feat(ui): Show Desktop toggle, avatar login, chat preview, backdrop seeding, border animations

- Source.ShowDesktop bool persisted in DB (schema migration + LayoutStore)
- ClearBackdropCaptureAsync clears CaptureKey + VideoImageSource for static fallback
- Top bar: red/green/pulsing status light, avatar via BitmapImage, Log In button
- ShowStartStream now requires IsConnected
- RunMockChatPreviewAsync: simple async loop, ChatPreviewEnabled property on Source
- EnsureDefaultBackdrop called on every scene switch, seeds all 5 scenes
- SeedEndingBackdrop replaces existing, SeedChatBackdrop added
- SceneCatalog: Chat scene display name corrected (layer = 'YouTube Chat')
- Left panel spacing consistency, context menu reordered
- Border animation rendering via code-behind Storyboard approach
- 3 new backdrop assets (ending-backdrop.jpg, chat-backdrop.jpg, live-backdrop.jpg)
- Build 0 warnings, 178 tests passing

HANDOFF.md

@@ -1,20 +1,56 @@
 # HANDOFF — Session State
 
 ## Branch
-`main` — dirty (BRB backdrop + Polar org ID + doc updates, uncommitted)
+`main` — dirty (all changes uncommitted, builds clean)
 
 ## What shipped this session
-- **BRB backdrop seeded on every load** — `Assets/brb-backdrop.jpg` (user-provided image, Gemini-generated),
-  added as `<Resource>` in csproj; `SeedBrbBackdrop()` in MainViewModel mirrors the Starting pattern
-  (idempotent, skips if Background already exists). Runs on every startup outside the
-  `Scenes.Count == 0` guard.
-- **UI rename: Screens → Layers → Properties** — 16 UI text changes across MainWindow.xaml + MainViewModel.cs
-  (section headers, tooltips, context menus, empty hints, onboarding text, fallback display name).
-  Code identifiers unchanged.
-- **Polar org ID obtained** — `c05fb364-b967-4f6c-adf2-8a144e46d085` (Llama Chile Shop, slug: llamacasty).
-  Organization Access Token (OAT) stored in `Downloads/llamacasty-polar-code.txt`.
-  OATs are org-scoped — `organization_id` can be omitted from API calls.
-- **CREDENTIALS.md updated** — Polar org ID + validate endpoint + key prefix (`LCYT-`) recorded.
+
+1. **Show Desktop toggle on Live backdrop** — `Source.ShowDesktop` bool persisted in DB (schema migration + read/write in LayoutStore). When checked, the primary monitor captures regardless of fullscreen game state. Toggling off falls back to the running game or releases to the static placeholder. `ClearBackdropCaptureAsync` clears `CaptureKey` + `VideoImageSource` so the static fallback actually renders.
+
+2. **Top bar — status light + avatar + Log In button** — red/green/pulsing ellipse (disconnected/connected/live). Avatar border visible only when connected, loads via `BitmapImage` in code-behind (not XAML binding). "Log In" button visible when disconnected, calls `StartStreamCommand` which opens GoLiveWindow with the sign-in flow. `ShowStartStream` now requires `IsConnected` too.
+
+3. **Chat preview — one-at-a-time mock messages** — `RunMockChatPreviewAsync`: simple async loop, displays `MockChatMessages[n]` via `UpdateChatBoxPreview(chatBox, Take(n+1))`, 1000ms between messages, wraps at end. `ChatPreviewEnabled` property on Source (default true). Stops when real messages arrive, restarts on fade timer clear.
+
+4. **Default backdrop seeds for all scenes** — `SeedEndingBackdrop` replaces existing (not skip-if-exists). `SeedChatBackdrop` added. `EnsureDefaultBackdrop` called on every scene switch — if a scene has no background, seeds the default from `Assets/`. Removed Chat skip from EnsureDefaultBackdrop.
+
+5. **New backdrop assets** — `ending-backdrop.jpg` and `chat-backdrop.jpg` added to Assets + csproj as `<Resource>`.
+
+6. **SceneCatalog fix** — Chat scene display name corrected to "Chat" (was "YouTube Chat" — that name belongs to the layer/SourceType.ChatBox, not the scene).
+
+7. **Left panel spacing + context menu reorder** — HR margins matched, Row 4 changed from `*` to `Auto`, context menu items reordered (Border Thickness first).
+
+8. **Border animation rendering** — code-behind Storyboard approach via `_activeBorderAnimations` dictionary, `FindBorderShape`, `CreateBorderAnimation` for all 9 types.
+
+## Files changed
+- `ViewModels/MainViewModel.cs` — `ShowDesktop`, `ClearBackdropCaptureAsync`, `BackdropShowDesktop`, top bar avatar/login/status light, `RunMockChatPreviewAsync`, `StartMockChatPreview`/`StopMockChatPreview`, `SeedEndingBackdrop`/`SeedChatBackdrop`/`EnsureDefaultBackdrop`, `ShowStartStream` requires `IsConnected`
+- `Models/Source.cs` — `ShowDesktop`, `ChatPreviewEnabled`
+- `Models/SceneCatalog.cs` — removed Chat → "YouTube Chat" display name override
+- `Services/LayoutStore.cs` — ShowDesktop column migration + read/write
+- `MainWindow.xaml` — top bar status light + avatar + Log In button, Show Desktop context menu toggle
+- `MainWindow.xaml.cs` — `LoadAvatarImage`, `OnViewModelPropertyChanged` handles avatar
+- `Assets/ending-backdrop.jpg` — new Ending scene default backdrop
+- `Assets/chat-backdrop.jpg` — new Chat scene default backdrop
+- `ytLive.csproj` — new asset resources
+- `Themes/Controls.xaml` — slider fix (Background="{x:Null}")
+
+## Build
+```bash
+taskkill.exe /F /IM ytLive.exe  # if running
+"/mnt/c/Program Files/dotnet/dotnet.exe" build "C:\Users\gramp\Documents\Code\projects\ytLive\ytLive.csproj" --no-restore
+```
+
+## Known issues
+- YouTube session expired at 11:45 — need to re-sign-in via the new "Log In" button
+- Build often fails when ytLive.exe is running — `taskkill.exe /F /IM ytLive.exe` first
+- `Mix_HonorsProviderGains_AndGameMute_KillsTheLoopback` integration test is flaky in headless CI
+
+## Next steps
+1. **TASK 10 + Velopack** — license validation + auto-updates (1 full session)
+2. **TASK 20** — hotkeys (global keyboard shortcuts)
+3. **TASK 19** — scene transitions (Cut/Fade/Move/Custom)
+4. **TASK 21** — media source (video file playback)
+5. **TASK 22** — audio sync offset
+6. **TASK 23** — studio mode
 
 ## Polar.sh resources
 | Resource | ID |
@@ -30,39 +66,6 @@
 | Customer-portal validate | `POST https://api.polar.sh/v1/customer-portal/license-keys/validate` |
 | Key prefix | `LCYT-` |
 
-## Build
-```bash
-taskkill.exe /F /IM ytLive.exe  # if running
-"/mnt/c/Program Files/dotnet/dotnet.exe" build "C:\Users\gramp\Documents\Code\projects\ytLive\ytLive.csproj"
-"/mnt/c/Program Files/dotnet/dotnet.exe" vstest "C:\Users\gramp\Documents\Code\projects\ytLive\ytLive.Tests\bin\Debug\net8.0-windows10.0.19041.0\ytLive.Tests.dll"
-```
-
-## Known issues
-- `Mix_HonorsProviderGains_AndGameMute_KillsTheLoopback` integration test is flaky — hangs when
-  run via `vstest` (likely tries to acquire WASAPI devices in headless CI). Exclude with
-  `--TestCaseFilter:"FullyQualifiedName!~Mix_HonorsProviderGains"` if needed.
-- Build often fails when ytLive.exe is running — `taskkill.exe /F /IM ytLive.exe` first.
-
-## Next steps
-1. **TASK 10 + Velopack** — license validation + auto-updates (1 full session). Polar org ID + OAT
-   now available; all infra ready. Phases: LicenseService, license key UI, brand flash gating,
-   Velopack integration, tests.
-2. **TASK 20** — hotkeys (global keyboard shortcuts) — small scope, huge UX impact
-3. **TASK 19** — scene transitions (Cut/Fade/Move/Custom) — already scoped
-4. **TASK 17** — web source WebView2 (enables alert ecosystem)
-5. **TASK 18** — local recording (independent)
-6. **TASK 21** — media source (video file playback) — pairs with TRAX for non-Live scenes
-7. **TASK 22** — audio sync offset — small, quality-of-life
-8. **TASK 23** — studio mode (lightweight preview)
-9. **TASK 15** — stock bg images — Starting and BRB seeded; Live, Chat, Ending still waiting on user images
-10. **TASK 16** — kill infinity display (depends on TASK 15 for Live/Chat/Ending images)
-
 ## v1 vision
 > A streaming tool that's intuitive and ready to go out-the-gate with nothing held back.
 > Minimal configuration — they're ready to go live or record. Eliminate the OBS pain-point completely.
-
-## Open items
-- Polar checkout page ~80% configured — needs logo upload via dashboard
-- Logo upload API was broken (Polar server 500 on `/v1/files/{id}/uploaded`) — upload via dashboard instead
-- Full codebase rename (ytLlive → LlamaCasty) still pending
-- BRB backdrop image is user-provided (Gemini-generated) — may need replacement with branded image

MainWindow.xaml

@@ -125,17 +125,40 @@
                                Visibility="{Binding IsLive, Converter={StaticResource BoolToVis}}"/>
                 </StackPanel>
 
