refactor: extract BottomBar out of MainWindow.xaml — Phase 2, Commit 12

New Controls/ folder + namespace ytLive.Controls. BottomBar takes the
Grid.Row=3 footer: gear menu button (with its GearButton_Click handler moved to
the control's code-behind), centered stream-stats (bitrate/FPS/dropped/
duration/health), and the quality dropdown. All bindings inherit the window
DataContext; app-level styles resolve from Themes/Controls.xaml as before.

Zero behavior change; build 0 warnings; 246 pass, only the 2 known failures.
Docs: ViewModels/index.md tracker gains a Phase 2 section in the same commit.

Controls/BottomBar.xaml

@@ -0,0 +1,64 @@
+<UserControl x:Class="ytLive.Controls.BottomBar"
+             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+    <Border Background="#0f3460" Padding="16,4">
+        <Grid>
+            <Grid.ColumnDefinitions>
+                <ColumnDefinition Width="Auto"/>
+                <ColumnDefinition Width="*"/>
+                <ColumnDefinition Width="Auto"/>
+            </Grid.ColumnDefinitions>
+
+            <!-- Gear icon: far left -->
+            <Button Grid.Column="0" ToolTip="Menu" Style="{StaticResource IconButton}"
+                    VerticalAlignment="Center" Click="GearButton_Click">
+                <Button.ContextMenu>
+                    <ContextMenu DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
+                        <MenuItem Header="App Settings" Command="{Binding OpenSettingsCommand}"/>
+                        <Separator/>
+                        <MenuItem Header="Report Bug" Command="{Binding OpenBugCommand}"/>
+                        <MenuItem Header="Feature Request" Command="{Binding OpenFeatureCommand}"/>
+                        <MenuItem Header="About" Command="{Binding OpenAboutCommand}"/>
+                    </ContextMenu>
+                </Button.ContextMenu>
+                <Path Data="M19.14,12.94c0.04,-0.3 0.06,-0.61 0.06,-0.94c0,-0.32 -0.02,-0.64 -0.07,-0.94l2.03,-1.58c0.18,-0.14 0.23,-0.41 0.12,-0.61l-1.92,-3.32c-0.12,-0.22 -0.37,-0.29 -0.59,-0.22l-2.39,0.96c-0.5,-0.38 -1.03,-0.7 -1.62,-0.94L14.4,2.81c-0.04,-0.24 -0.24,-0.41 -0.48,-0.41h-3.84c-0.24,0 -0.43,0.17 -0.47,0.41L9.25,5.35C8.66,5.59 8.12,5.92 7.63,6.29L5.24,5.33c-0.22,-0.08 -0.47,0 -0.59,0.22L2.74,8.87C2.62,9.08 2.66,9.34 2.86,9.48l2.03,1.58C4.84,11.36 4.8,11.69 4.8,12s0.02,0.64 0.07,0.94l-2.03,1.58c-0.18,0.14 -0.23,0.41 -0.12,0.61l1.92,3.32c0.12,0.22 0.37,0.29 0.59,0.22l2.39,-0.96c0.5,0.38 1.03,0.7 1.62,0.94l0.36,2.54c0.05,0.24 0.24,0.41 0.48,0.41h3.84c0.24,0 0.44,-0.17 0.47,-0.41l0.36,-2.54c0.59,-0.24 1.13,-0.56 1.62,-0.94l2.39,0.96c0.22,0.08 0.47,0 0.59,-0.22l1.92,-3.32c0.12,-0.22 0.07,-0.47 -0.12,-0.61L19.14,12.94zM12,15.6c-1.98,0 -3.6,-1.62 -3.6,-3.6s1.62,-3.6 3.6,-3.6s3.6,1.62 3.6,3.6S13.98,15.6 12,15.6z"
+                      Fill="#d0d0d0" Width="16" Height="16" Stretch="Uniform"/>
+            </Button>
+
+            <!-- Stream stats: centered under the preview pane -->
+            <StackPanel Grid.Column="1" Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
+                <TextBlock Text="Bitrate:" Style="{StaticResource YtLabel}" Margin="0,0,4,0"/>
+                <TextBlock Style="{StaticResource YtLabel}"
+                           Foreground="White" Margin="0,0,20,0">
+                    <Run Text="{Binding CurrentHealth.CurrentBitrate, Mode=OneWay}"/>
+                    <Run Text=" Mbps"/>
+                </TextBlock>
+
+                <TextBlock Text="FPS:" Style="{StaticResource YtLabel}" Margin="0,0,4,0"/>
+                <TextBlock Style="{StaticResource YtLabel}"
+                           Foreground="White" Margin="0,0,24,0">
+                    <Run Text="{Binding CurrentHealth.FPS, Mode=OneWay, StringFormat={}{0:0}}"/>
+                </TextBlock>
+
+                <TextBlock Text="Dropped:" Style="{StaticResource YtLabel}" Margin="0,0,4,0"/>
+                <TextBlock Text="{Binding CurrentHealth.DroppedFrames}" Style="{StaticResource YtLabel}"
+                           Foreground="White" Margin="0,0,20,0"/>
+
+                <TextBlock Text="Duration:" Style="{StaticResource YtLabel}" Margin="0,0,4,0"/>
+                <TextBlock Text="{Binding CurrentHealth.StreamDuration}" Style="{StaticResource YtLabel}"
+                           Foreground="White"/>
+
+                <TextBlock Text="{Binding CurrentHealth.HealthMessage}" Style="{StaticResource YtLabel}"
+                           Foreground="#e94560" Margin="20,0,0,0"/>
+            </StackPanel>
+
+            <!-- Resolution dropdown: far right -->
+            <ComboBox Grid.Column="2" Style="{StaticResource YtComboBox}" MinWidth="150"
+                      ItemsSource="{Binding QualityOptions}"
+                      SelectedItem="{Binding SelectedQuality}"
+                      DisplayMemberPath="Label"
+                      ToolTip="{Binding ResolutionHelp}"
+                      IsEnabled="{Binding IsOffline}"/>
+        </Grid>
+    </Border>
+</UserControl>

