fix(worker,ui): route details-pane task delete through worker to advance blocked parents

Deleting a child from the details pane hard-deleted straight from the UI
process via TaskRepository, bypassing TaskStateService.TryAdvanceParentAsync
entirely. Deleting the last child of a WaitingForChildren parent that way
left it wedged forever. WorkerHub.DeleteTask now mirrors the MCP delete_task
tool (running-task guard, FK-friendly error, advance-parent call), and the
UI goes through it.

TryAdvanceParentAsync also short-circuited when zero children remained,
treating "no children left" as "nothing to evaluate" instead of "all done" -
removed the early return so an empty child list (vacuously) counts as all
terminal.

docs/explore-notes/worker-task-pipeline.md

@@ -50,6 +50,9 @@ How a task moves Queued → Running → terminal, across `src/ClaudeDo.Worker`
    - **Done** CompleteAsync (Running → Done) — top-level success.
    - **WaitingForReview** SubmitForReviewAsync (Running → WaitingForReview) — review gate.
    - **WaitingForChildren** SubmitForChildrenAsync (Running → WaitingForChildren) — blocks on children.
+     Advances to WaitingForReview via `TryAdvanceParentAsync` once every remaining child is
+     terminal (Done/Failed/Cancelled) — including zero children left, e.g. after the last child
+     is deleted (`WorkerHub.DeleteTask` / `ExternalMcpService.DeleteTask` both call it).
    - **Failed** FailAsync (Running/Queued → Failed).
    - **Cancelled** CancelAsync (Running/Queued/WaitingForReview/WaitingForChildren → Cancelled).
 

src/ClaudeDo.Ui/Services/Interfaces/IWorkerClient.cs

@@ -57,6 +57,10 @@ public interface IWorkerClient : INotifyPropertyChanged
     Task<PendingQuestionDto?> GetPendingQuestionAsync(string taskId);
     Task ResetTaskAsync(string taskId);
     Task CancelTaskAsync(string taskId);
+    /// <summary>Deletes a task via the worker (mirrors the MCP delete_task tool), so a deleted
+    /// child correctly advances a WaitingForChildren parent. Returns (false, message) instead of
+    /// throwing when the task has children or is running, preserving the FK-error UX.</summary>
+    Task<(bool Ok, string? Error)> DeleteTaskAsync(string taskId);
     Task<List<AgentInfo>> GetAgentsAsync();
     Task RefreshAgentsAsync();
     Task<SeedResultDto?> RestoreDefaultAgentsAsync();

src/ClaudeDo.Ui/Services/WorkerClient.cs

@@ -327,6 +327,19 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
         await _hub.InvokeAsync("CancelTask", taskId);
     }
 
+    public async Task<(bool Ok, string? Error)> DeleteTaskAsync(string taskId)
+    {
+        try
+        {
+            await _hub.InvokeAsync("DeleteTask", taskId, CancellationToken.None);
+            return (true, null);
+        }
+        catch (HubException ex)
+        {
+            return (false, ex.Message);
+        }
+    }
+
     public async Task WakeQueueAsync()
     {
         await _hub.InvokeAsync("WakeQueue");

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

@@ -946,18 +946,14 @@ public sealed partial class DetailsIslandViewModel : ViewModelBase, IDisposable
             var ok = await ConfirmAsync($"Delete \"{row.Title}\"? This cannot be undone.");
             if (!ok) return;
         }
-        try
-        {
-            await using var ctx = _dbFactory.CreateDbContext();
-            var repo = new TaskRepository(ctx);
-            await repo.DeleteAsync(row.Id);
-        }
-        catch (Microsoft.EntityFrameworkCore.DbUpdateException ex) when (
-               ex.Message.Contains("FOREIGN KEY", StringComparison.OrdinalIgnoreCase)
-            || ex.InnerException?.Message.Contains("FOREIGN KEY", StringComparison.OrdinalIgnoreCase) == true)
+        // Routed through the worker (mirrors the MCP delete_task tool) so a deleted child
+        // correctly advances a WaitingForChildren parent — a direct-repo delete from here used
+        // to bypass TaskStateService.TryAdvanceParentAsync and could wedge the parent forever.
+        var (deleted, error) = await _worker.DeleteTaskAsync(row.Id);
+        if (!deleted)
         {
             if (ShowErrorAsync != null)
-                await ShowErrorAsync("This task has child tasks. Discard the planning session or delete child tasks first.");
+                await ShowErrorAsync(error ?? "Delete failed.");
             return;
         }
         if (DeleteFromList != null)

