feat(ui): agent config inline in detail panel, file picker, subtask UI

TaskDetailView now edits Model / SystemPrompt / Agent inline (LostFocus
save), matching the modal editor. Both TaskEditorView and TaskDetailView
gain a Browse button that opens a .md file picker — external agent
paths are preserved on reload via a synthetic AgentInfo entry. Both
views also render the per-task subtask checklist (CheckBox + TextBox +
remove), with diff-on-save in the editor and inline-save in the detail
panel.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Ui/ViewModels/SubtaskItemViewModel.cs

@@ -0,0 +1,23 @@
+using ClaudeDo.Data.Models;
+using CommunityToolkit.Mvvm.ComponentModel;
+
+namespace ClaudeDo.Ui.ViewModels;
+
+public partial class SubtaskItemViewModel : ObservableObject
+{
+    [ObservableProperty] private string _title = string.Empty;
+    [ObservableProperty] private bool _completed;
+
+    public string Id { get; set; } = string.Empty;
+    public string? OriginalTitle { get; set; }
+    public bool OriginalCompleted { get; set; }
+
+    public static SubtaskItemViewModel From(SubtaskEntity e) => new()
+    {
+        Id = e.Id,
+        Title = e.Title,
+        Completed = e.Completed,
+        OriginalTitle = e.Title,
+        OriginalCompleted = e.Completed,
+    };
+}

src/ClaudeDo.Ui/ViewModels/TaskDetailViewModel.cs

@@ -20,6 +20,7 @@ public partial class TaskDetailViewModel : ViewModelBase
     private readonly GitService _git;
     private readonly WorkerClient _worker;
     private readonly TagRepository _tagRepo;
+    private readonly SubtaskRepository _subtaskRepo;
 
     [ObservableProperty] private string _title = "";
     [ObservableProperty] private string? _description;
@@ -28,9 +29,14 @@ public partial class TaskDetailViewModel : ViewModelBase
     [ObservableProperty] private string _statusText = "";
     [ObservableProperty] private string _statusChoice = "Manual";
     [ObservableProperty] private string _commitType = "chore";
+    [ObservableProperty] private string _modelChoice = "(list default)";
+    [ObservableProperty] private string? _systemPromptOverride;
+    [ObservableProperty] private AgentInfo? _selectedAgent;
+    public List<AgentInfo> AvailableAgents { get; } = [];
 
     public static string[] StatusChoices { get; } = ["Manual", "Queued", "Running", "Done", "Failed"];
     public static string[] CommitTypes { get; } = ["feat", "fix", "refactor", "docs", "test", "chore", "ci", "perf", "style", "build"];
+    public static string[] ModelChoices { get; } = ["(list default)", "Sonnet", "Opus", "Haiku"];
 
     // Worktree
     [ObservableProperty] private bool _hasWorktree;
@@ -44,6 +50,7 @@ public partial class TaskDetailViewModel : ViewModelBase
     private StreamLineFormatter _formatter = new();
     public ObservableCollection<TagEntity> Tags { get; } = new();
     [ObservableProperty] private string _newTagInput = "";
+    public ObservableCollection<SubtaskItemViewModel> Subtasks { get; } = new();
 
     private string? _taskId;
     private string? _listId;
@@ -52,7 +59,8 @@ public partial class TaskDetailViewModel : ViewModelBase
     public event Action<string>? TaskChanged;
 
     public TaskDetailViewModel(TaskRepository taskRepo, WorktreeRepository worktreeRepo,
-        ListRepository listRepo, GitService git, WorkerClient worker, TagRepository tagRepo)
+        ListRepository listRepo, GitService git, WorkerClient worker, TagRepository tagRepo,
+        SubtaskRepository subtaskRepo)
     {
         _taskRepo = taskRepo;
         _worktreeRepo = worktreeRepo;
@@ -60,6 +68,7 @@ public partial class TaskDetailViewModel : ViewModelBase
         _git = git;
         _worker = worker;
         _tagRepo = tagRepo;
+        _subtaskRepo = subtaskRepo;
 
         worker.TaskMessageEvent += OnTaskMessage;
         worker.WorktreeUpdatedEvent += OnWorktreeUpdated;
@@ -77,6 +86,13 @@ public partial class TaskDetailViewModel : ViewModelBase
         var task = await _taskRepo.GetByIdAsync(taskId);
         if (task is null) return;
 
