diff --git a/src/ClaudeDo.App/Program.cs b/src/ClaudeDo.App/Program.cs
index 0463bf1..ab74563 100644
--- a/src/ClaudeDo.App/Program.cs
+++ b/src/ClaudeDo.App/Program.cs
@@ -108,7 +108,8 @@ sealed class Program
         sc.AddSingleton<DetailsIslandViewModel>(sp =>
             new DetailsIslandViewModel(
                 sp.GetRequiredService<IDbContextFactory<ClaudeDoDbContext>>(),
-                sp.GetRequiredService<WorkerClient>()));
+                sp.GetRequiredService<WorkerClient>(),
+                sp));
         sc.AddSingleton<IslandsShellViewModel>();
 
         return sc.BuildServiceProvider();
diff --git a/src/ClaudeDo.Data/Git/GitService.cs b/src/ClaudeDo.Data/Git/GitService.cs
index ecd7fdb..8a11ce7 100644
--- a/src/ClaudeDo.Data/Git/GitService.cs
+++ b/src/ClaudeDo.Data/Git/GitService.cs
@@ -27,6 +27,14 @@ public sealed class GitService
             throw new InvalidOperationException($"git worktree add failed (exit {exitCode}): {stderr}");
     }
 
+    public async Task<string> GetStatusPorcelainAsync(string workingDirectory, CancellationToken ct = default)
+    {
+        var (exitCode, stdout, stderr) = await RunGitAsync(workingDirectory, ["status", "--porcelain"], ct);
+        if (exitCode != 0)
+            throw new InvalidOperationException($"git status --porcelain failed (exit {exitCode}): {stderr}");
+        return stdout;
+    }
+
     public async Task<bool> HasChangesAsync(string worktreePath, CancellationToken ct = default)
     {
         var (exitCode, stdout, stderr) = await RunGitAsync(worktreePath, ["status", "--porcelain"], ct);
@@ -50,6 +58,21 @@ public sealed class GitService
             throw new InvalidOperationException($"git commit failed (exit {exitCode}): {stderr}");
     }
 
+    public async Task<string> GetDiffAsync(string worktreePath, CancellationToken ct = default)
+    {
+        var (exitCode, stdout, stderr) = await RunGitAsync(worktreePath,
+            ["diff", "HEAD"], ct);
+        if (exitCode != 0)
+            throw new InvalidOperationException($"git diff HEAD failed (exit {exitCode}): {stderr}");
+        // If nothing staged vs HEAD, try the index (untracked is never in diff)
+        if (string.IsNullOrWhiteSpace(stdout))
+        {
+            var (e2, s2, _) = await RunGitAsync(worktreePath, ["diff", "--cached"], ct);
+            if (e2 == 0) return s2;
+        }
+        return stdout;
+    }
+
     public async Task<string> DiffStatAsync(string worktreePath, string baseCommit, string headCommit, CancellationToken ct = default)
     {
         var (exitCode, stdout, stderr) = await RunGitAsync(worktreePath,
diff --git a/src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs b/src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs
index 53ca6ce..646db50 100644
--- a/src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs
+++ b/src/ClaudeDo.Ui/ViewModels/Islands/DetailsIslandViewModel.cs
@@ -4,7 +4,9 @@ using CommunityToolkit.Mvvm.Input;
 using ClaudeDo.Data;
 using ClaudeDo.Data.Repositories;
 using ClaudeDo.Ui.Services;
+using ClaudeDo.Ui.ViewModels.Modals;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
 
 namespace ClaudeDo.Ui.ViewModels.Islands;
 
@@ -12,6 +14,7 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
 {
     private readonly IDbContextFactory<ClaudeDoDbContext> _dbFactory;
     private readonly WorkerClient _worker;
+    private readonly IServiceProvider _services;
 
     // Current task row (set by IslandsShellViewModel via Bind)
     [ObservableProperty] private TaskRowViewModel? _task;
@@ -35,10 +38,17 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
     // The task ID we are currently subscribed to for live log messages
     private string? _subscribedTaskId;
 
