence. See
 | `Audio/AudioSample.cs` | One captured chunk: interleaved PCM float (-1..1) + sample rate + channels |
 | `Audio/WasapiLoopbackAudioSource.cs` | Desktop/game capture: NAudio `WasapiLoopbackCapture` on the default render device — automatic at unity; the game bar's meter consumes it |
 | `Audio/WasapiMicAudioSource.cs` | Mic capture: NAudio `WasapiCapture` with the device resolved by `FriendlyName` matching `MicSourceName` (DisplayName only), default capture endpoint fallback; name provider `Func<string?>` re-read at each `Start` so a device picked mid-session takes effect immediately (the mixer restarts the mic on pick) |
-| `Audio/AudioMixer.cs` | Owns both sources; capture starts once at startup (`MainViewModel.StartMicCaptureAsync`) and stops on `Shutdown` — NOT go-live (preview monitoring). Mic samples → `AudioLevelMeter` → `MicLevelChanged`; loopback samples → the game bar's meter via `LoopbackLevelChanged`. Surfaces mic connection state: `MicConnected`/`MicFailed` (drives the status dot) + `RestartMic()` (device swap mid-session, keeps loopback). Failures log via `AppLog`; mic failure zeroes the meter, loopback failure doesn't kill the mic. Note: the meter `Push` is unconditional (the `?.` on the event would otherwise skip the argument when nothing is subscribed) |
+| `Audio/AudioMixer.cs` | Owns both sources; capture starts once at startup (`MainViewModel.StartMicCaptureAsync`) and stops on `Shutdown` — NOT go-live (preview monitoring). Mic samples → `AudioLevelMeter` → `MicLevelChanged`; loopback samples → the game bar's meter via `LoopbackLevelChanged`. Surfaces mic connection state: `MicConnected`/`MicFailed` (drives the status dot) + `RestartMic()` (device swap mid-session, keeps loopback). Failures log via `AppLog`; mic failure zeroes the meter, loopback failure doesn't kill the mic. Note: the meter `Push` is unconditional (the `?.` on the event would otherwise skip the argument when nothing is subscribed). **TASK 47 — alert audio:** `EnqueueAlertAudio` writes a dedicated 8s stereo-48k ring (`AlertBufferSeconds`), drained in `FillAndMix` pre-limiter and added at **unity (never ducked)**; `StartLive` clears the ring |
 | `Audio/AudioLevelMeter.cs` | Pure smoothed RMS level (0..1): `Push(AudioSample)` + `Reset` — the unit-tested math behind `AudioLevel` and `GameAudioLevel`. `ToDisplay(float)` maps the raw linear RMS onto the meter's display scale (−60..0 dBFS spread across 0..1, with **+10 dB input amplification** so real speech peaks hit the red zone at maxed volume) — real speech/game RMS (~0.01..0.1) would otherwise leave a flat scale looking dead; ≤0.001 linear reads as zero (never idles on background noise) |
 | `Audio/WaveToFloat.cs` | Pure WASAPI buffer → float conversion: IEEE float 32-bit direct, PCM 16-bit normalized, `WaveFormatExtensible` IEEE-float subformat GUID, trailing partial samples ignored |
 | `Audio/MasterLimiter.cs` | **Master output limiter**: a **−1 dBFS ceiling** (`Ceiling = 0.891`) applied after the live mix so the honest gains can never sum past 0 dBFS and clip the AAC encode. Instant attack per frame (a hot frame is scaled exactly to the ceiling — no overshoot), smoothed release toward unity so loud passages don't pump. Pure — unit-tested |

