diff --git a/src/ClaudeDo.App/Program.cs b/src/ClaudeDo.App/Program.cs
index 68dbd87..8d274af 100644
--- a/src/ClaudeDo.App/Program.cs
+++ b/src/ClaudeDo.App/Program.cs
@@ -8,14 +8,21 @@ using ClaudeDo.Ui.ViewModels;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using System;
+using System.Runtime.InteropServices;
 
 namespace ClaudeDo.App;
 
 sealed class Program
 {
+    [DllImport("shell32.dll", CharSet = CharSet.Unicode)]
+    private static extern int SetCurrentProcessExplicitAppUserModelID(string appId);
+
     [STAThread]
     public static void Main(string[] args)
     {
+        if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            SetCurrentProcessExplicitAppUserModelID("ClaudeDo.App");
+
         var services = BuildServices();
         App.Services = services;
 
diff --git a/src/ClaudeDo.Ui/ViewModels/TaskItemViewModel.cs b/src/ClaudeDo.Ui/ViewModels/TaskItemViewModel.cs
index a834084..bc2a70d 100644
--- a/src/ClaudeDo.Ui/ViewModels/TaskItemViewModel.cs
+++ b/src/ClaudeDo.Ui/ViewModels/TaskItemViewModel.cs
@@ -1,7 +1,11 @@
+using System.Collections.ObjectModel;
 using Avalonia.Media;
+using ClaudeDo.Data;
 using ClaudeDo.Data.Models;
+using ClaudeDo.Data.Repositories;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
+using Microsoft.EntityFrameworkCore;
 using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
 
 namespace ClaudeDo.Ui.ViewModels;
@@ -15,6 +19,11 @@ public partial class TaskItemViewModel : ViewModelBase
     [ObservableProperty] private string? _description;
     [ObservableProperty] private TaskStatus _status;
     [ObservableProperty] private bool _isStarting;
+    [ObservableProperty] private bool _isExpanded;
+    [ObservableProperty] private bool _hasSubtasks;
+    [ObservableProperty] private int _subtaskCount;
+
+    public ObservableCollection<SubtaskItemViewModel> Subtasks { get; } = new();
 
     public string Id { get; }
     public string ListId { get; }
@@ -23,9 +32,13 @@ public partial class TaskItemViewModel : ViewModelBase
     private readonly Func<string, Task>? _runNow;
     private readonly Func<bool> _canRunNow;
     private readonly Func<string, Task>? _toggleDone;
+    private readonly IDbContextFactory<ClaudeDoDbContext> _dbFactory;
+    private bool _subtasksLoaded;
 
     public TaskItemViewModel(TaskEntity entity, IReadOnlyList<TagEntity> tags,
-        Func<string, Task>? runNow, Func<bool> canRunNow, Func<string, Task>? toggleDone = null)
+        Func<string, Task>? runNow, Func<bool> canRunNow,
+        IDbContextFactory<ClaudeDoDbContext> dbFactory, int subtaskCount,
+        Func<string, Task>? toggleDone = null)
     {
         Entity = entity;
         Id = entity.Id;
@@ -39,6 +52,9 @@ public partial class TaskItemViewModel : ViewModelBase
         _runNow = runNow;
         _canRunNow = canRunNow;
         _toggleDone = toggleDone;
+        _dbFactory = dbFactory;
+        _subtaskCount = subtaskCount;
+        _hasSubtasks = subtaskCount > 0;
     }
 
