feat(worker): add leaveConflictsInTree option to TaskMergeService.MergeAsync

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

src/ClaudeDo.Worker/Services/TaskMergeService.cs

@@ -45,6 +45,7 @@ public sealed class TaskMergeService
         string targetBranch,
         bool removeWorktree,
         string commitMessage,
+        bool leaveConflictsInTree,
         CancellationToken ct)
     {
         TaskEntity task;
@@ -89,6 +90,11 @@ public sealed class TaskMergeService
             try { files = await _git.ListConflictedFilesAsync(list.WorkingDir, ct); }
             catch { files = new(); }
 
+            if (leaveConflictsInTree && files.Count > 0)
+            {
+                return new MergeResult(StatusConflict, files, null);
+            }
+
             // If abort fails the repo is left mid-merge; the caller must resolve manually.
             // Return Blocked (not conflict) so the UI does not offer a stale conflict list.
             try { await _git.MergeAbortAsync(list.WorkingDir, ct); }
@@ -141,6 +147,14 @@ public sealed class TaskMergeService
         return new MergeResult(StatusMerged, Array.Empty<string>(), cleanupWarning);
     }
 
+    public Task<MergeResult> MergeAsync(
+        string taskId,
+        string targetBranch,
+        bool removeWorktree,
+        string commitMessage,
+        CancellationToken ct)
+        => MergeAsync(taskId, targetBranch, removeWorktree, commitMessage, leaveConflictsInTree: false, ct);
+
     public async Task<MergeTargets> GetTargetsAsync(string taskId, CancellationToken ct)
     {
         TaskEntity task;

tests/ClaudeDo.Worker.Tests/Services/TaskMergeServiceTests.cs

@@ -51,6 +51,22 @@ public class TaskMergeServiceTests : IDisposable
             NullLogger<WorktreeManager>.Instance);
     }
 
+    private static async Task SeedWorktree(
+        DbFixture db, string taskId, string path, string branchName, string baseCommit)
+    {
+        var wt = new WorktreeEntity
+        {
+            TaskId = taskId,
+            Path = path,
+            BranchName = branchName,
+            BaseCommit = baseCommit,
+            State = WorktreeState.Active,
+            CreatedAt = DateTime.UtcNow,
+        };
+        using var ctx = db.CreateContext();
+        await new WorktreeRepository(ctx).AddAsync(wt);
+    }
+
     private static async Task<(ListEntity list, TaskEntity task)> SeedListAndTask(
         DbFixture db, string workingDir, TaskStatus status)
     {
@@ -351,6 +367,44 @@ public class TaskMergeServiceTests : IDisposable
         Assert.Equal("blocked", result.Status);
         Assert.Contains("switch target branch", result.ErrorMessage ?? "");
     }
+
+    [Fact]
+    public async Task MergeAsync_LeaveConflicts_DoesNotAbortAndReturnsConflictFiles()
+    {
+        if (!GitRepoFixture.IsGitAvailable()) return;
+
+        var db = NewDb();
+        var repo = NewRepo();
+        GitRepoFixture.RunGit(repo.RepoDir, "branch", "-m", "main");
+
+        File.WriteAllText(Path.Combine(repo.RepoDir, "README.md"), "# main change\n");
+        GitRepoFixture.RunGit(repo.RepoDir, "commit", "-am", "main change");
+
+        var wtPath = Path.Combine(Path.GetTempPath(), $"wt_{Guid.NewGuid():N}");
+        _wtCleanups.Add((repo.RepoDir, wtPath));
+        GitRepoFixture.RunGit(repo.RepoDir, "worktree", "add", "-b", "claudedo/t1", wtPath, repo.BaseCommit);
+        File.WriteAllText(Path.Combine(wtPath, "README.md"), "# branch change\n");
+        GitRepoFixture.RunGit(wtPath, "commit", "-am", "branch change");
+
+        var (_, task) = await SeedListAndTask(db, workingDir: repo.RepoDir, status: TaskStatus.Done);
+        await SeedWorktree(db, task.Id, wtPath, "claudedo/t1", repo.BaseCommit);
+
+        var (svc, _) = BuildService(db);
+
+        var result = await svc.MergeAsync(
+            task.Id, "main", removeWorktree: false, "msg",
+            leaveConflictsInTree: true,
+            CancellationToken.None);
+
+        Assert.Equal(TaskMergeService.StatusConflict, result.Status);
+        Assert.Contains("README.md", result.ConflictFiles);
+
+        var midMerge = File.Exists(Path.Combine(repo.RepoDir, ".git", "MERGE_HEAD"));
+        Assert.True(midMerge, "repo should be left in mid-merge state");
+
+        // Cleanup
+        GitRepoFixture.RunGit(repo.RepoDir, "merge", "--abort");
+    }
 }
 
 #region Test doubles