Merge claudedo/973ea49ec0a642ea9b1ddcff9b71b6fe

src/ClaudeDo.Worker/Planning/Interfaces/IActiveMergeState.cs

@@ -0,0 +1,10 @@
+namespace ClaudeDo.Worker.Planning;
+
+// Lets TaskStateService guard CancelAsync against an in-progress unit merge without a
+// hard constructor cycle back to PlanningMergeOrchestrator (which itself depends on
+// ITaskStateService) — TaskStateService takes a Func<IActiveMergeState> instead, resolved
+// lazily so both singletons can finish constructing before either calls into the other.
+public interface IActiveMergeState
+{
+    bool HasActiveMerge(string taskId);
+}

src/ClaudeDo.Worker/Planning/PlanningMergeOrchestrator.cs

@@ -13,7 +13,7 @@ namespace ClaudeDo.Worker.Planning;
 /// <summary>A unit-merge conflict currently paused, driven by an MCP session rather than the UI.</summary>
 public sealed record ExternalPlanningMergeConflict(string PlanningTaskId, string SubtaskId);
 
-public sealed class PlanningMergeOrchestrator
+public sealed class PlanningMergeOrchestrator : IActiveMergeState
 {
     private readonly IDbContextFactory<ClaudeDoDbContext> _dbFactory;
     private readonly TaskMergeService _merge;

src/ClaudeDo.Worker/Program.cs

@@ -101,12 +101,16 @@ builder.Services.AddSingleton<IQueuePicker, QueuePicker>();
 builder.Services.AddSingleton<RunCancellationRegistry>();
 
 builder.Services.AddSingleton<Func<ITaskStateService>>(sp => () => sp.GetRequiredService<ITaskStateService>());
+// PlanningMergeOrchestrator itself depends on ITaskStateService, so TaskStateService can only
+// reach it lazily (Func<IActiveMergeState>) — same cycle-breaking shape as the Func above.
+builder.Services.AddSingleton<Func<IActiveMergeState>>(sp => () => sp.GetRequiredService<PlanningMergeOrchestrator>());
 builder.Services.AddSingleton<ITaskStateService>(sp => new TaskStateService(
     sp.GetRequiredService<IDbContextFactory<ClaudeDoDbContext>>(),
     sp.GetRequiredService<HubBroadcaster>(),
     sp.GetRequiredService<IQueueWaker>(),
     sp.GetRequiredService<PlanningChainCoordinator>(),
     sp.GetRequiredService<RunCancellationRegistry>(),
+    sp.GetRequiredService<Func<IActiveMergeState>>(),
     sp.GetRequiredService<ILogger<TaskStateService>>()));
 
 // Agent file management.

src/ClaudeDo.Worker/State/TaskStateService.cs

@@ -16,6 +16,7 @@ public sealed class TaskStateService : ITaskStateService
     private readonly IQueueWaker _waker;
     private readonly PlanningChainCoordinator _chain;
     private readonly RunCancellationRegistry _runCancels;
+    private readonly Func<IActiveMergeState> _mergeState;
     private readonly ILogger<TaskStateService> _logger;
 
     public TaskStateService(
@@ -24,6 +25,7 @@ public sealed class TaskStateService : ITaskStateService
         IQueueWaker waker,
         PlanningChainCoordinator chain,
         RunCancellationRegistry runCancels,
+        Func<IActiveMergeState> mergeState,
         ILogger<TaskStateService> logger)
     {
         _dbFactory = dbFactory;
@@ -31,6 +33,7 @@ public sealed class TaskStateService : ITaskStateService
         _waker = waker;
         _chain = chain;
         _runCancels = runCancels;
+        _mergeState = mergeState;
         _logger = logger;
     }
 
@@ -255,6 +258,14 @@ public sealed class TaskStateService : ITaskStateService
     public async Task<TransitionResult> CancelAsync(
         string taskId, DateTime finishedAt, CancellationToken ct, bool allowFromIdle = false)
     {
+        // A unit merge drains its children's worktrees onto the target branch while the parent
+        // sits in WaitingForReview for the whole (potentially minutes-long) drain. Cancelling out
+        // from under it would flip the parent to Cancelled while the orchestrator keeps merging —
+        // FinalizeParentDoneAsync then finds the parent no longer WaitingForReview and gives up,
+        // leaving the merged children's diffs stranded with no way to roll them back.
+        if (_mergeState().HasActiveMerge(taskId))
+            return new TransitionResult(false, "A merge is in progress for this task; wait for it to finish before cancelling.");
+
         List<string> cancelledChildIds;
         await using (var ctx = await _dbFactory.CreateDbContextAsync(ct))
         {