ClaudeDo/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="using:ClaudeDo.Ui.ViewModels.Modals"
        xmlns:ctl="using:ClaudeDo.Ui.Views.Controls"
        x:Class="ClaudeDo.Ui.Views.Modals.DiffModalView"
        x:DataType="vm:DiffModalViewModel"
        Title="Diff"
        Width="1200" Height="800"
        WindowDecorations="None"
        ExtendClientAreaToDecorationsHint="True"
        WindowStartupLocation="CenterOwner"
        Background="{DynamicResource SurfaceBrush}">

  <Window.KeyBindings>
    <KeyBinding Gesture="Escape" Command="{Binding CloseCommand}"/>
  </Window.KeyBindings>

  <Window.Styles>
    <!-- diff line row tints via Tag selector (compiled-binding-friendly) -->
    <Style Selector="Border.diff-line[Tag=add]">
      <Setter Property="Background" Value="{StaticResource RunningTintBrush}"/>
    </Style>
    <Style Selector="Border.diff-line[Tag=del]">
      <Setter Property="Background" Value="{StaticResource ErrorTintBrush}"/>
    </Style>
    <Style Selector="Border.diff-line[Tag=ctx]">
      <Setter Property="Background" Value="Transparent"/>
    </Style>
    <Style Selector="Border.diff-line[Tag=add] TextBlock.diff-sign">
      <Setter Property="Foreground" Value="{StaticResource MossBrightBrush}"/>
    </Style>
    <Style Selector="Border.diff-line[Tag=del] TextBlock.diff-sign">
      <Setter Property="Foreground" Value="{StaticResource BloodBrush}"/>
    </Style>
    <Style Selector="Border.diff-line[Tag=ctx] TextBlock.diff-sign">
      <Setter Property="Foreground" Value="{StaticResource TextFaintBrush}"/>
    </Style>
    <Style Selector="Border.diff-line[Tag=add] TextBlock.diff-text">
      <Setter Property="Foreground" Value="{StaticResource MossBrightBrush}"/>
    </Style>
    <Style Selector="Border.diff-line[Tag=del] TextBlock.diff-text">
      <Setter Property="Foreground" Value="{StaticResource BloodBrush}"/>
    </Style>
    <Style Selector="Border.diff-line[Tag=ctx] TextBlock.diff-text">
      <Setter Property="Foreground" Value="{StaticResource TextDimBrush}"/>
    </Style>
  </Window.Styles>

  <ctl:ModalShell Title="DIFF" CloseCommand="{Binding CloseCommand}">
    <ctl:ModalShell.Footer>
      <StackPanel Orientation="Horizontal" Spacing="8"
                  HorizontalAlignment="Right" VerticalAlignment="Center"
                  Margin="16,0">
        <Button Content="Merge…" Command="{Binding MergeCommand}"/>
      </StackPanel>
    </ctl:ModalShell.Footer>

    <!-- Body: sidebar + diff content -->
    <Grid ColumnDefinitions="240,*">

      <!-- File sidebar -->
      <Border Grid.Column="0"
              BorderBrush="{DynamicResource LineBrush}"
              BorderThickness="0,0,1,0"
              Background="{DynamicResource DeepBrush}">
        <ListBox ItemsSource="{Binding Files}"
                 SelectedItem="{Binding SelectedFile, Mode=TwoWay}"
                 Background="Transparent"
                 BorderThickness="0"
                 ScrollViewer.HorizontalScrollBarVisibility="Disabled">
          <ListBox.ItemTemplate>
            <DataTemplate x:DataType="vm:DiffFileViewModel">
              <Border Padding="10,8" Background="Transparent">
                <StackPanel Spacing="4">
                  <TextBlock Classes="path-mono" Text="{Binding Path}"
                             TextTrimming="PrefixCharacterEllipsis"/>
                  <StackPanel Orientation="Horizontal" Spacing="6">
                    <Border Classes="chip" Padding="5,2">
                      <TextBlock Foreground="{DynamicResource MossBrightBrush}"
                                 Text="{Binding Additions, StringFormat='+{0}'}"/>
                    </Border>
                    <Border Classes="chip" Padding="5,2">
                      <TextBlock Foreground="{DynamicResource BloodBrush}"
                                 Text="{Binding Deletions, StringFormat='−{0}'}"/>
                    </Border>
                  </StackPanel>
                </StackPanel>
              </Border>
            </DataTemplate>
          </ListBox.ItemTemplate>
        </ListBox>
      </Border>

      <!-- Diff content -->
      <Grid Grid.Column="1" Background="{DynamicResource VoidBrush}">
        <TextBlock Classes="body" Text="{Binding StatusMessage}"
                   IsVisible="{Binding StatusMessage, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"
                   HorizontalAlignment="Center"
                   VerticalAlignment="Center"/>
        <ScrollViewer HorizontalScrollBarVisibility="Auto"
                    VerticalScrollBarVisibility="Auto">
        <ItemsControl ItemsSource="{Binding SelectedFile.Lines}">
          <ItemsControl.ItemTemplate>
            <DataTemplate x:DataType="vm:DiffLineViewModel">
              <Border Classes="diff-line"
                      Tag="{Binding ClassName}"
                      Padding="4,1">
                <Grid ColumnDefinitions="48,48,16,*">
                  <!-- Old line number -->
                  <TextBlock Grid.Column="0"
                             Text="{Binding OldNo}"
                             Classes="diff-lineno"
                             FontFamily="{DynamicResource MonoFont}"
                             FontSize="{StaticResource FontSizeMono}"
                             Foreground="{DynamicResource TextFaintBrush}"
                             HorizontalAlignment="Right"
                             Margin="0,0,8,0"/>
                  <!-- New line number -->
                  <TextBlock Grid.Column="1"
                             Text="{Binding NewNo}"
                             Classes="diff-lineno"
                             FontFamily="{DynamicResource MonoFont}"
                             FontSize="{StaticResource FontSizeMono}"
                             Foreground="{DynamicResource TextFaintBrush}"
                             HorizontalAlignment="Right"
                             Margin="0,0,8,0"/>
                  <!-- Sign -->
                  <TextBlock Grid.Column="2"
                             Classes="diff-sign"
                             Text="{Binding Sign}"
                             FontFamily="{DynamicResource MonoFont}"
                             FontSize="{StaticResource FontSizeMono}"/>
                  <!-- Line text -->
                  <TextBlock Grid.Column="3"
                             Classes="diff-text"
                             Text="{Binding Text}"
                             FontFamily="{DynamicResource MonoFont}"
                             FontSize="{StaticResource FontSizeMono}"
                             TextWrapping="NoWrap"/>
                </Grid>
              </Border>
            </DataTemplate>
          </ItemsControl.ItemTemplate>
        </ItemsControl>
        </ScrollViewer>
      </Grid>
    </Grid>
  </ctl:ModalShell>
</Window>