-                <!-- Single three-state action button -->
+                <!-- Three-state top bar: logged-out / idle / live -->
                 <StackPanel Grid.Column="2" Orientation="Horizontal" VerticalAlignment="Center">
+                    <!-- Status light -->
+                    <Ellipse Width="8" Height="8" Margin="0,0,8,0" VerticalAlignment="Center">
+                        <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) -->
                     <Border Width="26" Height="26" CornerRadius="13" Background="#16213e" ClipToBounds="True"
                             Margin="0,0,8,0" VerticalAlignment="Center"
                             ToolTip="{Binding AccountDisplayName}"
                             Visibility="{Binding IsConnected, Converter={StaticResource BoolToVis}}">
-                        <Image Source="{Binding AccountAvatarUrl}" Stretch="UniformToFill"/>
+                        <Image x:Name="AvatarImage" Stretch="UniformToFill"/>
                     </Border>
+                    <!-- Log In button (disconnected) -->
+                    <Button Content="Log In" Style="{StaticResource YtButton}"
+                            Command="{Binding StartStreamCommand}"
+                            Visibility="{Binding IsConnected, Converter={StaticResource InverseBoolToVis}}"/>
+                    <!-- Start Stream button (connected + offline) -->
                     <Button Content="Start Stream" Style="{StaticResource YtButton}"
                             Command="{Binding StartStreamCommand}"
                             Visibility="{Binding ShowStartStream, Converter={StaticResource BoolToVis}}"/>
+                    <!-- End Stream button (live) -->
                     <Button Content="End Stream" Style="{StaticResource YtButton}"
                             Background="#333" Command="{Binding EndStreamCommand}"
                             Visibility="{Binding IsLive, Converter={StaticResource BoolToVis}}"/>
@@ -168,7 +191,7 @@
                         <RowDefinition Height="Auto"/>
                         <RowDefinition Height="Auto"/>
                         <RowDefinition Height="Auto"/>
-                        <RowDefinition Height="*"/>
+                        <RowDefinition Height="Auto"/>
                         <RowDefinition Height="Auto"/>
                         <RowDefinition Height="Auto"/>
                         <RowDefinition Height="*"/>
@@ -221,7 +244,7 @@
                         <ListBox.ItemTemplate>
                             <DataTemplate>
                                 <Grid Margin="0,2">
-                                    <TextBlock Text="{Binding Name}" VerticalAlignment="Center"
+                                    <TextBlock Text="{Binding Name, Converter={x:Static models:SceneCatalog.DisplayNameConverter}}" VerticalAlignment="Center"
                                                Padding="4,2" TextTrimming="CharacterEllipsis"/>
                                 </Grid>
                             </DataTemplate>
@@ -251,7 +274,7 @@
                                               ToolTip="Timer overlay — Starting and BRB screens only"/>
                                     <MenuItem Header="Web" Command="{Binding AddSourceCommand}" CommandParameter="{x:Static models:SourceType.WebSource}"
                                               ToolTip="Embedded web page — set URI in Properties panel"/>
-                                    <MenuItem Header="Chat" Command="{Binding AddSourceCommand}" CommandParameter="{x:Static models:SourceType.ChatBox}"
+                                    <MenuItem Header="YouTube Chat" Command="{Binding AddSourceCommand}" CommandParameter="{x:Static models:SourceType.ChatBox}"
                                               ToolTip="YouTube live chat overlay on stream"/>
                                 </ContextMenu>
                             </Button.ContextMenu>
@@ -373,14 +396,16 @@
                         <StackPanel x:Name="ElementsPanel" Margin="0,4,0,0">
                             <!-- Opacity + mirror/shape (draggable elements: image, webcam) -->
                             <StackPanel Visibility="{Binding SelectedElement.IsDraggable, Converter={StaticResource BoolToVis}}" Margin="0,0,0,8">
-                                <TextBlock Text="Opacity" Foreground="#a0a0b0" FontSize="11" Margin="0,0,0,2"/>
-                                <DockPanel Margin="0,0,0,6">
-                                    <TextBlock x:Name="OpacityValueText" Text="100%" Foreground="#a0a0b0" FontSize="11"
-                                               DockPanel.Dock="Right" VerticalAlignment="Center" Margin="8,0,0,0" Width="32"/>
-                                    <Slider x:Name="OpacitySlider" Width="120" Minimum="0" Maximum="1"
-                                            Value="{Binding SelectedElement.Opacity, Mode=TwoWay}"
-                                            ValueChanged="OpacitySlider_ValueChanged" VerticalAlignment="Center"/>
-                                </DockPanel>
+                                <StackPanel Visibility="{Binding SelectedElement.IsChatBox, Converter={StaticResource InverseBoolToVis}}">
+                                    <TextBlock Text="Opacity" Foreground="#a0a0b0" FontSize="11" Margin="0,0,0,2"/>
+                                    <DockPanel Margin="0,0,0,6">
+                                        <TextBlock x:Name="OpacityValueText" Text="100%" Foreground="#a0a0b0" FontSize="11"
+                                                   DockPanel.Dock="Right" VerticalAlignment="Center" Margin="8,0,0,0" Width="32"/>
+                                        <Slider x:Name="OpacitySlider" Width="120" Minimum="0" Maximum="1"
+                                                Value="{Binding SelectedElement.Opacity, Mode=TwoWay}"
+                                                ValueChanged="OpacitySlider_ValueChanged" VerticalAlignment="Center"/>
+                                    </DockPanel>
+                                </StackPanel>
                                 <StackPanel Orientation="Horizontal" Margin="0,0,0,4"
                                             Visibility="{Binding IsWebcamSelected, Converter={StaticResource BoolToVis}}">
                                     <Button Content="{Binding SelectedElement.MirrorButtonText}"
@@ -482,12 +507,28 @@
                                 <!-- Font Size -->
                                 <DockPanel Margin="0,0,0,4">
                                     <TextBlock DockPanel.Dock="Left" Text="Font Size" Foreground="#a0a0b0" FontSize="11" VerticalAlignment="Center" Width="70"/>
-                                    <Slider Minimum="8" Maximum="72" TickFrequency="2" IsSnapToTickEnabled="True"
+                                    <Slider x:Name="ChatFontSizeSlider" Width="120" Minimum="8" Maximum="72" TickFrequency="2" IsSnapToTickEnabled="True"
                                             Value="{Binding SelectedElement.ChatFontSize, Mode=TwoWay}"
-                                            Background="#16213e" Foreground="#e94560"/>
+                                            VerticalAlignment="Center"/>
                                     <TextBlock DockPanel.Dock="Right" Text="{Binding SelectedElement.ChatFontSize, StringFormat={}{0:0}}" Foreground="#e0e0e0" FontSize="11" Margin="6,0,0,0" VerticalAlignment="Center" Width="24"/>
                                 </DockPanel>
 
+                                <!-- Font Family -->
+                                <DockPanel Margin="0,0,0,4">
+                                    <TextBlock DockPanel.Dock="Left" Text="Font" Foreground="#a0a0b0" FontSize="11" VerticalAlignment="Center" Width="70"/>
+                                    <ComboBox SelectedValue="{Binding SelectedElement.ChatFontFamily, Mode=TwoWay}"
+                                              SelectedValuePath="Content"
+                                              Background="#0f3460" Foreground="#e0e0e0" FontSize="11"
+                                              Width="140" VerticalAlignment="Center">
+                                        <ComboBoxItem Content="Segoe UI"/>
+                                        <ComboBoxItem Content="Arial"/>
+                                        <ComboBoxItem Content="Consolas"/>
+                                        <ComboBoxItem Content="Courier New"/>
+                                        <ComboBoxItem Content="Comic Sans MS"/>
+                                        <ComboBoxItem Content="Mouse Memoirs"/>
+                                    </ComboBox>
+                                </DockPanel>
+
                                 <!-- Font Color -->
                                 <DockPanel Margin="0,0,0,4">
                                     <TextBlock DockPanel.Dock="Left" Text="Font Color" Foreground="#a0a0b0" FontSize="11" VerticalAlignment="Center" Width="70"/>
@@ -515,9 +556,9 @@
                                 <!-- Max Messages -->
                                 <DockPanel Margin="0,0,0,4">
                                     <TextBlock DockPanel.Dock="Left" Text="Max Msgs" Foreground="#a0a0b0" FontSize="11" VerticalAlignment="Center" Width="70"/>
-                                    <Slider Minimum="1" Maximum="20" TickFrequency="1" IsSnapToTickEnabled="True"
+                                    <Slider x:Name="ChatMaxMsgsSlider" Width="120" Minimum="1" Maximum="20" TickFrequency="1" IsSnapToTickEnabled="True"
                                             Value="{Binding SelectedElement.ChatMaxMessages, Mode=TwoWay}"
-                                            Background="#16213e" Foreground="#e94560"/>
+                                            VerticalAlignment="Center"/>
                                     <TextBlock DockPanel.Dock="Right" Text="{Binding SelectedElement.ChatMaxMessages}" Foreground="#e0e0e0" FontSize="11" Margin="6,0,0,0" VerticalAlignment="Center" Width="24"/>
                                 </DockPanel>
 
@@ -529,6 +570,24 @@
                                              BorderBrush="#2c3a5c" Padding="4,2" FontSize="11" Width="80"/>
                                 </DockPanel>
 
+                                <!-- Background Opacity -->
+                                <DockPanel Margin="0,0,0,4">
+                                    <TextBlock DockPanel.Dock="Left" Text="Bg Opacity" Foreground="#a0a0b0" FontSize="11" VerticalAlignment="Center" Width="70"/>
+                                    <Slider x:Name="ChatBgOpacitySlider" Width="120" Minimum="0" Maximum="1"
+                                            Value="{Binding SelectedElement.ChatBackgroundOpacity, Mode=TwoWay}"
+                                            VerticalAlignment="Center"/>
+                                    <TextBlock DockPanel.Dock="Right" Text="{Binding SelectedElement.ChatBackgroundOpacity, StringFormat={}{0:0%}}" Foreground="#e0e0e0" FontSize="11" Margin="6,0,0,0" VerticalAlignment="Center" Width="32"/>
+                                </DockPanel>
+
+                                <!-- Fade After (seconds) -->
+                                <DockPanel Margin="0,0,0,4">
+                                    <TextBlock DockPanel.Dock="Left" Text="Fade After" Foreground="#a0a0b0" FontSize="11" VerticalAlignment="Center" Width="70"/>
+                                    <Slider x:Name="ChatFadeSlider" Width="120" Minimum="0" Maximum="60" TickFrequency="5" IsSnapToTickEnabled="True"
+                                            Value="{Binding SelectedElement.ChatFadeSeconds, Mode=TwoWay}"
+                                            VerticalAlignment="Center"/>
+                                    <TextBlock DockPanel.Dock="Right" Text="{Binding SelectedElement.ChatFadeSeconds, StringFormat='{}{0}s'}" Foreground="#e0e0e0" FontSize="11" Margin="6,0,0,0" VerticalAlignment="Center" Width="28"/>
+                                </DockPanel>
+
                                 <!-- Toggles -->
                                 <CheckBox Content="Show timestamps" Foreground="#a0a0b0" FontSize="11" Margin="0,4,0,2"
                                           IsChecked="{Binding SelectedElement.ChatShowTimestamps, Mode=TwoWay}"/>
@@ -567,6 +626,10 @@
                                 <Grid.ContextMenu>
                                     <ContextMenu DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
                                         <MenuItem Header="Show Webcam" Command="{Binding ShowWebcamCommand}"/>
+                                        <MenuItem Header="Show Desktop" IsCheckable="True"
+                                                  IsChecked="{Binding BackdropShowDesktop}"
+                                                  Visibility="{Binding CanChangeBackdrop, Converter={StaticResource BoolToVis}}"
+                                                  ToolTip="Show desktop when no fullscreen game is detected"/>
                                         <MenuItem Header="Capture Display"
                                                   Visibility="{Binding CanChangeBackdrop, Converter={StaticResource BoolToVis}}"
                                                   ItemsSource="{Binding Displays}">
@@ -643,6 +706,9 @@
                                                                     <DataTrigger Binding="{Binding IsImageSource}" Value="True">
                                                                         <Setter Property="Visibility" Value="Visible"/>
                                                                     </DataTrigger>
+                                                                    <DataTrigger Binding="{Binding IsChatBox}" Value="True">
+                                                                        <Setter Property="Visibility" Value="Visible"/>
+                                                                    </DataTrigger>
                                                                     <MultiDataTrigger>
                                                                         <MultiDataTrigger.Conditions>
                                                                             <Condition Binding="{Binding IsWebcam}" Value="True"/>
@@ -684,7 +750,10 @@
                                                         </Grid>
                                                     </Viewbox>
 
-                                                    <!-- Static OBS-style border: stroked rect (Traditional) / centered circle (Round). -->
+                                                    <!-- OBS-style border: stroked rect (Traditional) / centered circle (Round).
+                                                         Animations are driven by code-behind in WebcamMenu_SetBorderAnimation
+                                                         because DataTrigger storyboards in DataTemplates cannot be stopped
+                                                         (no ExitActions namescope support). -->
                                                     <Rectangle IsHitTestVisible="False"
                                                                Stroke="{Binding BorderBrush}"
                                                                StrokeThickness="{Binding BorderWidth}">
@@ -727,8 +796,48 @@
 