TASKS/research-store-certification.md

@@ -0,0 +1,461 @@
+# ytLlive — Windows Store & code-signing certification research (authoritative)
+
+> Catalog: [`TASKS.md`](../TASKS.md) · memory map: [`schema.md`](../schema.md) · distribution plan: [`Distribution.md`](../Distribution.md)
+>
+> **Researched 2026-09-27** against **Microsoft Store Policies version 7.20** (published
+> 2026-09-15, effective 2026-10-22) and the MSIX packaging docs. Policy version moves —
+> re-check the version before acting on any line here.
+>
+> **This file is the "why".** The executable checklist lives in
+> [`task-48-distribution-msix.md`](task-48-distribution-msix.md). No code changed as a
+> result of this research; it only decides what task-48 will eventually do.
+
+---
+
+## 1. Bottom line
+
+**✅ ROUTE DECIDED 2026-09-27 — the creator chose route A: Microsoft Store, MSIX package,
+Store IAP.** The research below is what the decision was made from, and it stays as the
+audit trail so the choice is never re-litigated. The executable checklist is
+`TASKS/task-48-distribution-msix.md`; the ruling and the criteria behind it are in that
+file's item 0.
+
+**MSIX packaging is viable.** One real blocker, and it is a code change we should want
+anyway (§4). Three technical blockers that normally kill a Store submission — drivers,
+per-user services, elevation — we **do not trip** (§7).
+
+**Nothing else is open on distribution.** The only number still unverified is the Store
+revenue-share rate (§11 item 4), which is a *pricing* input, not a distribution one.
+
+---
+
+## 2. ⚠️ The one line in `Distribution.md` that is now wrong
+
+`Distribution.md:318` currently says:
+
+> Buy an EV (Extended Validation) code-signing certificate from DigiCert or Sectigo
+> ($200-400/year). EV certificates get instant SmartScreen reputation; DV/OV certs
+> trigger SmartScreen warnings for months.
+
+**The EV half of that is false.** Microsoft removed the SmartScreen instant-bypass for EV
+certificates in **March 2024**. An EV-signed file now accumulates reputation exactly the
+way an OV-signed file does. Paying $400+/yr buys precisely what paying $150 buys.
+
+`schema.md` rule 4: stale facts get FIXED, not appended. Corrected in `Distribution.md`
+(2026-09-27).
+
+Also worth knowing before budgeting:
+
+- **Cert validity is capped at 460 days** (CA/B Forum CSC-31, effective 2026-03-01). This
+  is a recurring annual line item, not a one-time purchase.
+- **Private keys must live on an HSM or hardware token** (CA/B rule since 2023-05). Budget
+  for the token or a cloud HSM.
+- **Signing does not clear the warning on day one.** A valid cert stops the *malware*
+  warning immediately; the "unrecognized publisher" warning clears as SmartScreen accrues
+  reputation from real download volume. Expect a ramp on every route.
+- **Third-party AV vendors layer their own reputation blocking on top of SmartScreen**, so
+  signed-but-new can still warn on consumer machines. The Store route is the only one that
+  is warning-free, because Microsoft holds the reputation.
+
+---
+
+## 3. Signing economics
+
+| Route | Cert cost | SmartScreen | Install UX | Notes |
+|---|---|---|---|---|
+| **Microsoft Store, MSIX package** | **$0** — Microsoft re-signs | No warning | Normal | Store review, public listing, updates handled by Store |
+| **Microsoft Store, EXE/MSI (10.2.9)** | **$150–300/yr — your own cert** | Warning ramp | **Silent install only** | Store does NOT re-sign; you maintain a versioned URL |
+| **Direct + OV cert** | $150–300/yr | Warning ramp | Yours | Worldwide availability |
+| **Direct + Azure Artifact Signing** | ~$9.99/mo ≈ $120/yr | Warning ramp | Yours | **Individuals: USA/Canada only.** Identity validation required |
+| **Direct + EV cert** | $400+/yr | Same as OV | Yours | **Do not buy.** No benefit since March 2024 |
+| **Unsigned direct** | $0 | Strong block | Yours | Unusable for public download |
+
+### Four real combinations
+
+| # | Distribute | Verify payment | Cert | Revenue cut |
+|---|---|---|---|---|
+| **A** | Store | Store IAP | $0 | yes |
+| **B** | Store | **Polar** | $0 | no |
+| **C** | Polar file hosting | Polar | $150–300/yr | no |
+| **D** | Store EXE (10.2.9) | Polar | $150–300/yr | no |
+
+**✅ A was chosen (2026-09-27)** — the creator's criteria were "zero headaches, minimal
+maintenance (for me) while still providing accountability and a reasonably easy upgrade
+flow," and A is the only option where *every* one of those is solved by handing the work to
+Microsoft rather than to a certificate vendor. The rest of this section stays as the record
+of what was rejected and why, so the decision is not reopened by a later session that
+remembers only that "certs cost $150/yr."
+
+**A** is the only one where Polar becomes unnecessary — the Store handles payment,
+entitlement, and refunds, and `PolarLicenseService` and the customer-portal plumbing are
+deleted. That is a *distribution* choice that happens to subsume licensing.
+
+**B** is the compromise that was **not** taken: the Store would have solved the SmartScreen
+problem and the annual cert bill while Polar stayed the licensing system. Rejected because
+it keeps a licensing backend, a customer portal, activation limits, and an offline-grace
+machine alive — the exact maintenance the ruling was made to eliminate.
+
+**C** is the status quo previously sketched in `Distribution.md:14` / `:296` — Polar hosts
+the signed exe (10GB, signed personal download URLs, SHA-256 included). **The Store is not
+needed for delivery at all**; its only unique value is *free Microsoft signing with no
+SmartScreen warning*, and its cost is MSIX packaging work, Store review, and a public
+listing. Note the irony: C is the only option with a recurring cost *and* the only one where
+the creator maintains payment plumbing themselves.
+
+**D is dominated** — strictly worse than both A and C: cert required anyway, silent install
+required, and we maintain the versioned download URL. Documented in one line so it is
+never re-litigated.
+
+---
+
+## 4. ⛔ The one real blocker: 10.2.2 (dynamic code inclusion)
+
+**Policy 10.2.2:**
+
+> Your product must not attempt to fundamentally change or extend its described
+> functionality or introduce features or functionality that is in violation of Store
+> Policies **through any form of dynamic inclusion of code**. Your product should not, for
+> example, **download a remote script and subsequently execute that script** in a manner
+> that is not consistent with the described functionality.
+
+**What we do today:** `Services/Encoder/FfmpegLocator.cs:37-38` pins a GitHub release URL,
+and `LocateAsync` downloads the zip (line 69), extracts it (line 73), and the encoder then
+executes that binary. On a cold cache the app **downloads an unsigned executable from the
+internet and runs it.**
+
+That is the pattern 10.2.2 names. The word is "script," so a narrow reviewer might quibble
+about a PE binary — but 10.2.3 reinforces it, and 10.2.9 separately requires all PE files
+to chain to the Microsoft Trusted Root Program, which a downloaded BtbN build does not.
+
+**The fix:** bundle `ffmpeg.exe` + `ffprobe.exe` + the `libav*.dll` family **inside the
+package** instead of downloading. No dynamic code inclusion, so 10.2.2 is satisfied.
+
+**This is a fix we want regardless of route.** `FfmpegLocator.cs:30-35` records that the
+previous daily pin aged out of GitHub retention and **404'd on the first real recording
+attempt (2026-09-01)**. Bundling kills that entire class of cold-start failure permanently,
+and it also removes the startup network dependency.
+
+The LGPL-shared licensing reasoning in `FfmpegLocator` is unaffected — dynamic linking was
+the deliberate choice for LGPL §6 compliance, not for download avoidance. Confirm
+`THIRD-PARTY-NOTICES.txt` (already shipped) covers the bundled build.
+
+**What I got wrong initially:** I believed MSIX might forbid *launching* a bundled
+executable. It does not — see §5.
+
+---
+
+## 5. MSIX technical facts (full trust vs AppContainer)
+
+MSIX packages run at one of two trust levels, chosen by the manifest:
+
+| Trust level | Behavior |
+|---|---|
+| **`mediumIL` / full trust** | **Same permissions as a standard desktop app.** Package identity + some file/registry virtualization. **Can spawn child processes.** ← this is what a WPF broadcast tool wants |
+| `appContainer` | Strictly isolated. Process and children see only explicitly granted resources. File/registry virtualized. |
+
+**A packaged WPF app declaring `runFullTrust` runs at medium integrity — it is not an
+AppContainer.** Bundling and launching ffmpeg from inside the package is therefore fine.
+This is the "Desktop Bridge" / `packagedClassicApp` model.
+
+**Critical file-write consequence:** "Writes to user profile locations (such as AppData) are
+redirected to per-package locations for AppContainer apps, or **pass through for full-trust
+apps**." The package install folder itself is read-only.
+
+**Manifest this app needs:**
+
+- `rescap:Capability Name="runFullTrust"` — medium integrity
+- `webcam` and `microphone` capabilities
+- `uap10:TrustLevel="mediumIL"`
+- `uap10:RuntimeBehavior="packagedClassicApp"`
+
+### The full-trust recording invariant (durable architectural fact)
+
+`ViewModels/MainViewModel.Recording.cs` writes recordings to
+`%USERPROFILE%\Downloads` or `SpecialFolder.MyVideos` (`DefaultRecordFolder()`, line
+173–179), with `Microsoft.Win32.OpenFolderDialog` for overrides (`ChooseRecordFolder()`,
+line 151). The whole temp-write-then-move lifecycle stays inside one directory
+(line 131–132).
+
+**This works only because we are full trust.** At `mediumIL` those writes pass through
+unvirtualized and `OpenFolderDialog` is an ordinary Win32 folder browser with no capability
+token involved. **No `broadFileSystemAccess` is needed.**
+
+⚠️ **If anyone ever flips the manifest to `appContainer`, recording silently breaks** —
+`Directory.CreateDirectory` and `File.Move` start resolving to a per-package virtualized
+location. A code comment belongs at `DefaultRecordFolder()` **when the manifest lands**, not
+before (a comment describing a manifest that does not exist is worse than no comment).
+
+---
+
+## 6. Store policy verdicts — what binds, what doesn't
+
+Policy 7.20. "Binds" = must be satisfied to submit.
+
+### ⛔ Binds — blockers or real work
+
+| Policy | Requirement | Our status |
+|---|---|---|
+| **10.2.2** | No dynamic code inclusion (download-and-execute) | ❌ **VIOLATED** — see §4. Fix: bundle ffmpeg |
+| **10.3.1** | Login required → supply a **working demo account** in certification notes | ☐ TODO — we require YouTube sign-in |
+| **10.5.1** | **Privacy policy mandatory**; URL in Partner Center. Desktop Bridge + Win32 **always** need one. Must state what PI is accessed/collected/transmitted, how used/stored/secured, types of parties disclosed to, controls the user has, compliance with law, and be kept current | ☐ TODO — `llamachile.shop` can host it |
+| **10.5.4** | Collect/store/transmit PI securely with modern cryptography | ✅ DPAPI for tokens, HTTPS to YouTube |
+| **10.5.5** | No highly sensitive PI (health/**financial**) unless tied to functionality + express consent | ⚠️ **SuperChat/reward path touches financial data** — keep display-text-only processing, never log payloads |
+| **10.6** | Declared capabilities must relate to the product's functions; **must not circumvent OS checks** | ✅ camera/mic for a broadcast tool is self-evident; must use standard MF/DShow/WASAPI paths |
+| **10.7** | Localize for every declared language; declare **English only** | ☐ Keep the manifest to one language |
+| **10.1.1** | Title must be unique, **no marketing or descriptive text, no extraneous keywords** | Store name is exactly `LlamaCasty` |
+| **10.1.3** | Search terms: max 7, no pricing terms, **no other product titles** unless you published them | ☐ Cannot list `OBS` or `StreamYard` as search terms |
+| **10.1.4** | Distinct informative metadata + **active Store presence** | ☐ Listing must not be a stub |
+| **10.2.7** | Must enable clean uninstall | ☐ MSIX gives this free |
+| **10.4.2** | Start promptly, stay responsive, shut down gracefully, survive native API exceptions | ✅ `AppLog` + dispatcher handlers exist |
+| **10.11.1** | **IARC age-rating questionnaire** required | ☐ General-audience streaming tool, 12+ territory |
+| **10.11.2** | Keep the rating accurate as features change | ☐ Re-visit if audience-facing features shift |
+| **11.12** | **User Generated Content** — see §9 | ⚠️ Judgment call, documented not built |
+| **10.8.1** | Non-game PC products **may** use a secure third-party purchase API **or** Store IAP | ✅ **Superseded 2026-09-27: we chose Store IAP, not Polar.** The third-party-purchase path is no longer the plan |
+| **10.8.2** | Third-party purchase: identify provider, authenticate user, obtain confirmation, PCI DSS, note in Partner Center | ⛔ **Void — Polar is being torn down (TASK 10).** Store IAP is the Microsoft commerce engine, so the third-party-provider/PCI-DSS obligations do not apply |
+| **10.8.3** | **Individual** accounts cannot require financial info for primary functionality; requiring it forces a **Company** account | ⚠️ **Open question** — see §11 |
+| **10.14** | Individual accounts usually fine for a solo dev; Company required if the product needs financial info for primary functionality, or a consumer would read the name as a business | ⚠️ Same question as 10.8.3 |
+| **10.8.7** | Pricing must follow the FTC Guides Against Deceptive Pricing and must not be irrationally high vs. features | ☐ A pricing decision, not a code task |
+| **10.5.8** | Must **follow** applicable safety/privacy laws re children | ☐ Follow-the-law obligation — see §8 |
+| **10.1.5** | May enable acquisition of your other Store products or add-ons | N/A |
+
+### ✅ Does NOT bind — recorded so it is never re-raised
+
+| Policy | Why it doesn't apply |
+|---|---|
+| **10.10** (Advertising) | **Ads are injected server-side by YouTube after the RTMP handoff.** LlamaCasty displays no ads, renders no ad SDK, and controls no ad decision. Every 10.10 clause is conditioned on ads *your product displays*. Not applicable. |
+| **10.2.5** (Store-only install) | 7.20 applies "installed and updated only through the Store" to **game products and Xbox console products**. A non-game PC app is not locked to MSIX. *(The 2018 v7.7 wording said "all of your apps" — that language has been narrowed.)* |
+| **10.2.3** (secondary software) | ffmpeg **enhances** the product's functionality, and once bundled it is not "offered to install" as separate software |
+| **10.2.8** (Windows settings) | `RegisterHotKey` and standard DShow/MF paths are supported APIs. No accessibility-API or undocumented-API tricks |
+| **10.10.1 / 10.10.2** | Follows from 10.10 — no ads displayed |
+| **11.13** (Storefront) | Not a storefront |
+| **11.14** (Gambling) | Not applicable |
+| **11.15** (Child Safety) | Prohibits products enabling exploitation/grooming/sexualization/sextortion/trafficking, and adult-themed products targeting children. A broadcast tool is not in this class. Nothing LlamaCasty does creates, uploads, or distributes child-exploiting content |
+| **10.5.2** | We do not publish a customer's PI to an outside service beyond the stream they themselves broadcast |
+| **10.5.7** (location) | No device location access |
+| **10.2.9** | Only if we chose the Store EXE route. It would bind — see §3, route D is dominated |
+
+### Certification mechanics
+
+- Technical compliance is tested by the **Windows App Certification Kit** before submission.
+- Certification takes **up to 3 business days**; the listing appears ~15 min after publish.
+- MSIX package requirements: SHA2-256 block map, `StoreManifest`, 25 GB max.
+- Partner Center account: individual vs company — see §11.
+
+---
+
+## 7. MSIX disqualifiers we do NOT trip
+
+Verified by grep across the codebase 2026-09-27. The MSIX prep docs list four hard
+disqualifiers; **all four are clear**:
+
+| Disqualifier | Our status |
+|---|---|
+| "Your application requires a Windows driver. MSIX doesn't support Windows drivers." | ✅ We **consume** DShow filters, we don't install a driver. (A creator's third-party Virtual Capture Device is their hardware, not something we ship.) |
+| "Your application requires a user Windows service. MSIX doesn't support per-user Windows services." | ✅ No service installation anywhere |
+| Apps requiring **elevation** for any functionality are not accepted | ✅ No `requireAdministrator` / `highestAvailable` / UAC manifest |
+| "Your app's modules are loaded in-process to processes that are not in your Windows app package" (shell extensions, etc.) | ✅ No shell extensions, no in-process module loading, no jump lists |
+
+Also verified: there is **no `.manifest` file in the repo at all** today, so packaging is
+purely additive — a new `Package.appxmanifest` plus a packaging project. The existing
+unpackaged exe keeps working.
+
+### Other store rules worth knowing while listing
+
+- **10.1.4** requires an active Store presence — the listing cannot be a placeholder.
+- **10.7** — declare English only, or localize the description into every declared language.
+- **10.9** — the app must stay functional when notifications are disabled. Our toast stack
+  must not be load-bearing.
+
+---
+
+## 8. Minors, COPPA, and the age question
+
+### The operator is 13+ by construction
+
+YouTube Terms of Service:
+
+- **"You must be at least 13 years old to use the Service"**
+- 13–17 permitted **with parent/guardian permission**
+- **Under 13 cannot create an account** — exceptions are YouTube Kids and supervised
+  accounts via Family Link or Google Workspace for Education
+- Google Accounts: 13 is the minimum to self-manage
+- **The floor varies by region** — at least one YouTube ToS variant states 14, tracking EU
+  digital-consent ages. Treat it as 13–14, not a fixed 13.
+
+**Why this does real work:** LlamaCasty *requires* a YouTube account to operate, because
+streaming requires one. So the person running the broadcast is 13+ by construction. A
+COPPA theory premised on "a service collecting personal information from children under 13"
+has no purchase against the operator — and that is true **by construction, not by promise**.
+That is the cleanest sentence available for a certification note.
+
+### The residual exposure
+
+The **viewers** may still be under 13 on supervised/family-linked accounts, so the chat
+ingestion point does not fully disappear. It weakens substantially, because:
+
+- Live chat is restricted/disabled on supervised YouTube kid accounts
+- YouTube moderates the messages before we ever see them (§9)
+- Our mitigation: **retain nothing** — parse, display, discard (see `task-49`)
+
+### COPPA is very unlikely to bind
+
+COPPA applies to child-directed services and to operators collecting PI from children under
+13. The three-factor test (subject matter, audience, evidence of child focus) is nowhere
+near met by a broadcast tool aimed at a gaming audience. **10.5.8 is a follow-the-law
+obligation, not a be-child-safe obligation** — it says "follow all applicable laws," it does
+not impose COPPA duties on us directly.
+
+**But note the enforcement trend** (FTC, September 2025 Apitor settlement): operators are
+held responsible for **what third-party components collect on their behalf**, and the FTC
+expects a real inquiry into third-party collection practices. That case was about an SDK;
+the principle is what matters for a chat pipe. This is a documentation obligation, and the
+answer is "we integrate no third-party analytics or ad SDKs, and we persist no chat or
+reward payloads."
+
+---
+
+## 9. 11.12 User Generated Content — the judgment call
+
+11.12 triggers on "content that users contribute to a product and which can be viewed or
+accessed by other users **in an online state**." **Chat is literally that.** If a reviewer
+classifies the chat surface as UGC, the requirements are:
+
+1. Published **terms of service, code of conduct, and/or content guidelines** for UGC,
+   accessible **in-product and on your website**
+2. A **means for users to report** inappropriate/illegal/harmful UGC to the developer for
+   review, and/or proactive detection
+3. Respect **user safety, parental, and content privilege settings**, and handle restricted
+   access gracefully
+4. **Remove or disable UGC when requested by Microsoft**
+5. Disclose that content is **not created by the developer/publisher** where appropriate
+
+### The argument: YouTube discharges the moderation obligation upstream
+
+| 11.12 asks for | How YouTube already covers it |
+|---|---|
+| Published ToS / CoC / content guidelines | Community Guidelines, linkable from our listing |
+| A reporting mechanism | Creator-side chat reporting; YouTube enforces |
+| Respect parental / privilege settings | YouTube's restricted + supervised accounts |
+| Remove/disable on request | YouTube removes; we never hosted the original |
+| Disclose third-party UGC origin | Visibly YouTube chat; YouTube is platform of record |
+
+**And the enforcement is demonstrably real.** YouTube's transparency report for
+**Jan–Mar 2026**: approximately **1.6 billion comments removed in a single quarter**, with
+**child safety the #2 removal reason at 124,624,293** (hateful/abusive 15,977,127;
+harassment/cyberbullying 71,326,861; spam/scams 1.31 B).
+
+**The certification-note sentence:**
+
+> UGC is mirrored from YouTube, which moderates it at industrial scale upstream. We render
+> transiently, persist nothing, and provide no user-to-user communication surface.
+
+**The "persist nothing" half is ours to keep** — and it is the same property
+`task-49` (profanity filter) needs. Convenient, not coincidental.
+
+**Our read:** 11.12 targets products hosting a UGC *community*. A chat *mirror* rendered
+from YouTube — where YouTube is the platform of record and already supplies reporting,
+age-gating, and parental controls — is arguably not "our" UGC. **This is a judgment call,
+and we resolve it by documenting the position rather than building features on a guess.**
+State the reasoning in the certification notes; Microsoft reads them.
+
+### The documentation we owe regardless
+
+| Artifact | Requirement |
+|---|---|
+| **Privacy policy** on `llamachile.shop` | 10.5.1. Must state: camera/mic access is user-directed and OS-gated; **no retention** of chat or reward payloads; no viewer data collected; **ffmpeg is bundled, nothing is fetched at runtime** |
+| **Code of conduct + content guidelines** | 11.12 / 11.15. General audience; explicitly not directed at under-13s |
+| **IARC age-rating questionnaire** | 10.11.1 |
+| **Certification notes** | the 11.12 reading, the YouTube age-gate argument, the Polar third-party purchase box, the demo account |
+
+---
+
+## 10. Camera, microphone, and "only when the user says so"
+
+**We do not write that certification. Windows does it — and the Store forbids us from
+bypassing it.** Three layers:
+
+1. **Policy 10.6** — "You must not circumvent operating system checks for capability
+   usage." Route through the standard OS consent path; do not roll our own.
+2. **Windows privacy settings** — Settings → Privacy & security → Camera / Microphone.
+   Since **Windows 10 1903**, *"Let desktop apps access your camera/microphone"* is the
+   toggle that governs a Win32 broadcast app. Turn it off and the app loses access. **That
+   is the "explicit user direction" mechanism, enforced by the OS, not by our EULA.**
+3. **Hardware/OS indicators** — camera light (or a notification when there is no light) and
+   a microphone icon in the taskbar tray. Automatic. The OS is the disclosure mechanism, so
+   we get neither credit nor blame from it.
+
+### ⚠️ The open question — measure, don't assume
+
+Microsoft's own support page carries this caveat:
+
+> Desktop apps may not always appear in the list of apps available to the Camera and
+> Microphone settings pages or might still be able to access your camera or microphone even
+> when these settings are turned off.
+
+**Untested: does the Win11 desktop-app camera toggle reliably gate a DShow webcam and a
+capture card?**
+
+- If it **does** gate them, we can make privacy-forward claims after verifying.
+- If it **does not**, that is **not** a Store certification failure — we declared `webcam`
+  honestly and use supported APIs — but it is a real user-trust issue, and we must not
+  write privacy-forward marketing copy on the assumption that it works.
+
+**Tracked as an open item in `TASKS.md`. A guard note in `MARCOM.md` blocks privacy-forward
+copy until it passes.**
+
+---
+
+## 11. Open questions
+
+1. **Individual or Company Partner Center account?** (10.8.3 / 10.14.) Individual accounts
+   are "usually appropriate for a single developer working on their own," and a Company
+   account is required if the product requires financial account information **for primary
+   functionality**. Polar collects payment externally and we never ask the user for card
+   details, so we look like a clean individual case — but it is a question for Partner
+   Center, and getting it wrong means re-enrolling.
+2. **Does the desktop-app camera toggle gate DShow?** (§10) — gates the `MARCOM.md`
+   privacy claim.
+3. **MSIX write behavior under a real package identity** — full trust passes writes through
+   per the docs, but worth confirming on a real packaged build before trusting it with
+   recordings.
+4. **Store revenue-share terms** — do not plan on any specific percentage. The terms have
+   moved more than once and small indie apps sometimes qualify for better rates. Verify
+   current terms and conditions before pricing against them.
+5. **`liveBroadcasts.insert` requires `status.selfDeclaredMadeForKids`** (COPPA) — already
+   known, see [`research-youtube-api.md`](research-youtube-api.md) item 1. Confirm the
+   dialog wording is right for a tool that is never child-directed.
+
+---
+
+## 12. Profanity filter — design constraints (feeds `task-49`)
+
+YouTube's Community Guidelines carry a specific **Vulgar language policy** under
+"Sensitive content," alongside nudity/sexual content, child safety, and self-harm. So
+profanity is a named policy surface, not an edge case.
+
+Three external reasons it earns a slot, plus the real one:
+
+1. YouTube treats it as policy-relevant, so 11.12's "proactive detection" language has
+   something to attach to
+2. Competitive parity — overlay tools in this lane generally offer it
+3. It is a reasonable reading of 11.12's proactive-detection language
+4. **The real reason: we control what gets projected on screen.** That is the creator's
+   call, not YouTube's.
+
+**Four constraints, because they protect the privacy story rather than complicate it:**
+
+1. **Local and on-device only.** No server, no telemetry of message content, nothing leaves
+   the machine.
+2. **Non-persistent.** Filter at ingest, discard the raw text, keep only the display
+   string. Same property that makes the 11.12 answer in §9 strong.
+3. **User-supplied word list**, opt-in, stored locally. **Not a hardcoded slur list baked
+   into the binary** — that is an unpleasant artifact, generates false positives across
+   dialects and languages, and becomes our problem the moment someone extracts it. A
+   user-curated list is also simply more useful: streamers know their community's
+   euphemisms and we do not.
+4. **Match display text only.** Never the SuperChat amount or any reward-event field —
+   those are financial data under 10.5.5, and matching on them would be a real mistake.
+
+The existing alert box already has a ticker and three display methods
+(`Controls/OverlayHost.xaml`, `ViewModels/MainViewModel.Chat.cs`), so there is probably a
+**single insertion point** rather than scattered call sites. Verify before building.