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -380,6 +380,38 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
 
     public bool CancelTask(string taskId) => _queue.CancelTask(taskId);
 
+    // Mirrors ExternalMcpService.DeleteTask so a UI-initiated delete gets the same
+    // TryAdvanceParentAsync side effect — a direct-repo delete from the details pane
+    // used to skip it, permanently wedging a WaitingForChildren parent whose last
+    // child was deleted from there.
+    public async Task DeleteTask(string taskId, CancellationToken cancellationToken)
+    {
+        await using var ctx = await _dbFactory.CreateDbContextAsync(cancellationToken);
+        var repo = new TaskRepository(ctx);
+        var task = await repo.GetByIdAsync(taskId, cancellationToken)
+            ?? throw new HubException("task not found");
+        if (task.Status == TaskStatus.Running)
+            throw new HubException("Cannot delete a running task. Cancel it first.");
+
+        try
+        {
+            await repo.DeleteAsync(taskId, cancellationToken);
+        }
+        // TaskRepository.DeleteAsync uses ExecuteDeleteAsync, which bypasses SaveChanges and
+        // surfaces provider errors directly as SqliteException rather than DbUpdateException.
+        catch (Exception ex) when (
+            (ex is Microsoft.Data.Sqlite.SqliteException || ex.InnerException is Microsoft.Data.Sqlite.SqliteException)
+            && (ex.Message.Contains("FOREIGN KEY", StringComparison.OrdinalIgnoreCase)
+                || ex.InnerException?.Message.Contains("FOREIGN KEY", StringComparison.OrdinalIgnoreCase) == true))
+        {
+            throw new HubException("This task has child tasks. Discard the planning session or delete child tasks first.");
+        }
+
+        if (task.ParentTaskId is not null)
+            await _state.TryAdvanceParentAsync(task.ParentTaskId);
+        await _broadcaster.TaskUpdated(taskId);
+    }
+
     public void WakeQueue() => _waker.Wake();
 
     public async Task<List<AgentInfo>> GetAgents() => await _agentService.ScanAsync();

src/ClaudeDo.Worker/State/TaskStateService.cs

@@ -505,8 +505,8 @@ public sealed class TaskStateService : ITaskStateService
                 .Select(t => t.Status)
                 .ToListAsync(CancellationToken.None);
         }
-        if (childStatuses.Count == 0) return;
-
+        // No early-out on an empty list: zero children left (e.g. the last one was just
+        // deleted) counts as "all terminal" — .All() on an empty sequence is vacuously true.
         bool allTerminal = childStatuses.All(s =>
             s == TaskStatus.Done || s == TaskStatus.Failed || s == TaskStatus.Cancelled);
         if (!allTerminal) return;

tests/ClaudeDo.Ui.Tests/StubWorkerClient.cs

@@ -79,6 +79,7 @@ public abstract class StubWorkerClient : IWorkerClient
     public virtual Task<PendingQuestionDto?> GetPendingQuestionAsync(string taskId) => Task.FromResult(PendingQuestion);
     public virtual Task ResetTaskAsync(string taskId) => Task.CompletedTask;
     public virtual Task CancelTaskAsync(string taskId) => Task.CompletedTask;
+    public virtual Task<(bool Ok, string? Error)> DeleteTaskAsync(string taskId) => Task.FromResult<(bool, string?)>((true, null));
     public virtual Task<List<AgentInfo>> GetAgentsAsync() => Task.FromResult(new List<AgentInfo>());
     public virtual Task RefreshAgentsAsync() => Task.CompletedTask;
     public virtual Task<SeedResultDto?> RestoreDefaultAgentsAsync() => Task.FromResult<SeedResultDto?>(null);