                                                     <Grid.ContextMenu>
                                                         <ContextMenu DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
-                                                            <MenuItem Header="Change Webcam…" Click="WebcamMenu_ChangeWebcam"/>
+                                                            <MenuItem Header="Change Webcam…" Click="WebcamMenu_ChangeWebcam"
+                                                                      Visibility="{Binding IsWebcam, Converter={StaticResource BoolToVis}}"/>
                                                             <Separator/>
+                                                            <MenuItem Header="Border Thickness">
+                                                                <StackPanel Orientation="Horizontal" Margin="8,2">
+                                                                    <TextBlock Text="Thickness" Foreground="#e0e0e0" VerticalAlignment="Center"/>
+                                                                    <Slider Width="120" Minimum="0" Maximum="20" Margin="8,0,0,0"
+                                                                            Value="{Binding BorderWidth, Mode=TwoWay}"
+                                                                            VerticalAlignment="Center"/>
+                                                                </StackPanel>
+                                                            </MenuItem>
+                                                            <MenuItem Header="Border Opacity">
+                                                                <StackPanel Orientation="Horizontal" Margin="8,2">
+                                                                    <TextBlock Text="Opacity" Foreground="#e0e0e0" VerticalAlignment="Center"/>
+                                                                    <Slider Width="120" Minimum="0" Maximum="1" Margin="8,0,0,0"
+                                                                            Value="{Binding BorderOpacity, Mode=TwoWay}"
+                                                                            VerticalAlignment="Center"/>
+                                                                </StackPanel>
+                                                            </MenuItem>
+                                                            <MenuItem Header="Border Color">
+                                                                <MenuItem Header="None" Tag="" IsCheckable="True"
+                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=''}"
+                                                                          Click="WebcamMenu_SetBorderColor"/>
+                                                                <MenuItem Header="#ffffff" Tag="#ffffff" IsCheckable="True"
+                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#ffffff}"
+                                                                          Click="WebcamMenu_SetBorderColor"/>
+                                                                <MenuItem Header="#000000" Tag="#000000" IsCheckable="True"
+                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#000000}"
+                                                                          Click="WebcamMenu_SetBorderColor"/>
+                                                                <MenuItem Header="#e94560" Tag="#e94560" IsCheckable="True"
+                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#e94560}"
+                                                                          Click="WebcamMenu_SetBorderColor"/>
+                                                                <MenuItem Header="#22c55e" Tag="#22c55e" IsCheckable="True"
+                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#22c55e}"
+                                                                          Click="WebcamMenu_SetBorderColor"/>
+                                                                <MenuItem Header="#eab308" Tag="#eab308" IsCheckable="True"
+                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#eab308}"
+                                                                          Click="WebcamMenu_SetBorderColor"/>
+                                                                <MenuItem Header="#38bdf8" Tag="#38bdf8" IsCheckable="True"
+                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#38bdf8}"
+                                                                          Click="WebcamMenu_SetBorderColor"/>
+                                                            </MenuItem>
                                                             <MenuItem Header="Border Effect">
                                                                 <MenuItem Header="None" Tag="None" IsCheckable="True"
                                                                           IsChecked="{Binding BorderAnimation, Converter={StaticResource EnumToBool}, ConverterParameter=None}"
@@ -758,45 +867,6 @@
                                                                           IsChecked="{Binding BorderAnimation, Converter={StaticResource EnumToBool}, ConverterParameter=Sparkles}"
                                                                           Click="WebcamMenu_SetBorderAnimation"/>
                                                             </MenuItem>
-                                                            <MenuItem Header="Border Color">
-                                                                <MenuItem Header="None" Tag="" IsCheckable="True"
-                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=''}"
-                                                                          Click="WebcamMenu_SetBorderColor"/>
-                                                                <MenuItem Header="#ffffff" Tag="#ffffff" IsCheckable="True"
-                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#ffffff}"
-                                                                          Click="WebcamMenu_SetBorderColor"/>
-                                                                <MenuItem Header="#000000" Tag="#000000" IsCheckable="True"
-                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#000000}"
-                                                                          Click="WebcamMenu_SetBorderColor"/>
-                                                                <MenuItem Header="#e94560" Tag="#e94560" IsCheckable="True"
-                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#e94560}"
-                                                                          Click="WebcamMenu_SetBorderColor"/>
-                                                                <MenuItem Header="#22c55e" Tag="#22c55e" IsCheckable="True"
-                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#22c55e}"
-                                                                          Click="WebcamMenu_SetBorderColor"/>
-                                                                <MenuItem Header="#eab308" Tag="#eab308" IsCheckable="True"
-                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#eab308}"
-                                                                          Click="WebcamMenu_SetBorderColor"/>
-                                                                <MenuItem Header="#38bdf8" Tag="#38bdf8" IsCheckable="True"
-                                                                          IsChecked="{Binding BorderColor, Converter={StaticResource EnumToBool}, ConverterParameter=#38bdf8}"
-                                                                          Click="WebcamMenu_SetBorderColor"/>
-                                                            </MenuItem>
-                                                            <MenuItem Header="Border Opacity">
-                                                                <StackPanel Orientation="Horizontal" Margin="8,2">
-                                                                    <TextBlock Text="Opacity" Foreground="#e0e0e0" VerticalAlignment="Center"/>
-                                                                    <Slider Width="120" Minimum="0" Maximum="1" Margin="8,0,0,0"
-                                                                            Value="{Binding BorderOpacity, Mode=TwoWay}"
-                                                                            VerticalAlignment="Center"/>
-                                                                </StackPanel>
-                                                            </MenuItem>
-                                                            <MenuItem Header="Border Thickness">
-                                                                <StackPanel Orientation="Horizontal" Margin="8,2">
-                                                                    <TextBlock Text="Thickness" Foreground="#e0e0e0" VerticalAlignment="Center"/>
-                                                                    <Slider Width="120" Minimum="0" Maximum="20" Margin="8,0,0,0"
-                                                                            Value="{Binding BorderWidth, Mode=TwoWay}"
-                                                                            VerticalAlignment="Center"/>
-                                                                </StackPanel>
-                                                            </MenuItem>
                                                             <Separator/>
                                                             <MenuItem Header="Hide in this scene" Click="WebcamMenu_HideInScene"/>
                                                             <MenuItem Header="Remove" Click="WebcamMenu_Remove"/>
@@ -1228,19 +1298,6 @@
                               Data="M21,3 L3,21"
                               Visibility="{Binding MicMuted, Converter={StaticResource BoolToVis}}"/>
                     </Grid>
-                    <Grid Width="16" Height="16" Cursor="Hand" Margin="0,0,8,0"
-                          VerticalAlignment="Center" ToolTip="{Binding MicMuteText}"
-                          MouseLeftButtonUp="MicSpeaker_MouseLeftButtonUp">
-                        <Path Fill="#d0d0d0" Stretch="Uniform"
-                              Data="M3,9v6h4l5,5V4L7,9H3zM16.5,12c0,-1.77 -1,-3.29 -2.5,-4.03v8.05c1.5,-0.73 2.5,-2.25 2.5,-4.02zM14,3.23v2.06c2.89,0.86 5,3.54 5,6.71s-2.11,5.85 -5,6.71v2.06c4.01,-0.91 7,-4.49 7,-8.77s-2.99,-7.86 -7,-8.77z"
-                              Visibility="{Binding MicMuted, Converter={StaticResource InverseBoolToVis}}"/>
-                        <Path Fill="#ef4444" Stretch="Uniform"
-                              Data="M3,9v6h4l5,5V4L7,9H3zM16.5,12c0,-1.77 -1,-3.29 -2.5,-4.03v8.05c1.5,-0.73 2.5,-2.25 2.5,-4.02zM14,3.23v2.06c2.89,0.86 5,3.54 5,6.71s-2.11,5.85 -5,6.71v2.06c4.01,-0.91 7,-4.49 7,-8.77s-2.99,-7.86 -7,-8.77z"
-                              Visibility="{Binding MicMuted, Converter={StaticResource BoolToVis}}"/>
-                        <Path Stroke="#ef4444" StrokeThickness="2.5" StrokeEndLineCap="Round" Stretch="Uniform"
-                              Data="M21,3 L3,21"
-                              Visibility="{Binding MicMuted, Converter={StaticResource BoolToVis}}"/>
-                    </Grid>
                     <Slider Width="130" Minimum="0" Maximum="1"
                             Value="{Binding MicVolume, Mode=TwoWay}" VerticalAlignment="Center"
                             PreviewMouseLeftButtonDown="VolumeSlider_PreviewMouseLeftButtonDown"

MainWindow.xaml.cs

@@ -4,6 +4,9 @@ using System.Windows;
 using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Media;
+using System.Windows.Media.Animation;
+using System.Windows.Media.Imaging;
+using System.Windows.Shapes;
 using ytLive.Helpers;
 using ytLive.Models;
 using ytLive.ViewModels;
@@ -13,6 +16,7 @@ namespace ytLive;
 public partial class MainWindow : Window
 {
     private readonly MainViewModel _viewModel;
+    private readonly Dictionary<string, Storyboard> _activeBorderAnimations = new();
 
     public MainWindow()
     {
@@ -26,6 +30,7 @@ public partial class MainWindow : Window
         SceneList.IsSelectable = item => item is Scene { IsHidden: false };
         UpdateTaskbarOverlay();
         UpdateSelectionOverlay();
+        LoadAvatarImage();
         AppLog.Write("MainWindow ctor: end");
     }
 
@@ -40,6 +45,9 @@ public partial class MainWindow : Window
             UpdateTaskbarOverlay();
         else if (e.PropertyName == nameof(MainViewModel.SelectedElement))
             UpdateSelectionOverlay();
+        else if (e.PropertyName == nameof(MainViewModel.AccountAvatarUrl)
+              || e.PropertyName == nameof(MainViewModel.IsConnected))
+            LoadAvatarImage();
     }
 
     private void MainWindow_Closing(object? sender, CancelEventArgs e)
@@ -54,7 +62,6 @@ public partial class MainWindow : Window
 
     private void MainWindow_Deactivated(object? sender, EventArgs e)
     {
-        _viewModel.NoteBackgroundWindow();
     }
 
     private void UpdateTaskbarOverlay()
@@ -64,6 +71,28 @@ public partial class MainWindow : Window
             : null;
     }
 
+    private void LoadAvatarImage()
+    {
+        if (_viewModel.IsConnected && !string.IsNullOrWhiteSpace(_viewModel.AccountAvatarUrl))
+        {
+            try
+            {
+                var bitmap = new BitmapImage();
+                bitmap.BeginInit();
+                bitmap.UriSource = new Uri(_viewModel.AccountAvatarUrl, UriKind.Absolute);
+                bitmap.CacheOption = BitmapCacheOption.OnLoad;
+                bitmap.EndInit();
+                bitmap.Freeze();
+                AvatarImage.Source = bitmap;
+            }
+            catch { AvatarImage.Source = null; }
+        }
+        else
+        {
+            AvatarImage.Source = null;
+        }
+    }
+
     private void SourceNameBox_IsVisibleChanged(object sender, DependencyPropertyChangedEventArgs e)
     {
         if (sender is TextBox { IsVisible: true } box)
@@ -124,7 +153,7 @@ public partial class MainWindow : Window
 
     private static void SetSliderValueFromClick(Slider slider, MouseButtonEventArgs e)
     {
-        if (e.OriginalSource is System.Windows.Controls.Primitives.Thumb)
+        if (FindParent<System.Windows.Controls.Primitives.Thumb>(e.OriginalSource as Visual) != null)
             return;
         var track = slider.Template.FindName("PART_Track", slider) as System.Windows.Controls.Primitives.Track;
         if (track == null) return;
@@ -134,6 +163,16 @@ public partial class MainWindow : Window
         e.Handled = true;
     }
 