+        if (AvailableAgents.Count == 0)
+        {
+            var agents = await _worker.GetAgentsAsync();
+            AvailableAgents.AddRange(agents);
+            OnPropertyChanged(nameof(AvailableAgents));
+        }
+
         _isLoading = true;
         try
         {
@@ -95,11 +111,39 @@ public partial class TaskDetailViewModel : ViewModelBase
             StatusText = task.Status.ToString().ToLowerInvariant();
             StatusChoice = task.Status.ToString();
             CommitType = task.CommitType;
+            ModelChoice = task.Model is not null
+                ? ListEditorViewModel.ModelIdToDisplay(task.Model)
+                : "(list default)";
+            SystemPromptOverride = task.SystemPrompt;
+            if (task.AgentPath is not null)
+            {
+                var match = AvailableAgents.FirstOrDefault(a => a.Path == task.AgentPath);
+                if (match is null)
+                {
+                    match = new AgentInfo(Path.GetFileNameWithoutExtension(task.AgentPath), "(external)", task.AgentPath);
+                    AvailableAgents.Add(match);
+                    OnPropertyChanged(nameof(AvailableAgents));
+                }
+                SelectedAgent = match;
+            }
+            else
+            {
+                SelectedAgent = null;
+            }
 
             Tags.Clear();
             var tags = await _taskRepo.GetTagsAsync(taskId);
             foreach (var tag in tags)
                 Tags.Add(tag);
+
+            Subtasks.Clear();
+            var subtasks = await _subtaskRepo.GetByTaskIdAsync(taskId);
+            foreach (var s in subtasks)
+            {
+                var vm = SubtaskItemViewModel.From(s);
+                vm.PropertyChanged += OnSubtaskPropertyChanged;
+                Subtasks.Add(vm);
+            }
         }
         finally
         {
@@ -119,6 +163,11 @@ public partial class TaskDetailViewModel : ViewModelBase
         entity.Title = Title;
         entity.Description = Description;
         entity.CommitType = CommitType;
+        entity.Model = ModelChoice != "(list default)"
+            ? ListEditorViewModel.ModelDisplayToId(ModelChoice)
+            : null;
+        entity.SystemPrompt = string.IsNullOrWhiteSpace(SystemPromptOverride) ? null : SystemPromptOverride.Trim();
+        entity.AgentPath = SelectedAgent?.Path;
 
         if (Enum.TryParse<Data.Models.TaskStatus>(StatusChoice, true, out var status))
             entity.Status = status;
@@ -155,6 +204,61 @@ public partial class TaskDetailViewModel : ViewModelBase
         TaskChanged?.Invoke(_taskId);
     }
 
+    [RelayCommand]
+    private async Task AddSubtask()
+    {
+        if (_taskId is null) return;
+        var entity = new SubtaskEntity
+        {
+            Id = Guid.NewGuid().ToString(),
+            TaskId = _taskId,
+            Title = "",
+            Completed = false,
+            OrderNum = Subtasks.Count,
+            CreatedAt = DateTime.UtcNow,
+        };
+        await _subtaskRepo.AddAsync(entity);
+        var vm = SubtaskItemViewModel.From(entity);
+        vm.PropertyChanged += OnSubtaskPropertyChanged;
+        Subtasks.Add(vm);
+    }
+
+    [RelayCommand]
+    private async Task RemoveSubtask(SubtaskItemViewModel item)
+    {
+        if (!string.IsNullOrEmpty(item.Id))
+            await _subtaskRepo.DeleteAsync(item.Id);
+        item.PropertyChanged -= OnSubtaskPropertyChanged;
+        Subtasks.Remove(item);
+    }
+
+    private async void OnSubtaskPropertyChanged(object? sender, System.ComponentModel.PropertyChangedEventArgs e)
+    {
+        if (_isLoading || sender is not SubtaskItemViewModel vm || string.IsNullOrEmpty(vm.Id)) return;
+        if (e.PropertyName is not (nameof(SubtaskItemViewModel.Title) or nameof(SubtaskItemViewModel.Completed))) return;
+        await _subtaskRepo.UpdateAsync(new SubtaskEntity
+        {
+            Id = vm.Id,
+            TaskId = _taskId ?? "",
+            Title = vm.Title,
+            Completed = vm.Completed,
+            OrderNum = Subtasks.IndexOf(vm),
+            CreatedAt = DateTime.UtcNow,
+        });
+    }
+
+    public void SetAgentFromPath(string path)
+    {
+        var existing = AvailableAgents.FirstOrDefault(a => a.Path == path);
+        if (existing is null)
+        {
+            existing = new AgentInfo(Path.GetFileNameWithoutExtension(path), "(external)", path);
+            AvailableAgents.Add(existing);
+            OnPropertyChanged(nameof(AvailableAgents));
+        }
+        SelectedAgent = existing;
+    }
+
     public void Clear()
     {
         _taskId = null;
@@ -169,8 +273,13 @@ public partial class TaskDetailViewModel : ViewModelBase
         _formatter = new StreamLineFormatter();
         Tags.Clear();
         NewTagInput = "";
+        foreach (var s in Subtasks) s.PropertyChanged -= OnSubtaskPropertyChanged;
+        Subtasks.Clear();
         StatusChoice = "Manual";
         CommitType = "chore";
+        ModelChoice = "(list default)";
+        SystemPromptOverride = null;
+        SelectedAgent = null;
     }
 