tests/ClaudeDo.Ui.Tests/ViewModels/DetailsIslandDeleteTaskTests.cs

@@ -0,0 +1,117 @@
+using ClaudeDo.Data;
+using ClaudeDo.Data.Models;
+using ClaudeDo.Ui.Services;
+using ClaudeDo.Ui.ViewModels.Islands;
+using Microsoft.EntityFrameworkCore;
+using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
+
+namespace ClaudeDo.Ui.Tests.ViewModels;
+
+public class DetailsIslandDeleteTaskTests : IDisposable
+{
+    private readonly string _dbPath;
+
+    public DetailsIslandDeleteTaskTests()
+    {
+        _dbPath = Path.Combine(Path.GetTempPath(), $"claudedo_delete_task_test_{Guid.NewGuid():N}.db");
+        using var ctx = NewContext();
+        ctx.Database.EnsureCreated();
+    }
+
+    public void Dispose()
+    {
+        try { File.Delete(_dbPath); } catch { }
+        try { File.Delete(_dbPath + "-wal"); } catch { }
+        try { File.Delete(_dbPath + "-shm"); } catch { }
+    }
+
+    private ClaudeDoDbContext NewContext()
+    {
+        var opts = new DbContextOptionsBuilder<ClaudeDoDbContext>()
+            .UseSqlite($"Data Source={_dbPath}")
+            .Options;
+        return new ClaudeDoDbContext(opts);
+    }
+
+    private sealed class TestDbFactory : IDbContextFactory<ClaudeDoDbContext>
+    {
+        private readonly Func<ClaudeDoDbContext> _create;
+        public TestDbFactory(Func<ClaudeDoDbContext> create) => _create = create;
+        public ClaudeDoDbContext CreateDbContext() => _create();
+    }
+
+    private sealed class NullServiceProvider : IServiceProvider
+    {
+        public object? GetService(Type serviceType) => null;
+    }
+
+    private sealed class StubNotesApi : ClaudeDo.Ui.Services.Interfaces.INotesApi
+    {
+        public Task<List<DailyNoteDto>> ListAsync(DateOnly day) =>
+            Task.FromResult(new List<DailyNoteDto>());
+        public Task<DailyNoteDto?> AddAsync(DateOnly day, string text) =>
+            Task.FromResult<DailyNoteDto?>(null);
+        public Task UpdateAsync(string id, string text) => Task.CompletedTask;
+        public Task DeleteAsync(string id) => Task.CompletedTask;
+    }
+
+    private sealed class RecordingWorkerClient : StubWorkerClient
+    {
+        public override bool IsConnected => true;
+        public (bool Ok, string? Error) Result { get; set; } = (true, null);
+        public string? DeletedTaskId { get; private set; }
+
+        public override Task<(bool Ok, string? Error)> DeleteTaskAsync(string taskId)
+        {
+            DeletedTaskId = taskId;
+            return Task.FromResult(Result);
+        }
+    }
+
+    private DetailsIslandViewModel BuildVm(RecordingWorkerClient worker)
+    {
+        var factory = new TestDbFactory(NewContext);
+        return new DetailsIslandViewModel(factory, worker, new NullServiceProvider(), new StubNotesApi(), new ClaudeDo.Ui.Services.MergeCoordinator());
+    }
+
+    [Fact]
+    public async Task DeleteTask_Succeeds_RemovesFromListAndClosesDetail()
+    {
+        var worker = new RecordingWorkerClient { Result = (true, null) };
+        var vm = BuildVm(worker);
+        vm.Bind(new TaskRowViewModel { Id = "task-del-1", Status = TaskStatus.Idle });
+
+        TaskRowViewModel? removed = null;
+        vm.DeleteFromList = row => { removed = row; return Task.CompletedTask; };
+        var closed = false;
+        vm.CloseDetail = () => closed = true;
+
+        await vm.DeleteTaskCommand.ExecuteAsync(null);
+
+        Assert.Equal("task-del-1", worker.DeletedTaskId);
+        Assert.Equal("task-del-1", removed?.Id);
+        Assert.True(closed);
+    }
+
+    [Fact]
+    public async Task DeleteTask_WhenTaskHasChildren_SurfacesErrorAndKeepsDetailOpen()
+    {
+        const string fkMessage = "This task has child tasks. Discard the planning session or delete child tasks first.";
+        var worker = new RecordingWorkerClient { Result = (false, fkMessage) };
+        var vm = BuildVm(worker);
+        vm.Bind(new TaskRowViewModel { Id = "task-del-2", Status = TaskStatus.WaitingForChildren });
+
+        var deleteFromListCalled = false;
+        vm.DeleteFromList = _ => { deleteFromListCalled = true; return Task.CompletedTask; };
+        var closed = false;
+        vm.CloseDetail = () => closed = true;
+        string? reportedError = null;
+        vm.ShowErrorAsync = msg => { reportedError = msg; return Task.CompletedTask; };
+
+        await vm.DeleteTaskCommand.ExecuteAsync(null);
+
+        Assert.Equal(fkMessage, reportedError);
+        Assert.False(deleteFromListCalled);
+        Assert.False(closed);
+    }
+}