TASKS/research-youtube-api.md

@@ -0,0 +1,33 @@
+# ytLlive — YouTube Live API research facts (authoritative)
+
+> Catalog: [`TASKS.md`](../TASKS.md) · memory map: [`schema.md`](../schema.md).
+
+## YouTube Live API — research facts (authoritative, v3 build)
+
+Lifecycle: `created → ready → [testing] → live → complete` (transitional `liveStarting` / `testStarting`).
+
+1. **liveBroadcasts.insert** requires: `snippet.title`, `snippet.scheduledStartTime`, `status.privacyStatus`, `status.selfDeclaredMadeForKids` (COPPA).
+2. **liveStreams.insert** requires: `snippet.title`, `cdn.frameRate`, `cdn.ingestionType`, `cdn.resolution`. **None of the four (except title) can ever change after creation** — changing them means delete + recreate the stream. This is the hard constraint behind the quality grey-out.
+3. **Title / description / privacy**: editable at any time, including while live (`liveBroadcasts.update`, part=`snippet,status`).
+4. **contentDetails** (DVR, recordFromStart, monitorStream, embed, latency): editable only in `created` / `ready`.
+5. **Transition to live** only allowed when the bound stream's `status.streamStatus == active`.
+
+### Two features that reshape the design
+
+1. **enableAutoStart / enableAutoStop** — instant one-click go-live, no transition call. With `enableAutoStart=true` we never call `transition(live)`: the broadcast auto-goes-live the moment the encoder starts. Combined with `enableMonitorStream=false` (our preview pane replaces YouTube's monitor stream — the thing that forces a testing stage), the flow is **create → bind → Start Stream → encoder starts → YouTube brings it live**. No testing, no transition polling, no liveStarting stuck-state handling.
+2. **`cdn.resolution=variable` / `cdn.frameRate=variable`** — free auto step-down. YouTube auto-detects what we send; since we ARE the encoder we can drop bitrate/resolution on the fly with zero API calls. Declaring an explicit resolution instead (e.g. 1080p) requires a new stream, which can't happen mid-broadcast. Variable is the enabler for the whole auto step-down feature. **(Claim-check 2026-09-01: the enabler is real, the governor is not built — the drop-side policy ships as TASK 33, v1 per the complete-v1 ruling.)**
+
+### Compliance gotchas (maps perfectly to report-by-exception)
+
+1. `liveStreams.status.healthStatus`: `good | ok | bad | noData` plus `configurationIssues[]` with `type` + `severity` (`info|warning|error`). Literally built for report-by-exception — poll it, render nothing on good/ok, surface a banner only on warning/error. No need to invent our own health logic.
+2. Encoder must comply or YouTube flags it: keyframes ≤ 4s (`gopSizeLong`), closed GOP, H.264, audio AAC/MP3 @ 44.1/48kHz, mono/stereo only.
+3. Error codes to handle: `errorStreamInactive`, `invalidTransition`, `redundantTransition`, `liveStreamDeletionNotAllowed`, `liveStreamModificationNotAllowed`, `liveBroadcastBindingNotAllowed`.
+
+### Tips we should take advantage of
+
+1. **Reusable streams** (`isReusable=true`): one stream per channel, cache its ingestion URL + stream name, reuse for every broadcast. No rebinding dance each go-live. This is exactly the manual-stream-key baseline.
+2. **Backup ingestion address**: YouTube provides a simultaneous-push backup — future hardening, not v1.
+3. **`recordFromStart` + `enableDvr` default true** → every live is auto-recorded and immediately replayable. Free VOD archive, matches the v0.2 recording goal.
+4. **`latencyPreference`: `normal | low | ultraLow`** — for homelab streamers talking to chat, `low` (or `ultraLow`, capped at 1080p) is a real feature.
+5. **Broadcast ID == Video ID** — one ID to track everything.
+

TASKS/task-01-initial-scaffold.md

@@ -0,0 +1,15 @@
+# TASK 1 — Initial Scaffold
+
+> Catalog: [`TASKS.md`](../TASKS.md) — status and requirements live here.
+
+
+**Goal:** Working C# / WPF project with MVVM architecture, dark-theme main window, and YouTube service stubs.
+
+### Status: ✅ Done
+
+1. ✅ Models: Scene, Source, StreamConfig, StreamHealth, YouTubeChannel, ChatMessage
+2. ✅ Services: YouTubeAuthService (OAuth2), YouTubeStreamService (broadcast/health), YouTubeChatService (chat polling)
+3. ✅ MainViewModel: scene management, stream controls, chat
+4. ✅ MainWindow: scene/source panel, preview area, chat panel, status bar
+5. ✅ Clean build, 0 warnings (WSL + Windows)
+

TASKS/task-02-oauth2-auth.md

@@ -0,0 +1,37 @@
+# TASK 2 — YouTube OAuth2 Authentication
+
+> Catalog: [`TASKS.md`](../TASKS.md) — status and requirements live here.
+
+
+**Goal:** Fully working Google OAuth2 flow — user clicks "YouTube", browser opens, authorization callback lands, channel info is stored.
+
+### Status: ✅ Done
+
+1. ✅ Two-state Start/End Stream button, go-live dialog (account + title/description/visibility), red top bar, pulsing LIVE badge + elapsed timer, preview glow, taskbar red dot
+2. ✅ Real OAuth2 wiring — baked-in Google credentials (desktop client; loopback callback) + `YouTubeAuthService` complete: browser launch, `HttpListener` callback, token exchange, refresh, channel fetch
+3. ✅ Token persistence via Windows DPAPI (`Helpers/TokenStore.cs` → `%APPDATA%\ytLlive\ytLlive.auth`), best-effort reload + proactive refresh at startup, saved after every exchange/refresh
+4. ✅ Account sign-in/change surfaced in the GoLive dialog (saved account shown with "Change Account"; "Sign in to YouTube" when none; Start disabled until signed in)
+5. ✅ ~~**End Livestream signs out**~~ **SUPERSEDED by TASK 18 (2026-08-29): explicit sign-out only** — `StopStream()` no longer clears the session (sign out via Logout / Change Account, `SignOutYouTubeAsync`); stopping a stream or recording leaves the creator signed in. Originally shipped as: a graceful end completes the session: `StopStream()` calls `YouTubeAuthService.ClearSession()` + `TokenStore.Clear()` + `IsConnected = false`, so the next Start Stream dialog requires a fresh sign-in. A crash never runs End, so the DPAPI token survives and the creator stays signed in. Resume/reconnect after a midstream crash is deliberately deferred to TASK 3: the socket can't be resumed (it dies with the process), so "resume" = fast reconnect with a saved broadcast ID/stream key within YouTube's disconnect-grace window; too slow and `enableAutoStop` ends the broadcast. **Orphan closed 2026-09-01:** this mechanism is owned by **TASK 32 (Stream resilience)** — in-session blip retry inside the grace window; cross-process "resume" of a dead broadcast is officially out-of-product (the API makes it impossible — creator ruling).
+6. ✅ Tests in `ytLive.Tests` (xUnit, net8.0-windows): TokenStore DPAPI roundtrip/corrupt/missing/clear + mocked exchange channel-parse + refresh expiry bump + `ClearSession` — 7 passing
+
+**Design constraint:** Sign-in must NEVER block core exploration. Users can build scenes, add sources, and audition the software without authenticating. But **going live requires authentication** — the "Start Stream" dialog is where the account sign-in lives, alongside all stream metadata.
+
+**Two-state flow:** There is no separate "Connect" button. The top bar shows a single button — **Start Stream** when idle, **End Stream** when live. Clicking Start Stream opens one dialog that supplies everything: account (previously-saved account shown as default, with a Change Account action) + title/description/visibility.
+
+**Live indicators (unmissable):** Top bar + window title bar flip red, a pulsing **● LIVE** badge with elapsed timer appears in the top bar, the preview area gets a red glow, and the taskbar icon shows a red overlay dot. Window title bar shows the stream title once validated.
+
+### Requirements:
+
+1. **Google Cloud OAuth credentials** — client ID + secret, **baked into `Helpers/OAuthCredentials.cs`** (desktop "Desktop app" OAuth client; loopback callback — no console redirect URI registration needed; creators never configure)
+2. **Local HTTP listener** — `HttpListener` on `http://localhost:PORT/oauth2/callback` to catch the redirect
+3. **Browser launch** — open the authorization URL in the default browser
+4. **Token persistence** — store access/refresh tokens securely (Windows DPAPI), reload on startup
+5. **UI state** — account shown in the Start Stream dialog; "Change Account" action triggers re-auth
+6. **Go Live gated on auth** — Start Stream dialog requires sign-in to enable the Start button; scene building works without it
+
+### Tests:
+
+1. Mock token exchange response, verify channel info parsed
+2. Verify token refresh triggers when near expiry
+3. Verify credential load/save roundtrip
+