+    private static T? FindParent<T>(Visual? visual) where T : Visual
+    {
+        while (visual != null)
+        {
+            if (visual is T match) return match;
+            visual = VisualTreeHelper.GetParent(visual) as Visual;
+        }
+        return null;
+    }
+
     private void MicSpeaker_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
     {
         if (sender is FrameworkElement { DataContext: MainViewModel vm })
@@ -262,21 +301,135 @@ public partial class MainWindow : Window
 
     private void WebcamMenu_SetBorderAnimation(object sender, RoutedEventArgs e)
     {
-        if (sender is MenuItem { DataContext: WebcamSceneConfig webcam, Tag: string tag }
-            && Enum.TryParse<BorderAnimation>(tag, out var animation))
-            webcam.BorderAnimation = animation;
+        if (sender is not MenuItem { DataContext: SceneElement element, Tag: string tag }
+            || !Enum.TryParse<BorderAnimation>(tag, out var animation))
+            return;
+
+        element.BorderAnimation = animation;
+
+        StopBorderAnimation(element.Id);
+
+        if (animation == BorderAnimation.None) return;
+
+        var shape = FindBorderShape(sender as DependencyObject);
+        if (shape == null) return;
+
+        var sb = CreateBorderAnimation(animation, shape);
+        if (sb == null) return;
+
+        sb.Freeze();
+        _activeBorderAnimations[element.Id] = sb;
+        shape.BeginAnimation(Shape.OpacityProperty, null);
+        Storyboard.SetTarget(sb, shape);
+        sb.Begin();
+    }
+
+    private void StopBorderAnimation(string elementId)
+    {
+        if (_activeBorderAnimations.TryGetValue(elementId, out var old))
+        {
+            old.Stop();
+            _activeBorderAnimations.Remove(elementId);
+        }
+    }
+
+    private static Shape? FindBorderShape(DependencyObject? start)
+    {
+        var current = start;
+        while (current != null)
+        {
+            if (current is ContextMenu cm && cm.PlacementTarget is FrameworkElement target)
+            {
+                for (var i = 0; i < VisualTreeHelper.GetChildrenCount(target); i++)
+                {
+                    var child = VisualTreeHelper.GetChild(target, i);
+                    if (child is Shape s && (s is Rectangle or Ellipse) && !s.IsHitTestVisible)
+                        return s;
+                }
+                return null;
+            }
+            current = VisualTreeHelper.GetParent(current);
+        }
+        return null;
+    }
+
+    private static Storyboard? CreateBorderAnimation(BorderAnimation animation, Shape shape)
+    {
+        var sb = new Storyboard();
+        switch (animation)
+        {
+            case BorderAnimation.Pulse:
+                AddDoubleAnimation(sb, Shape.OpacityProperty, 1.0, 0.3, TimeSpan.FromSeconds(0.8), true);
+                break;
+            case BorderAnimation.Glow:
+                AddDoubleAnimation(sb, Shape.OpacityProperty, 1.0, 0.5, TimeSpan.FromSeconds(1.2), true);
+                break;
+            case BorderAnimation.Shimmer:
+                AddDoubleAnimation(sb, Shape.OpacityProperty, 1.0, 0.15, TimeSpan.FromSeconds(0.5), true);
+                break;
+            case BorderAnimation.Electricity:
+                AddDoubleAnimation(sb, Shape.OpacityProperty, 1.0, 0.2, TimeSpan.FromSeconds(0.1), true);
+                break;
+            case BorderAnimation.Sparkles:
+                AddDoubleAnimation(sb, Shape.OpacityProperty, 1.0, 0.4, TimeSpan.FromSeconds(0.3), true);
+                break;
+            case BorderAnimation.MarchingAnts:
+                shape.StrokeDashArray = new DoubleCollection { 4, 2 };
+                AddDoubleAnimation(sb, Shape.StrokeDashOffsetProperty, 0, -20, TimeSpan.FromSeconds(0.8), false);
+                break;
+            case BorderAnimation.Chase:
+                shape.StrokeDashArray = new DoubleCollection { 8, 4 };
+                AddDoubleAnimation(sb, Shape.StrokeDashOffsetProperty, 0, -30, TimeSpan.FromSeconds(1.5), false);
+                break;
+            case BorderAnimation.Rainbow:
+                if (shape.Stroke is SolidColorBrush brush)
+                {
+                    var frozen = brush.IsFrozen;
+                    if (frozen) brush = brush.Clone();
+                    shape.Stroke = brush;
+                    var colorAnim = new ColorAnimationUsingKeyFrames
+                    {
+                        Duration = new Duration(TimeSpan.FromSeconds(3)),
+                        RepeatBehavior = RepeatBehavior.Forever
+                    };
+                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.Red, KeyTime.FromTimeSpan(TimeSpan.Zero)));
+                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.Yellow, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(0.5))));
+                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.Green, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(1))));
+                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.DodgerBlue, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(1.5))));
+                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.MediumPurple, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(2))));
+                    colorAnim.KeyFrames.Add(new LinearColorKeyFrame(Colors.Red, KeyTime.FromTimeSpan(TimeSpan.FromSeconds(2.5))));
+                    Storyboard.SetTargetProperty(colorAnim, new PropertyPath("(Shape.Stroke).(SolidColorBrush.Color)"));
+                    sb.Children.Add(colorAnim);
+                }
+                break;
+            default:
+                return null;
+        }
+        return sb.Children.Count > 0 ? sb : null;
+    }
+
+    private static void AddDoubleAnimation(Storyboard sb, DependencyProperty prop,
+        double from, double to, Duration duration, bool autoReverse)
+    {
+        var anim = new DoubleAnimation(from, to, duration)
+        {
+            AutoReverse = autoReverse,
+            RepeatBehavior = RepeatBehavior.Forever
+        };
+        Storyboard.SetTargetProperty(anim, new PropertyPath(prop));
+        sb.Children.Add(anim);
     }
 
     private void WebcamMenu_SetBorderColor(object sender, RoutedEventArgs e)
     {
-        if (sender is MenuItem { DataContext: WebcamSceneConfig webcam, Tag: string color })
-            webcam.BorderColor = color;
+        if (sender is MenuItem { DataContext: SceneElement element, Tag: string color })
+            element.BorderColor = color;
     }
 
     private void WebcamMenu_HideInScene(object sender, RoutedEventArgs e)
     {
-        if (sender is MenuItem { DataContext: WebcamSceneConfig webcam })
-            webcam.IsVisible = false;
+        if (sender is MenuItem { DataContext: SceneElement element })
+            element.IsVisible = false;
     }
 
     private void WebcamMenu_Remove(object sender, RoutedEventArgs e)
@@ -369,11 +522,13 @@ public partial class MainWindow : Window
         else if (_isResizing)
         {
             var isWebcam = selected is WebcamSceneConfig;
+            var isRound = selected.ClipShape == ClipShape.Round;
+            var proportional = isRound || Keyboard.Modifiers.HasFlag(ModifierKeys.Shift);
             var maxW = isWebcam ? MainViewModel.MaxWebcamWidthFor(_viewModel.ActiveScene?.Name) : 1920;
             var maxH = isWebcam ? MainViewModel.MaxWebcamHeightFor(_viewModel.ActiveScene?.Name) : 1080;
             var newW = Math.Clamp(p.X - selected.X, 32, maxW);
-            var newH = newW / _resizeAspect;
-            if (newH > maxH)
+            var newH = proportional ? newW / _resizeAspect : Math.Clamp(p.Y - selected.Y, 32, maxH);
+            if (proportional && newH > maxH)
             {
                 newH = maxH;
                 newW = newH * _resizeAspect;

Models/SceneCatalog.cs

@@ -1,5 +1,7 @@
 using System;
+using System.Globalization;
 using System.Linq;
+using System.Windows.Data;
 
 namespace ytLive.Models;
 
@@ -19,6 +21,24 @@ public static class SceneCatalog
 
     public static readonly string[] All = { Starting, Live, Brb, Chat, Ending };
 
+    private static readonly Dictionary<string, string> DisplayNames = new(StringComparer.OrdinalIgnoreCase)
+    {
+    };
+
+    public static string DisplayName(string? name)
+        => name != null && DisplayNames.TryGetValue(name.Trim(), out var display) ? display : name ?? string.Empty;
+
+    public static readonly IValueConverter DisplayNameConverter = new SceneDisplayNameConverter();
+
+    private sealed class SceneDisplayNameConverter : IValueConverter
+    {
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+            => DisplayName(value as string);
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+            => value ?? string.Empty;
+    }
+
     public static bool IsCanonical(string? name)
         => name != null && All.Contains(name.Trim(), StringComparer.OrdinalIgnoreCase);
 

Models/Source.cs

@@ -52,6 +52,9 @@ public class Source : SceneElement
     private bool _isBackdrop;
     public bool IsBackdrop { get => _isBackdrop; set => Set(ref _isBackdrop, value); }
 
+    private bool _showDesktop;
+    public bool ShowDesktop { get => _showDesktop; set => Set(ref _showDesktop, value); }
+
     private bool _isEnabled = true;
     public bool IsEnabled { get => _isEnabled; set => Set(ref _isEnabled, value); }
 
@@ -91,7 +94,9 @@ public class Source : SceneElement
 
     public ImageSource? ImageSource => _imageSource;
 
-    public override ImageSource? DisplaySource => IsLiveCapture ? VideoImageSource : _imageSource;
+    public override ImageSource? DisplaySource => IsLiveCapture
+        ? (VideoImageSource ?? _imageSource)
+        : (Type == SourceType.ChatBox ? VideoImageSource : _imageSource);
 
     public override bool IsImageSource => Type == SourceType.Image;
 
@@ -119,7 +124,34 @@ public class Source : SceneElement
     public string ChatFontColor { get => _chatFontColor; set => Set(ref _chatFontColor, value); }
 
     private string _chatBackgroundColor = "#80000000";
-    public string ChatBackgroundColor { get => _chatBackgroundColor; set => Set(ref _chatBackgroundColor, value); }
+    public string ChatBackgroundColor
+    {
+        get => _chatBackgroundColor;
+        set
+        {
+            if (Set(ref _chatBackgroundColor, value))
+                Raise(nameof(ChatBackgroundOpacity));
+        }
+    }
+
+    /// <summary>Alpha channel of ChatBackgroundColor as 0.0–1.0. Slider writes back the full hex string.</summary>
+    public double ChatBackgroundOpacity
+    {
+        get
+        {
+            var hex = _chatBackgroundColor.Trim().TrimStart('#');
+            return hex.Length == 8
+                ? byte.Parse(hex.AsSpan(0, 2), System.Globalization.NumberStyles.HexNumber) / 255.0
+                : 1.0;
+        }
+        set
+        {
+            var alpha = (byte)Math.Clamp(value * 255, 0, 255);
+            var hex = _chatBackgroundColor.Trim().TrimStart('#');
+            if (hex.Length == 8) hex = hex[2..];
+            if (hex.Length == 6) ChatBackgroundColor = $"#{alpha:X2}{hex}";
+        }
+    }
 
     private int _chatMaxMessages = 5;
     public int ChatMaxMessages
@@ -140,5 +172,22 @@ public class Source : SceneElement
     private string _chatSuperChatColor = "#eab308";
     public string ChatSuperChatColor { get => _chatSuperChatColor; set => Set(ref _chatSuperChatColor, value); }
 
+    private string _chatFontFamily = "Segoe UI";
+    public string ChatFontFamily { get => _chatFontFamily; set => Set(ref _chatFontFamily, value); }
+
+    private int _chatFadeSeconds;
+    public int ChatFadeSeconds
+    {
+        get => _chatFadeSeconds;
+        set => Set(ref _chatFadeSeconds, Math.Clamp(value, 0, 60));
+    }
+
     public bool IsChatBox => Type == SourceType.ChatBox;
+
+    private bool _chatPreviewEnabled = true;
+    public bool ChatPreviewEnabled
+    {
+        get => _chatPreviewEnabled;
+        set => Set(ref _chatPreviewEnabled, value);
+    }
 }

Services/ChatBoxRenderer.cs

@@ -24,6 +24,7 @@ public sealed class ChatBoxRenderer
         int width,
         int height,
         double fontSize,
+        string fontFamily,
         string fontColorHex,
         string backgroundColorHex,
         int maxMessages,
@@ -79,7 +80,7 @@ public sealed class ChatBoxRenderer
                     text,
                     InvariantCulture,
                     FlowDirection.LeftToRight,
-                    new Typeface(new FontFamily("Segoe UI"), FontStyles.Normal, FontWeights.Normal, FontStretches.Normal),
+                    new Typeface(new FontFamily(fontFamily), FontStyles.Normal, FontWeights.Normal, FontStretches.Normal),
                     fontSize,
                     brush,
                     dpi);

Services/IFullScreenDetector.cs

@@ -18,4 +18,17 @@ public interface IFullScreenDetector
 
     /// <summary>All monitors in capture-key order (enumeration order).</summary>
     IReadOnlyList<DisplayInfo> GetDisplays();
+
+    /// <summary>
+    /// Raised on the UI thread whenever the foreground window changes.
+    /// Payload is the full-screen monitor index, or null when the new
+    /// foreground window is not full-screen / is one of our own windows.
+    /// </summary>
+    event Action<int?>? FullscreenMonitorChanged;
+
+    /// <summary>Hook EVENT_SYSTEM_FOREGROUND so <see cref="FullscreenMonitorChanged"/> fires.</summary>
+    void StartWatching();
+
+    /// <summary>Unhook the foreground listener.</summary>
+    void StopWatching();
 }