     private async Task LoadWorktreeAsync(string taskId)

src/ClaudeDo.Ui/ViewModels/TaskEditorViewModel.cs

@@ -1,4 +1,7 @@
+using System.Collections.ObjectModel;
+using System.IO;
 using ClaudeDo.Data.Models;
+using ClaudeDo.Data.Repositories;
 using ClaudeDo.Ui.Services;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
@@ -8,6 +11,8 @@ namespace ClaudeDo.Ui.ViewModels;
 
 public partial class TaskEditorViewModel : ViewModelBase
 {
+    private readonly SubtaskRepository _subtaskRepo;
+
     [ObservableProperty] private string _title = "";
     [ObservableProperty] private string? _description;
     [ObservableProperty] private string _commitType = "chore";
@@ -18,6 +23,7 @@ public partial class TaskEditorViewModel : ViewModelBase
     [ObservableProperty] private string? _systemPromptOverride;
     [ObservableProperty] private AgentInfo? _selectedAgent;
     public List<AgentInfo> AvailableAgents { get; set; } = [];
+    public ObservableCollection<SubtaskItemViewModel> Subtasks { get; } = new();
 
     private string? _editId;
     private string _listId = "";
@@ -34,11 +40,28 @@ public partial class TaskEditorViewModel : ViewModelBase
     public static string[] StatusChoices { get; } =
         ["manual", "queued"];
 
+    public TaskEditorViewModel(SubtaskRepository subtaskRepo)
+    {
+        _subtaskRepo = subtaskRepo;
+    }
+
     public async Task LoadAgentsAsync(WorkerClient worker)
     {
         AvailableAgents = await worker.GetAgentsAsync();
     }
 
+    public void SetAgentFromPath(string path)
+    {
+        var existing = AvailableAgents.FirstOrDefault(a => a.Path == path);
+        if (existing is null)
+        {
+            existing = new AgentInfo(Path.GetFileNameWithoutExtension(path), "(external)", path);
+            AvailableAgents.Add(existing);
+            OnPropertyChanged(nameof(AvailableAgents));
+        }
+        SelectedAgent = existing;
+    }
+
     public IReadOnlyList<string> SelectedTagNames =>
         TagsInput.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
             .Distinct()
@@ -51,8 +74,54 @@ public partial class TaskEditorViewModel : ViewModelBase
         _createdAt = DateTime.UtcNow;
         CommitType = defaultCommitType;
         WindowTitle = "New Task";
+        Subtasks.Clear();
     }
 
