diff --git a/src/ClaudeDo.Data/Repositories/TaskRepository.cs b/src/ClaudeDo.Data/Repositories/TaskRepository.cs
index 9161ee9..48ca97a 100644
--- a/src/ClaudeDo.Data/Repositories/TaskRepository.cs
+++ b/src/ClaudeDo.Data/Repositories/TaskRepository.cs
@@ -194,6 +194,27 @@ public sealed class TaskRepository
         }
     }
 
+    public async Task SetTagsAsync(string taskId, IReadOnlyList<string> tagNames, CancellationToken ct = default)
+    {
+        var task = await _context.Tasks.Include(t => t.Tags).FirstOrDefaultAsync(t => t.Id == taskId, ct);
+        if (task is null) return;
+
+        task.Tags.Clear();
+
+        foreach (var name in tagNames.Where(n => !string.IsNullOrWhiteSpace(n)).Distinct(StringComparer.OrdinalIgnoreCase))
+        {
+            var tag = await _context.Tags.FirstOrDefaultAsync(t => t.Name == name, ct);
+            if (tag is null)
+            {
+                tag = new TagEntity { Name = name };
+                _context.Tags.Add(tag);
+            }
+            task.Tags.Add(tag);
+        }
+
+        await _context.SaveChangesAsync(ct);
+    }
+
     public async Task<List<TagEntity>> GetTagsAsync(string taskId, CancellationToken ct = default)
     {
         return await _context.Tasks
@@ -276,6 +297,41 @@ public sealed class TaskRepository
         return child;
     }
 
+    public async Task UpdateChildAsync(
+        string taskId,
+        string? title,
+        string? description,
+        string? commitType,
+        IReadOnlyList<string>? tagNames,
+        TaskStatus? status,
+        CancellationToken ct = default)
+    {
+        var task = await _context.Tasks.Include(t => t.Tags).FirstOrDefaultAsync(t => t.Id == taskId, ct)
+            ?? throw new InvalidOperationException($"Task {taskId} not found.");
+
+        if (title is not null) task.Title = title;
+        if (description is not null) task.Description = description;
+        if (commitType is not null) task.CommitType = commitType;
+        if (status.HasValue) task.Status = status.Value;
+
+        if (tagNames is not null)
+        {
+            task.Tags.Clear();
+            foreach (var name in tagNames.Where(n => !string.IsNullOrWhiteSpace(n)).Distinct(StringComparer.OrdinalIgnoreCase))
+            {
+                var tag = await _context.Tags.FirstOrDefaultAsync(t => t.Name == name, ct);
+                if (tag is null)
+                {
+                    tag = new TagEntity { Name = name };
+                    _context.Tags.Add(tag);
+                }
+                task.Tags.Add(tag);
+            }
+        }
+
+        await _context.SaveChangesAsync(ct);
+    }
+
     public async Task UpdatePlanningTaskAsync(
         string taskId,
         string? title,
diff --git a/tests/ClaudeDo.Worker.Tests/Repositories/TaskRepositoryTests.cs b/tests/ClaudeDo.Worker.Tests/Repositories/TaskRepositoryTests.cs
index 690cdb0..017f0d6 100644
--- a/tests/ClaudeDo.Worker.Tests/Repositories/TaskRepositoryTests.cs
+++ b/tests/ClaudeDo.Worker.Tests/Repositories/TaskRepositoryTests.cs
@@ -340,4 +340,60 @@ public sealed class TaskRepositoryTests : IDisposable
         Assert.Contains("code", names);
         Assert.Contains("manual", names);
     }
+
+    [Fact]
+    public async Task SetTagsAsync_AttachesNewTagsAndCreatesMissingRows()
+    {
+        var listId = await CreateListAsync("L");
+        var task = MakeTask(listId);
+        await _tasks.AddAsync(task);
+
+        await _tasks.SetTagsAsync(task.Id, new[] { "agent", "novel-tag" });
+
+        var tags = await _tasks.GetTagsAsync(task.Id);
+        Assert.Contains(tags, t => t.Name == "agent");
+        Assert.Contains(tags, t => t.Name == "novel-tag");
+        Assert.Equal(2, tags.Count);
+    }
+
+    [Fact]
+    public async Task SetTagsAsync_ReplacesExistingTagSet()
+    {
+        var listId = await CreateListAsync("L");
+        var task = MakeTask(listId);
+        await _tasks.AddAsync(task);
+        await _tasks.SetTagsAsync(task.Id, new[] { "agent" });
+
+        await _tasks.SetTagsAsync(task.Id, new[] { "manual" });
+
+        var tags = await _tasks.GetTagsAsync(task.Id);
+        Assert.Single(tags);
+        Assert.Equal("manual", tags[0].Name);
+    }
+
+    [Fact]
+    public async Task SetTagsAsync_DeduplicatesCaseInsensitively()
+    {
+        var listId = await CreateListAsync("L");
+        var task = MakeTask(listId);
+        await _tasks.AddAsync(task);
+
+        await _tasks.SetTagsAsync(task.Id, new[] { "agent", "AGENT", "Agent" });
+
+        var tags = await _tasks.GetTagsAsync(task.Id);
+        Assert.Single(tags);
+    }
+
+    [Fact]
+    public async Task SetTagsAsync_EmptyListClearsAllTags()
+    {
+        var listId = await CreateListAsync("L");
+        var task = MakeTask(listId);
+        await _tasks.AddAsync(task);
+        await _tasks.SetTagsAsync(task.Id, new[] { "agent" });
+
+        await _tasks.SetTagsAsync(task.Id, Array.Empty<string>());
+
+        Assert.Empty(await _tasks.GetTagsAsync(task.Id));
+    }
 }