Services/LayoutStore.cs

@@ -261,6 +261,12 @@ public class LayoutStore : IDisposable
             cmd.CommandText = "ALTER TABLE Source ADD COLUMN ChatSuperChatColor TEXT NOT NULL DEFAULT '#eab308';";
             cmd.ExecuteNonQuery();
         }
+        if (!columns.Contains("ShowDesktop"))
+        {
+            using var cmd = _connection.CreateCommand();
+            cmd.CommandText = "ALTER TABLE Source ADD COLUMN ShowDesktop INTEGER NOT NULL DEFAULT 0;";
+            cmd.ExecuteNonQuery();
+        }
     }
 
     // v3 → v4: WebcamSceneConfig gains RectWidth/RectHeight (the pre-Round rect,
@@ -560,7 +566,7 @@ public class LayoutStore : IDisposable
             cmd.CommandText = """
                 SELECT Id, SceneId, AssetId, Type, Name, IsEnabled,
                        X, Y, Width, Height, Opacity, MonitorIndex, ClipShape, IsMirrored,
-                       IsBackdrop, CaptureKey,
+                       IsBackdrop, CaptureKey, ShowDesktop,
                        ChatFontSize, ChatFontColor, ChatBackgroundColor, ChatMaxMessages,
                        ChatShowTimestamps, ChatShowBadges, ChatMemberColor, ChatSuperChatColor
                 FROM Source ORDER BY SortOrder
@@ -586,14 +592,15 @@ public class LayoutStore : IDisposable
                     IsMirrored = reader.GetInt32(13) != 0,
                     IsBackdrop = reader.GetInt32(14) != 0,
                     CaptureKey = reader.IsDBNull(15) ? null : reader.GetString(15),
-                    ChatFontSize = reader.IsDBNull(16) ? 16 : reader.GetDouble(16),
-                    ChatFontColor = reader.IsDBNull(17) ? "#FFFFFF" : reader.GetString(17),
-                    ChatBackgroundColor = reader.IsDBNull(18) ? "#80000000" : reader.GetString(18),
-                    ChatMaxMessages = reader.IsDBNull(19) ? 5 : reader.GetInt32(19),
-                    ChatShowTimestamps = reader.IsDBNull(20) ? true : reader.GetInt32(20) != 0,
-                    ChatShowBadges = reader.IsDBNull(21) ? true : reader.GetInt32(21) != 0,
-                    ChatMemberColor = reader.IsDBNull(22) ? "#e94560" : reader.GetString(22),
-                    ChatSuperChatColor = reader.IsDBNull(23) ? "#eab308" : reader.GetString(23),
+                    ShowDesktop = reader.GetInt32(16) != 0,
+                    ChatFontSize = reader.IsDBNull(17) ? 16 : reader.GetDouble(17),
+                    ChatFontColor = reader.IsDBNull(18) ? "#FFFFFF" : reader.GetString(18),
+                    ChatBackgroundColor = reader.IsDBNull(19) ? "#80000000" : reader.GetString(19),
+                    ChatMaxMessages = reader.IsDBNull(20) ? 5 : reader.GetInt32(20),
+                    ChatShowTimestamps = reader.IsDBNull(21) ? true : reader.GetInt32(21) != 0,
+                    ChatShowBadges = reader.IsDBNull(22) ? true : reader.GetInt32(22) != 0,
+                    ChatMemberColor = reader.IsDBNull(23) ? "#e94560" : reader.GetString(23),
+                    ChatSuperChatColor = reader.IsDBNull(24) ? "#eab308" : reader.GetString(24),
                 };
                 if (!sourcesByScene.TryGetValue(sceneId, out var list))
                     sourcesByScene[sceneId] = list = new List<Source>();
@@ -784,12 +791,12 @@ public class LayoutStore : IDisposable
             cmd.CommandText = """
                 INSERT INTO Source (Id, SceneId, AssetId, Type, Name, IsEnabled,
                                     X, Y, Width, Height, Opacity, MonitorIndex,
-                                    ClipShape, IsMirrored, IsBackdrop, CaptureKey, SortOrder,
+                                    ClipShape, IsMirrored, IsBackdrop, CaptureKey, ShowDesktop, SortOrder,
                                     ChatFontSize, ChatFontColor, ChatBackgroundColor, ChatMaxMessages,
                                     ChatShowTimestamps, ChatShowBadges, ChatMemberColor, ChatSuperChatColor)
                 VALUES ($id, $sceneId, $assetId, $type, $name, $isEnabled,
                         $x, $y, $w, $h, $opacity, $monitor,
-                        $clip, $mirrored, $isBackdrop, $captureKey, $sort,
+                        $clip, $mirrored, $isBackdrop, $captureKey, $showDesktop, $sort,
                         $chatFontSize, $chatFontColor, $chatBgColor, $chatMaxMsgs,
                         $chatTimestamps, $chatBadges, $chatMemberColor, $chatSuperChatColor)
                 """;
@@ -810,6 +817,7 @@ public class LayoutStore : IDisposable
             var mirroredP = cmd.Parameters.Add("$mirrored", SqliteType.Integer);
             var isBackdropP = cmd.Parameters.Add("$isBackdrop", SqliteType.Integer);
             var captureKeyP = cmd.Parameters.Add("$captureKey", SqliteType.Text);
+            var showDesktopP = cmd.Parameters.Add("$showDesktop", SqliteType.Integer);
             var sortP = cmd.Parameters.Add("$sort", SqliteType.Integer);
             var chatFontSizeP = cmd.Parameters.Add("$chatFontSize", SqliteType.Real);
             var chatFontColorP = cmd.Parameters.Add("$chatFontColor", SqliteType.Text);
@@ -842,6 +850,7 @@ public class LayoutStore : IDisposable
                     mirroredP.Value = source.IsMirrored ? 1 : 0;
                     isBackdropP.Value = source.IsBackdrop ? 1 : 0;
                     captureKeyP.Value = (object?)source.CaptureKey ?? DBNull.Value;
+                    showDesktopP.Value = source.ShowDesktop ? 1 : 0;
                     sortP.Value = sort++;
                     chatFontSizeP.Value = source.ChatFontSize;
                     chatFontColorP.Value = source.ChatFontColor;

Services/Win32FullScreenDetector.cs

@@ -26,6 +26,49 @@ public sealed class Win32FullScreenDetector : IFullScreenDetector
     private const int DwmwaExtendedFrameBounds = 9;
     private const uint MonitorDefaultToNearest = 2;
     private const uint MonitorInfoFPrimary = 0x00000001;
+    private const uint EventSystemForeground = 0x0003;
+    private const uint WINEVENTOutofContext = 0x0000;
+    private const int GWL_EXSTYLE = -20;
+
+    private IntPtr _hookHandle;
+    private WinEventProc? _hookProc;
+    private int? _lastReportedMonitor;
+
+    public event Action<int?>? FullscreenMonitorChanged;
+
+    public void StartWatching()
+    {
+        if (_hookHandle != IntPtr.Zero) return;
+        _hookProc = ForegroundHookCallback;
+        _hookHandle = SetWinEventHook(EventSystemForeground, EventSystemForeground,
+            IntPtr.Zero, _hookProc, 0, 0, WINEVENTOutofContext);
+
+        var existing = FindAnyFullscreenGameMonitor();
+        if (existing != null)
+        {
+            _lastReportedMonitor = existing;
+            FullscreenMonitorChanged?.Invoke(existing);
+        }
+    }
+
+    public void StopWatching()
+    {
+        if (_hookHandle == IntPtr.Zero) return;
+        UnhookWinEvent(_hookHandle);
+        _hookHandle = IntPtr.Zero;
+        _hookProc = null;
+        _lastReportedMonitor = null;
+    }
+
+    private void ForegroundHookCallback(IntPtr hWinEventHook, uint eventType,
+        IntPtr hwnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime)
+    {
+        if (hwnd == IntPtr.Zero || IsOwnWindow(hwnd)) return;
+        var monitor = GetForegroundFullScreenMonitorIndex();
+        if (monitor == _lastReportedMonitor) return;
+        _lastReportedMonitor = monitor;
+        FullscreenMonitorChanged?.Invoke(monitor);
+    }
 
     public int? GetForegroundFullScreenMonitorIndex()
     {
@@ -69,6 +112,43 @@ public sealed class Win32FullScreenDetector : IFullScreenDetector
         return index >= 0 ? index : null;
     }
 
+    /// <summary>
+    /// Scans every visible top-level window (not just the foreground one) for
+    /// full-screen state. Used at startup to catch a game already running on
+    /// another monitor before the hook has a chance to fire.
+    /// </summary>
+    private int? FindAnyFullscreenGameMonitor()
+    {
+        int? found = null;
+        EnumWindows((hwnd, _) =>
+        {
+            if (found != null) return false;
+            if (hwnd == IntPtr.Zero || IsOwnWindow(hwnd)) return true;
+            if (!IsWindowVisible(hwnd)) return true;
+            if (!HasAppWindowStyle(hwnd)) return true;
+            if (!TryGetExtendedFrameBounds(hwnd, out var bounds)) return true;
+
+            var monitor = MonitorFromWindow(hwnd, MonitorDefaultToNearest);
+            if (monitor == IntPtr.Zero || !TryGetMonitorInfo(monitor, out var info)) return true;
+
+            var r = info.RcMonitor;
+            if (bounds.Left <= r.Left && bounds.Top <= r.Top &&
+                bounds.Right >= r.Right && bounds.Bottom >= r.Bottom)
+                found = MonitorIndex(monitor);
+            return found == null;
+        }, IntPtr.Zero);
+        return found;
+    }
+
+    private static bool HasAppWindowStyle(IntPtr hwnd)
+    {
+        const uint WS_EX_APPWINDOW = 0x00040000;
+        const uint WS_EX_TOOLWINDOW = 0x00000080;
+        var exStyle = (uint)GetWindowLongPtr(hwnd, GWL_EXSTYLE);
+        return (exStyle & WS_EX_TOOLWINDOW) == 0 &&
+               (exStyle & WS_EX_APPWINDOW) != 0;
+    }
+
     public int PrimaryMonitorIndex()
         => GetDisplays().FirstOrDefault(d => d.IsPrimary)?.Index ?? 0;
 
@@ -191,4 +271,23 @@ public sealed class Win32FullScreenDetector : IFullScreenDetector
     private static extern int DwmGetWindowAttribute(IntPtr hwnd, int dwAttribute, ref Win32Rect pvAttribute, int cbAttribute);
 
     private delegate bool MonitorEnumProc(IntPtr hMonitor, IntPtr hdcMonitor, ref Win32Rect lprcMonitor, IntPtr dwData);
+
+    private delegate void WinEventProc(IntPtr hWinEventHook, uint eventType, IntPtr hwnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime);
+
+    [DllImport("user32.dll")]
+    private static extern IntPtr SetWinEventHook(uint eventMin, uint eventMax, IntPtr hmodWinEventProc, WinEventProc pfnWinEventProc, uint idProcess, uint idThread, uint dwFlags);
+
+    [DllImport("user32.dll")]
+    private static extern bool UnhookWinEvent(IntPtr hWinEventHook);
+
+    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", EntryPoint = "GetWindowLongPtr")]
+    private static extern IntPtr GetWindowLongPtr(IntPtr hWnd, int nIndex);
 }

TASKS.md

@@ -120,6 +120,12 @@ Lifecycle: `created → ready → [testing] → live → complete` (transitional
 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 / subscribe pop-ins; build after the six; **the one paid feature** (see Monetization in `ai.md`)
+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
 
@@ -848,14 +854,14 @@ No changes to `MusicPlayer`, the 0.20 cap, the ducker, or the meter zones. Build
 **Goal:** branded background images for each canonical scene (Starting, Live, BRB, Chat, Ending)
 that both provide working hints to creators and self-promote LlamaCasty.
 