+    public async Task InitForEditAsync(TaskEntity entity, IReadOnlyList<TagEntity> taskTags, CancellationToken ct = default)
+    {
+        _editId = entity.Id;
+        _listId = entity.ListId;
+        _createdAt = entity.CreatedAt;
+        Title = entity.Title;
+        Description = entity.Description;
+        CommitType = entity.CommitType;
+        StatusChoice = entity.Status switch
+        {
+            TaskStatus.Manual => "manual",
+            TaskStatus.Queued => "queued",
+            _ => entity.Status.ToString().ToLowerInvariant(),
+        };
+        TagsInput = string.Join(", ", taskTags.Select(t => t.Name));
+        ModelChoice = entity.Model is not null
+            ? ListEditorViewModel.ModelIdToDisplay(entity.Model)
+            : "(list default)";
+        SystemPromptOverride = entity.SystemPrompt;
+
+        if (entity.AgentPath is not null)
+        {
+            var match = AvailableAgents.FirstOrDefault(a => a.Path == entity.AgentPath);
+            if (match is null)
+            {
+                match = new AgentInfo(Path.GetFileNameWithoutExtension(entity.AgentPath), "(external)", entity.AgentPath);
+                AvailableAgents.Add(match);
+                OnPropertyChanged(nameof(AvailableAgents));
+            }
+            SelectedAgent = match;
+        }
+        else
+        {
+            SelectedAgent = null;
+        }
+
+        WindowTitle = $"Edit Task: {entity.Title}";
+
+        Subtasks.Clear();
+        var list = await _subtaskRepo.GetByTaskIdAsync(entity.Id, ct);
+        foreach (var s in list)
+            Subtasks.Add(SubtaskItemViewModel.From(s));
+    }
+
+    // Keep old sync overload for callers that haven't loaded agents yet
     public void InitForEdit(TaskEntity entity, IReadOnlyList<TagEntity> taskTags)
     {
         _editId = entity.Id;
@@ -72,14 +141,34 @@ public partial class TaskEditorViewModel : ViewModelBase
             ? ListEditorViewModel.ModelIdToDisplay(entity.Model)
             : "(list default)";
         SystemPromptOverride = entity.SystemPrompt;
-        SelectedAgent = entity.AgentPath is not null
+
-            ? AvailableAgents.FirstOrDefault(a => a.Path == entity.AgentPath)
+        if (entity.AgentPath is not null)
-            : null;
+        {
+            var match = AvailableAgents.FirstOrDefault(a => a.Path == entity.AgentPath);
+            if (match is null)
+            {
+                match = new AgentInfo(Path.GetFileNameWithoutExtension(entity.AgentPath), "(external)", entity.AgentPath);
+                AvailableAgents.Add(match);
+                OnPropertyChanged(nameof(AvailableAgents));
+            }
+            SelectedAgent = match;
+        }
+        else
+        {
+            SelectedAgent = null;
+        }
+
         WindowTitle = $"Edit Task: {entity.Title}";
     }
 