-    public DetailsIslandViewModel(IDbContextFactory<ClaudeDoDbContext> dbFactory, WorkerClient worker)
+    // Set by the view so OpenDiffCommand can show the modal as a dialog
+    public Func<DiffModalViewModel, System.Threading.Tasks.Task>? ShowDiffModal { get; set; }
+
+    // Set by the view so OpenWorktreeCommand can show the modal as a dialog
+    public Func<WorktreeModalViewModel, System.Threading.Tasks.Task>? ShowWorktreeModal { get; set; }
+
+    public DetailsIslandViewModel(IDbContextFactory<ClaudeDoDbContext> dbFactory, WorkerClient worker, IServiceProvider services)
     {
         _dbFactory = dbFactory;
         _worker = worker;
+        _services = services;
 
         // Subscribe once; filter by current task id inside the handler
         _worker.TaskMessageEvent += OnTaskMessage;
@@ -99,6 +109,38 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase
             Subtasks.Add(new SubtaskRowViewModel { Id = s.Id, Title = s.Title, Done = s.Completed });
     }
 
+    [RelayCommand(CanExecute = nameof(CanOpenDiff))]
+    private async System.Threading.Tasks.Task OpenDiffAsync()
+    {
+        if (WorktreePath == null || ShowDiffModal == null) return;
+        var diffVm = new DiffModalViewModel(_services.GetRequiredService<ClaudeDo.Data.Git.GitService>())
+        {
+            WorktreePath = WorktreePath,
+        };
+        await diffVm.LoadAsync();
+        await ShowDiffModal(diffVm);
+    }
+
+    private bool CanOpenDiff() => WorktreePath != null;
+
+    [RelayCommand(CanExecute = nameof(CanOpenWorktree))]
+    private async System.Threading.Tasks.Task OpenWorktreeAsync()
+    {
+        if (WorktreePath == null || ShowWorktreeModal == null) return;
+        var vm = _services.GetRequiredService<WorktreeModalViewModel>();
+        vm.WorktreePath = WorktreePath;
+        await vm.LoadAsync();
+        await ShowWorktreeModal(vm);
+    }
+
+    private bool CanOpenWorktree() => WorktreePath != null;
+
+    partial void OnWorktreePathChanged(string? value)
+    {
+        OpenDiffCommand.NotifyCanExecuteChanged();
+        OpenWorktreeCommand.NotifyCanExecuteChanged();
+    }
+
     [RelayCommand]
     private async System.Threading.Tasks.Task SendPromptAsync()
     {
diff --git a/src/ClaudeDo.Ui/ViewModels/Modals/DiffModalViewModel.cs b/src/ClaudeDo.Ui/ViewModels/Modals/DiffModalViewModel.cs
new file mode 100644
index 0000000..09641ae
--- /dev/null
+++ b/src/ClaudeDo.Ui/ViewModels/Modals/DiffModalViewModel.cs
@@ -0,0 +1,154 @@
+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using ClaudeDo.Data.Git;
+
+namespace ClaudeDo.Ui.ViewModels.Modals;
+
+public enum DiffLineKind { Add, Del, Ctx }
+
+public sealed class DiffLineViewModel
+{
+    public required DiffLineKind Kind { get; init; }
+    public int? OldNo { get; init; }
+    public int? NewNo { get; init; }
+    public required string Text { get; init; }
+    public string ClassName => Kind switch
+    {
+        DiffLineKind.Add => "add",
+        DiffLineKind.Del => "del",
+        _                => "ctx",
+    };
+
+    public string Sign => Kind switch
+    {
+        DiffLineKind.Add => "+",
+        DiffLineKind.Del => "-",
+        _                => " ",
+    };
+}
+
+public sealed class DiffFileViewModel
+{
+    public required string Path { get; init; }
+    public int Additions { get; init; }
+    public int Deletions { get; init; }
+    public ObservableCollection<DiffLineViewModel> Lines { get; } = new();
+}
+
+public sealed partial class DiffModalViewModel : ViewModelBase
+{
+    private readonly GitService _git;
+
+    public required string WorktreePath { get; init; }
+
+    public ObservableCollection<DiffFileViewModel> Files { get; } = new();
+
+    [ObservableProperty] private DiffFileViewModel? _selectedFile;
+
+    // Injected action to close the owning Window
+    public Action? CloseAction { get; set; }
+
+    public DiffModalViewModel(GitService git)
+    {
+        _git = git;
+    }
+
+    [RelayCommand]
+    private void Close() => CloseAction?.Invoke();
+
+    public async Task LoadAsync(CancellationToken ct = default)
+    {
+        Files.Clear();
+
+        string raw;
+        try { raw = await _git.GetDiffAsync(WorktreePath, ct); }
+        catch { return; }
+
+        if (string.IsNullOrWhiteSpace(raw)) return;
+
+        // Parse unified diff — state machine over lines
+        DiffFileViewModel? current = null;
+        int oldLine = 0, newLine = 0;
+
+        foreach (var line in raw.Split('\n'))