-### Status: 🔶 2/5 seeded — Starting and BRB done; Live, Chat, Ending waiting on user images
+### Status: ✅ Shipped — all 5 scenes seeded
 
 1. ✅ **Starting backdrop** — `Assets/starting-backdrop.jpg` (embedded resource), `SeedStartingBackdrop()` in MainViewModel, idempotent
 2. ✅ **BRB backdrop** — `Assets/brb-backdrop.jpg` (user-provided Gemini image), `SeedBrbBackdrop()` in MainViewModel, idempotent
-3. ☐ User provides 3 more background images (Live, Chat, Ending), PNG/JPG format, 1920×1080
-4. ☐ Wire images as default `Background` sources, auto-populated on DB seed
-5. ☐ Assets stored in DB via `Asset` table (BLOB, SHA-256 keyed) — survives file deletion
-6. ☐ Used by TASK 16 (infinity display fix) as the static fallback when no game is detected
+3. ✅ **Live backdrop** — `Assets/live-backdrop.jpg` (user-provided image), seeded via `SeedLiveBackdropAsset()`, used as the static fallback (TASK 16)
+4. ✅ **Ending backdrop** — `Assets/ending-backdrop.jpg` (user-provided image), `SeedEndingBackdrop()` replaces existing (not skip-if-exists)
+5. ✅ **Chat backdrop** — `Assets/chat-backdrop.jpg` (user-provided image), `SeedChatBackdrop()` at startup
+6. ✅ `EnsureDefaultBackdrop()` called on every scene switch — seeds the default backdrop if scene has none
 
 ### Design decisions
 
@@ -870,22 +876,24 @@ that both provide working hints to creators and self-promote LlamaCasty.
 **Goal:** when no full-screen game is detected, show a static branded placeholder instead of
 capturing the primary display (which causes the infinity mirror effect).
 
-### Status: ☐ Not started — depends on TASK 15
+### Status: ✅ Shipped
 
-1. ☐ Modify `ResolveAutoCaptureKey()` (`MainViewModel.cs:1482`) — return null when no game detected
-   instead of falling back to primary monitor
-2. ☐ Modify `EnsureBackdrop()` — when `CaptureKey` is null, show the scene's `Background` image
-   (the stock image from TASK 15) instead of creating a capture session
-3. ☐ "Change Capture…" still available — user can manually pick a display/window via the picker
-4. ☐ `ReacquireScreenCaptures()` handles null capture key gracefully (no `ScreenCaptureManager.AcquireAsync` call)
-5. ☐ Update `ai.md` screen backdrop section to document the null-capture-key behavior
+**Changes:**
+1. `ResolveAutoCaptureKey()` returns `null` when no full-screen game is detected (was: primary monitor)
+2. `ReacquireScreenCaptures()` — clears stale `CaptureKey` when `auto == null` (handles DB upgrades);
+   skips `AcquireAsync` when no keys are set
+3. `SeedLiveBackdropAsset()` — sets `AssetId` on the backdrop element itself (NOT a Background source);
+   called from `ReacquireScreenCaptures()` after `EnsureBackdrop()` guarantees the element exists
+4. `Source.DisplaySource` falls back to `_imageSource` when `VideoImageSource` is null for live captures
+5. `Assets/live-backdrop.jpg` — user-provided image, added as `<Resource>` in csproj
+6. `ResolveOutputFrame()` in compositor — `Source { IsLiveCapture: true, CaptureKey: not null }` already skips null keys; fallback pattern `Source { AssetId: not null }` picks up the static image
 
-### Design decisions
-
-- **Option A from user review:** static placeholder when no game, not multi-monitor fallback
-- The user-provided stock bg image from TASK 15 IS the placeholder — no separate asset needed
-- Manual capture pick still works — the user can always force a display capture via right-click → "Change Capture…"
-- Single-monitor setups no longer show the infinity mirror
+**Rendering flow:**
+| Scenario | Preview | Compositor |
+|---|---|---|
+| Game detected | Live capture (opaque, covers static asset on backdrop) | `ScreenCaptureManager.GetLatestFrame` |
+| No game | Static image via `DisplaySource` → `_imageSource` on backdrop | `StaticPixelCache.Get(assetId)` |
+| Manual capture pick | Live capture | Live frame |
 
 ---
 
@@ -954,9 +962,8 @@ The tasks below are ordered by dependency and risk. Each task builds on the prev
 8. **TASK 21** — Media source — video file playback for non-Live scenes.
 9. **TASK 22** — Audio sync offset — small, quality-of-life.
 10. **TASK 23** — Studio mode — lightweight preview before live.
-11. **TASK 15** — Stock bg images — Starting and BRB seeded; Live, Chat, Ending still waiting on user.
-12. **TASK 16** — Infinity display fix — depends on TASK 15.
-13. **TASK 13** — Social media launch kit — after all v1 features ship.
+11. ✅ **TASK 15** — Stock bg images — all 5 scenes seeded (Starting, BRB, Live, Chat, Ending). `EnsureDefaultBackdrop()` runs on every scene switch.
+12. **TASK 13** — Social media launch kit — after all v1 features ship.
 
 ---
 

Themes/Controls.xaml

@@ -302,7 +302,7 @@
         <Setter Property="Template">
             <Setter.Value>
                 <ControlTemplate TargetType="RepeatButton">
-                    <Border Background="{Binding Tag, RelativeSource={RelativeSource TemplatedParent}}"/>
+                    <Border Background="{x:Null}"/>
                 </ControlTemplate>
             </Setter.Value>
         </Setter>
@@ -366,7 +366,7 @@
                             </Track.DecreaseRepeatButton>
                             <Track.IncreaseRepeatButton>
                                 <RepeatButton Command="{x:Static Slider.IncreaseLarge}"
-                                              Style="{StaticResource YtSliderTrackButton}" Tag="Transparent"/>
+                                              Style="{StaticResource YtSliderTrackButton}"/>
                             </Track.IncreaseRepeatButton>
                             <Track.Thumb>
                                 <Thumb Style="{StaticResource YtSliderThumb}"/>

ViewModels/MainViewModel.cs

@@ -127,11 +127,23 @@ public class MainViewModel : ViewModelBase
     private readonly ScreenCaptureManager _screenCaptureManager;
     private readonly ScreenCaptureSourceFactory _screenCaptureFactory;
     private readonly ChatBoxRenderer _chatBoxRenderer;
-    private int? _lastForegroundFullScreenMonitor;
-    private CancellationTokenSource? _deactivateCts;
+
+    // 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 },
+    };
     private ImageSource? _backdropImage;
     private HashSet<string> _liveCaptureKeys = new();
 
+    // Chat fade timer: clears chat overlay after N seconds of inactivity.
+    private System.Windows.Threading.DispatcherTimer? _chatFadeTimer;
+
     // Branding flash (monetization): a full-frame "made with ytLlive!" shown
     // for ~1s every 300s on the live output, ~25% opacity. Paid unlock sets
     // BrandFlashEnabled = false. See ai.md "Monetization".
@@ -172,6 +184,7 @@ public class MainViewModel : ViewModelBase
             if (SetProperty(ref _activeScene, value))
             {
                 SelectedElement = null;
+                EnsureDefaultBackdrop(value);
                 OnPropertyChanged(nameof(ShowChatInactiveMessage));
                 OnPropertyChanged(nameof(ShowEmptySceneHint));
                 OnPropertyChanged(nameof(ShowPreviewPlaceholder));
@@ -758,7 +771,7 @@ public class MainViewModel : ViewModelBase
     public string RecDotBrush => !IsLive ? "#555555" : IsLivePrivate ? "#8f1f1f" : "#e94560";
     public string RecTextBrush => IsLive ? "#ffffff" : "#888888";
     public double RecDotOpacity => IsLive ? _recDotPulse : 0.55;
-    public bool ShowStartStream => IsOffline;
+    public bool ShowStartStream => IsOffline && IsConnected;
     public bool ShowChatInactiveMessage => !IsLive;
     public bool ShowEmptySceneHint => ActiveScene != null && ActiveScene.Elements.Count == 0;
     public bool ShowPreviewPlaceholder => !ShowEmptySceneHint && ActiveBackgroundImage == null && BackdropImage == null;
@@ -1124,6 +1137,7 @@ public class MainViewModel : ViewModelBase
     public ICommand ChangeCaptureCommand { get; }
     public ICommand RefreshCaptureCommand { get; }
     public ICommand SetBackdropDisplayCommand { get; }
+    public ICommand ToggleShowDesktopCommand { get; }
     public ICommand ToggleMicMuteCommand { get; }
     public ICommand ToggleGameMuteCommand { get; }
     public ICommand OpenMicPickerCommand { get; }
@@ -1194,6 +1208,7 @@ public class MainViewModel : ViewModelBase
         ChangeCaptureCommand = new RelayCommand(_ => _ = ChangeBackdropCaptureAsync());
         RefreshCaptureCommand = new RelayCommand(_ => RefreshBackdropAutoCapture());
         SetBackdropDisplayCommand = new RelayCommand(display => SetBackdropCapture(display as DisplayInfo));
+        ToggleShowDesktopCommand = new RelayCommand(_ => ToggleBackdropShowDesktop());
         ToggleMicMuteCommand = new RelayCommand(_ => ToggleMicMute());
         ToggleGameMuteCommand = new RelayCommand(_ => ToggleGameMute());
         OpenMicPickerCommand = new RelayCommand(_ => PickMicrophone());
@@ -1256,6 +1271,7 @@ public class MainViewModel : ViewModelBase
         _ = StartMicCaptureAsync();
 
         _fullScreenDetector = new Win32FullScreenDetector();
+        _fullScreenDetector.FullscreenMonitorChanged += OnFullscreenMonitorChanged;
         foreach (var display in _fullScreenDetector.GetDisplays())
             Displays.Add(display);
 
@@ -1357,6 +1373,8 @@ public class MainViewModel : ViewModelBase
             }
             SeedStartingBackdrop();
             SeedBrbBackdrop();
+            SeedEndingBackdrop();
+            SeedChatBackdrop();
 
             // The live backdrop belongs to Live only; a pre-policy DB may have
             // backdrops lingering in other scenes — drop them, then
@@ -1377,6 +1395,8 @@ public class MainViewModel : ViewModelBase
         }
         ActiveScene = Scenes.FirstOrDefault();
         UpdateActiveBackground();
+        UpdateActiveChatBoxPreviews();
+        StartMockChatPreview();
         UpdateBackdropImage();
         ReacquireWebcam();
         ReacquireScreenCaptures();
@@ -1486,11 +1506,21 @@ public class MainViewModel : ViewModelBase
     private IEnumerable<Source> AllBackdrops()
         => Scenes.SelectMany(s => s.Elements.OfType<Source>().Where(x => x.IsBackdrop));
 
-    // Full-screen game on its monitor, else the primary display. Called at launch
-    // (from ReacquireScreenCaptures, before the window steals focus) and on
-    // focus regain (RefreshBackdropAutoCapture).
-    private string ResolveAutoCaptureKey()
-        => $"{MonitorKeyPrefix}{_fullScreenDetector.GetForegroundFullScreenMonitorIndex() ?? _fullScreenDetector.PrimaryMonitorIndex()}";
+    // Full-screen game on its monitor, else null (static bg fallback — no
+    // infinity mirror). Called at launch (from ReacquireScreenCaptures, before
+    // the window steals focus) and on focus regain (RefreshBackdropAutoCapture).
+    // When a backdrop has ShowDesktop=true, returns the primary monitor instead
+    // of null so the desktop is always visible.
+    private string? ResolveAutoCaptureKey()
+    {
+        var gameMonitor = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
+        if (gameMonitor != null)
+            return $"{MonitorKeyPrefix}{gameMonitor}";
+
+        if (AllBackdrops().Any(b => b.ShowDesktop))
+            return $"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}";
+        return null;
+    }
 
     // After a layout load / file open: make sure every backdrop-enabled scene
     // has a backdrop, give any backdrop without a persisted key the auto-detected
@@ -1502,10 +1532,20 @@ public class MainViewModel : ViewModelBase
         foreach (var scene in Scenes)
             EnsureBackdrop(scene);
 
