feat(ui): planning commands and expand/collapse in TasksIslandViewModel

- Add IWorkerClient interface; WorkerClient implements it
- TasksIslandViewModel accepts IWorkerClient? and gains OpenPlanningSession,
  ResumePlanningSession, DiscardPlanningSession, FinalizePlanningSession,
  and ToggleExpand commands
- Regroup() is hierarchy-aware: children of collapsed planning parents are hidden
- InternalsVisibleTo ClaudeDo.Worker.Tests for Regroup()
- 4 new unit tests covering collapse/expand and guard logic

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/ClaudeDo.Ui/ViewModels/Islands/TasksIslandViewModel.cs

@@ -13,7 +13,8 @@ namespace ClaudeDo.Ui.ViewModels.Islands;
 public sealed partial class TasksIslandViewModel : ViewModelBase
 {
     private readonly IDbContextFactory<ClaudeDoDbContext> _dbFactory;
-    private readonly WorkerClient? _worker;
+    private readonly IWorkerClient? _worker;
+    private readonly Dictionary<string, bool> _expandedState = new();
     private ListNavItemViewModel? _currentList;
     private CancellationTokenSource? _loadCts;
 
@@ -41,7 +42,7 @@ public sealed partial class TasksIslandViewModel : ViewModelBase
     [ObservableProperty] private bool _showOpenLabel;
     [ObservableProperty] private string _completedHeader = "COMPLETED";
 
-    public TasksIslandViewModel(IDbContextFactory<ClaudeDoDbContext> dbFactory, WorkerClient? worker = null)
+    public TasksIslandViewModel(IDbContextFactory<ClaudeDoDbContext> dbFactory, IWorkerClient? worker = null)
     {
         _dbFactory = dbFactory;
         _worker = worker;
@@ -105,14 +106,35 @@ public sealed partial class TasksIslandViewModel : ViewModelBase
         catch (OperationCanceledException) { }
     }
 
-    private void Regroup()
+    internal void Regroup()
     {
         OverdueItems.Clear();
         OpenItems.Clear();
         CompletedItems.Clear();
 
-        var today = DateTime.Today;
+        // Restore IsExpanded from saved state
         foreach (var r in Items)
+        {
+            if (_expandedState.TryGetValue(r.Id, out var saved))
+                r.IsExpanded = saved;
+        }
+
+        // Build hierarchy-aware flat list: top-level rows interleaved with visible children.
+        // Items is already ordered by SortOrder from the DB query.
+        var topLevel = Items.Where(r => !r.IsChild);
+        var flat = new List<TaskRowViewModel>();
+        foreach (var parent in topLevel)
+        {
+            flat.Add(parent);
+            if (parent.IsPlanningParent && parent.IsExpanded)
+            {
+                var children = Items.Where(r => r.ParentTaskId == parent.Id);
+                flat.AddRange(children);
+            }
+        }
+
+        var today = DateTime.Today;
+        foreach (var r in flat)
         {
             if (r.Done)
                 CompletedItems.Add(r);
@@ -356,6 +378,48 @@ public sealed partial class TasksIslandViewModel : ViewModelBase
     [RelayCommand]
     private void OpenListSettings() => OpenListSettingsRequested?.Invoke(this, EventArgs.Empty);
 
+    [RelayCommand]
+    private async Task OpenPlanningSessionAsync(TaskRowViewModel? row)
+    {
+        if (row is null || row.Status != TaskStatus.Manual) return;
+        try { await _worker!.StartPlanningSessionAsync(row.Id); }
+        catch { }
+    }
+
+    [RelayCommand]
+    private async Task ResumePlanningSessionAsync(TaskRowViewModel? row)
+    {
+        if (row is null || !row.IsPlanningParent) return;
+        try { await _worker!.ResumePlanningSessionAsync(row.Id); }
+        catch { }
+    }
+
+    [RelayCommand]
+    private async Task DiscardPlanningSessionAsync(TaskRowViewModel? row)
+    {
+        if (row is null) return;
+        try { await _worker!.DiscardPlanningSessionAsync(row.Id); }
+        catch { }
+    }
+
+    [RelayCommand]
+    private async Task FinalizePlanningSessionAsync(TaskRowViewModel? row)
+    {
+        if (row is null) return;
+        try { await _worker!.FinalizePlanningSessionAsync(row.Id, queueAgentTasks: true); }
+        catch { }
+    }
+
+    [RelayCommand]
+    private void ToggleExpand(TaskRowViewModel? row)
+    {
+        if (row is null) return;
+        var next = !(_expandedState.TryGetValue(row.Id, out var current) ? current : row.IsExpanded);
+        _expandedState[row.Id] = next;
+        row.IsExpanded = next;
+        Regroup();
+    }
+
     partial void OnSelectedTaskChanged(TaskRowViewModel? value)
     {
         foreach (var i in Items) i.IsSelected = ReferenceEquals(i, value);