     public bool IsDone => Status == TaskStatus.Done;
@@ -104,4 +120,55 @@ public partial class TaskItemViewModel : ViewModelBase
         if (_toggleDone is not null)
             await _toggleDone(Id);
     }
+
+    [RelayCommand]
+    private async Task ToggleExpanded()
+    {
+        IsExpanded = !IsExpanded;
+        if (IsExpanded && !_subtasksLoaded)
+            await LoadSubtasksAsync();
+    }
+
+    private async Task LoadSubtasksAsync()
+    {
+        using var context = _dbFactory.CreateDbContext();
+        var repo = new SubtaskRepository(context);
+        var entities = await repo.GetByTaskIdAsync(Id);
+        Subtasks.Clear();
+        foreach (var e in entities)
+            Subtasks.Add(SubtaskItemViewModel.From(e));
+        _subtasksLoaded = true;
+    }
+
+    [RelayCommand]
+    private async Task ToggleSubtaskDone(string subtaskId)
+    {
+        var vm = Subtasks.FirstOrDefault(s => s.Id == subtaskId);
+        if (vm is null) return;
+        vm.Completed = !vm.Completed;
+
+        using var context = _dbFactory.CreateDbContext();
+        var entity = await context.Subtasks.FindAsync(subtaskId);
+        if (entity is not null)
+        {
+            entity.Completed = vm.Completed;
+            await context.SaveChangesAsync();
+        }
+    }
+
+    public async Task RefreshSubtasksAsync(int newCount)
+    {
+        SubtaskCount = newCount;
+        HasSubtasks = newCount > 0;
+        if (!HasSubtasks)
+        {
+            IsExpanded = false;
+            Subtasks.Clear();
+            _subtasksLoaded = false;
+        }
+        else if (_subtasksLoaded || IsExpanded)
+        {
+            await LoadSubtasksAsync();
+        }
+    }
 }
diff --git a/src/ClaudeDo.Ui/ViewModels/TaskListViewModel.cs b/src/ClaudeDo.Ui/ViewModels/TaskListViewModel.cs
index 1df6795..fc2eae9 100644
--- a/src/ClaudeDo.Ui/ViewModels/TaskListViewModel.cs
+++ b/src/ClaudeDo.Ui/ViewModels/TaskListViewModel.cs
@@ -91,10 +91,17 @@ public partial class TaskListViewModel : ViewModelBase
             using var context = _dbFactory.CreateDbContext();
             var taskRepo = new TaskRepository(context);
             var entities = await taskRepo.GetByListIdAsync(listId);
+            var taskIds = entities.Select(e => e.Id).ToList();
+            var subtaskCounts = await context.Subtasks
+                .Where(s => taskIds.Contains(s.TaskId))
+                .GroupBy(s => s.TaskId)
+                .ToDictionaryAsync(g => g.Key, g => g.Count());
             foreach (var e in entities)
             {
                 var tags = await taskRepo.GetEffectiveTagsAsync(e.Id);
-                Tasks.Add(new TaskItemViewModel(e, tags, RunNowAsync, () => _worker.IsConnected, ToggleDoneAsync));
+                subtaskCounts.TryGetValue(e.Id, out var count);
+                Tasks.Add(new TaskItemViewModel(e, tags, RunNowAsync, () => _worker.IsConnected,
+                    _dbFactory, count, ToggleDoneAsync));
             }
         }
         catch (Exception ex)
@@ -135,7 +142,8 @@ public partial class TaskListViewModel : ViewModelBase
             var taskRepo = new TaskRepository(context);
             await taskRepo.AddAsync(entity);
             var tags = await taskRepo.GetEffectiveTagsAsync(entity.Id);
-            var vm = new TaskItemViewModel(entity, tags, RunNowAsync, () => _worker.IsConnected, ToggleDoneAsync);
+            var vm = new TaskItemViewModel(entity, tags, RunNowAsync, () => _worker.IsConnected,
+                _dbFactory, 0, ToggleDoneAsync);
             Tasks.Add(vm);
             SelectedTask = vm;
             InlineAddTitle = "";
@@ -183,7 +191,8 @@ public partial class TaskListViewModel : ViewModelBase
             }
 
             var tags = await taskRepo.GetEffectiveTagsAsync(saved.Id);
-            Tasks.Add(new TaskItemViewModel(saved, tags, RunNowAsync, () => _worker.IsConnected, ToggleDoneAsync));
+            Tasks.Add(new TaskItemViewModel(saved, tags, RunNowAsync, () => _worker.IsConnected,
+                _dbFactory, 0, ToggleDoneAsync));
 