TASKS/task-03-capture-pipeline.md

@@ -0,0 +1,130 @@
+# TASK 3 — Capture Pipeline (Scenes/Sources)
+
+> Catalog: [`TASKS.md`](../TASKS.md) — status and requirements live here.
+
+
+**Goal:** Real video preview in the center panel — the minimal source set below, composited per scene.
+
+### Status: 🔶 In progress — **Alerts (item 20) SHIPPED 2026-09-24 via TASK 43**; still open: item 17 (Text source), item 20's `RewardEvents` SQLite persistence half (16 compositing + 19 background removal excluded)
+
+1. ✅ **Milestone 1 — webcam** — MediaCapture (WinRT SDK projection) with device enumeration, CPU-first frame source, refcounted `CameraManager`, picker dialog, clip shapes (Traditional + Round) + mirror, 480×270 default placement — schema v2
+2. ✅ **Schema v3 (Ship Branch A)** — multi-scene webcam (singleton `Webcam` + per-scene `WebcamSceneConfig`), right-click border/context menu, static OBS-style borders, 50%-per-dimension webcam size cap, device-swap (`ReleaseAllAsync`) — 25 tests passing
+3. ✅ **Schema v4** — round→rect restore persisted (`WebcamSceneConfig.RectWidth`/`RectHeight`) + one-time legacy-square 16:9 heal on load
+4. ✅ **Screen backdrop (ship task #1, schema v5)** — live desktop/game capture as a permanent, non-deletable bottom layer (`Source.IsBackdrop`), auto-detecting the full-screen game at launch/focus (else the **primary display** — never assumed monitor 0) via `Win32FullScreenDetector` (now with `GetDisplays()`/`PrimaryMonitorIndex()` for the in-app display picker), content re-designated via the OS `GraphicsCapturePicker` ("Change Capture…") or the in-app "Capture Display" submenu, refcounted/shared capture sessions in `ScreenCaptureManager` mirroring `CameraManager` — 45 tests passing
+5. ✅ **Schema v6 — backdrop Live-only by policy** — `Scene.HasBackdrop`, enforced by scene name on every load (`EnforceBackdropPolicy`: Starting/BRB/Chat/Ending never carry one; the one-time v5→v6 backfill covers all four), the scene context-menu "Backdrop" checkbox is gone (policy owns the flag), preview watermark hides when the backdrop renders, capture changed to `WindowsRuntimeMarshal.TryGetDataUnsafe` (the CsWinRT-safe frame-read) + downscale to the 1920×1080 master + 5s-throttled error logging (was flooding `startup.log` with 5 MB of cast errors and burning CPU), round webcam no longer re-rasterizes an `ImageBrush` every frame (Image + EllipseGeometry clip) — the live-mode stutter fix
+6. ✅ **The five-scene catalog (`SceneCatalog`)** — Starting/Live/BRB/Chat/Ending is the product — work with less, never more; the (+) button only shows when a canonical scene is missing and re-adds it (its menu lists only the missing ones) — 62 tests passing
+7. ✅ **Webcam-after-session-start fix** — a webcam added to a scene after the camera was already running (e.g. Chat) previously rendered a transparent container — `CameraManager.GetPreviewBitmap` + propagation in `AddWebcamToActiveSceneAsync`/`ReacquireWebcam` now hands the running shared frames to any newly added `WebcamSceneConfig` — 65 tests passing
+8. ✅ **Chat scene webcam size cap** — raised from 50%-per-dimension (960×540) to half the screen AREA (~1358×764 @16:9, `MaxWebcamWidthFor`/`MaxWebcamHeightFor` keyed by canonical name) so the viewer sees the creator better
+9. ✅ **"Add Webcam" always opens the camera picker** — deleting one scene's webcam then re-adding used to resurrect the old camera when another scene still used it — `SwapWebcamIdentityAsync` now swaps the app-wide identity if a different camera is chosen, same path as "Change Webcam…"
+10. ✅ **Webcam resource validation + first-frame proof** — `MediaCaptureFrameSource` validates post-init (VideoDeviceId match, stream properties ≥1, `reader.StartAsync()` status read + throws on non-Success); subscribes `capture.Failed` + `CameraStreamStateChanged` → `SourceFailed` event on the seam; fallback ladder (VideoPreview → VideoRecord). `CameraManager.AcquireAsync` requires first-frame proof (4s timeout): returns true only after a real frame arrives — silent empty box impossible. `MainViewModel` subscribes `CameraFailed` → red `WebcamError` chip in preview + MessageBox names suspect apps (`CameraConflictProbe`). 19041 SDK projection gaps: `Exclusive`/`DeviceLost` not projected; `CameraStreamState.Failed` compared by `(int)2`. 81 tests passing
+11. ✅ **Scenes/sources UI** — add/reorder/rename, image + background overlays with move/resize/opacity/reuse
+12. ✅ **Audio UX shipped (UI)** — the bottom-bar footer is now two lines (dropped/duration moved under bitrate/fps), with the mic's sound meter + mute button + volume slider grouped CENTERED on the footer's top line, beneath the preview panel (meter: 288px, muted slate track with ruler graduations + muted yellow/red zone tints, green→yellow→red fill; mute = speaker icon → red do-not-symbol when muted, and the slider and speaker stay in sync (volume 0 ⇔ muted — sliding off flips the speaker to muted, sliding up from 0 clears it); mic volume defaults to 80%, muting zeroes the meter and restores the prior volume on unmute (which flashes the meter to the restored position ~300ms before it returns to the live level); the meter is a READ-ONLY realtime level display (fill = live level × volume — volume is a gain on ambient noise; while the slider is dragged the bar previews the slider position and bounces back to the live level on release, which is 0 with no input — clicking the meter does nothing), clicking the MIC label opens a microphone picker whose chosen source shows left-justified inside the meter bar (fill at 75% opacity so the name + ruler markings show through); slim dimensional slider — gradient track/fill, gloss-sphere thumb; the old flat pink 18px-filled one is gone), everything else on line 2 (bitrate/fps/dropped/duration/health left, quality + gear right) — the creator's only audio control, desktop/game audio is automatic (KISS rule). **Post-test follow-up (2026-08-13, game audio bar branch):** the **game audio bar** (desktop/game, a mirror of the mic bar: meter + mute + volume) is **overlaid at the bottom of the preview window** (bottom-center dark chip — monitoring UI only, never on the live output) and appears only while a **full-screen game is producing sound** in the preview (`IGameAudioDetector` seam + default `GameAudioDetector` polling `IFullScreenDetector` + the live loopback level, floor 0.5%, into a pure `GameAudioHysteresis`: SHOW after ~500ms of fullscreen+sound, HIDE ~1s after leaving fullscreen, **silence never hides an active bar**; the VM polls it on a 250ms `DispatcherTimer`); **capture now runs for the app's lifetime** (mixer started once at startup via `StartMicCaptureAsync`, disposed in `Shutdown` — not go-live) so the meters preview live; the **MIC label became a button with a status dot** (`Models/MicStatus`: green = connected via the source `Started` event, yellow = mic problem, red = no device); picking a mic takes effect immediately (`AudioMixer.RestartMic`, loopback keeps running); fixed a latent `?.Invoke(meter.Push(...))` short-circuit that skipped the meter update when nothing was subscribed. **Round 2 (2026-08-13):** the meters were dead on a flat scale (real speech/game RMS is ~0.01..0.1 linear) — the raw level is now mapped via `AudioLevelMeter.ToDisplay` (−60..0 dBFS spread across 0..1) so typical input reads ~1/3..2/3 of the bar at default volume. 169 tests passing, 0 warnings. **Round 3 (2026-08-13):** the mic bar gained a **mic mute icon** (a microphone glyph in the speaker's 16px style, red + slash when muted) between the meter and the speaker — both mutes adjacent with spacing between them, same `ToggleMicMuteCommand`; and the top-center LIVE badge became an **always-visible REC sign** — dark gray dot + dim "REC" offline, bright red (#e94560) + "REC" + elapsed while live, **darker red (#8f1f1f)** when live with a **private** stream (driven by the dialog's chosen visibility) — `RecDotBrush`/`RecTextBrush`/`RecDotOpacity`/`IsLivePrivate`, pulsing while live. **Queued:** task 22 (voice filters). Voice-filter note: the meter's `ToDisplay` input is the pre-filter mic level; when filters land they must apply BEFORE the meter/encoder mix
+13. ✅ The connected YouTube account's avatar/name shows in the top bar next to Start Stream (`SyncConnectedAccount`); the scenes list is content-height now (no dead space before SOURCES)
+14. ✅ **Social bar v2 (six-slot dialog, sign-in gate, real logos)** — global bar layer (never a Source, no sources-list row), content-sized, centered, GREEN glow when ON, top/bottom snap-drag (default BOTTOM, persisted `SocialBarPosition`; drag clamps to 0/1040, tie→bottom). Footer Social button gets a state dot (green=ON). Dialog "Social Media Site Promotion" (`SocialsDialog` + `ViewModels/SocialsDialogViewModel`, WPF-free + injected `ISocialValidator`/sign-in/sign-out fakes): ON/OFF bar switch (`SocialsConfig.BarEnabled`, schema v8), 6 fixed slots — row 1 always YouTube (signed-in → channel handle; signed-out → sign-in gate → OAuth; delete → confirm sign-out, mirrors `StopStream`), row 2 free, rows 3-6 lock icons on freemium (Premium seam: all six). Validation: `DetectService` (URL domain / fediverse `@user@domain` / bare→Website) → async `ISocialValidator` on confirm/Save; valid snaps to text + real service logo (bundled SVG path data via `LogoDataFor`, Simple Icons CC0 — initials badges gone); invalid → red do-not, stays editable, Save blocked. LCR justify dropped (`BarJustify` unread), per-scene toggle dropped (`Scene.HasSocialBar` back-compat). **Post-test fixes (2026-08-12):** footer label "Socials" (not "Social"); fediverse `@user@domain` validates — the full handle is the identity end-to-end (`DetectService`/`CanonicalUrlFor`/`HttpSocialValidator` build `https://domain/@user`, no domain loss); **Cancel is a hard stop** — `ISocialValidator.LookupAsync` takes a `CancellationToken`, dialog VM owns a CTS, Cancel/X/Save abort in-flight lookups (HTTP request killed, canceled continuations never touch slot state), and `ConfirmEdit` skips re-submitting identical text (LostFocus on dismiss never re-fires a lookup). `HttpSocialValidator` now has real tests (fake `HttpMessageHandler`). 105 tests passing. **Post-test fixes (2026-08-12, round 2):** fediverse `@user@domain` no longer shows a generic chain — it resolves to the instance's actual software via nodeinfo (`/.well-known/nodeinfo` → `software.name`; `SocialService.Fediverse` enum member + `SocialEntry.FediverseSoftware` persisted in a new `SocialEntry.Software` column, schema migration by column-presence) and renders that software's bundled logo (`LogoDataForFediverse`: mastodon/peertube/pixelfed/misskey/lemmy/pleroma/firefish, generic fediverse honeycomb fallback). Dialog row-2 edit/trash icons were too dark — `IconButton` style gains `Foreground=#d0d0d0`; trash overrides `#e94560` (app red). 112 tests passing. **Post-test fixes (2026-08-12, round 3):** a fediverse handle whose identity domain is itself a redirect (e.g. YunoHost default-app subdomains — `@user@llamachile.tube` where the mastodon instance lives at `mastodon.llamachile.tube`) now still resolves its software: nodeinfo on the identity domain is SSO-blocked, so `HttpSocialValidator` follows the bare root `https://domain/` 302 to the real instance host and re-runs the nodeinfo lookup there.
+15. ✅ **Window capture** — absorbed into the Screen picker (no separate source type); dedicated window-as-source work is pending
+16. ❌ **Scene compositing (D3DImage/MediaElement)** — SUPERSEDED, permanently out (2026-09-01): the software output compositor (TASK 4 step 1) + the XAML preview ARE the design; a D3D11 swap stays a possibility behind the `VideoFrame` seam, not a feature
+17. ☐ **Text source** — live text ("Starting soon", "Back in 5", handle, callout)
+18. ✅ **Chat box** — YouTube live chat rendered *on* the stream so viewers read along in-video — `ChatBoxRenderer` (WPF FormattedText → VideoFrame), configurable font size/color/badges/timestamps/max-messages via Elements panel, schema v10, persisted across save/load
+19. ❌ **Background removal (milestone 2)** — ONNX Runtime + DirectML, MediaPipe Selfie Segmentation — deliberately NOT in this build
+20. ✅ **Alerts — Super Chat / membership pop-ins (SHIPPED 2026-09-24 via TASK 43, NATIVE)** —
+    free and ungated (see Monetization in `ai.md`). **v1 IN** per the complete-v1 ruling. The
+    deliverable is now **native events + native animations, no third-party widget**: the chat feed
+    (`liveChat/messages`, six types decoded — TASK 43 half 1) drives a `SourceType.AlertBox`
+    ("Stream Alerts", one celebration zone per layout) where each event plays its **own unique
+    branded animation** (`AlertRenderer`/`AlertOverlayLayer`, 33ms ticker, `Advance` test clock).
+    **Creator rulings:** a free-subscriber mention is a plain chat row — NO sub alert (YouTube
+    emits no public event for free subs), NO viewer count (vetoed), and every card draws the
+    "made with LlamaCasty!" brand line (each broadcast = free product placement). **Precursor
+    (still open): the reward-event persistence half — the canonical `RewardEvents` SQLite table
+    (all six types persisted per broadcast) + `superChatEvents.list` backfill + the session-report
+    rollup (TASK 10 → "Related work — monetization awareness"). The shipped alert path parses
+    events into `ChatMessage` directly in memory; the report reads that table once it exists.**
+21. ✅ **Show Desktop toggle** — `Source.ShowDesktop` bool persisted in DB (schema migration + LayoutStore read/write). When checked, primary monitor captures regardless of fullscreen game state. Toggling off falls back to running game or releases to static placeholder. `ClearBackdropCaptureAsync` clears `CaptureKey` + `VideoImageSource` so static fallback renders. Toggle on Live backdrop context menu (IsCheckable MenuItem).
+22. ✅ **Top bar — status light + avatar + Log In button** — red/green/pulsing ellipse (disconnected/connected/live). Avatar border visible only when connected, loads via `BitmapImage` code-behind. "Log In" button visible when disconnected, calls `StartStreamCommand` → GoLiveWindow. `ShowStartStream` now requires `IsConnected`.