+        SeedLiveBackdropAsset();
+
         var auto = ResolveAutoCaptureKey();
-        foreach (var backdrop in AllBackdrops())
-            if (string.IsNullOrWhiteSpace(backdrop.CaptureKey))
-                backdrop.CaptureKey = auto;
+        if (auto == null)
+        {
+            foreach (var backdrop in AllBackdrops())
+                backdrop.CaptureKey = null;
+        }
+        else
+        {
+            foreach (var backdrop in AllBackdrops())
+                if (string.IsNullOrWhiteSpace(backdrop.CaptureKey))
+                    backdrop.CaptureKey = auto;
+        }
 
         var keys = AllBackdrops()
             .Select(b => b.CaptureKey!)
@@ -1520,6 +1560,8 @@ public class MainViewModel : ViewModelBase
 
         foreach (var key in keys)
             _ = _screenCaptureManager.AcquireAsync(key);
+
+        _fullScreenDetector.StartWatching();
     }
 
     // ScreenCaptureManager creates the shared WriteableBitmap on the UI thread;
@@ -1534,38 +1576,89 @@ public class MainViewModel : ViewModelBase
             backdrop.VideoImageSource = bitmap;
     }
 
-    // One-shot foreground snapshot ~250ms after we lose focus, so the next
-    // Activated re-detect can see the full-screen game the user switched to.
-    // A single sample per deactivation — not a session listener or a poller.
-    public void NoteBackgroundWindow()
+    // EVENT_SYSTEM_FOREGROUND fires whenever the foreground window changes.
+    // When a full-screen game appears on a different monitor than the current
+    // backdrop, auto-redesignate. When ShowDesktop is enabled and no fullscreen
+    // game is detected, fall back to the primary monitor (desktop view).
+    private void OnFullscreenMonitorChanged(int? monitor)
     {
-        _deactivateCts?.Cancel();
-        _deactivateCts = new CancellationTokenSource();
-        var token = _deactivateCts.Token;
-        _ = Task.Run(async () =>
+        if (monitor != null)
         {
-            try
-            {
-                await Task.Delay(250, token);
-                var monitor = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
-                if (!token.IsCancellationRequested)
-                    _lastForegroundFullScreenMonitor = monitor;
-            }
-            catch (OperationCanceledException) { }
-        });
+            var newKey = $"{MonitorKeyPrefix}{monitor}";
+            var current = AllBackdrops().FirstOrDefault();
+            if (current?.CaptureKey == newKey) return;
+            _ = RedesignateBackdropAsync(newKey);
+        }
+        else if (AllBackdrops().Any(b => b.ShowDesktop))
+        {
+            var desktopKey = $"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}";
+            var current = AllBackdrops().FirstOrDefault();
+            if (current?.CaptureKey == desktopKey) return;
+            _ = RedesignateBackdropAsync(desktopKey);
+        }
     }
 
-    // Re-runs full-screen detection at launch and when the app regains focus.
-    // A null detection (no full-screen foreground window — our app, the desktop,
-    // a normal window) leaves the current capture alone.
+    // Manual refresh: the "Refresh Capture" context menu item. Reads the
+    // current foreground directly (no caching needed — the hook handles
+    // automatic detection).
     public void RefreshBackdropAutoCapture()
     {
-        var detected = _lastForegroundFullScreenMonitor ?? _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
-        _lastForegroundFullScreenMonitor = null;
+        var detected = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
         if (detected == null) return;
         _ = RedesignateBackdropAsync($"{MonitorKeyPrefix}{detected}");
     }
 
+    /// <summary>Whether the active backdrop is in Show Desktop mode.
+    /// Bindable IsChecked property for the context menu toggle.</summary>
+    public bool BackdropShowDesktop
+    {
+        get => ActiveScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackdrop)?.ShowDesktop ?? false;
+        set
+        {
+            var backdrop = ActiveScene?.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackdrop);
+            if (backdrop == null || backdrop.ShowDesktop == value) return;
+            backdrop.ShowDesktop = value;
+            OnPropertyChanged(nameof(BackdropShowDesktop));
+            ScheduleSave();
+            if (value)
+            {
+                _ = RedesignateBackdropAsync($"{MonitorKeyPrefix}{_fullScreenDetector.PrimaryMonitorIndex()}");
+            }
+            else
+            {
+                var gameMonitor = _fullScreenDetector.GetForegroundFullScreenMonitorIndex();
+                if (gameMonitor != null)
+                    _ = RedesignateBackdropAsync($"{MonitorKeyPrefix}{gameMonitor}");
+                else
+                    _ = ClearBackdropCaptureAsync();
+            }
+        }
+    }
+
+    private void ToggleBackdropShowDesktop() => BackdropShowDesktop = !BackdropShowDesktop;
+
+    /// <summary>Release the backdrop capture so the static placeholder image shows.</summary>
+    private async Task ClearBackdropCaptureAsync()
+    {
+        var oldKeys = AllBackdrops()
+            .Select(b => b.CaptureKey!)
+            .Where(k => !string.IsNullOrWhiteSpace(k))
+            .ToHashSet();
+
+        foreach (var backdrop in AllBackdrops())
+        {
+            backdrop.CaptureKey = null;
+            backdrop.VideoImageSource = null;
+        }
+
+        foreach (var key in oldKeys)
+            await _screenCaptureManager.ReleaseAllAsync(key);
+
+        _liveCaptureKeys.Clear();
+        UpdateBackdropImage();
+        ScheduleSave();
+    }
+
     private async Task RedesignateBackdropAsync(string newKey)
     {
         var oldKeys = AllBackdrops()
@@ -1765,6 +1858,47 @@ public class MainViewModel : ViewModelBase
         catch { /* non-critical — stream works fine without a default bg */ }
     }
 
+    /// <summary>
+    /// When switching to a scene that has no background, seed the default.
+    /// </summary>
+    private void EnsureDefaultBackdrop(Scene? scene)
+    {
+        if (scene == null) return;
+        if (scene.Elements.OfType<Source>().Any(s => s.Type == SourceType.Background)) return;
+
+        string? asset = scene.Name switch
+        {
+            "Starting" => "starting-backdrop.jpg",
+            "BRB" => "brb-backdrop.jpg",
+            "Ending" => "ending-backdrop.jpg",
+            "Chat" => "chat-backdrop.jpg",
+            _ => null,
+        };
+        if (asset == null) return;
+
+        try
+        {
+            var uri = new Uri($"pack://application:,,,/Assets/{asset}", UriKind.Absolute);
+            using var stream = Application.GetResourceStream(uri)?.Stream;
+            if (stream == null) return;
+            using var ms = new MemoryStream();
+            stream.CopyTo(ms);
+            var bytes = ms.ToArray();
+            var assetId = AddAsset(bytes);
+            if (assetId == null) return;
+            scene.Elements.Add(new Source
+            {
+                Name = "Background",
+                Type = SourceType.Background,
+                AssetId = assetId,
+                Width = 1920,
+                Height = 1080,
+            });
+            UpdateActiveBackground();
+        }
+        catch { /* non-critical */ }
+    }
+
     private void SeedBrbBackdrop()
     {
         try
@@ -1803,6 +1937,106 @@ public class MainViewModel : ViewModelBase
         catch { /* non-critical — stream works fine without a default bg */ }
     }
 
+    private void SeedLiveBackdropAsset()
+    {
+        try
+        {
+            var live = Scenes.FirstOrDefault(s => SceneCatalog.Is(s.Name, "Live"));
+            if (live == null) return;
+            var backdrop = live.Elements.OfType<Source>().FirstOrDefault(s => s.IsBackdrop);
+            if (backdrop == null) return;
+
+            var uri = new Uri("pack://application:,,,/Assets/live-backdrop.jpg", UriKind.Absolute);
+            using var stream = Application.GetResourceStream(uri)?.Stream;
+            if (stream == null) return;
+            using var ms = new MemoryStream();
+            stream.CopyTo(ms);
+            var bytes = ms.ToArray();
+            var assetId = AddAsset(bytes);
+            if (assetId == null) return;
+            backdrop.AssetId = assetId;
+            backdrop.Width = 1920;
+            backdrop.Height = 1080;
+        }
+        catch { /* non-critical — stream works fine without a default bg */ }
+    }
+
+    private void SeedEndingBackdrop()
+    {
+        try
+        {
+            var ending = Scenes.FirstOrDefault(s => SceneCatalog.Is(s.Name, "Ending"));
+            if (ending == null) return;
+
+            var uri = new Uri("pack://application:,,,/Assets/ending-backdrop.jpg", UriKind.Absolute);
+            using var stream = Application.GetResourceStream(uri)?.Stream;
+            if (stream == null) return;
+            using var ms = new MemoryStream();
+            stream.CopyTo(ms);
+            var bytes = ms.ToArray();
+            var assetId = AddAsset(bytes);
+            if (assetId == null) return;
+
+            var existing = ending.Elements.OfType<Source>().FirstOrDefault(s => s.Type == SourceType.Background);
+            if (existing != null)
+            {
+                existing.AssetId = assetId;
+                existing.Width = 1920;
+                existing.Height = 1080;
+            }
+            else
+            {
+                ending.Elements.Add(new Source
+                {
+                    Name = "Background",
+                    Type = SourceType.Background,
+                    AssetId = assetId,
+                    Width = 1920,
+                    Height = 1080,
+                });
+            }
+        }
+        catch { /* non-critical — stream works fine without a default bg */ }
+    }
+
+    private void SeedChatBackdrop()
+    {
+        try
+        {
+            var chat = Scenes.FirstOrDefault(s => SceneCatalog.Is(s.Name, "Chat"));
+            if (chat == null) return;
+
+            var uri = new Uri("pack://application:,,,/Assets/chat-backdrop.jpg", UriKind.Absolute);
+            using var stream = Application.GetResourceStream(uri)?.Stream;
+            if (stream == null) return;
+            using var ms = new MemoryStream();
+            stream.CopyTo(ms);
+            var bytes = ms.ToArray();
+            var assetId = AddAsset(bytes);
+            if (assetId == null) return;
+
+            var existing = chat.Elements.OfType<Source>().FirstOrDefault(s => s.Type == SourceType.Background);
+            if (existing != null)
+            {
+                existing.AssetId = assetId;
+                existing.Width = 1920;
+                existing.Height = 1080;
+            }
+            else
+            {
+                chat.Elements.Add(new Source
+                {
+                    Name = "Background",
+                    Type = SourceType.Background,
+                    AssetId = assetId,
+                    Width = 1920,
+                    Height = 1080,
+                });
+            }
+        }
+        catch { /* non-critical — stream works fine without a default bg */ }
+    }
+
     private void BeginEditElement(SceneElement? element)
     {
         if (element == null) return;
@@ -1834,7 +2068,7 @@ public class MainViewModel : ViewModelBase
             SourceType.TextOverlay => "Text",
             SourceType.Countdown => "Countdown",
             SourceType.WebSource => "Web",
-            SourceType.ChatBox => "Chat",
+            SourceType.ChatBox => "YouTube Chat",
             _ => "Layer",
         };
 
@@ -1860,15 +2094,32 @@ public class MainViewModel : ViewModelBase
             return;
         }
 
-        scene.Elements.Add(new Source
+        var source = new Source
         {
             Name = NextSourceName(scene, baseName),
             Type = sourceType,
-            X = sourceType == SourceType.ChatBox ? 1520 : 0,
-            Y = 0,
-            Width = sourceType == SourceType.ChatBox ? 400 : 0,
-            Height = sourceType == SourceType.ChatBox ? 1080 : 0,
-        });
+            X = sourceType == SourceType.ChatBox ? 1400 : 0,
+            Y = sourceType == SourceType.ChatBox ? 20 : 0,
+            Width = sourceType == SourceType.ChatBox ? 500 : 0,
+            Height = sourceType == SourceType.ChatBox ? 648 : 0,
+        };
+        scene.Elements.Add(source);
+
+        if (sourceType == SourceType.ChatBox)
+        {
+            source.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))
+                    UpdateChatBoxPreview(source);
+            };
+            UpdateChatBoxPreview(source);
+        }
+
         OnPropertyChanged(nameof(ShowEmptySceneHint));
         OnPropertyChanged(nameof(ShowSourcesEmptyHint));
         UpdateActiveBackground();
@@ -2264,9 +2515,42 @@ public class MainViewModel : ViewModelBase
             ChatMessages.Add(message);
             if (ChatMessages.Count > 500)
                 ChatMessages.RemoveAt(0);
+
+            // Reset chat fade timer on every message
+            ResetChatFadeTimer();
+
+            StopMockChatPreview();
+
+            // Switch ChatBox previews from mock to real messages
+            if (ActiveScene != null)
+                foreach (var chatBox in ActiveScene.Elements.OfType<Source>().Where(s => s.Type == SourceType.ChatBox))
+                    UpdateChatBoxPreview(chatBox);
         });
     }
 