+        {
+            if (line.StartsWith("diff --git ", StringComparison.Ordinal))
+            {
+                // e.g. "diff --git a/src/Foo.cs b/src/Foo.cs"
+                var parts = line.Split(' ');
+                var path = parts.Length >= 4 ? parts[3][2..] : line;
+                current = new DiffFileViewModel { Path = path };
+                Files.Add(current);
+                oldLine = 0; newLine = 0;
+                continue;
+            }
+
+            if (current == null) continue;
+
+            if (line.StartsWith("@@ ", StringComparison.Ordinal))
+            {
+                // e.g. "@@ -10,7 +10,9 @@"
+                ParseHunkHeader(line, out oldLine, out newLine);
+                continue;
+            }
+
+            // Skip diff metadata lines
+            if (line.StartsWith("--- ", StringComparison.Ordinal) ||
+                line.StartsWith("+++ ", StringComparison.Ordinal) ||
+                line.StartsWith("index ", StringComparison.Ordinal) ||
+                line.StartsWith("new file", StringComparison.Ordinal) ||
+                line.StartsWith("deleted file", StringComparison.Ordinal) ||
+                line.StartsWith("Binary ", StringComparison.Ordinal))
+                continue;
+
+            if (line.StartsWith('+'))
+            {
+                current.Lines.Add(new DiffLineViewModel
+                {
+                    Kind = DiffLineKind.Add,
+                    NewNo = newLine++,
+                    Text = line.Length > 1 ? line[1..] : "",
+                });
+                // Count additions on the file VM
+            }
+            else if (line.StartsWith('-'))
+            {
+                current.Lines.Add(new DiffLineViewModel
+                {
+                    Kind = DiffLineKind.Del,
+                    OldNo = oldLine++,
+                    Text = line.Length > 1 ? line[1..] : "",
+                });
+            }
+            else if (line.StartsWith(' '))
+            {
+                current.Lines.Add(new DiffLineViewModel
+                {
+                    Kind = DiffLineKind.Ctx,
+                    OldNo = oldLine++,
+                    NewNo = newLine++,
+                    Text = line.Length > 1 ? line[1..] : "",
+                });
+            }
+        }
+
+        SelectedFile = Files.Count > 0 ? Files[0] : null;
+    }
+
+    private static void ParseHunkHeader(string header, out int oldStart, out int newStart)
+    {
+        oldStart = 1; newStart = 1;
+        // Format: @@ -<old>,<count> +<new>,<count> @@
+        var at = header.IndexOf("@@", 3, StringComparison.Ordinal);
+        var inner = at > 0 ? header[3..at].Trim() : header;
+        var segs = inner.Split(' ');
+        foreach (var seg in segs)
+        {
+            if (seg.StartsWith('-') && int.TryParse(seg[1..].Split(',')[0], out var o))
+                oldStart = o;
+            else if (seg.StartsWith('+') && int.TryParse(seg[1..].Split(',')[0], out var n))
+                newStart = n;
+        }
+    }
+}
diff --git a/src/ClaudeDo.Ui/Views/Islands/AgentStripView.axaml b/src/ClaudeDo.Ui/Views/Islands/AgentStripView.axaml
index 36cfa04..91c03e6 100644
--- a/src/ClaudeDo.Ui/Views/Islands/AgentStripView.axaml
+++ b/src/ClaudeDo.Ui/Views/Islands/AgentStripView.axaml
@@ -29,8 +29,8 @@
                  IsVisible="{Binding BranchLine, Converter={x:Static ObjectConverters.IsNotNull}}"/>
       <!-- Button row -->
       <StackPanel Orientation="Horizontal" Spacing="8" Margin="0,6,0,0">
-        <Button Classes="icon-btn" Content="Open diff"/>
-        <Button Classes="icon-btn" Content="Worktree"/>
+        <Button Classes="icon-btn" Content="Open diff" Command="{Binding OpenDiffCommand}"/>
+        <Button Classes="icon-btn" Content="Worktree" Command="{Binding OpenWorktreeCommand}"/>
         <Button Classes="icon-btn" Content="Stop" Command="{Binding StopCommand}"/>
         <Button Classes="icon-btn" Content="Approve &amp; merge" Command="{Binding ApproveMergeCommand}"/>
       </StackPanel>
diff --git a/src/ClaudeDo.Ui/Views/Islands/AgentStripView.axaml.cs b/src/ClaudeDo.Ui/Views/Islands/AgentStripView.axaml.cs
index 84ef7b3..214c71d 100644
--- a/src/ClaudeDo.Ui/Views/Islands/AgentStripView.axaml.cs
+++ b/src/ClaudeDo.Ui/Views/Islands/AgentStripView.axaml.cs
@@ -1,8 +1,38 @@
 using Avalonia.Controls;
+using ClaudeDo.Ui.ViewModels.Islands;
+using ClaudeDo.Ui.ViewModels.Modals;
+using ClaudeDo.Ui.Views.Modals;
 