             // Auto wake-queue if agent+queued
             if (saved.Status == TaskStatus.Queued &&
@@ -282,7 +291,11 @@ public partial class TaskListViewModel : ViewModelBase
         }
         var tags = await taskRepo.GetEffectiveTagsAsync(taskId);
         if (existing is not null)
+        {
             existing.Refresh(entity, tags);
+            var subtaskCount = await context.Subtasks.CountAsync(s => s.TaskId == taskId);
+            await existing.RefreshSubtasksAsync(subtaskCount);
+        }
     }
 
     private async Task RunNowAsync(string taskId)
diff --git a/src/ClaudeDo.Ui/Views/TaskListView.axaml b/src/ClaudeDo.Ui/Views/TaskListView.axaml
index 8115794..5506e83 100644
--- a/src/ClaudeDo.Ui/Views/TaskListView.axaml
+++ b/src/ClaudeDo.Ui/Views/TaskListView.axaml
@@ -31,72 +31,128 @@
                  KeyDown="OnTaskListKeyDown">
             <ListBox.ItemTemplate>
                 <DataTemplate x:DataType="vm:TaskItemViewModel">
-                    <Grid ColumnDefinitions="Auto,*" Margin="4,4"
+                    <Grid RowDefinitions="Auto,Auto"
                           Background="Transparent"
-                          Opacity="{Binding RowOpacity}"
-                          DoubleTapped="OnTaskItemDoubleTapped"
-                          PointerPressed="OnTaskItemPointerPressed">
-                        <Grid.ContextFlyout>
-                            <MenuFlyout>
-                                <MenuItem Header="Edit"
-                                          Command="{Binding #Root.((vm:TaskListViewModel)DataContext).EditTaskCommand}"/>
-                                <MenuItem Header="Delete"
-                                          Command="{Binding #Root.((vm:TaskListViewModel)DataContext).DeleteTaskCommand}"/>
-                                <Separator/>
-                                <MenuItem Header="Run Now"
-                                          Command="{Binding RunNowCommand}"/>
-                            </MenuFlyout>
-                        </Grid.ContextFlyout>
+                          Opacity="{Binding RowOpacity}">
+                        <!-- Row 0: Task row -->
+                        <Grid Grid.Row="0" ColumnDefinitions="20,Auto,*" Margin="4,4"
+                              DoubleTapped="OnTaskItemDoubleTapped"
+                              PointerPressed="OnTaskItemPointerPressed">
+                            <Grid.ContextFlyout>
+                                <MenuFlyout>
+                                    <MenuItem Header="Edit"
+                                              Command="{Binding #Root.((vm:TaskListViewModel)DataContext).EditTaskCommand}"/>
+                                    <MenuItem Header="Delete"
+                                              Command="{Binding #Root.((vm:TaskListViewModel)DataContext).DeleteTaskCommand}"/>
+                                    <Separator/>
+                                    <MenuItem Header="Run Now"
+                                              Command="{Binding RunNowCommand}"/>
+                                </MenuFlyout>
+                            </Grid.ContextFlyout>
 
-                        <!-- Circular checkbox -->
-                        <Border Grid.Column="0" Width="22" Height="22"
-                                CornerRadius="11"
-                                BorderThickness="2"
-                                BorderBrush="{Binding StatusText, Converter={x:Static conv:CheckboxBorderConverter.Instance}}"
-                                Background="Transparent"
-                                VerticalAlignment="Center" Margin="0,0,10,0"
-                                Cursor="Hand"
-                                PointerPressed="OnCheckboxPressed">
-                            <Panel>
-                                <!-- Checkmark for done -->
-                                <Canvas Width="12" Height="12"
-                                        IsVisible="{Binding IsDone}"
-                                        HorizontalAlignment="Center" VerticalAlignment="Center">
-                                    <Path Stroke="{StaticResource StatusGreenBrush}" StrokeThickness="2"
-                                          Data="M 1,6 L 4.5,9.5 L 11,3"/>
-                                </Canvas>
-                                <!-- Running dot -->
-                                <Ellipse Width="8" Height="8"
-                                         Fill="{StaticResource StatusOrangeBrush}"
-                                         IsVisible="{Binding IsRunning}"
-                                         HorizontalAlignment="Center" VerticalAlignment="Center"/>
-                                <!-- Starting dot -->
-                                <Ellipse Width="8" Height="8" Fill="#FFD700"
-                                         IsVisible="{Binding IsStarting}"
-                                         HorizontalAlignment="Center" VerticalAlignment="Center"/>
-                            </Panel>
-                        </Border>
+                            <!-- Expand/collapse chevron -->
+                            <Button Grid.Column="0"
+                                    Command="{Binding ToggleExpandedCommand}"
+                                    IsVisible="{Binding HasSubtasks}"
+                                    Background="Transparent"
+                                    BorderThickness="0"
+                                    Padding="0"
+                                    Width="16" Height="16"
+                                    VerticalAlignment="Center"
+                                    Cursor="Hand">
+                                <Panel>
+                                    <Canvas Width="10" Height="10"
+                                            IsVisible="{Binding !IsExpanded}">
+                                        <Path Stroke="{StaticResource TextDimBrush}" StrokeThickness="1.5"
+                                              Data="M 2,0 L 8,5 L 2,10"/>
+                                    </Canvas>
+                                    <Canvas Width="10" Height="10"
+                                            IsVisible="{Binding IsExpanded}">
+                                        <Path Stroke="{StaticResource TextDimBrush}" StrokeThickness="1.5"
+                                              Data="M 0,2 L 5,8 L 10,2"/>
+                                    </Canvas>
+                                </Panel>
+                            </Button>
 