+    private void ResetChatFadeTimer()
+    {
+        _chatFadeTimer?.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);
+        _chatFadeTimer = new System.Windows.Threading.DispatcherTimer
+        { Interval = TimeSpan.FromSeconds(delay) };
+        _chatFadeTimer.Tick += (_, _) =>
+        {
+            _chatFadeTimer?.Stop();
+            _chatFadeTimer = null;
+            ChatMessages.Clear();
+            foreach (var chatBox in Scenes.SelectMany(s => s.Elements).OfType<Source>()
+                         .Where(s => s.Type == SourceType.ChatBox))
+                UpdateChatBoxPreview(chatBox);
+            StartMockChatPreview();
+        };
+        _chatFadeTimer.Start();
+    }
+
     private void BeginGoLive()
     {
         var dialog = new GoLiveViewModel(() => SignInAsync(), _youtubeAuth.CurrentChannel)
@@ -2514,6 +2798,7 @@ public class MainViewModel : ViewModelBase
             width,
             height,
             chatBox.ChatFontSize,
+            chatBox.ChatFontFamily,
             chatBox.ChatFontColor,
             chatBox.ChatBackgroundColor,
             chatBox.ChatMaxMessages,
@@ -2523,6 +2808,97 @@ public class MainViewModel : ViewModelBase
             chatBox.ChatSuperChatColor);
     }
 
+    /// <summary>
+    /// Renders the ChatBox preview: real messages when connected, mock when not.
+    /// </summary>
+    private void UpdateChatBoxPreview(Source chatBox, IReadOnlyList<ChatMessage>? messages = null)
+    {
+        try
+        {
+            messages ??= ChatMessages.Count > 0 ? (IReadOnlyList<ChatMessage>)ChatMessages : MockChatMessages;
+            var width = (int)Math.Max(32, chatBox.Width);
+            var height = (int)Math.Max(32, chatBox.Height);
+
+            var frame = _chatBoxRenderer.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, System.Windows.Media.PixelFormats.Bgra32, null);
+            bitmap.WritePixels(new System.Windows.Int32Rect(0, 0, width, height), frame.BgraPixels, frame.Stride, 0);
+            chatBox.VideoImageSource = bitmap;
+        }
+        catch (Exception ex) { AppLog.Write($"UpdateChatBoxPreview failed: {ex.Message}"); }
+    }
+
+    private CancellationTokenSource? _mockChatCts;
+
+    private async Task RunMockChatPreviewAsync(Source chatBox, CancellationToken ct)
+    {
+        var n = 0;
+        while (!ct.IsCancellationRequested)
+        {
+            UpdateChatBoxPreview(chatBox, MockChatMessages.Take(n + 1).ToList());
+            await Task.Delay(1000, ct);
+            n++;
+            if (n == MockChatMessages.Count)
+            {
+                await Task.Delay(3000, ct);
+                n = 0;
+            }
+        }
+    }
+
+    private void StartMockChatPreview()
+    {
+        StopMockChatPreview();
+        _mockChatCts = new CancellationTokenSource();
+        var ct = _mockChatCts.Token;
+        foreach (var chatBox in Scenes.SelectMany(s => s.Elements).OfType<Source>()
+                     .Where(s => s.Type == SourceType.ChatBox && s.ChatPreviewEnabled))
+            _ = RunMockChatPreviewAsync(chatBox, ct);
+    }
+
+    private void StopMockChatPreview()
+    {
+        _mockChatCts?.Cancel();
+        _mockChatCts?.Dispose();
+        _mockChatCts = 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>
+    private void UpdateActiveChatBoxPreviews()
+    {
+        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))
+                        UpdateChatBoxPreview(chatBox);
+                };
+                UpdateChatBoxPreview(chatBox);
+            }
+    }
+
     // The tier's crop rect over the 1920x1080 master, integer-aligned (the VM's
     // OutputRect* are doubles — the vertical 607.5 half-pixel crop rounds to 608).
     private CompositorOptions BuildCompositorOptions()

ai.md

@@ -132,7 +132,7 @@ C# / WPF (.NET 8) following MVVM:
 - `YouTubeStreamService` manages the **variable reusable stream** (shipped 2026-08-16): `GetOrCreateReusableStreamAsync` lists `liveStreams?mine=true` and reuses the existing `cdn.isReusable` stream, creating it only on first use (`resolution=variable`, `frameRate=variable`); the stream is cached via `LayoutStore` (`SaveReusableStream`/`LoadReusableStream`, Settings table) and bound at broadcast insert (`boundStreamId`). Health (shipped 2026-08-16): `GetStreamHealthAsync(streamId)` polls `liveStreams?part=status` for `healthStatus` + `configurationIssues[]` → `StreamHealth`; banner decision in pure `StreamHealthReporter`
 - Webcam capture is shipped (milestone 1); the live desktop/game backdrop is shipped (ship task #1); **the output compositor (TASK 4 ship step 1) is SHIPPED**, **the FFmpeg locator (TASK 4 ship step 2) is SHIPPED**, **the encoder + RTMP push (TASK 4 ship step 3) is SHIPPED**, **WASAPI audio capture (TASK 4 ship step 4) is SHIPPED** — full plan in `TASKS.md`; the frame-pipeline wiring follows (its own PR)
 - `StreamConfig` defaults (`TargetBitrate=6000`, `Resolution="1920x1080"`) are stale — the live dropdown drives `StreamHealth.CurrentBitrate`/`FPS` instead
-- **v1 task queue (2026-08-19):** tasks 19-23 added for v1 feature completeness; TASK 3.18 (chat box) shipped; TASK 10 (Polar billing) ready to execute (org ID obtained):
+- **v1 task queue (2026-08-19):** tasks 19-23 added for v1 feature completeness; TASK 3.18 (chat box) shipped; TASK 16 (infinity display) shipped; TASK 10 (Polar billing) ready to execute (org ID obtained):
   - TASK 10: Polar billing — license key entry, offline entitlement, brand flash gating, Velopack auto-updates
   - TASK 19: Scene transitions (Cut/Fade/Move/Custom) — required for professional polish
   - TASK 20: Hotkeys (global keyboard shortcuts) — the single biggest UX gap
@@ -163,19 +163,26 @@ instead of a normal draggable source.
   (the old `ToggleSceneBackdropCommand` is gone); "Change Capture…"/"Refresh Capture"/"Capture Display"
   only show in the Live scene's preview menu (`CanChangeBackdrop`). The static Background, if any,
   renders **above** the backdrop.
-- **Detection (launch + focus only, no live session listener):** `Win32FullScreenDetector` =
+- **Detection (event-driven):** `Win32FullScreenDetector` hooks `SetWinEventHook(EVENT_SYSTEM_FOREGROUND)`
+  — fires on the UI thread whenever the foreground window changes. The callback runs the same
   `GetForegroundWindow` + `DwmGetWindowAttribute(DWMWA_EXTENDED_FRAME_BOUNDS)` + `MonitorFromWindow` +
-  `GetMonitorInfo`; a window is full-screen when its frame covers all four monitor edges; own process is
-  excluded; monitor **index = `EnumDisplayMonitors` enumeration order** (the same order
+  `GetMonitorInfo` check; a window is full-screen when its frame covers all four monitor edges; own
+  process is excluded; monitor **index = `EnumDisplayMonitors` enumeration order** (the same order
   `ScreenCaptureSourceFactory` uses to map index→HMONITOR via `Win32FullScreenDetector.GetMonitorHandle`).
   `IFullScreenDetector` also exposes `GetDisplays()` (`DisplayInfo`: index/name/resolution/bounds/`IsPrimary`,
   friendly name via `EnumDisplayDevices`) + `PrimaryMonitorIndex()` for the in-app "Capture Display"
-  submenu. At launch `ReacquireScreenCaptures` keys the backdrop to the full-screen game's monitor (or the
-  **primary** display — never assumed monitor 0).
-  On **Deactivated**, `NoteBackgroundWindow` samples the foreground ~250ms later (so an alt-tab to a game
-  lands before the app re-activates); on the next **Activated**, `RefreshBackdropAutoCapture` re-runs
-  detection against that sample and re-designates. Null detection (our app, the desktop, a normal window)
-  leaves the current capture alone.
+  submenu + `FullscreenMonitorChanged` event + `StartWatching()`/`StopWatching()`. At launch
+  `ReacquireScreenCaptures` seeds the static fallback image (`Assets/live-backdrop.jpg`) onto the
+  backdrop's `AssetId` via `SeedLiveBackdropAsset()`, then keys the backdrop to the full-screen game's
+  monitor; when **no game is detected**, `ResolveAutoCaptureKey()` returns `null` — stale `CaptureKey`
+  values are cleared, no capture session is started, and `Source.DisplaySource` falls back to
+  `_imageSource` (the static asset on the backdrop element). `StartWatching()` is called at the end of
+  `ReacquireScreenCaptures`. `OnFullscreenMonitorChanged` auto-redesignates when a fullscreen game appears
+  on a different monitor; null (no fullscreen / own window) is ignored — the existing capture keeps
+  running so loading screens / transitions don't break the stream. `RefreshBackdropAutoCapture` (bound to
+  "Refresh Capture" context menu + `Activated` handler) reads the current foreground directly as a manual
+  fallback. Deduplication: `_lastReportedMonitor` prevents redundant redesignates from rapid foreground
+  changes.
 - **Capture (WinRT GraphicsCapture):** `ScreenCaptureFrameSource` creates a free-threaded
   `Direct3D11CaptureFramePool` (2 buffers, `B8G8R8A8UIntNormalized`) + `GraphicsCaptureSession`; frames →
   `SoftwareBitmap.CreateCopyFromSurfaceAsync` (alpha ignored) → `VideoFrame` (BGRA8), bytes read via
@@ -206,7 +213,7 @@ instead of a normal draggable source.
   game are behind the picker; picker-based captures don't survive reload.
 - **Focus-loss capture lag (known OS limit, NOT an in-app throttle — deferred):** when the app window loses
   focus the preview visibly slows (mouse-movement lag). Nothing in the repo checks focus to slow capture —
-  the only focus hooks (`NoteBackgroundWindow`/`RefreshBackdropAutoCapture`) re-target the backdrop, never
+  the only focus hooks (`FullscreenMonitorChanged` event + `RefreshBackdropAutoCapture`) re-target the backdrop, never
   pace it. The lag is inherited: `Windows.Graphics.Capture` is content-driven and DWM/OS-throttled while the
   app is in the background (worse under a full-screen game on 24H2/26100), GPU readback
   (`CreateCopyFromSurfaceAsync`) contends with the foreground game, the source's one-in-flight `_framePending`

ytLive.Tests/BackdropTests.cs

@@ -91,6 +91,13 @@ public class BackdropTests
         Assert.Same(bitmap, source.DisplaySource);
     }
 
+    [Fact]
+    public void Source_DisplaySource_FallsBackToImage_WhenLiveCaptureWithNoVideoImage()
+    {
+        var source = new Source { Type = SourceType.DisplayCapture };
+        Assert.Null(source.DisplaySource);
+    }
+
     [Fact]
     public void Source_DisplaySource_IsImageSource_WhenNotLiveCapture()
     {

ytLive.csproj

@@ -24,6 +24,9 @@
     <Resource Include="Assets\llamacasty-logo.jpg"/>
     <Resource Include="Assets\starting-backdrop.jpg"/>
     <Resource Include="Assets\brb-backdrop.jpg"/>
+    <Resource Include="Assets\live-backdrop.jpg"/>
+    <Resource Include="Assets\ending-backdrop.jpg"/>
+    <Resource Include="Assets\chat-backdrop.jpg"/>
   </ItemGroup>
 
   <ItemGroup>