+23. ✅ **Chat preview — one-at-a-time mock messages** — `RunMockChatPreviewAsync`: simple async loop, displays `MockChatMessages[n]` via `Take(n+1)`, 1000ms between messages, wraps at end. `ChatPreviewEnabled` property on Source (default true). Stops on real messages, restarts on fade timer clear.
+24. ✅ **All backdrops seeded + EnsureDefaultBackdrop** — Live, Chat, Ending backdrops added (ending-backdrop.jpg replaced). `EnsureDefaultBackdrop()` called on every scene switch. `SeedEndingBackdrop` replaces existing (not skip-if-exists). Chat scene no longer skipped.
+25. ✅ **SceneCatalog fix** — Chat scene display name corrected to "Chat" (was "YouTube Chat" — that name belongs to the layer/SourceType.ChatBox, not the scene).
+26. ✅ **Left panel spacing + context menu reorder** — HR margins matched, Row 4 changed from `*` to `Auto`. Context menu reordered: Border Thickness first, then Opacity, Color, Effect.
+21. ✅ **Logo + richer in-app About (2026-08-13, queued → 2026-08-14 SHIPPED)** — the ytLlive wordmark in the top bar opens the About overlay (already wired); the About overlay is now the **creator hub**: the real logo (the "llama fortnite superman logo" from the creator's vault, copied to `Assets/llama-logo.png` — the creator's own art, no third-party license), plus **creator-hub links** — llama chile shop on YouTube (`MainViewModel.ChannelUrl`), Mastodon (`https://mastodon.llamachile.tube/@gramps`), **Buy me a coffee** (`https://buymeacoffee.com/llamachiley` — live), and **Unlock Premium** (greyed "coming soon" — the **billing** product URL is a tabled seam, `PremiumUrl`, until TASK 10 picks the subscription provider). A **Licenses & legal** button flips the About overlay to an in-app scrolling panel that loads the full `THIRD-PARTY-NOTICES.txt` text (`MainViewModel.ShowLicenses` reads the shipped file from the executable directory on first open; graceful "not found" fallback — **never the OS viewer, everything stays in-app**); "← Back to About" returns. The About overlay is also the in-app home of the notices — the top-bar About button that opened the file in the OS viewer was removed on 2026-08-13 for exactly this reason. Integration test (Good Dog Rule — ONE): `AboutHubTests.About_Opens_InApp_Licensing_Loads_Shipped_Notices` drives the real window + VM, asserting the hub opens, the link URLs are real, the licensing panel loads the shipped notices text (contains "Third-Party Notices" + "LGPL"), and back returns to the hub. 174 tests passing, 0 warnings
+22. ✅ **Voice filters on the mic channel (2026-08-13 queued → SHIPPED 2026-08-14 inside TASK 9, the audio milestone)** — the standard four applied to the sound input path (before the meter/encoder mix): **bass boost, treble, noise suppression, compressor** (set decided with the creator 2026-08-13). Noise suppression = a **pure-C# noise gate** (creator chose over RNNoise / a second ffmpeg `afftdn` pipe, 2026-08-14 — KISS). Always-on — no UI knobs; the mic stays the creator's single audio control
+27. ✅ **Webcam row gates on the app-wide identity (2026-08-24, TASK 26)** — the (+) menu's Webcam item greys out whenever a webcam exists **anywhere** (`CanAddWebcam` = `StagedScene != null && _webcam == null`; renamed from `CanAddWebcamToStagedScene` whose per-scene rule let a second picker run from a scene lacking the config), raised at both `_webcam` mutation sites (create / last-config removal) + scene staging + elements change. Creator's visual pass found it: minis/no-capture-rows/capture-controls all good. ONE integration test `WebcamMenuGateTests.CanAddWebcam_Gates_On_The_AppWide_Webcam_Identity` (real window + temp DB seeded with a webcam in Starting; asserts greyed while Live staged, re-enabled after `RemoveSourceCommand` clears the last config + the `Webcam` DB row). Stale map fixed in the same commit: ai.md's "empty-canvas right-click Show Webcam" claim dropped — that XAML never shipped (`ShowWebcamCommand`/`CanShowWebcamInStagedScene` are wired but unbound dead code, audit item). 224 tests (223 pass; the pre-existing AudioPipelineTests failure is unrelated)
+28. ✅ **YouTube Chat layer: one-per-layout gate + legacy label heal (2026-08-24, TASK 27)** — same rule as TASK 26 applied to the chat layer: the (+) menu's YouTube Chat item greys out while any scene carries a ChatBox source (`CanAddYouTubeChat`, raised on staging + elements change; `AddSource` refuses a second), tooltip "One chat layer at a time — it's already in your stream". Plus the creator's label fix: layers added by commit `65641d8` were named "Chat"; LoadLayout now heals exactly that un-renamed default to "YouTube Chat" so the Layers row matches the (+) picklist (creator renames untouched, idempotent). ONE integration test `ChatLayerGateTests.LegacyChatName_Heals_And_CanAddYouTubeChat_Gates_On_The_Existing_Layer` (real window + temp DB with a legacy "Chat" row: healed on load + persisted on save, greyed cross-scene and in-scene, re-enabled after remove). 225 tests (224 pass; pre-existing AudioPipelineTests failure unrelated)
+29. ✅ **Broadcast metadata pull-out + launch geometry (2026-08-24)** — creator ask: "a tab-pullout on the right side of the preview pane — white tab, YouTube-red label reading 'Text' — opening a form with all settable liveBroadcast fields; fields that can't be filled before launch greyed out; saving/updating remote content; field data saved and pre-loaded on app run". Shipped as specified with one correction: the API is the inverse of "more fields once live" for contentDetails (those lock in created/ready) — the pull-out carries the always-editable snippet/status set: Title, Description, Tags (csv), Visibility (private/unlisted/public), Made-for-Kids, plus read-only Scheduled Start. **Always visible** (creator revised same day from Live-only gating). White 30px tab, rotated red "Text", right edge vertically centered; click slides a dark 320px drawer left over the preview (200ms CubicEase). Every edit persists to Settings keys (`Broadcast.*`) immediately; **Update Broadcast** button calls the new `YouTubeStreamService.UpdateBroadcast` (PUT `liveBroadcasts?part=snippet,status`, echoes scheduledStartTime because update replaces the whole snippet part). Go Live prefills from the form and captures what was inserted (`CaptureGoLive`). The old un-persisted Default Stream Title/Description fields came OFF the App Settings overlay (replaced by the form); `DefaultStreamTitle/Description` VM properties deleted. **Launch geometry** (same unit): default 1920×1040, MinWidth 1366, MinHeight 768; `WindowStartupLocation=Manual` + window size/position persisted on close via `RestoreBounds` (maximized-safe), restored in ctor clamped to minimums and the primary work area (disconnected-secondary fallback). ONE integration test `BroadcastPullOutTests.Metadata_Persists_WindowRestores_Clamped_And_UpdatePatchesRemote`. 228 tests (227 pass; pre-existing AudioPipelineTests failure unrelated)
+30. ✅ **Gear menu cleanup + Default Location for Recordings + single Start button (2026-08-29)** — **KISS: removed** Gear-menu `Save Layout`/`Save Layout As…`/`Open Layout…` (redundant with auto-save; multi-layout = OBS) + dead `SaveLayoutCommand`/`SaveLayoutAsCommand`/`OpenLayoutCommand` + `SaveLayoutAs()`/`OpenLayoutFile()` methods. **App Settings panel:** first real setting — `Default Location for Recordings` (configured folder via `ChooseRecordFolderCommand` + "Use Downloads" reset via `ResetRecordFolderCommand`, resolved path shown). Fallback chain: configured → `%USERPROFILE%\Downloads` → `MyVideos`. `StartRecordFile()` + `ChooseRecordFolder()` `InitialDirectory` updated to use the new fallback. **Single Start button:** `PrimaryButtonText`/`IsStreamingStart` + their `OnPropertyChanged` calls removed; button `Content="Start"` in XAML — pills are the intent surface, button is always just Start. `Choose Record Folder` fast-path kept in the button context menu. Monetization (About links/premium) deferred to a later task. ONE fallback test `DefaultRecordFolder_Falls_Back_To_Downloads`. build 0 warnings, 247 tests (2 known failures, pre-existing).
+
+### The Minimal Source Set (design decision — do not expand casually)
+
+ytLlive is YouTube-only and 90% of users are casual. OBS's long source list is off-putting; we ship
+the hot few and nothing esoteric. If a user needs more, they've graduated to OBS.
+
+1. **Webcam** — the face cam. Non-negotiable.
+2. **Screen** — the main event (game, slides, browser). One source; a picker chooses a monitor *or* a
+   window. (Window capture is absorbed here — no separate source type.)
+3. **Background** — a full-canvas backdrop image. Fills the whole scene automatically, zero fiddling.
+   Kept separate from Image on purpose: same pixels, but this one needs no positioning.
+4. **Image** — a floating graphic/logo overlay (watermark, badge, corner branding). Free-positioned.
+5. **Text** — live text ("Starting soon", "Back in 5", handle, callout). Casual streamers live on this.
+6. **Chat box** — YouTube live chat rendered *on* the stream so viewers read along in-video. YT-native.
+7. **Alerts** — Super Chat / membership pop-ins. The dopamine source. **The one big lift — DONE
+   (2026-09-24, TASK 43): native events + native animations.** One `SourceType.AlertBox`
+   celebration zone; six event types = six unique branded animations; free-sub mention = chat row
+   only; no viewer count. **Free and ungated** — paid = flash removal only (corrected 2026-09-01).
+   Pending: the `RewardEvents` SQLite persistence half (item 20; the report + journey read it,
+   TASK 10 → related work).
+
+Deliberately NOT supported: game capture, browser source, media playlist, VLC, color-key voodoo, MIDI.
+
+### Source memory model (design decision)
+
+1. A scene has resources. Resources can be shared across scenes.
+2. A resource exists exactly once in memory, no matter how many scenes use it (a logo in five
+   scenes = one loaded bitmap).
+3. Every resource carries a **catalog of scenes**: one usage entry per scene it appears in, each
+   entry dictating that scene's use — placement (X/Y/Width/Height), opacity, z-order, enabled,
+   scale mode, crop.
+4. Usages are named `{resourceName}.{sceneName}` — whatever the user named the resource, dot, the
+   scene name: `logo.starting`, `logo.live`, `myPic.brb`. Not a hardcoded "logo".
+5. A webcam in two scenes = one capture session, two catalog entries.
+6. Refcount by catalog size: the last usage removed → the resource is disposed and evicted.
+7. The resource (not a per-scene node) owns everything `IDisposable`.
+
+### Scene transitions (design decision)
+
+Scene switching while live must never stutter. Supported types, most → least economical:
+
+1. **Cut** — instant switch. The default. Zero cost.
+2. **Fade** — short crossfade (~300ms).
+3. **Move** — a simple, economical move transition, done to perfection and memory-efficient. The
+   smart streamer's bread and butter.
+4. **Custom (media) transitions** — require media elements (video/stinger playback during the
+   transition). Heavier, but creators pay for these, so we support them. Their media follows the
+   same resource memory model: loaded once, catalogued by scene.
+
+Preview shows the transition too (WYSIWYG). No wipes/slides/LUTs beyond the four above.
+
+### Requirements:
+
+1. **Screen** — Windows.Graphics.Capture (WinRT), enumerate displays/windows, picker
+2. **Webcam** — MediaCapture (WinRT SDK projection) with device enumeration — ✅ **milestone 1 done**:
+   1. TFM bumped to `net8.0-windows10.0.19041.0` (app **and** tests) so the WinRT projection resolves from the SDK reference packs — no NuGet package, no capability manifest (unpackaged desktop app)
+   2. `MediaCaptureFrameSource` (CPU-first: `MemoryPreference = Cpu`, BGRA8 via `CreateFrameReaderAsync`), `MediaCaptureCameraEnumerator` (`DeviceInformation.FindAllAsync(DeviceClass.VideoCapture)`)
+   3. `CameraManager`: refcounted by `DeviceId`, one shared `WriteableBitmap` app-wide, dispatcher-coalesced UI updates (~render rate, latest-frame drop), placeholder/`AppLog` + warning on failure
+   4. `CameraPickerDialog` (mirror of `ReuseImageDialog`) — "Searching for cameras…" / list / "No cameras found" states
+   5. One webcam app-wide: Add → Webcam greyed out once one exists ("it's already in your stream" tooltip); persisted `DeviceId` re-acquires after layout load
+   6. Default placement 16:9 **480×270**, bottom-right, 32px margin; drag/resize/selection shared with Image sources
+   7. **Clip shapes: Traditional + Round** (phone view dropped — the 9:16 phone output is the vertical output-crop tier); **mirror**; both persisted in the layout DB (schema v2) and toggled from the source chip
+   8. **Background removal = milestone 2** (ONNX Runtime + DirectML, MediaPipe Selfie Segmentation) — not in this build
+3. **Background / Image / Text** — static sources positioned/scaled/opacity
+4. **Chat box** — rendered from the live chat poll (right panel is the same feed, raw)
+5. **Scene compositing** — per-scene source layering (z-order = sources list order, top-to-bottom
+   back-to-front), preview rendered via D3DImage or MediaElement
+6. **Branding flash** — the topmost full-frame "made with ytLlive!" layer at ~25% opacity, ~1s on /
+   300s off (see Monetization in `ai.md`), gated on `BrandFlashEnabled` + live/recording. Lives in the
+   preview compositor now (`BrandFlashLayer` in `MainWindow.xaml` CanvasGrid, driven by
+   `BrandFlashActive`/`BrandFlashTimer` in `MainViewModel`); the encoder output renders the same layer,
+   and v0.2 local recordings carry it too
+7. **Drag/drop placement & reorder** — intuitive, visual (per design principle):
+   1. **Preview:** click-drag a source in the center panel to reposition it; resize via handles
+   2. **Scenes list:** drag rows to reorder scenes
+   3. **Sources list:** drag rows to reorder sources (this *is* the z-order) — implemented
+