     [RelayCommand]
-    private void Save()
+    private void AddSubtask() => Subtasks.Add(new SubtaskItemViewModel());
+
+    [RelayCommand]
+    private void RemoveSubtask(SubtaskItemViewModel item) => Subtasks.Remove(item);
+
+    [RelayCommand]
+    private async Task Save()
     {
         if (string.IsNullOrWhiteSpace(Title)) return;
         var status = StatusChoice switch
@@ -87,9 +176,10 @@ public partial class TaskEditorViewModel : ViewModelBase
             "queued" => TaskStatus.Queued,
             _ => TaskStatus.Manual,
         };
+        var taskId = _editId ?? Guid.NewGuid().ToString();
         var entity = new TaskEntity
         {
-            Id = _editId ?? Guid.NewGuid().ToString(),
+            Id = taskId,
             ListId = _listId,
             Title = Title.Trim(),
             Description = string.IsNullOrWhiteSpace(Description) ? null : Description.Trim(),
@@ -102,6 +192,42 @@ public partial class TaskEditorViewModel : ViewModelBase
             : null;
         entity.SystemPrompt = string.IsNullOrWhiteSpace(SystemPromptOverride) ? null : SystemPromptOverride.Trim();
         entity.AgentPath = SelectedAgent?.Path;
+
+        // Persist subtask changes
+        if (_editId is not null)
+        {
+            var existing = await _subtaskRepo.GetByTaskIdAsync(taskId);
+            var existingIds = existing.Select(s => s.Id).ToHashSet();
+            var currentIds = Subtasks.Where(s => s.Id != "").Select(s => s.Id).ToHashSet();
+
+            // Deleted
+            foreach (var id in existingIds.Except(currentIds))
+                await _subtaskRepo.DeleteAsync(id);
+
+            // Updated
+            foreach (var (vm, idx) in Subtasks.Select((v, i) => (v, i)))
+            {
+                if (vm.Id == "") continue;
+                if (vm.Title != vm.OriginalTitle || vm.Completed != vm.OriginalCompleted)
+                    await _subtaskRepo.UpdateAsync(new SubtaskEntity { Id = vm.Id, TaskId = taskId, Title = vm.Title, Completed = vm.Completed, OrderNum = idx, CreatedAt = DateTime.UtcNow });
+                else
+                {
+                    // update order_num if position changed
+                    var orig = existing.FirstOrDefault(e => e.Id == vm.Id);
+                    if (orig is not null && orig.OrderNum != idx)
+                        await _subtaskRepo.UpdateAsync(new SubtaskEntity { Id = vm.Id, TaskId = taskId, Title = vm.Title, Completed = vm.Completed, OrderNum = idx, CreatedAt = orig.CreatedAt });
+                }
+            }
+        }
+
+        // Added (id == "" means new)
+        foreach (var (vm, idx) in Subtasks.Select((v, i) => (v, i)).Where(x => x.v.Id == ""))
+        {
+            if (string.IsNullOrWhiteSpace(vm.Title)) continue;
+            var newId = Guid.NewGuid().ToString();
+            await _subtaskRepo.AddAsync(new SubtaskEntity { Id = newId, TaskId = taskId, Title = vm.Title.Trim(), Completed = vm.Completed, OrderNum = idx, CreatedAt = DateTime.UtcNow });
+        }
+
         _tcs.TrySetResult(entity);
         RequestClose?.Invoke();
     }

src/ClaudeDo.Ui/ViewModels/TaskListViewModel.cs

@@ -194,7 +194,7 @@ public partial class TaskListViewModel : ViewModelBase
         var taskTags = await _taskRepo.GetTagsAsync(entity.Id);
         var editor = _editorFactory();
         await editor.LoadAgentsAsync(_worker);
-        editor.InitForEdit(entity, taskTags);
+        await editor.InitForEditAsync(entity, taskTags);
 
         var window = new TaskEditorView { DataContext = editor };
         editor.RequestClose += () => window.Close();

src/ClaudeDo.Ui/Views/TaskDetailView.axaml

@@ -86,6 +86,71 @@
                      PlaceholderText="Add a description..."
                      LostFocus="OnFieldLostFocus"/>
 