-                        <!-- Task content -->
-                        <StackPanel Grid.Column="1" VerticalAlignment="Center">
-                            <TextBlock Text="{Binding Title}" FontWeight="Medium"
-                                       Foreground="{Binding TitleForeground}"
-                                       TextDecorations="{Binding TitleDecorations}"
-                                       TextTrimming="CharacterEllipsis"/>
-                            <TextBlock FontSize="11"
-                                       Foreground="{StaticResource TextDimBrush}"
-                                       IsVisible="{Binding TagsText, Converter={x:Static StringConverters.IsNotNullOrEmpty}}">
-                                <TextBlock.Text>
-                                    <MultiBinding StringFormat="{}{0} · {1}">
-                                        <Binding Path="TagsText"/>
-                                        <Binding Path="StatusText"/>
-                                    </MultiBinding>
-                                </TextBlock.Text>
-                            </TextBlock>
-                            <TextBlock Text="{Binding StatusText}" FontSize="11"
-                                       Foreground="{StaticResource TextDimBrush}"
-                                       IsVisible="{Binding TagsText, Converter={x:Static StringConverters.IsNullOrEmpty}}"/>
-                        </StackPanel>
+                            <!-- Circular checkbox -->
+                            <Border Grid.Column="1" Width="22" Height="22"
+                                    CornerRadius="11"
+                                    BorderThickness="2"
+                                    BorderBrush="{Binding StatusText, Converter={x:Static conv:CheckboxBorderConverter.Instance}}"
+                                    Background="Transparent"
+                                    VerticalAlignment="Center" Margin="0,0,10,0"
+                                    Cursor="Hand"
+                                    PointerPressed="OnCheckboxPressed">
+                                <Panel>
+                                    <Canvas Width="12" Height="12"
+                                            IsVisible="{Binding IsDone}"
+                                            HorizontalAlignment="Center" VerticalAlignment="Center">
+                                        <Path Stroke="{StaticResource StatusGreenBrush}" StrokeThickness="2"
+                                              Data="M 1,6 L 4.5,9.5 L 11,3"/>
+                                    </Canvas>
+                                    <Ellipse Width="8" Height="8"
+                                             Fill="{StaticResource StatusOrangeBrush}"
+                                             IsVisible="{Binding IsRunning}"
+                                             HorizontalAlignment="Center" VerticalAlignment="Center"/>
+                                    <Ellipse Width="8" Height="8" Fill="#FFD700"
+                                             IsVisible="{Binding IsStarting}"
+                                             HorizontalAlignment="Center" VerticalAlignment="Center"/>
+                                </Panel>
+                            </Border>
+
+                            <!-- Task content -->
+                            <StackPanel Grid.Column="2" VerticalAlignment="Center">
+                                <TextBlock Text="{Binding Title}" FontWeight="Medium"
+                                           Foreground="{Binding TitleForeground}"
+                                           TextDecorations="{Binding TitleDecorations}"
+                                           TextTrimming="CharacterEllipsis"/>
+                                <TextBlock FontSize="11"
+                                           Foreground="{StaticResource TextDimBrush}"
+                                           IsVisible="{Binding TagsText, Converter={x:Static StringConverters.IsNotNullOrEmpty}}">
+                                    <TextBlock.Text>
+                                        <MultiBinding StringFormat="{}{0} · {1}">
+                                            <Binding Path="TagsText"/>
+                                            <Binding Path="StatusText"/>