Controls/BottomBar.xaml.cs

@@ -0,0 +1,22 @@
+using System.Windows;
+using System.Windows.Controls;
+
+namespace ytLive.Controls;
+
+public partial class BottomBar : UserControl
+{
+    public BottomBar()
+    {
+        InitializeComponent();
+    }
+
+    private void GearButton_Click(object sender, RoutedEventArgs e)
+    {
+        if (sender is Button { ContextMenu: { } menu } button)
+        {
+            menu.PlacementTarget = button;
+            menu.Placement = System.Windows.Controls.Primitives.PlacementMode.Bottom;
+            menu.IsOpen = true;
+        }
+    }
+}

MainWindow.xaml

@@ -6,6 +6,7 @@
         xmlns:vm="clr-namespace:ytLive.ViewModels"
         xmlns:models="clr-namespace:ytLive.Models"
         xmlns:Helpers="clr-namespace:ytLive.Helpers"
+        xmlns:controls="clr-namespace:ytLive.Controls"
         xmlns:notifications="clr-namespace:Notification.Wpf.Controls;assembly=Notification.Wpf"
         mc:Ignorable="d"
         Title="{Binding WindowTitle}" Height="1040" Width="1920"
@@ -1437,68 +1438,8 @@
             </Border>
         </Grid>
 
-        <!-- ═══ BOTTOM BAR: Stream stats + controls ═══ -->
-        <Border Grid.Row="3" Background="#0f3460" Padding="16,4">
-            <Grid>
-                <Grid.ColumnDefinitions>
-                    <ColumnDefinition Width="Auto"/>
-                    <ColumnDefinition Width="*"/>
-                    <ColumnDefinition Width="Auto"/>
-                </Grid.ColumnDefinitions>
-
-                <!-- Gear icon: far left -->
-                <Button Grid.Column="0" ToolTip="Menu" Style="{StaticResource IconButton}"
-                        VerticalAlignment="Center" Click="GearButton_Click">
-                    <Button.ContextMenu>
-                        <ContextMenu DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
-                            <MenuItem Header="App Settings" Command="{Binding OpenSettingsCommand}"/>
-                            <Separator/>
-                            <MenuItem Header="Report Bug" Command="{Binding OpenBugCommand}"/>
-                            <MenuItem Header="Feature Request" Command="{Binding OpenFeatureCommand}"/>
-                            <MenuItem Header="About" Command="{Binding OpenAboutCommand}"/>
-                        </ContextMenu>
-                    </Button.ContextMenu>
-                    <Path Data="M19.14,12.94c0.04,-0.3 0.06,-0.61 0.06,-0.94c0,-0.32 -0.02,-0.64 -0.07,-0.94l2.03,-1.58c0.18,-0.14 0.23,-0.41 0.12,-0.61l-1.92,-3.32c-0.12,-0.22 -0.37,-0.29 -0.59,-0.22l-2.39,0.96c-0.5,-0.38 -1.03,-0.7 -1.62,-0.94L14.4,2.81c-0.04,-0.24 -0.24,-0.41 -0.48,-0.41h-3.84c-0.24,0 -0.43,0.17 -0.47,0.41L9.25,5.35C8.66,5.59 8.12,5.92 7.63,6.29L5.24,5.33c-0.22,-0.08 -0.47,0 -0.59,0.22L2.74,8.87C2.62,9.08 2.66,9.34 2.86,9.48l2.03,1.58C4.84,11.36 4.8,11.69 4.8,12s0.02,0.64 0.07,0.94l-2.03,1.58c-0.18,0.14 -0.23,0.41 -0.12,0.61l1.92,3.32c0.12,0.22 0.37,0.29 0.59,0.22l2.39,-0.96c0.5,0.38 1.03,0.7 1.62,0.94l0.36,2.54c0.05,0.24 0.24,0.41 0.48,0.41h3.84c0.24,0 0.44,-0.17 0.47,-0.41l0.36,-2.54c0.59,-0.24 1.13,-0.56 1.62,-0.94l2.39,0.96c0.22,0.08 0.47,0 0.59,-0.22l1.92,-3.32c0.12,-0.22 0.07,-0.47 -0.12,-0.61L19.14,12.94zM12,15.6c-1.98,0 -3.6,-1.62 -3.6,-3.6s1.62,-3.6 3.6,-3.6s3.6,1.62 3.6,3.6S13.98,15.6 12,15.6z"
-                          Fill="#d0d0d0" Width="16" Height="16" Stretch="Uniform"/>
-                </Button>
-
-                <!-- Stream stats: centered under the preview pane -->
-                <StackPanel Grid.Column="1" Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
-                    <TextBlock Text="Bitrate:" Style="{StaticResource YtLabel}" Margin="0,0,4,0"/>
-                    <TextBlock Style="{StaticResource YtLabel}"
-                               Foreground="White" Margin="0,0,20,0">
-                        <Run Text="{Binding CurrentHealth.CurrentBitrate, Mode=OneWay}"/>
-                        <Run Text=" Mbps"/>
-                    </TextBlock>
-
-                    <TextBlock Text="FPS:" Style="{StaticResource YtLabel}" Margin="0,0,4,0"/>
-                    <TextBlock Style="{StaticResource YtLabel}"
-                               Foreground="White" Margin="0,0,24,0">
-                        <Run Text="{Binding CurrentHealth.FPS, Mode=OneWay, StringFormat={}{0:0}}"/>
-                    </TextBlock>
-
-                    <TextBlock Text="Dropped:" Style="{StaticResource YtLabel}" Margin="0,0,4,0"/>
-                    <TextBlock Text="{Binding CurrentHealth.DroppedFrames}" Style="{StaticResource YtLabel}"
-                               Foreground="White" Margin="0,0,20,0"/>
-
-                    <TextBlock Text="Duration:" Style="{StaticResource YtLabel}" Margin="0,0,4,0"/>
-                    <TextBlock Text="{Binding CurrentHealth.StreamDuration}" Style="{StaticResource YtLabel}"
-                               Foreground="White"/>
-
-                    <TextBlock Text="{Binding CurrentHealth.HealthMessage}" Style="{StaticResource YtLabel}"
-                               Foreground="#e94560" Margin="20,0,0,0"/>
-                </StackPanel>
-
-                <!-- Resolution dropdown: far right -->
-                <ComboBox Grid.Column="2" Style="{StaticResource YtComboBox}" MinWidth="150"
-                          ItemsSource="{Binding QualityOptions}"
-                          SelectedItem="{Binding SelectedQuality}"
-                          DisplayMemberPath="Label"
-                          ToolTip="{Binding ResolutionHelp}"
-                          IsEnabled="{Binding IsOffline}"/>
-            </Grid>
-        </Border>
 