+            <!-- Sub-Tasks -->
+            <Border Height="1" Background="{StaticResource BorderSubtleBrush}" Margin="0,8,0,4"/>
+            <TextBlock Text="Sub-Tasks" FontWeight="Bold" FontSize="13"
+                       Foreground="{StaticResource TextPrimaryBrush}"/>
+            <ItemsControl ItemsSource="{Binding Subtasks}">
+                <ItemsControl.ItemTemplate>
+                    <DataTemplate x:DataType="vm:SubtaskItemViewModel">
+                        <StackPanel Orientation="Horizontal" Spacing="6" Margin="0,2,0,2">
+                            <CheckBox IsChecked="{Binding Completed}" VerticalAlignment="Center"/>
+                            <TextBox Text="{Binding Title}" PlaceholderText="Subtask title..." Width="220"
+                                     VerticalAlignment="Center"
+                                     LostFocus="OnSubtaskTitleLostFocus"/>
+                            <Button Content="✕" Padding="6,2"
+                                    Background="Transparent" BorderThickness="0"
+                                    Foreground="{StaticResource TextMutedBrush}"
+                                    Command="{Binding $parent[UserControl].((vm:TaskDetailViewModel)DataContext).RemoveSubtaskCommand}"
+                                    CommandParameter="{Binding}"/>
+                        </StackPanel>
+                    </DataTemplate>
+                </ItemsControl.ItemTemplate>
+            </ItemsControl>
+            <Button Content="+ Add Sub-Task" Command="{Binding AddSubtaskCommand}"
+                    Background="Transparent" BorderThickness="0"
+                    Foreground="{StaticResource AccentLightBrush}" HorizontalAlignment="Left"/>
+
+            <!-- Agent Config (overrides) -->
+            <Border Height="1" Background="{StaticResource BorderSubtleBrush}" Margin="0,8,0,4"/>
+            <TextBlock Text="Agent Config (overrides)" FontWeight="Bold" FontSize="13"
+                       Foreground="{StaticResource TextPrimaryBrush}"/>
+
+            <Grid ColumnDefinitions="*,12,*" Margin="0,4,0,0">
+                <StackPanel Grid.Column="0" Spacing="4">
+                    <TextBlock Text="Model" FontSize="12" FontWeight="SemiBold"
+                               Foreground="{StaticResource TextSecondaryBrush}"/>
+                    <ComboBox ItemsSource="{Binding ModelChoices}"
+                              SelectedItem="{Binding ModelChoice}"
+                              MinWidth="100"
+                              LostFocus="OnFieldLostFocus"/>
+                </StackPanel>
+                <StackPanel Grid.Column="2" Spacing="4">
+                    <TextBlock Text="Agent File" FontSize="12" FontWeight="SemiBold"
+                               Foreground="{StaticResource TextSecondaryBrush}"/>
+                    <StackPanel Orientation="Horizontal" Spacing="4">
+                        <ComboBox ItemsSource="{Binding AvailableAgents}"
+                                  SelectedItem="{Binding SelectedAgent}"
+                                  MinWidth="100"
+                                  LostFocus="OnFieldLostFocus">
+                            <ComboBox.ItemTemplate>
+                                <DataTemplate x:DataType="m:AgentInfo">
+                                    <TextBlock Text="{Binding Name}"/>
+                                </DataTemplate>
+                            </ComboBox.ItemTemplate>
+                        </ComboBox>
+                        <Button Content="…" Click="OnBrowseAgent" ToolTip.Tip="Browse for agent .md file"/>
+                    </StackPanel>
+                </StackPanel>
+            </Grid>
+
+            <TextBlock Text="System Prompt" FontSize="12" FontWeight="SemiBold"
+                       Foreground="{StaticResource TextSecondaryBrush}" Margin="0,4,0,2"/>
+            <TextBox Text="{Binding SystemPromptOverride}"
+                     PlaceholderText="(inherits from list)"
+                     AcceptsReturn="True" TextWrapping="Wrap" MinHeight="50"
+                     LostFocus="OnFieldLostFocus"/>
+
             <!-- === READ-ONLY ZONE === -->
 
             <TextBlock Text="Result" FontWeight="SemiBold" FontSize="12"

src/ClaudeDo.Ui/Views/TaskDetailView.axaml.cs

@@ -2,6 +2,7 @@ using System.ComponentModel;
 using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Interactivity;
+using Avalonia.Platform.Storage;
 using ClaudeDo.Ui.ViewModels;
 
 namespace ClaudeDo.Ui.Views;
@@ -19,6 +20,31 @@ public partial class TaskDetailView : UserControl
             await vm.SaveAsync();
     }
 
+    private void OnSubtaskTitleLostFocus(object? sender, RoutedEventArgs e)
+    {
+        // Title change is handled by SubtaskItemViewModel.PropertyChanged → OnSubtaskPropertyChanged in the VM
+    }
+
+    private async void OnBrowseAgent(object? sender, RoutedEventArgs e)
+    {
+        var topLevel = TopLevel.GetTopLevel(this);
+        if (topLevel is null) return;
+        var files = await topLevel.StorageProvider.OpenFilePickerAsync(new FilePickerOpenOptions
+        {
+            Title = "Select Agent File",
+            AllowMultiple = false,
+            FileTypeFilter = new[] { new FilePickerFileType("Agent Files") { Patterns = ["*.md"] } },
+        });
+        if (files.Count == 0) return;
+        var path = files[0].TryGetLocalPath();
+        if (path is null) return;
+        if (DataContext is TaskDetailViewModel vm)
+        {
+            vm.SetAgentFromPath(path);
+            await vm.SaveAsync();
+        }
+    }
+
     private void OnTagInputKeyDown(object? sender, KeyEventArgs e)
     {
         if (e.Key == Key.Enter && DataContext is TaskDetailViewModel vm)

src/ClaudeDo.Ui/Views/TaskEditorView.axaml

@@ -35,6 +35,30 @@
         <TextBlock Text="Tags (comma-separated)" FontWeight="SemiBold" Foreground="{StaticResource TextSecondaryBrush}"/>
         <TextBox Text="{Binding TagsInput}" PlaceholderText="agent, manual, code, ..."/>
 