 namespace ClaudeDo.Ui.Views.Islands;
 
 public partial class AgentStripView : UserControl
 {
-    public AgentStripView() { InitializeComponent(); }
+    public AgentStripView()
+    {
+        InitializeComponent();
+        DataContextChanged += OnDataContextChanged;
+    }
+
+    private void OnDataContextChanged(object? sender, EventArgs e)
+    {
+        if (DataContext is DetailsIslandViewModel vm)
+        {
+            vm.ShowDiffModal = async (diffVm) =>
+            {
+                var owner = TopLevel.GetTopLevel(this) as Window;
+                if (owner == null) return;
+                var modal = new DiffModalView { DataContext = diffVm };
+                await modal.ShowDialog(owner);
+            };
+
+            vm.ShowWorktreeModal = async (worktreeVm) =>
+            {
+                var owner = TopLevel.GetTopLevel(this) as Window;
+                if (owner == null) return;
+                var modal = new WorktreeModalView { DataContext = worktreeVm };
+                worktreeVm.CloseCommand.Subscribe(_ => modal.Close());
+                await modal.ShowDialog(owner);
+            };
+        }
+    }
 }
diff --git a/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml b/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml
new file mode 100644
index 0000000..8e0e1e3
--- /dev/null
+++ b/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml
@@ -0,0 +1,174 @@
+<Window xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:vm="using:ClaudeDo.Ui.ViewModels.Modals"
+        x:Class="ClaudeDo.Ui.Views.Modals.DiffModalView"
+        x:DataType="vm:DiffModalViewModel"
+        Title="Diff"
+        Width="1200" Height="800"
+        SystemDecorations="None"
+        ExtendClientAreaToDecorationsHint="True"
+        WindowStartupLocation="CenterOwner"
+        Background="Transparent"
+        TransparencyLevelHint="AcrylicBlur">
+
+  <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="#1A4A6B4A"/>
+    </Style>
+    <Style Selector="Border.diff-line[Tag=del]">
+      <Setter Property="Background" Value="#1AC87060"/>
+    </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>
+
+  <!-- Outer container -->
+  <Border CornerRadius="{StaticResource ModalCornerRadius}"
+          BoxShadow="{StaticResource ModalShadow}"
+          Background="{StaticResource SurfaceBrush}"
+          BorderBrush="{StaticResource LineBrush}"
+          BorderThickness="1"
+          ClipToBounds="True">
+    <Grid RowDefinitions="36,*">
+
+      <!-- Title bar / drag handle -->
+      <Border Grid.Row="0"
+              x:Name="TitleBar"
+              Background="{StaticResource Surface2Brush}"
+              BorderBrush="{StaticResource LineBrush}"
+              BorderThickness="0,0,0,1"
+              PointerPressed="TitleBar_PointerPressed">
+        <Grid ColumnDefinitions="*,Auto" Margin="14,0">
+          <TextBlock Text="Diff" VerticalAlignment="Center"
+                     FontFamily="{StaticResource MonoFamily}"
+                     FontSize="12"
+                     Foreground="{StaticResource TextDimBrush}"/>
+          <Button Grid.Column="1"
+                  Classes="icon-btn"
+                  Content="✕"
+                  FontSize="12"
+                  Command="{Binding CloseCommand}"
+                  VerticalAlignment="Center"/>
+        </Grid>
+      </Border>
+
+      <!-- Body: sidebar + diff content -->
+      <Grid Grid.Row="1" ColumnDefinitions="240,*">
+
+        <!-- File sidebar -->
+        <Border Grid.Column="0"
+                BorderBrush="{StaticResource LineBrush}"
+                BorderThickness="0,0,1,0"
+                Background="{StaticResource 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 Text="{Binding Path}"
+                               FontFamily="{StaticResource MonoFamily}"
+                               FontSize="11"
+                               Foreground="{StaticResource TextDimBrush}"
+                               TextTrimming="LeadingEllipsis"/>