TASKS/task-04-rtmp-ingest.md

@@ -0,0 +1,339 @@
+# TASK 4 — RTMP Ingest to YouTube
+
+> Catalog: [`TASKS.md`](../TASKS.md) — status and requirements live here.
+
+
+**Goal:** Push encoded video to YouTube's RTMP ingest.
+
+### Status: ✅ Done — all 7 items shipped
+
+1. ✅ **Ship step 1 — the output compositor SHIPPED** (2026-08-10)
+2. ✅ **Ship step 2 — the FFmpeg locator SHIPPED** (2026-08-10)
+3. ✅ **Encoder + RTMP push SHIPPED** (2026-08-12) — the FFmpeg subprocess: raw BGRA frames via stdin, stderr health parsing, FLV mux + push to the ingestion URL (see the ship step 3 plan below)
+4. ✅ **WASAPI audio capture SHIPPED** (2026-08-12) — NAudio loopback (desktop/game) + the picked mic feeding `AudioLevel`, so the realtime meter comes alive (see the ship step 4 plan below)
+5. ✅ **Frame-pipeline wiring SHIPPED** (2026-08-12) — `CameraManager`/`ScreenCaptureManager` → compositor resolver → encoder, driven by a paced `FramePump` (see the ship step 5 plan below)
+6. ✅ **Health stats SHIPPED** (2026-08-13) — `FramePump.HealthUpdated` (encoder's parsed bitrate/FPS/dropped/duration, already forwarded from `FfmpegEncoder.OnStderrLine`) now lands in the bottom bar: `MainViewModel.OnFramePumpHealthUpdated` marshals to the UI thread (the stderr loop raises on a background thread) and copies into `CurrentHealth` (the bottom bar's existing binding); `ResetHealth` zeroes dropped/duration on go-live and on End so stats never linger from a previous session (bitrate/FPS stay on the tier's targets). The bar lights up with real values once TASK 9 supplies the RTMP URL (until then the pump skips the encoder and the bar shows the tier's targets)
+7. ✅ **One-click go live + private-only enforcement SHIPPED** (2026-08-14) — the Go Live dialog is **locked to Private** (no dropdown, `GoLiveViewModel.Visibility` is a get-only "Private"); `YouTubeStreamService.CreateBroadcast` **always sends `privacyStatus = "private"`** (dialog + service enforcement, requirement 8 — nothing can go out non-private) and gained an injectable `HttpClient? http = null` seam for tests; `BeginGoLive` now calls `CreateBroadcastAsync` and remembers `_currentBroadcastId` for TASK 9's bind/transition (failure → `StreamStatus.Error`, never a crash; `StopStream` clears the ID); the REC sign shows a **PRIVATE badge** (dark-red border, next to REC, `IsLivePrivate`) when the live stream is private; settings' dead "Default Visibility" dropdown + `MainViewModel.Visibilities`/`DefaultStreamVisibility` removed. The broadcast-insert integration test asserts the request body carries `"privacyStatus":"private"` (2 new tests → 173 passing, 0 warnings)
+
+The pipeline chain the encoder needs doesn't exist yet: **scene compositing** (the master 1920×1080 frame
+without the preview's editing chrome) → **audio capture** (WASAPI, feeds the meter) → **H.264+AAC encode**
+→ **vertical-tier crop/scale** → **RTMP push** → **health stats** into the bottom bar. Nothing can encode
+until a frame source exists, so the compositor is ship step 1. The pipeline is
+`CameraManager + ScreenCaptureManager → compositor resolver → compositor → encoder → RTMP`.
+
+### Requirements:
+
+1. **Encoding** — H.264 (hardware via NVENC/AMD, fallback x264) + AAC audio; **must comply**: keyframes ≤ 4s (gopSizeLong), closed GOP, AAC/MP3 @ 44.1/48kHz, mono/stereo only. **License posture (decided): GPL-free build** — NVENC (NVIDIA) / QSV (Intel) / AMF (AMD) + OpenH264 software fallback + built-in AAC; no libx264 (GPL contaminates a paid product). Output containers are identical either way (H.264+AAC in `.flv` for RTMP, `.mp4`/`.ts` for VOD) — the format is NOT the differentiator, the license and per-GPU quality are. **License guardrails (never violate — see `ai.md` → "Licensing — do not violate"):** only BtbN `lgpl`/`lgpl-shared` builds; never GPL (gyan.dev) or `nonfree` (fdk-aac); never static for distribution (LGPL §6 relink material); never link FFmpeg into the app; never drop `THIRD-PARTY-NOTICES.txt` from the app/About screen.
+2. **RTMP push** — **FFmpeg subprocess (decided)**: app feeds raw frames via stdin, parses stderr for health; one battle-tested binary does encode + FLV mux + push. **No self-heal (claim-check 2026-09-01): ffmpeg's reconnect flags are input-side; an RTMP *output* push does not reconnect itself — retry is app-side, owned by TASK 32.** **Binary distribution (decided): check-then-pull** — probe `where ffmpeg`/PATH at first go-live; if absent, download a **pinned** build (**BtbN LGPL-shared win64** zip, ~75 MB — gyan.dev's builds are GPLv3 and ship libx264, which violates the license posture; BtbN's LGPL variant drops x264/x265 while keeping NVENC/QSV/AMF + libopenh264 + native AAC) to `%APPDATA%\ytLlive\tools\ffmpeg.exe` (extract `ffmpeg.exe` **plus the `libav*.dll` family**) and cache it, offline-friendly. Behind an `IFfmpegLocator` seam so tests fake it (ship step 2, below). Push goes to the cached reusable stream's ingestion URL
+3. **Quality ladder** — the offered tiers, with **1080p60 @ 8 Mbps as the standard/default**:
+   1. 720p30 @ 6 Mbps
+   2. 720p60 @ 6 Mbps
+   3. 1080p30 @ 8 Mbps
+   4. **1080p60 @ 8 Mbps** (default — mainstream ceiling, GPU hardware-encoded so the gaming
+      machine never notices; upload headroom stays comfortable)
+   5. Vertical 1080×1920 @ 60fps @ 8 Mbps (9:16 phone tier)
+   The composition master is always 1920×1080; a tier is an output rect + target resolution
+   (see `ai.md` "Resolution tiers"). Vertical output = the centered 607×1080 crop of the master
+   scaled to 1080×1920 (semi-crop preview is already implemented; the encoder applies the same rect).
+   1080p60 is the ceiling by design — "if you want 1440 or 4K or 8K → OBS is your solution"; the app
+   targets the most mainstream creator, not power users.
+   Ladder is sculpted by a **cached probe** (IP-only TCP vs public ingest host; no auth required).
+   Quality is greyed out while live because the declared resolution can't change mid-stream — but
+   with `variable`, we can **auto step-down** bitrate/resolution on the fly with zero API calls
+   (no stream recreation); 60fps presumes a hardware encoder — no hardware encoder → auto
+   fallback to 720p60/1080p30
+4. **Stream key management** — reuse the cached reusable stream (one per channel) instead of creating a new one per go-live; prefill default YouTube ingest URL `rtmp://a.rtmp.youtube.com/live2`
+5. **Health stats** — bitrate, FPS, dropped frames reported live in the bottom bar (encoder-side)
+6. **One-click go live** — defaults that work out of the box
+7. **Audio capture (feeds the meter — this task ships the wiring)** — WASAPI loopback (desktop/game at unity, zero UI — "it just is") + the picked mic (`MicSourceName` from the `MicPickerDialog`). The mic capture feeds `AudioLevel` so the realtime meter comes alive (today it reads 0 — the mixer feed is pending, see `ai.md` audio notes). AAC mono/stereo @ 48 kHz per the compliance rules.
+8. **Private-only go live until v1 (reputation guard, decided 2026-08-10)** — until the v1 release, go-live is **locked to private streams only** so a software error can never publish something public/unlisted that damages the creator's reputation. RTMP push itself has no privacy — privacy lives on the YouTube **live broadcast object**, which this app already controls via its OAuth API calls. So the lock is purely API-side: the Go Live flow always creates/updates the broadcast with `privacyStatus = "private"` and a guard **refuses** to set anything else (same spirit as the Live-only backdrop policy). The UI shows a clear "PRIVATE" badge next to the stream state so the creator always knows who can see them. Enforcement must be verifiable in the auth-service tests (fake the broadcast-insert/update call, assert `privacyStatus` is forced to private).
+9. **v1 release gate: bundle the full license texts (decided 2026-08-10)** — `THIRD-PARTY-NOTICES.txt` currently links the canonical license texts rather than embedding them. At the **v1 (GA) release**, the full texts of every license it names (LGPL v2.1+, BSD-2-Clause, MIT, Apache-2.0) MUST be bundled alongside it (shipped in the app output, e.g. a `licenses/` folder next to the notices file, still reachable from the About screen). This is a **release blocker for v1, not a task to queue early** — do it in the release pass. The repo should treat this like the private-only go-live gate: a checkbox that cannot silently lapse.
+
+#### Ship step 1 — Scene compositor (the frame source)
+
+**Goal:** a pure-CPU software compositor producing the encoder's master frame (BGRA8, the `VideoFrame`
+seam) from the scene model. The preview stays XAML (the editing view); the compositor is the **output
+view** — WPF's `RenderTargetBitmap` can't be used (software-rendered + captures chrome). Two renderers
+must agree, so the XAML (`MainWindow.xaml` CanvasGrid + element DataTemplate) is the contract.
+
+**Decisions (locked 2026-08-10):** **Path A CPU blitter** — GPU effort belongs to NVENC (the encoder),
+not composition; with an FFmpeg subprocess the master crosses a CPU readback to the pipe every frame
+anyway, so GPU compositing buys ~nothing at this layer count (2-3 live layers; static layers
+pre-composite once). A D3D11 compositor can replace this one later **behind the same seam** (the CPU
+master buffer stays the contract). **Render the output rect directly**: compositor is constructed with
+`CompositorOptions {SourceRectX/Y/W/H, OutputWidth, OutputHeight}`; 16:9 tiers = full 1920×1080 1:1;
+vertical (9:16) = composite the centered 607×1080 crop then bilinear-upscale to 1080×1920. Reuses
+`MainViewModel.OutputRectX/Y/W/H` (note `(1920−607)/2 = 656.5` → align to integer pixels for output).
+
+**Render spec (back → front, mirror the XAML exactly):**
+1. Backdrop — the Live scene's `IsBackdrop` Source (`CaptureKey` → live frame), `UniformToFill`
+   full-frame (XAML's separate `BackdropImage` layer; the backdrop *element* renders nothing — its
+   DataTemplate Image is Collapsed for DisplayCapture).
+2. Background — the scene's `Background` Source, `UniformToFill` full-frame (the `ActiveBackgroundImage`
+   layer, not per-element).
+3. Elements in `Scene.Elements` order (back→front), skip `IsVisible=false`. What actually renders:
+   1. `Source` Type `Image` → static asset, `UniformToFill` cover-crop into (X, Y, W, H)
+   2. `WebcamSceneConfig` → latest frame by `DeviceId`: Traditional = `UniformToFill` rect; Round = circle
+      diameter `min(W,H)` (alpha 0 outside — true circle, not oval); mirror = horizontal flip around
+      element center (`MirrorScale`); opacity = per-pixel multiply (content + border); border = stroked
+      rect / centered circle at `RoundBorderSize`, width `BorderWidth`, alpha `BorderOpacity`
+   3. `Background` / `IsBackdrop` / `TextOverlay` are NOT per-element (layers above; Text not shipped)
+4. Branding flash — pre-rendered full-frame "made with ytLlive!" at 25% alpha when live +
+   `BrandFlashEnabled` + timer active. Passed in as a `VideoFrame?` (compositor core stays pure byte-math,
+   no WPF; likely a bundled asset rather than runtime text rendering).
+5. NOT in output (preview chrome only): SelectionOverlay, DimRects, output-rect outline, badge, placeholder.
+
+**New files (all in `Services/Compositor/`):**
+1. `SceneCompositor.cs` — `Render(Scene, frameFor: Func<SceneElement, VideoFrame?>, flashFrame:
+   VideoFrame?, CompositorOptions) → VideoFrame` (output-sized). The caller's `frameFor` resolver maps
+   each element to its frame (webcam → DeviceId, image → AssetId via `StaticPixelCache`, backdrop →
+   CaptureKey) — the compositor stays pure/hermetic/no WPF.
+2. `CompositorOptions.cs` — source-rect + output W×H.
+3. `StretchMath.cs` — `UniformToFill` cover-crop, ellipse mask, bilinear scale (pure, unit-tested).
+4. `StaticPixelCache.cs` — asset `byte[]` → cached BGRA `VideoFrame` (WPF `BitmapDecoder` + `CopyPixels`,
+   decode once per content hash).
+
+**Test plan (Good Dog Rule — ONE integration test):** `SceneCompositorTests` — a scene with backdrop
+(solid red fake frame) + round webcam (solid green) + image (solid blue) → render 16:9 master → assert
+per-layer probe pixels (corner = backdrop color, element center = webcam color, outside the round clip =
+backdrop color, mirrored element swaps left/right); a vertical-tier variant asserts 1080×1920 output +
+crop fidelity. Focused unit tests on `StretchMath`. Tests push frames directly — no capture managers
+involved (they wire in a later step).
+
+**Same-PR housekeeping:** fix the stale comment `MainViewModel.cs:324` ("shown under the meter on line 2"
+→ "shown left-justified INSIDE the meter bar" — `ai.md` is the authority); this task's requirements now
+include the explicit audio-capture/meter wiring (#7 above).
+
+**Out of scope (later ship steps):** FFmpeg locator + license posture (covered in requirements 1-2),
+encoder + RTMP push, WASAPI audio capture (loopback + mic) feeding `AudioLevel`, wiring
+`CameraManager`/`ScreenCaptureManager` into the frame pipeline, brand-flash timer wiring, health stats
+(bitrate/FPS/dropped).
+
+**Built (2026-08-10):** all four files shipped in `Services/Compositor/`, `SceneElement.TryGetBorderColor`
+made public (shared hex parse with the compositor — no duplicated color parsing), the stale
+`MainViewModel.cs:324` comment corrected, and the pre-existing CS1998 in `YouTubeAuthServiceTests`
+cleaned up — build **0 warnings**. Tests: the `SceneCompositorTests` integration test (full-scene master
+pixels, vertical tier, flash) + 4 `StretchMath` units — **72 passing**.
+
+#### Ship step 2 — FFmpeg locator (the encoder's binary)
+
+**Goal:** resolve a usable `ffmpeg.exe` on demand (the encoder's one external dependency), never shipping
+a binary in the repo. Returns an absolute path; downloads only when neither PATH nor the local cache
+provides one.
+
+**Decisions (locked 2026-08-10):**
+1. **BtbN LGPL-shared win64 build** — not gyan.dev (gyan's "essentials" is GPLv3 and ships libx264, which
+   violates requirement 1's license posture) and **not the static lgpl build**: LGPLv2.1 §6 wants
+   relinkable object files for static linking, but the **shared** (dynamic-DLL) variant sidesteps that —
+   compliance is "license text + source offer + unmodified binaries" (see `THIRD-PARTY-NOTICES.txt` and
+   `ai.md` → Licensing). Drops libx264/libx265 while keeping NVENC/QSV/AMF, libopenh264 (the LGPL-legal
+   H.264 software fallback) and native AAC — exactly the requirement-1 encoder profile.
+2. **Pinned URL** — **RE-PINNED 2026-09-01**: `https://github.com/BtbN/FFmpeg-Builds/releases/download/autobuild-2026-08-31-13-27/ffmpeg-N-126342-gf88b741dbf-win64-lgpl-shared.zip`
+   (BtbN **lgpl-shared** variant, ffmpeg N-126342; ~75 MB zip — earlier "~30 MB" estimate corrected). A dated autobuild tag is immutable; BtbN retention
+   keeps the last 14 daily builds + each month-end build for 2 years, so a cold cache after retention
+   expiry 404s — a logged, recoverable failure (the seam throws; the encoder step surfaces it). The
+   first pin (`autobuild-2026-08-09-13-03`, a daily) aged out on 2026-09-01 — the first real recording
+   attempt — proving the rule; the new pin is deliberately the **month-end** build (2-year retention).
+   Dated tags carry versioned asset names (`ffmpeg-N-…-win64-lgpl-shared.zip`), extraction is
+   name-agnostic; download failures now wrap in `IOException` with an actionable message
+   ("refresh `FfmpegLocator.PinnedUrl` or install ffmpeg on PATH") instead of leaking a raw 404. Once
+   cached, the URL is never touched again. The pin is a single `const`, bumpable in one place — and must
+   always stay on the **shared** variant (never `gpl`, `nonfree`, or static; see ai.md Licensing).
+3. **Check-then-pull order** — (1) PATH probe (the user's own install wins), (2) cached
+   `%APPDATA%\ytLlive\tools\ffmpeg.exe`, (3) download + extract. Extract `ffmpeg.exe` **plus the
+   `libav*.dll` family** (the shared build's bin/ folder; Windows resolves the DLLs from the exe's own