tests/ClaudeDo.Worker.Tests/Hub/DeleteTaskHubTests.cs

@@ -0,0 +1,107 @@
+using ClaudeDo.Data.Models;
+using ClaudeDo.Data.Repositories;
+using ClaudeDo.Worker.Hub;
+using ClaudeDo.Worker.Tests.Infrastructure;
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.EntityFrameworkCore;
+using Xunit;
+using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
+
+namespace ClaudeDo.Worker.Tests.Hub;
+
+public sealed class DeleteTaskHubTests : IDisposable
+{
+    private readonly DbFixture _db = new();
+
+    public void Dispose() => _db.Dispose();
+
+    private WorkerHub CreateHub()
+    {
+        var factory = _db.CreateFactory();
+        var built = TaskStateServiceBuilder.Build(factory);
+        var broadcaster = new HubBroadcaster(new CapturingHubContext());
+        var hub = new WorkerHub(
+            null!, null!, null!, null!, broadcaster, factory,
+            null!, null!, null!, null!, null!, null!, null!, null!, null!, null!,
+            built.State,
+            null!, null!,
+            null!, new ClaudeDo.Worker.Online.OnlineInboxConfig(), new ClaudeDo.Worker.Online.OnlineTokenStore(),
+            new ClaudeDo.Worker.Runner.PendingQuestionRegistry(), null!);
+        hub.Clients = new FakeHubCallerClients(new RecordingClientProxy());
+        hub.Context = new FakeHubCallerContext();
+        return hub;
+    }
+
+    private async Task<(string ParentId, string ChildId)> SeedParentWithChildAsync(TaskStatus childStatus)
+    {
+        using var ctx = _db.CreateContext();
+        var listId = Guid.NewGuid().ToString();
+        await new ListRepository(ctx).AddAsync(new ListEntity
+        {
+            Id = listId, Name = "L", CreatedAt = DateTime.UtcNow,
+        });
+
+        var repo = new TaskRepository(ctx);
+        var parentId = Guid.NewGuid().ToString();
+        await repo.AddAsync(new TaskEntity
+        {
+            Id = parentId, ListId = listId, Title = "Parent",
+            Status = TaskStatus.WaitingForChildren, PlanningPhase = PlanningPhase.Finalized,
+            CreatedAt = DateTime.UtcNow, CommitType = "feat",
+        });
+
+        var childId = Guid.NewGuid().ToString();
+        await repo.AddAsync(new TaskEntity
+        {
+            Id = childId, ListId = listId, Title = "Child", ParentTaskId = parentId,
+            Status = childStatus, CreatedAt = DateTime.UtcNow, CommitType = "feat",
+        });
+
+        return (parentId, childId);
+    }
+
+    [Fact]
+    public async Task DeleteTask_LastChildOfWaitingForChildrenParent_AdvancesParentToWaitingForReview()
+    {
+        var (parentId, childId) = await SeedParentWithChildAsync(TaskStatus.Idle);
+        var hub = CreateHub();
+
+        await hub.DeleteTask(childId, default);
+
+        await using var ctx = _db.CreateContext();
+        Assert.Null(await ctx.Tasks.FindAsync(childId));
+        var parent = await ctx.Tasks.FindAsync(parentId);
+        Assert.Equal(TaskStatus.WaitingForReview, parent!.Status);
+    }
+
+    [Fact]
+    public async Task DeleteTask_RunningTask_Throws_AndDoesNotDelete()
+    {
+        var (_, childId) = await SeedParentWithChildAsync(TaskStatus.Running);
+        var hub = CreateHub();
+
+        await Assert.ThrowsAsync<HubException>(() => hub.DeleteTask(childId, default));
+
+        await using var ctx = _db.CreateContext();
+        Assert.NotNull(await ctx.Tasks.FindAsync(childId));
+    }
+
+    [Fact]
+    public async Task DeleteTask_TaskWithChildren_ThrowsFriendlyForeignKeyMessage()
+    {
+        var (parentId, _) = await SeedParentWithChildAsync(TaskStatus.Idle);
+        var hub = CreateHub();
+
+        var ex = await Assert.ThrowsAsync<HubException>(() => hub.DeleteTask(parentId, default));
+
+        Assert.Contains("child tasks", ex.Message, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public async Task DeleteTask_Missing_Throws()
+    {
+        var hub = CreateHub();
+
+        await Assert.ThrowsAsync<HubException>(() => hub.DeleteTask("does-not-exist", default));
+    }
+}