+                                        </MultiBinding>
+                                    </TextBlock.Text>
+                                </TextBlock>
+                                <TextBlock Text="{Binding StatusText}" FontSize="11"
+                                           Foreground="{StaticResource TextDimBrush}"
+                                           IsVisible="{Binding TagsText, Converter={x:Static StringConverters.IsNullOrEmpty}}"/>
+                            </StackPanel>
+                        </Grid>
+
+                        <!-- Row 1: Subtask list (visible when expanded) -->
+                        <ItemsControl Grid.Row="1"
+                                      ItemsSource="{Binding Subtasks}"
+                                      IsVisible="{Binding IsExpanded}"
+                                      Margin="40,0,0,4">
+                            <ItemsControl.ItemTemplate>
+                                <DataTemplate x:DataType="vm:SubtaskItemViewModel">
+                                    <Grid ColumnDefinitions="Auto,*" Margin="0,2"
+                                          PointerPressed="OnSubtaskPointerPressed">
+                                        <Grid.ContextFlyout>
+                                            <MenuFlyout>
+                                                <MenuItem Header="Edit Task"
+                                                          Command="{Binding #Root.((vm:TaskListViewModel)DataContext).EditTaskCommand}"/>
+                                            </MenuFlyout>
+                                        </Grid.ContextFlyout>
+                                        <CheckBox Grid.Column="0"
+                                                  IsChecked="{Binding Completed, Mode=OneWay}"
+                                                  VerticalAlignment="Center"
+                                                  Margin="0,0,6,0"
+                                                  MinWidth="0"
+                                                  Click="OnSubtaskCheckboxClick"/>
+                                        <TextBlock Grid.Column="1"
+                                                   Text="{Binding Title}"
+                                                   FontSize="12"
+                                                   Foreground="{StaticResource TextDimBrush}"
+                                                   VerticalAlignment="Center"
+                                                   TextTrimming="CharacterEllipsis"/>
+                                    </Grid>
+                                </DataTemplate>
+                            </ItemsControl.ItemTemplate>
+                        </ItemsControl>
                     </Grid>
                 </DataTemplate>
             </ListBox.ItemTemplate>
diff --git a/src/ClaudeDo.Ui/Views/TaskListView.axaml.cs b/src/ClaudeDo.Ui/Views/TaskListView.axaml.cs
index c739070..5e1ca90 100644
--- a/src/ClaudeDo.Ui/Views/TaskListView.axaml.cs
+++ b/src/ClaudeDo.Ui/Views/TaskListView.axaml.cs
@@ -1,3 +1,4 @@
+using System.Collections.ObjectModel;
 using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -97,6 +98,29 @@ public partial class TaskListView : UserControl
         }
     }
 
+    private void OnSubtaskPointerPressed(object? sender, PointerPressedEventArgs e)
+    {
+        if (e.GetCurrentPoint(null).Properties.IsRightButtonPressed
+            && sender is Control { DataContext: SubtaskItemViewModel subtask }
+            && DataContext is TaskListViewModel vm)
+        {
+            var parent = vm.Tasks.FirstOrDefault(t => t.Subtasks.Contains(subtask));
+            if (parent is not null)
+                vm.SelectedTask = parent;
+        }
+    }
+
+    private async void OnSubtaskCheckboxClick(object? sender, RoutedEventArgs e)
+    {
+        if (sender is CheckBox { DataContext: SubtaskItemViewModel subtask }
+            && DataContext is TaskListViewModel vm)
+        {
+            var parent = vm.Tasks.FirstOrDefault(t => t.Subtasks.Contains(subtask));
+            if (parent is not null)
+                await parent.ToggleSubtaskDoneCommand.ExecuteAsync(subtask.Id);
+        }
+    }
+
     public void FocusInlineAdd()
     {
         this.FindControl<TextBox>("InlineAddBox")?.Focus();