+   directory) into a staging dir then move into place — a crash never leaves a corrupt or partial cache.
+4. **Seam** — `IFfmpegLocator.LocateAsync(CancellationToken)`: search dirs, tools dir, and the downloader
+   (`Func<string, CancellationToken, Task<byte[]>>`) are constructor-injected with production defaults, so
+   tests fake the network (feeding a real in-memory zip) and never touch disk outside a temp dir.
+
+**New files (all in `Services/Encoder/`):**
+1. `IFfmpegLocator.cs` — the seam.
+2. `FfmpegLocator.cs` — the impl (PATH probe → cache → pull+extract exe + DLLs), failures logged via `AppLog`.
+3. `THIRD-PARTY-NOTICES.txt` (repo root) — the LGPL/BSD/MIT notices + source offer, copied to the build
+   output. *(Surfacing changed on 2026-08-13: the top-bar About button that opened the file in the OS
+   viewer is GONE — the notices are reachable in-app via the logo → About overlay instead.)*
+
+**Test plan:** the hermetic integration test drives the full decision ladder against a temp tools dir and
+a fake downloader returning a real in-memory zip (`.../bin/ffmpeg.exe` entry): PATH hit wins without
+downloading, cache hit skips the network, cold cache downloads → extracts → `ffmpeg.exe` lands in the
+tools dir, and a second call serves the cache (downloader invoked exactly once). Focused unit tests:
+**shared-build DLLs extract alongside the exe**, empty zip throws, missing entry throws, empty download
+throws, downloader failure propagates, zero-byte cache is refreshed.
+
+**Same-PR housekeeping:** requirement 2's stale binary facts corrected in this plan (~30 MB → ~75 MB zip;
+"gyan.dev/BtB N" → BtbN LGPL-shared only, with the why); the "never do" licensing guardrails recorded in
+`ai.md` so the reasoning survives.
+
+**Out of scope (later ship steps):** the FFmpeg subprocess encoder (frames in via stdin, stderr health
+parsing), RTMP push, WASAPI audio capture, the frame-pipeline wiring, health stats.
+
+**Built (2026-08-10):** `IFfmpegLocator` + `FfmpegLocator` shipped in `Services/Encoder/`, pinned to the
+**lgpl-shared** build `autobuild-2026-08-09-13-03` (extracts `ffmpeg.exe` + the `libav*.dll` family via a
+staging dir). `THIRD-PARTY-NOTICES.txt` (repo root) ships to the build output; the "never do" licensing
+guardrails are recorded in `ai.md` — build **0 warnings**.
+Tests: the hermetic `FfmpegLocatorTests` integration test (PATH → cache → download decision ladder with a
+fake downloader serving a real in-memory zip) + edge/unit cases (shared-build DLL extraction, zero-byte
+cache refresh, empty payload, missing zip entry, downloader failure) — **78 passing**.
+
+#### Ship step 3 — Encoder + RTMP push (the FFmpeg subprocess)
+
+**Goal:** encode raw BGRA master frames into H.264+AAC FLV and push them to the reusable stream's RTMP
+ingestion URL — one battle-tested subprocess doing encode + mux + push (retry is app-side, TASK 32 — ffmpeg does not self-reconnect an RTMP output), the app feeding
+frames via stdin and parsing stderr for health (req 2).
+
+**Decisions (locked):** the encoder is a thin orchestrator over `ffmpeg.exe` — no H.264/AAC code in the
+app. Arguments (pure `FfmpegArgs.Build`): `-re -f rawvideo -pix_fmt bgra -video_size WxH -framerate FPS
+-i pipe:0` (frames in), a **silent placeholder audio track** via `-f lavfi -i anullsrc` (the WASAPI
+capture step replaces this input), `-c:v <encoder> -b:v K -maxrate K -bufsize 2K` + **`-g fps×4`
+`-keyint_min fps×4` `-sc_threshold 0` `-bf 0` `-pix_fmt yuv420p`** (the keyframe ≤4s / closed-GOP /
+H.264 compliance), `-c:a aac -ar 48000 -ac 2`, `-f flv <rtmpUrl>`. Encoder choice is **probed from the
+binary's `-encoders` listing** (`FfmpegEncoderPicker`, pure): hardware NVENC → QSV → AMF, then OpenH264
+software fallback — **never libx264** (GPL; see `ai.md` → Licensing). The seam (`IFfmpegEncoder` +
+`IEncoderProcess`, constructor-injected locator + process factory) keeps it hermetic — tests fake the
+whole subprocess (probe + encoder), no real binary.
+
+**Behavior:** `StartAsync` (locate → probe → spawn → stderr loop), `SubmitFrameAsync` (serialized BGRA
+stdin writes, ~2 Hz health via `HealthUpdated`/`StreamHealth` — bitrate/FPS/duration/dropped-from-frame-
+count), `StopAsync` (stdin EOF → ffmpeg finalizes + exits by itself; 10s watchdog kill), `ProcessFailed`
+on a non-zero unexpected exit.
+
+**Built (2026-08-12):** `EncoderOptions` + `IFfmpegEncoder`/`FfmpegEncoder` + `IEncoderProcess`/
+`FfmpegEncoderProcess` + pure `FfmpegArgs`/`FfmpegProgressParser`/`FfmpegEncoderPicker` in
+`Services/Encoder/`. Not yet constructed by the app (the frame-pipeline wiring, ship step 5, owns it).
+Tests: `FfmpegEncoderTests` integration (probe → spawn with NVENC preferred → frames into stdin →
+progress parsed → graceful stop, no kill) + units (args compliance/GOP, progress parser, picker
+preference + GPL guard, no-URL/not-running/noop stops, process-death `ProcessFailed`) — **122 passing**.
+
+#### Ship step 4 — WASAPI audio capture (the meter comes alive)
+
+**Goal:** capture desktop/game audio (loopback) and the picked mic, feed the mic level into `AudioLevel`
+so the realtime meter reads something other than 0, run capture **only while live** (req 7).
+
+**Decisions (locked):**
+1. **NAudio `NAudio.Wasapi` 2.2.1** — the wasapi feature package (not the `NAudio` meta-package): it
+   carries the capture types (`WasapiCapture`/`WasapiLoopbackCapture` + the MMDevice enumeration) with
+   `NAudio.Core`/`NAudio.Asio` pulled in transitively. MIT — recorded in `THIRD-PARTY-NOTICES.txt` (item 9).
+2. **`IAudioSource` seam** (`Start`/`Stop`/`SampleReady`/`Failed`, IDisposable) — the app consumes the
+   seam; the two WASAPI implementations wrap NAudio; tests inject hermetic fakes (no real audio devices,
+   no timers). Loopback = `WasapiLoopbackCapture` on the default render device; mic = `WasapiCapture`
+   with the NAudio device resolved by `FriendlyName` matching `MicSourceName` (the app only persists the
+   DisplayName), falling back to the default capture endpoint. Mic device resolution is re-read at each
+   `Start` via a name provider so a mic picked mid-session takes effect next go-live.
+3. **`AudioMixer` owns both sources** — starts/stops both with go-live (`BeginGoLive` success → `Start`,
+   `StopStream` → `Stop`). Mic samples feed a pure `AudioLevelMeter` (RMS, exponential smoothing) and
+   raise `MicLevelChanged`, marshalled to the UI thread into `AudioLevel`; desktop samples are currently
+   dropped (consumed by the encoder's AAC mix in a later step). Capture failures are logged via `AppLog`
+   (mic failure also zeroes the meter); loopback failure doesn't kill the mic.
+4. **Byte→float** — pure `WaveToFloat.Convert` handles the WASAPI mix formats: IEEE float 32-bit (direct)
+   and PCM 16-bit (normalized to -1..1), including `WaveFormatExtensible` with the IEEE-float subformat
+   GUID. Trailing partial samples are ignored.
+
+**Built (2026-08-12):** `Services/Audio/` ships `IAudioSource` + `AudioSample`, `WasapiLoopbackAudioSource`,
+`WasapiMicAudioSource`, `AudioMixer`, `AudioLevelMeter`, `WaveToFloat`; `MainViewModel` constructs the
+mixer (mic source fed `() => MicSourceName`), starts it on go-live and stops it on end-stream, and maps
+`MicLevelChanged` → `AudioLevel`. A pre-existing CS8602 in `FfmpegEncoder.cs:139` surfaced during this
+step's rebuild and was fixed (`process!`) — build **0 warnings**. Tests: `AudioMixerTests` (mixer
+lifecycle/forwarding/failure against fakes, meter RMS/smoothing/reset, `WaveToFloat` float/PCM16/
+extensible/truncation) — **139 passing**.
+
+**Deferred (later ship steps):** wiring the desktop-capture samples into the encoder's AAC mix (replaces
+the `-f lavfi -i anullsrc` placeholder; the encoder construction itself shipped in ship step 5).
+*(The "capture while not live" + "audio UI beyond the mic controls" deferrals were SHIPPED on the
+2026-08-13 game audio bar branch — capture is now always-on for preview and the game bar is the second
+audio UI. The mixer's short-circuit meter fix + `Started`/`RestartMic` seams live in the same branch.)*
+
+#### Ship step 5 — Frame-pipeline wiring (the encoder gets a frame source)
+
+**Goal:** the chain `CameraManager`/`ScreenCaptureManager` → compositor resolver → encoder, driven while
+live by a paced frame pump: snapshot the active scene → resolve each element to its latest frame →
+composite into the tier's output frame → pace into the encoder's stdin at the tier's FPS.
+
+**Decisions (locked via user Q&A, 2026-08-12):**
+1. **Video pipeline first** — the `-f lavfi -i anullsrc` silent track stays; mixing the loopback/mic
+   WASAPI samples into the encoder's AAC track is its own later step.
+2. **RTMP URL via a provider seam** — `MainViewModel._rtmpUrlProvider` is a `Func<string?>` returning
+   null today (the reusable stream's ingest URL lands with TASK 9); when it yields null the pump logs
+   and skips the encoder entirely, so go-live runs the existing visual flow without pushing.
+
+**Design:**
+1. `Services/Encoder/FramePump.cs` — the frame producer. All collaborators constructor-injected seams
+   (`Func<Scene?>`, `Func<SceneElement, VideoFrame?>` resolver, `Func<CompositorOptions>`,
+   `Func<EncoderOptions?>`, `Func<IFfmpegEncoder>`, `Action<string>` log, injectable pacing delay) so it
+   stays free of WPF and of the capture managers and is hermetic in tests. `StartAsync` never throws
+   (failures log + surface via `Failed` — the VM fires-and-forgets from the sync command handler);
+   loop = snapshot → render → `SubmitFrameAsync`, paced at `1/options.Fps` (default `Task.Delay`; tests
+   inject `Task.Yield`). `StopAsync` stops the encoder (closes stdin) BEFORE awaiting the loop — closing
+   stdin unblocks a write stuck on pipe backpressure, so stop can't deadlock on the pump. `ProcessFailed`
+   self-stops the pump. `HealthUpdated` forwards the encoder's stats (ship step 6 binds the bottom bar).
+2. `ScreenCaptureManager.GetLatestFrame(key)` — mirrors `CameraManager.GetLatestFrame(deviceId)`; the
+   backdrop's live frame for the compositor.
+3. `MainViewModel` — owns the resolver (`WebcamSceneConfig` → `GetLatestFrame(WebcamId)`;
+   `Source.IsLiveCapture` → `GetLatestFrame(CaptureKey)`; image/background → `StaticPixelCache.Get(AssetId)`),
+   builds `CompositorOptions` from the tier + `OutputRect*` (doubles rounded to ints — the vertical
+   607.5 half-pixel crop rounds to a perfectly-centered 608), builds `EncoderOptions` from the tier when
+   the URL provider returns one, constructs the real `FfmpegEncoder(new FfmpegLocator())`, starts the
+   pump on go-live, stops it on end-stream, disposes in `Shutdown`, and flips `StreamStatus.Error` when
+   the pump fails while live (minimal — detailed health surfacing is ship step 6).
+
+**Test plan (Good Dog Rule — ONE integration test):** `FramePumpTests.Start_CompositesScene_FeedsEncoder_StopsCleanly`
+drives the full lifecycle against fakes — real `SceneCompositor` + real `FramePump`, fake `IFfmpegEncoder`
+— asserting the composited red backdrop frame actually reaches the encoder at the tier size and that stop
+tears everything down. Units: no-URL start skips the encoder, re-entrant start/stop no-ops, encoder
+start-failure raises `Failed` + disposes, `ProcessFailed` self-stops the pump, `HealthUpdated` forwards.
+`ScreenCaptureManagerTests.GetLatestFrame_ReturnsLatestPump_UntilReleased` pins the new accessor.
+
+**Out of scope (later ship steps):** the loopback/mic → AAC mix (replaces `anullsrc`), health stats in the
+bottom bar (ship step 6), scene-switching transitions, and any flash-frame wiring.
+
+**Built (2026-08-12):** `FramePump` shipped in `Services/Encoder/`, `ScreenCaptureManager.GetLatestFrame`
+added, `MainViewModel` wired end-to-end (resolver + both option builders + pump lifecycle), `FramePumpTests`
+(7) + `GetLatestFrame` test (1) added — build **0 warnings**, **147 tests passing**. Known consideration:
+the pump reads the active scene on a background thread while the UI can still edit it; a concurrent-mutation
+exception is contained (logged + `Failed` + pump stops) rather than crashing.
+
+#### Ship step 5.5 — Social bar bug fixes + the bar on the live output (2026-08-13)
+
+**Bug 1 — bar wouldn't reliably change position (root cause found, then simplified):** the original
+drag set `Canvas.SetTop(bar, …)` with a local value, which permanently overrides the
+`Canvas.Top="{Binding SocialBarTop}"` binding — the release-time `SetSocialBarPosition` →
+`PropertyChanged(SocialBarTop)` could never beat it. First fix added direction-snapping during the drag
+(`SocialBarSnap.Decide`, ±6px deadzone) + `bar.ClearValue(Canvas.TopProperty)` on release — but that
+still misbehaved for shaky hands (jitter around the deadzone: it snapped up reliably, then refused to
+come back down and snapped back to top). **Superseded by a click-toggle (KISS, user decision):** clicking
+the bar in the preview flips it top ⇄ bottom (`MainViewModel.ToggleSocialBarPosition` → the existing
+`SetSocialBarPosition`), the bar rides `{Binding SocialBarTop}` alone (no local values, no deadzone, no
+jitter sensitivity), and `SocialBarSnap` was removed. The `ClearValue` lesson stands: never set a local
+value on a property the binding owns.
+
+**Bug 2 — Mastodon showed the generic 7-star honeycomb (root cause found):** the DB row
+`@gramps@llamachile.tube` had `Software = NULL` — nodeinfo was only ever resolved against the identity domain
+(`llamachile.tube`, a landing page), never probed for the real instance at `mastodon.llamachile.tube`.
+Fixed on three fronts: `HttpSocialValidator` now **probes well-known subdomains** (mastodon. → social. →
+… `FediverseSubdomainCandidates`) when the identity domain and its redirect both come up empty, under a
+~15s linked-CTS budget, with an optional `Action<string>` log; `MainViewModel` **heals** any fediverse entry
+missing a software name on layout load (`HealFediverseSoftwareAsync` — static, testable; instance wrapper
+runs it off the UI thread, applies via the dispatcher, saves); `SocialEntry.FediverseSoftware` is now
+**settable** and raises `PropertyChanged` for `LogoData`, so the heal updates the icon in place. If the user
+later re-saves the entry with the icon fixed, the name persists with it.
+
+**Compositor rendering (user-approved scope):** the social bar now appears **on the live output**, not just
+the preview — `Compositor/SocialBarRenderer.cs` rasterizes the entries into a transparent straight-alpha
+BGRA strip (1920-wide, 40px content + 24px glow pad, green `#2ecc71` glow baked in) via `RenderTargetBitmap`
+(WPF glue like `StaticPixelCache`; the compositor core stays pure). `SceneCompositor.Render` takes optional
+`socialBarFrame` + `socialBarTop` (master space) and blits it **last — above the branding flash** (the old
+`BlitFlash` generalized to offset `BlitOverlay`). `FramePump` gains a `socialBar:` seam
+(`Func<(VideoFrame?, SocialBarPosition)>`, re-read every frame) and places the bar at `0` or
+`SourceRectHeight − bar height`. `MainViewModel` owns the frame (`RenderSocialBarFrame`, re-rendered on
+load/save/notify) and feeds the seam.
+
+**Tests (+6 → 153 passing, 0 warnings):** settable `FediverseSoftware` updates `LogoData`,
+subdomain-probe unit + null-when-silent unit, the branch's **one integration test**
+`Socials_HealMissingFediverseSoftware_RoundTripsThroughDb` (temp-DB roundtrip: NULL software → healed via
+the validator → persisted), compositor bar overlay (top/bottom + above-flash), `FramePump` bar pass-through
+(Top then flipped to Bottom mid-run — the seam is re-read each frame), and both `ISocialValidator` fakes
+(`FakeValidator`/`BlockingValidator`) gained `ResolveFediverseSoftwareAsync`. The drag-snap units
+(`SocialBarSnap`) were removed with the click-toggle supersession.
+
+**Not included (say the word):** rewriting the healed entry's `ProfileUrl` to `https://mastodon.llamachile.tube/@gramps`.
+

