feat(state): advance WaitingForChildren parent to review when children terminal

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

src/ClaudeDo.Worker/State/TaskStateService.cs

@@ -392,5 +392,56 @@ public sealed class TaskStateService : ITaskStateService
         {
             _logger.LogWarning(ex, "TryCompleteParent failed for {ParentId}", parentId);
         }
+
+        try
+        {
+            await TryAdvanceImprovementParentAsync(parentId);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogWarning(ex, "TryAdvanceImprovementParent failed for {ParentId}", parentId);
+        }
+    }
+
+    // Improvement parents sit in WaitingForChildren while their suggested children run.
+    // Once every child is terminal (Done/Failed/Cancelled) the parent surfaces for review;
+    // a failed or cancelled child does not wedge the parent — it is flagged on the result.
+    private async Task TryAdvanceImprovementParentAsync(string parentId)
+    {
+        string? parentResult;
+        List<TaskStatus> childStatuses;
+        await using (var ctx = await _dbFactory.CreateDbContextAsync(CancellationToken.None))
+        {
+            var parent = await ctx.Tasks.AsNoTracking()
+                .FirstOrDefaultAsync(t => t.Id == parentId, CancellationToken.None);
+            if (parent is null || parent.Status != TaskStatus.WaitingForChildren) return;
+            parentResult = parent.Result;
+            childStatuses = await ctx.Tasks
+                .Where(t => t.ParentTaskId == parentId)
+                .Select(t => t.Status)
+                .ToListAsync(CancellationToken.None);
+        }
+        if (childStatuses.Count == 0) return;
+
+        bool allTerminal = childStatuses.All(s =>
+            s == TaskStatus.Done || s == TaskStatus.Failed || s == TaskStatus.Cancelled);
+        if (!allTerminal) return;
+
+        int failed = childStatuses.Count(s => s == TaskStatus.Failed);
+        int cancelled = childStatuses.Count(s => s == TaskStatus.Cancelled);
+        var newResult = parentResult;
+        if (failed + cancelled > 0)
+        {
+            var note = $"⚠ Children: {failed} failed, {cancelled} cancelled.";
+            newResult = string.IsNullOrWhiteSpace(parentResult) ? note : $"{parentResult}\n\n{note}";
+        }
+
+        await using var writeCtx = await _dbFactory.CreateDbContextAsync(CancellationToken.None);
+        await writeCtx.Tasks
+            .Where(t => t.Id == parentId && t.Status == TaskStatus.WaitingForChildren)
+            .ExecuteUpdateAsync(s => s
+                .SetProperty(t => t.Status, TaskStatus.WaitingForReview)
+                .SetProperty(t => t.Result, newResult), CancellationToken.None);
+        await _broadcaster.TaskUpdated(parentId);
     }
 }