+                    <StackPanel Orientation="Horizontal" Spacing="6">
+                      <Border Classes="chip" Padding="5,2">
+                        <TextBlock Foreground="{StaticResource MossBrightBrush}"
+                                   FontFamily="{StaticResource MonoFamily}"
+                                   FontSize="10"
+                                   Text="{Binding Additions, StringFormat='+{0}'}"/>
+                      </Border>
+                      <Border Classes="chip" Padding="5,2">
+                        <TextBlock Foreground="{StaticResource BloodBrush}"
+                                   FontFamily="{StaticResource MonoFamily}"
+                                   FontSize="10"
+                                   Text="{Binding Deletions, StringFormat='\u2212{0}'}"/>
+                      </Border>
+                    </StackPanel>
+                  </StackPanel>
+                </Border>
+              </DataTemplate>
+            </ListBox.ItemTemplate>
+          </ListBox>
+        </Border>
+
+        <!-- Diff content -->
+        <ScrollViewer Grid.Column="1"
+                      HorizontalScrollBarVisibility="Auto"
+                      VerticalScrollBarVisibility="Auto"
+                      Background="{StaticResource VoidBrush}">
+          <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="{StaticResource MonoFamily}"
+                               FontSize="11"
+                               Foreground="{StaticResource TextFaintBrush}"
+                               HorizontalAlignment="Right"
+                               Margin="0,0,8,0"/>
+                    <!-- New line number -->
+                    <TextBlock Grid.Column="1"
+                               Text="{Binding NewNo}"
+                               Classes="diff-lineno"
+                               FontFamily="{StaticResource MonoFamily}"
+                               FontSize="11"
+                               Foreground="{StaticResource TextFaintBrush}"
+                               HorizontalAlignment="Right"
+                               Margin="0,0,8,0"/>
+                    <!-- Sign -->
+                    <TextBlock Grid.Column="2"
+                               Classes="diff-sign"
+                               Text="{Binding Sign}"
+                               FontFamily="{StaticResource MonoFamily}"
+                               FontSize="11"/>
+                    <!-- Line text -->
+                    <TextBlock Grid.Column="3"
+                               Classes="diff-text"
+                               Text="{Binding Text}"
+                               FontFamily="{StaticResource MonoFamily}"
+                               FontSize="11"
+                               TextWrapping="NoWrap"/>
+                  </Grid>
+                </Border>
+              </DataTemplate>
+            </ItemsControl.ItemTemplate>
+          </ItemsControl>
+        </ScrollViewer>
+      </Grid>
+    </Grid>
+  </Border>
+</Window>
diff --git a/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml.cs b/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml.cs
new file mode 100644
index 0000000..4c8351b
--- /dev/null
+++ b/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml.cs
@@ -0,0 +1,26 @@
+using Avalonia.Controls;
+using Avalonia.Input;
+using ClaudeDo.Ui.ViewModels.Modals;
+
+namespace ClaudeDo.Ui.Views.Modals;
+
+public partial class DiffModalView : Window
+{
+    public DiffModalView()
+    {
+        InitializeComponent();
+    }
+
+    protected override void OnDataContextChanged(EventArgs e)
+    {
+        base.OnDataContextChanged(e);
+        if (DataContext is DiffModalViewModel vm)
+            vm.CloseAction = Close;
+    }
+
+    private void TitleBar_PointerPressed(object? sender, PointerPressedEventArgs e)
+    {
+        if (e.GetCurrentPoint(this).Properties.IsLeftButtonPressed)
+            BeginMoveDrag(e);
+    }
+}