+        <controls:BottomBar Grid.Row="3"/>
         <!-- ═══ OVERLAY: Settings / Bug / Feature / About ═══ -->
         <Grid Grid.RowSpan="3"
               Visibility="{Binding IsAnyOverlayOpen, Converter={StaticResource BoolToVis}}">

MainWindow.xaml.cs

@@ -291,16 +291,6 @@ public partial class MainWindow : Window
         e.Handled = true; // the button's right-click context menu must not fire
     }
 
-    private void GearButton_Click(object sender, RoutedEventArgs e)
-    {
-        if (sender is Button { ContextMenu: { } menu } button)
-        {
-            menu.PlacementTarget = button;
-            menu.Placement = System.Windows.Controls.Primitives.PlacementMode.Bottom;
-            menu.IsOpen = true;
-        }
-    }
-
     private void BackToAbout_Click(object sender, RoutedEventArgs e)
     {
         if (DataContext is ViewModels.MainViewModel vm)

ViewModels/index.md

@@ -51,7 +51,10 @@ Progress (Commit N/12 · tag):
 - [x] **Commit 9/12 · `refactor-commit-9`** — **Streaming** → `MainViewModel.Streaming.cs`
 - [x] **Commit 10/12 · `refactor-commit-10`** — **Chat** → `MainViewModel.Chat.cs`
 - [x] **Commit 11/12 · `refactor-commit-11`** — **Overlays** → `MainViewModel.Overlays.cs`
-- [x] **Phase 1 complete:** core `MainViewModel.cs` split into 10 functional partials (1,890 → 758 lines). Phase 2 (splitting `MainWindow.xaml` into UserControls) not yet started.
+- [x] **Phase 1 complete:** core `MainViewModel.cs` split into 10 functional partials (1,890 → 758 lines).
+
+**Phase 2 — `MainWindow.xaml` split into UserControls** (new `Controls/` folder, namespace `ytLive.Controls`):
+- [x] **Commit 12 · `refactor-commit-12`** — **BottomBar** → `Controls/BottomBar.xaml(.cs)` (gear menu + stream stats + quality dropdown; `GearButton_Click` moved to the control's code-behind). Pending: TopBar, health banner, left scene/chat panel, preview pane, overlay host.
 
 The partial `.cs` files land next to `MainViewModel.cs` in this folder as the split
 proceeds; each partial carries its own `using`s and re-declares nothing from core.