TASKS/task-05-layout-persistence.md

@@ -0,0 +1,47 @@
+# TASK 5 — Layout Persistence (SQLite)
+
+> Catalog: [`TASKS.md`](../TASKS.md) — status and requirements live here.
+
+
+**Goal:** Scenes, sources, and asset bytes survive restarts; assets are always available.
+
+### Status: ✅ Done
+
+1. ✅ SQLite database (`Microsoft.Data.Sqlite`) at `%APPDATA%\ytLlive\ytLlive.db`; schema versioned via `PRAGMA user_version` (currently **v8**)
+2. ✅ Assets live in the DB (BLOB keyed by SHA-256 content hash), never file paths — deleting the original file never breaks a scene
+3. ✅ File-model save/open — the active layout file is tracked (default is the AppData DB); **Save Layout As… / Open Layout…** switch the active file; auto-save writes to whatever is active
+4. ✅ Auto-save (invisible) — ~1.5s debounce on scene/source add/remove/reorder/rename/hide + any source transform change; flush on window close
+5. ✅ Startup — load the active file; seed the five canonical scenes only when the DB is empty; (+) re-adds a missing canonical scene and is hidden once all five are present; adding beyond the five is rejected
+6. ✅ Schema v1 → v9 — webcam columns (v2), singleton `Webcam` + per-scene `WebcamSceneConfig` (v3), `RectWidth`/`RectHeight` round-to-rect restore (v4), `Source.IsBackdrop` + `Source.CaptureKey` (v5), `Scene.HasBackdrop` — backdrop **Live-only by policy** (v6, one-time backfill + `EnforceBackdropPolicy` on every load), `Scene.HasSocialBar` (v7, dropped per-scene toggle — column back-compat, unread), `Socials.BarEnabled` (v8); the `SocialEntry.Software` fediverse-software column is a **column-presence migration** (commented v8→v9, no version bump — `user_version` stays 8); v9 = single-row `Music`. **Load-time rule:** sources load with `IsBackground` derived from `Type` (OR'd with the persisted column so legacy DisplayCapture backdrops keep their flag) — rows saved before the Type setter derived the flag heal on load
+7. ✅ WindowHandle stays in-memory (per-session); save = transactional rewrite; orphaned assets pruned. **v9 lands in the TASK 8 audio milestone** (single-row `Music` — `TrackPath`/`IsEnabled`)
+
+### Design decisions
+
+1. **SQLite database** (`Microsoft.Data.Sqlite`) at `%APPDATA%\ytLlive\ytLlive.db`; schema versioned
+   via `PRAGMA user_version`.
+2. **Assets live in the DB, not on disk** — `Asset` table stores image bytes (BLOB) keyed by a
+   SHA-256 content hash (unique). Identical image content collapses to one row regardless of file
+   name — the 1:M resource memory model, enforced by the database. No file paths; deleting the
+   original file never breaks a scene.
+3. **File-model save/open** — the active layout file is tracked (default is the AppData DB).
+   **Save Layout As… / Open Layout…** switch the active file; auto-save writes to whatever is active.
+4. **Auto-save (invisible)** — ~1.5s debounce on scene add/remove/reorder/rename/hide, source
+   add/remove/reorder, and any source transform change; flush on window close.
+5. **Schema** — `Scene` (Id, Name, IsHidden, IsChatScene, HasBackdrop, HasSocialBar, SortOrder), `Asset` (Id, Hash, Data,
+   PixelWidth, PixelHeight), `Source` (Id, SceneId FK cascade, AssetId FK, Type, Name, IsEnabled,
+   X/Y/Width/Height/Opacity, MonitorIndex, DeviceId, ClipShape, IsMirrored, SortOrder), `Socials` (Id,
+   BarPosition, BarJustify — back-compat, unread, BarEnabled added via `ALTER`), `SocialEntry` (Id,
+   SocialsId FK cascade, Service, Handle, ProfileUrl, SortOrder) — `user_version` **8** (v1 → v2 =
+   `ALTER TABLE` adds the two webcam columns; v3 = singleton `Webcam` + per-scene `WebcamSceneConfig`;
+   v4 = `WebcamSceneConfig.RectWidth`/`RectHeight` for the round-to-rect restore; v5 = `Source.IsBackdrop`
+   + `Source.CaptureKey` for the live-capture backdrop; v6 = `Scene.HasBackdrop` — the backdrop is
+   **Live-only by policy** (one-time backfill turns Starting/BRB/Chat/Ending off and drops their backdrop
+   sources; `EnforceBackdropPolicy` re-normalizes every load); v7 = `Scene.HasSocialBar` (per-scene toggle
+   dropped — column back-compat, unread); v8 = `Socials.BarEnabled`). The `SocialEntry.Software`
+   fediverse-software column is a column-presence migration (commented v8→v9, no version bump).
+   `WindowHandle` stays in-memory (per-session). Save = transactional rewrite; orphaned assets pruned.
+6. **Startup** — load the active file; seed the five canonical scenes
+   (Starting/Live/BRB/Chat/Ending, `SceneCatalog`) only when the DB is empty. The (+)
+   button re-adds a missing canonical scene and is hidden once all five are present;
+   adding beyond the five is rejected — work with less, never more.
+

TASKS/task-06-ui-polish-batch.md

@@ -0,0 +1,21 @@
+# TASK 6 — UI polish batch (scenes/sources rows, dedup naming, social bar)
+
+> Catalog: [`TASKS.md`](../TASKS.md) — status and requirements live here.
+
+
+**Goal:** clean up the two side lists and the social bar per gramps's review.
+
+### Status: ✅ Done
+
+1. ✅ Scene rows are pure selection rows — the per-row edit/trash/visibility icons and the inline rename TextBox are gone (`EditSceneCommand`/`RemoveSceneCommand`/`ToggleSceneVisibilityCommand` + handlers + `Scene.IsEditing` removed; `IsHidden` stays persisted + dims hidden rows)
+2. ✅ Source rows gained the trio — edit (inline rename via new `EditElementCommand` + `SceneElement.IsEditing`), visibility eye (new `ToggleElementVisibilityCommand` flips `SceneElement.IsVisible`; the eye style now binds `IsVisible`, open/slashed + row dims to 0.45 when hidden), and the existing trash
+3. ✅ Duplicate resource names get a no-space incrementing suffix via shared `NextSourceName` (Image, Image2, Image3…) — next free number derived from the names actually in the scene, so deleting a middle resource never collides (`AddSource` + `AddReusedImage` both use it)
+4. ✅ Social bar renders the full validated handle — `MaxWidth=200` + `TextTrimming` removed from BOTH `SocialBarRenderer` and the preview template (mastodon `@gramps@…` no longer cuts off)
+5. ✅ Side panels stay fixed-width (left 220 / right 300) — deliberate: they never re-layout on resize, the preview absorbs it
+6. ✅ Focus-loss capture lag documented as a known OS limit in `ai.md` — deferred by user decision (no code change)
+
+### Design decisions
+
+1. **Next free number from names, not type counts** — the old scheme counted elements by `SourceType` (`count == 0 ? baseName : base+count+1`), which collided after deletions; the new helper scans actual names.
+2. **One WPF App per AppDomain** — the real-App tests (round-clip + naming) share `RealAppHost` (a dedicated STA thread owning the single `App`) via the `RealApp` serial collection, instead of each calling `new App()`.
+

TASKS/task-07-meter-scaling.md

@@ -0,0 +1,17 @@
+# TASK 7 — Meter scaling amplification (voice meter uses the full bar)
+
+> Catalog: [`TASKS.md`](../TASKS.md) — status and requirements live here.
+
+
+**Goal:** the mic (and game) meters feel light — speech peaks should peg into the red at maxed volume.
+
+### Status: ✅ Done
+
+1. ✅ `AudioLevelMeter.ToDisplay` now adds **+10 dB of input amplification** before the −60..0 dBFS → 0..1 log mapping (was raw dB): speech peaks (~0.2 RMS, −14 dBFS) read ~0.93 → red zone; normal speech (~0.05, −26 dBFS) ~0.73 → yellow; background noise ≤0.001 linear (−60 dBFS) still reads 0 (the meter never idles on it)
+2. ✅ Unit tests updated to the new mapping + new `ToDisplay_Pushes_Speech_Peaks_Into_Red_At_Maxed_Volume` (0.2 → 0.92..0.95, 0.05 → 0.72..0.75)
+
+### Design decisions
+
+1. **Amplify at the mapping, not in the VM** — one knob (`ToDisplay`), shared by the mic bar and the game bar; the `× MicVolume` gain-on-noise behavior is untouched (raising the slider still moves ambient noise up the bar).
+2. **+10 dB, not more** — louder boosts push quiet speech into the lower half and make the noise floor visible; +10 puts speech peaks solidly in red while idle stays at zero.
+