diff --git a/src/ClaudeDo.Data/Repositories/TaskRepository.cs b/src/ClaudeDo.Data/Repositories/TaskRepository.cs
index 8796e39..d746589 100644
--- a/src/ClaudeDo.Data/Repositories/TaskRepository.cs
+++ b/src/ClaudeDo.Data/Repositories/TaskRepository.cs
@@ -377,6 +377,33 @@ public sealed class TaskRepository
         return true;
     }
 
+    public async Task TryCompleteParentAsync(
+        string parentId,
+        CancellationToken ct = default)
+    {
+        var parent = await _context.Tasks.AsNoTracking().FirstOrDefaultAsync(t => t.Id == parentId, ct);
+        if (parent is null || parent.Status != TaskStatus.Planned) return;
+
+        var children = await _context.Tasks
+            .Where(t => t.ParentTaskId == parentId)
+            .Select(t => t.Status)
+            .ToListAsync(ct);
+
+        if (children.Count == 0) return;
+
+        bool allTerminal = children.All(s => s == TaskStatus.Done || s == TaskStatus.Failed);
+        if (!allTerminal) return;
+
+        bool anyFailed = children.Any(s => s == TaskStatus.Failed);
+        var finalStatus = anyFailed ? TaskStatus.Failed : TaskStatus.Done;
+        var finishedAt = DateTime.UtcNow;
+        await _context.Tasks
+            .Where(t => t.Id == parentId)
+            .ExecuteUpdateAsync(s => s
+                .SetProperty(t => t.Status, finalStatus)
+                .SetProperty(t => t.FinishedAt, finishedAt), ct);
+    }
+
     #endregion
 
     #region Queue selection
diff --git a/tests/ClaudeDo.Worker.Tests/Repositories/TaskRepositoryParentCompletionTests.cs b/tests/ClaudeDo.Worker.Tests/Repositories/TaskRepositoryParentCompletionTests.cs
new file mode 100644
index 0000000..1c2e563
--- /dev/null
+++ b/tests/ClaudeDo.Worker.Tests/Repositories/TaskRepositoryParentCompletionTests.cs
@@ -0,0 +1,136 @@
+using ClaudeDo.Data;
+using ClaudeDo.Data.Models;
+using ClaudeDo.Data.Repositories;
+using ClaudeDo.Worker.Tests.Infrastructure;
+using Microsoft.EntityFrameworkCore;
+using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
+
+namespace ClaudeDo.Worker.Tests.Repositories;
+
+public sealed class TaskRepositoryParentCompletionTests : IDisposable
+{
+    private readonly DbFixture _db = new();
+    private readonly ClaudeDoDbContext _ctx;
+    private readonly TaskRepository _tasks;
+    private readonly ListRepository _lists;
+
+    public TaskRepositoryParentCompletionTests()
+    {
+        _ctx = _db.CreateContext();
+        _tasks = new TaskRepository(_ctx);
+        _lists = new ListRepository(_ctx);
+    }
+
+    public void Dispose() { _ctx.Dispose(); _db.Dispose(); }
+
+    private async Task<string> ListAsync()
+    {
+        var id = Guid.NewGuid().ToString();
+        await _lists.AddAsync(new ListEntity { Id = id, Name = "L", CreatedAt = DateTime.UtcNow });
+        return id;
+    }
+
+    private async Task<TaskEntity> PlannedParentAsync(string listId)
+    {
+        var parent = new TaskEntity
+        {
+            Id = Guid.NewGuid().ToString(),
+            ListId = listId,
+            Title = "p",
+            Status = TaskStatus.Planned,
+            CreatedAt = DateTime.UtcNow,
+            CommitType = "chore",
+        };
+        await _tasks.AddAsync(parent);
+        return parent;
+    }
+
+    private async Task<TaskEntity> ChildAsync(string listId, string parentId, TaskStatus status)
+    {
+        var child = new TaskEntity
+        {
+            Id = Guid.NewGuid().ToString(),
+            ListId = listId,
+            Title = "c",
+            Status = status,
+            CreatedAt = DateTime.UtcNow,
+            CommitType = "chore",
+            ParentTaskId = parentId,
+        };
+        await _tasks.AddAsync(child);
+        return child;
+    }
+
+    [Fact]
+    public async Task TryCompleteParentAsync_AllChildrenDone_ParentBecomesDone()
+    {
+        var listId = await ListAsync();
+        var parent = await PlannedParentAsync(listId);
+        await ChildAsync(listId, parent.Id, TaskStatus.Done);
+        await ChildAsync(listId, parent.Id, TaskStatus.Done);
+
+        await _tasks.TryCompleteParentAsync(parent.Id);
+
+        var loaded = await _tasks.GetByIdAsync(parent.Id);
+        Assert.Equal(TaskStatus.Done, loaded!.Status);
+        Assert.NotNull(loaded.FinishedAt);
+    }
+
+    [Fact]
+    public async Task TryCompleteParentAsync_OneFailedRestDone_ParentBecomesFailed()
+    {
+        var listId = await ListAsync();
+        var parent = await PlannedParentAsync(listId);
+        await ChildAsync(listId, parent.Id, TaskStatus.Done);
+        await ChildAsync(listId, parent.Id, TaskStatus.Failed);
+
+        await _tasks.TryCompleteParentAsync(parent.Id);
+
+        var loaded = await _tasks.GetByIdAsync(parent.Id);
+        Assert.Equal(TaskStatus.Failed, loaded!.Status);
+        Assert.NotNull(loaded.FinishedAt);
+    }
+
+    [Fact]
+    public async Task TryCompleteParentAsync_OneStillRunning_ParentStaysPlanned()
+    {
+        var listId = await ListAsync();
+        var parent = await PlannedParentAsync(listId);
+        await ChildAsync(listId, parent.Id, TaskStatus.Done);
+        await ChildAsync(listId, parent.Id, TaskStatus.Running);
+
+        await _tasks.TryCompleteParentAsync(parent.Id);
+
+        var loaded = await _tasks.GetByIdAsync(parent.Id);
+        Assert.Equal(TaskStatus.Planned, loaded!.Status);
+        Assert.Null(loaded.FinishedAt);
+    }
+
+    [Fact]
+    public async Task TryCompleteParentAsync_ChildStillDraft_ParentStaysPlanned()
+    {
+        var listId = await ListAsync();
+        var parent = await PlannedParentAsync(listId);
+        await ChildAsync(listId, parent.Id, TaskStatus.Done);
+        await ChildAsync(listId, parent.Id, TaskStatus.Draft);
+
+        await _tasks.TryCompleteParentAsync(parent.Id);
+
+        var loaded = await _tasks.GetByIdAsync(parent.Id);
+        Assert.Equal(TaskStatus.Planned, loaded!.Status);
+    }
+
+    [Fact]
+    public async Task TryCompleteParentAsync_ParentIsNotPlanned_NoChange()
+    {
+        var listId = await ListAsync();
+        var parent = await PlannedParentAsync(listId);
+        await _ctx.Database.ExecuteSqlRawAsync("UPDATE tasks SET status = 'planning' WHERE id = {0}", parent.Id);
+        await ChildAsync(listId, parent.Id, TaskStatus.Done);
+
+        await _tasks.TryCompleteParentAsync(parent.Id);
+
+        var loaded = await _tasks.GetByIdAsync(parent.Id);
+        Assert.Equal(TaskStatus.Planning, loaded!.Status);
+    }
+}