+        <!-- Sub-Tasks -->
+        <Border Height="1" Background="{StaticResource BorderSubtleBrush}" Margin="0,6,0,2"/>
+        <TextBlock Text="Sub-Tasks" FontWeight="Bold" FontSize="13"
+                   Foreground="{StaticResource TextPrimaryBrush}"/>
+        <ItemsControl ItemsSource="{Binding Subtasks}">
+            <ItemsControl.ItemTemplate>
+                <DataTemplate x:DataType="vm:SubtaskItemViewModel">
+                    <StackPanel Orientation="Horizontal" Spacing="6" Margin="0,2,0,2">
+                        <CheckBox IsChecked="{Binding Completed}" VerticalAlignment="Center"/>
+                        <TextBox Text="{Binding Title}" PlaceholderText="Subtask title..." Width="320"
+                                 VerticalAlignment="Center"/>
+                        <Button Content="✕" Padding="6,2"
+                                Background="Transparent" BorderThickness="0"
+                                Foreground="{StaticResource TextMutedBrush}"
+                                Command="{Binding $parent[Window].((vm:TaskEditorViewModel)DataContext).RemoveSubtaskCommand}"
+                                CommandParameter="{Binding}"/>
+                    </StackPanel>
+                </DataTemplate>
+            </ItemsControl.ItemTemplate>
+        </ItemsControl>
+        <Button Content="+ Add Sub-Task" Command="{Binding AddSubtaskCommand}"
+                Background="Transparent" BorderThickness="0"
+                Foreground="{StaticResource AccentLightBrush}" HorizontalAlignment="Left"/>
+
         <!-- Divider -->
         <Border Height="1" Background="{StaticResource BorderSubtleBrush}" Margin="0,6,0,2"/>
 
@@ -55,6 +79,7 @@
 
         <TextBlock Text="Agent File" FontWeight="SemiBold"
                    Foreground="{StaticResource TextSecondaryBrush}"/>
+        <StackPanel Orientation="Horizontal" Spacing="6">
             <ComboBox ItemsSource="{Binding AvailableAgents}"
                       SelectedItem="{Binding SelectedAgent}"
                       MinWidth="150">
@@ -64,6 +89,8 @@
                     </DataTemplate>
                 </ComboBox.ItemTemplate>
             </ComboBox>
+            <Button Content="…" Click="OnBrowseAgent" ToolTip.Tip="Browse for agent .md file"/>
+        </StackPanel>
 
         <StackPanel Orientation="Horizontal" Spacing="8" HorizontalAlignment="Right" Margin="0,10,0,0">
             <Button Content="Save" Command="{Binding SaveCommand}" IsDefault="True" MinWidth="80"

src/ClaudeDo.Ui/Views/TaskEditorView.axaml.cs

@@ -1,4 +1,7 @@
 using Avalonia.Controls;
+using Avalonia.Interactivity;
+using Avalonia.Platform.Storage;
+using ClaudeDo.Ui.ViewModels;
 
 namespace ClaudeDo.Ui.Views;
 
@@ -8,4 +11,19 @@ public partial class TaskEditorView : Window
     {
         InitializeComponent();
     }
+
+    private async void OnBrowseAgent(object? sender, RoutedEventArgs e)
+    {
+        var files = await StorageProvider.OpenFilePickerAsync(new FilePickerOpenOptions
+        {
+            Title = "Select Agent File",
+            AllowMultiple = false,
+            FileTypeFilter = new[] { new FilePickerFileType("Agent Files") { Patterns = ["*.md"] } },
+        });
+        if (files.Count == 0) return;
+        var path = files[0].TryGetLocalPath();
+        if (path is null) return;
+        if (DataContext is TaskEditorViewModel vm)
+            vm.SetAgentFromPath(path);
+    }
 }