tests/ClaudeDo.Worker.Tests/State/TaskStateServiceTests.cs

@@ -479,4 +479,42 @@ public sealed class TaskStateServiceTests : IDisposable
         Assert.Equal(TaskStatus.Queued, t2.Status);
         Assert.Equal(c1, t2.BlockedByTaskId);
     }
+
+    // ─── TryAdvanceParentAsync ────────────────────────────────────────────
+
+    [Fact]
+    public async Task TryAdvanceParentAsync_ZeroChildren_AdvancesToWaitingForReview()
+    {
+        // Mirrors deleting the last remaining child: no terminal transition fires for it,
+        // so the caller invokes TryAdvanceParentAsync directly with zero children left.
+        var parent = await SeedTaskAsync(TaskStatus.WaitingForChildren, phase: PlanningPhase.Finalized);
+
+        await _sut.TryAdvanceParentAsync(parent);
+
+        Assert.Equal(TaskStatus.WaitingForReview, await GetStatusAsync(parent));
+    }
+
+    [Fact]
+    public async Task TryAdvanceParentAsync_AllChildrenTerminal_AdvancesToWaitingForReview()
+    {
+        var parent = await SeedTaskAsync(TaskStatus.WaitingForChildren, phase: PlanningPhase.Finalized);
+        await SeedTaskAsync(TaskStatus.Done, parentId: parent);
+        await SeedTaskAsync(TaskStatus.Done, parentId: parent);
+
+        await _sut.TryAdvanceParentAsync(parent);
+
+        Assert.Equal(TaskStatus.WaitingForReview, await GetStatusAsync(parent));
+    }
+
+    [Fact]
+    public async Task TryAdvanceParentAsync_SomeChildrenStillRunning_DoesNotAdvance()
+    {
+        var parent = await SeedTaskAsync(TaskStatus.WaitingForChildren, phase: PlanningPhase.Finalized);
+        await SeedTaskAsync(TaskStatus.Done, parentId: parent);
+        await SeedTaskAsync(TaskStatus.Running, parentId: parent);
+
+        await _sut.TryAdvanceParentAsync(parent);
+
+        Assert.Equal(TaskStatus.WaitingForChildren, await GetStatusAsync(parent));
+    }
 }

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

@@ -47,6 +47,7 @@ sealed class FakeWorkerClient : IWorkerClient
     public Task<PendingQuestionDto?> GetPendingQuestionAsync(string taskId) => Task.FromResult<PendingQuestionDto?>(null);
     public Task ResetTaskAsync(string taskId) => Task.CompletedTask;
     public Task CancelTaskAsync(string taskId) => Task.CompletedTask;
+    public Task<(bool Ok, string? Error)> DeleteTaskAsync(string taskId) => Task.FromResult<(bool, string?)>((true, null));
     public Task<List<AgentInfo>> GetAgentsAsync() => Task.FromResult(new List<AgentInfo>());
     public Task RefreshAgentsAsync() => Task.CompletedTask;
     public Task<SeedResultDto?> RestoreDefaultAgentsAsync() => Task.FromResult<SeedResultDto?>(null);