feat(data): TaskRepository.CreateChildAsync

tests/ClaudeDo.Worker.Tests/Repositories/TaskRepositoryPlanningTests.cs

@@ -80,4 +80,43 @@ public sealed class TaskRepositoryPlanningTests : IDisposable
         Assert.Equal("b", children[0].Title);
         Assert.Equal("a", children[1].Title);
     }
+
+    [Fact]
+    public async Task CreateChildAsync_CreatesDraftUnderParent()
+    {
+        var listId = await CreateListAsync();
+        var parent = MakeTask(listId, TaskStatus.Planning);
+        await _tasks.AddAsync(parent);
+
+        var child = await _tasks.CreateChildAsync(
+            parent.Id,
+            title: "child title",
+            description: "child desc",
+            tagNames: new[] { "agent" },
+            commitType: "feat");
+
+        Assert.Equal(TaskStatus.Draft, child.Status);
+        Assert.Equal(parent.Id, child.ParentTaskId);
+        Assert.Equal(listId, child.ListId);
+        Assert.Equal("child title", child.Title);
+        Assert.Equal("child desc", child.Description);
+        Assert.Equal("feat", child.CommitType);
+
+        var loaded = await _tasks.GetByIdAsync(child.Id);
+        Assert.NotNull(loaded);
+        Assert.Equal(TaskStatus.Draft, loaded!.Status);
+
+        var tags = await _tasks.GetTagsAsync(child.Id);
+        Assert.Contains(tags, t => t.Name == "agent");
+    }
+
+    [Fact]
+    public async Task CreateChildAsync_ThrowsIfParentNotFound()
+    {
+        var listId = await CreateListAsync();
+        _ = listId; // just to create the DB
+
+        await Assert.ThrowsAsync<InvalidOperationException>(() =>
+            _tasks.CreateChildAsync("nonexistent-parent-id", "t", null, null, null));
+    }
 }