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>

tests/ClaudeDo.Worker.Tests/UiVm/TasksIslandViewModelPlanningTests.cs

@@ -0,0 +1,129 @@
+using ClaudeDo.Data;
+using ClaudeDo.Data.Models;
+using ClaudeDo.Ui.Services;
+using ClaudeDo.Ui.ViewModels.Islands;
+using CommunityToolkit.Mvvm.Input;
+using Microsoft.EntityFrameworkCore;
+using Xunit;
+using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
+
+namespace ClaudeDo.Worker.Tests.UiVm;
+
+// ── Fake worker client ────────────────────────────────────────────────────────
+
+sealed class FakeWorkerClient : IWorkerClient
+{
+    public int StartPlanningCalls { get; private set; }
+    public int ResumePlanningCalls { get; private set; }
+    public int DiscardPlanningCalls { get; private set; }
+    public int FinalizePlanningCalls { get; private set; }
+    public int WakeQueueCalls { get; private set; }
+
+    public Task WakeQueueAsync() { WakeQueueCalls++; return Task.CompletedTask; }
+    public Task StartPlanningSessionAsync(string taskId, CancellationToken ct = default) { StartPlanningCalls++; return Task.CompletedTask; }
+    public Task ResumePlanningSessionAsync(string taskId, CancellationToken ct = default) { ResumePlanningCalls++; return Task.CompletedTask; }
+    public Task DiscardPlanningSessionAsync(string taskId, CancellationToken ct = default) { DiscardPlanningCalls++; return Task.CompletedTask; }
+    public Task FinalizePlanningSessionAsync(string taskId, bool queueAgentTasks = true, CancellationToken ct = default) { FinalizePlanningCalls++; return Task.CompletedTask; }
+}
+
+// ── Helper to build VM with pre-seeded Items ──────────────────────────────────
+
+file static class VmFactory
+{
+    // Minimal SQLite :memory: factory — never actually called in these tests
+    // (we seed Items directly), but required by the VM constructor.
+    private static IDbContextFactory<ClaudeDoDbContext> NullDbFactory()
+    {
+        var opts = new DbContextOptionsBuilder<ClaudeDoDbContext>()
+            .UseSqlite("DataSource=:memory:")
+            .Options;
+        return new NullDbContextFactory(opts);
+    }
+
+    private sealed class NullDbContextFactory(DbContextOptions<ClaudeDoDbContext> opts)
+        : IDbContextFactory<ClaudeDoDbContext>
+    {
+        public ClaudeDoDbContext CreateDbContext() => new(opts);
+    }
+
+    public static (TasksIslandViewModel vm, FakeWorkerClient worker) Create(
+        IEnumerable<TaskRowViewModel> rows)
+    {
+        var worker = new FakeWorkerClient();
+        var vm = new TasksIslandViewModel(NullDbFactory(), worker);
+        foreach (var r in rows)
+            vm.Items.Add(r);
+        vm.Regroup();
+        return (vm, worker);
+    }
+}
+
+// ── Tests ─────────────────────────────────────────────────────────────────────
+
+public class TasksIslandViewModelPlanningTests
+{
+    private static TaskRowViewModel MakeRow(string id, TaskStatus status, string? parentId = null, int sortOrder = 0)
+        => new TaskRowViewModel { Id = id, Status = status, ParentTaskId = parentId };
+
+    [Fact]
+    public void ToggleExpand_CollapsesChildrenOfPlanningParent()
+    {
+        var parent = MakeRow("p1", TaskStatus.Planning);
+        var child1 = MakeRow("c1", TaskStatus.Draft, "p1");
+        var child2 = MakeRow("c2", TaskStatus.Draft, "p1");
+
+        var (vm, _) = VmFactory.Create([parent, child1, child2]);
+
+        // Initially expanded — children visible in OpenItems
+        Assert.Contains(child1, vm.OpenItems);
+        Assert.Contains(child2, vm.OpenItems);
+
+        // Collapse the parent
+        vm.ToggleExpandCommand.Execute(parent);
+
+        // Children should no longer appear
+        Assert.DoesNotContain(child1, vm.OpenItems);
+        Assert.DoesNotContain(child2, vm.OpenItems);
+        // Parent still present
+        Assert.Contains(parent, vm.OpenItems);
+    }
+
+    [Fact]
+    public async Task OpenPlanningSession_IgnoresNonManualRow()
+    {
+        var row = MakeRow("t1", TaskStatus.Queued);
+        var (vm, worker) = VmFactory.Create([row]);
+
+        await ((IAsyncRelayCommand<TaskRowViewModel?>)vm.OpenPlanningSessionCommand).ExecuteAsync(row);
+
+        Assert.Equal(0, worker.StartPlanningCalls);
+    }
+
+    [Fact]
+    public async Task OpenPlanningSession_CallsWorkerForManualRow()
+    {
+        var row = MakeRow("t1", TaskStatus.Manual);
+        var (vm, worker) = VmFactory.Create([row]);
+
+        await ((IAsyncRelayCommand<TaskRowViewModel?>)vm.OpenPlanningSessionCommand).ExecuteAsync(row);
+
+        Assert.Equal(1, worker.StartPlanningCalls);
+    }
+
+    [Fact]
+    public void ToggleExpand_ExpandsCollapsedParentAgain()
+    {
+        var parent = MakeRow("p1", TaskStatus.Planned);
+        var child = MakeRow("c1", TaskStatus.Draft, "p1");
+
+        var (vm, _) = VmFactory.Create([parent, child]);
+
+        // Collapse
+        vm.ToggleExpandCommand.Execute(parent);
+        Assert.DoesNotContain(child, vm.OpenItems);
+
+        // Re-expand
+        vm.ToggleExpandCommand.Execute(parent);
+        Assert.Contains(child, vm.OpenItems);
+    }
+}