feat(worker): record merge commit SHA and add revert_merge tool

Persists the merge commit SHA on WorktreeEntity for every successful single-task and unit merge, and adds a TaskMergeService.RevertMergeAsync + revert_merge MCP tool that undoes a merged task's merge via `git revert -m 1` (never reset/rewrite, since the target checkout is shared). Rejects cleanly when there's no recorded SHA, the repo is mid-merge/mid-revert, or the target has foreign uncommitted changes; a conflicting revert aborts immediately. Also exposes the new mergeCommit field via get_task_worktree.
2026-08-05 11:46:51 +02:00
parent 6c5acd09b9
commit 10e561f336
14 changed files with 1452 additions and 14 deletions
@@ -226,4 +226,95 @@ public class GitServiceMergeTests : IDisposable

        await git.MergeAbortAsync(repo.RepoDir);
    }
+
+    [Fact]
+    public async Task IsMidRevertAsync_FreshRepo_ReturnsFalse()
+    {
+        if (!GitRepoFixture.IsGitAvailable()) return;
+        var repo = NewRepo();
+        var git = new GitService();
+
+        Assert.False(await git.IsMidRevertAsync(repo.RepoDir));
+    }
+
+    [Fact]
+    public async Task IsMidRevertAsync_RevertHeadPresent_ReturnsTrue()
+    {
+        if (!GitRepoFixture.IsGitAvailable()) return;
+        var repo = NewRepo();
+        var revertHead = Path.Combine(repo.RepoDir, ".git", "REVERT_HEAD");
+        File.WriteAllText(revertHead, "0000000000000000000000000000000000000000\n");
+
+        var git = new GitService();
+        Assert.True(await git.IsMidRevertAsync(repo.RepoDir));
+    }
+
+    [Fact]
+    public async Task RevertMergeCommitAsync_CleanMerge_ReturnsZero_AndUndoesMergedChange()
+    {
+        if (!GitRepoFixture.IsGitAvailable()) return;
+        var repo = NewRepo();
+
+        GitRepoFixture.RunGit(repo.RepoDir, "checkout", "-b", "feature/revert");
+        File.WriteAllText(Path.Combine(repo.RepoDir, "feature.txt"), "hello\n");
+        GitRepoFixture.RunGit(repo.RepoDir, "add", "-A");
+        GitRepoFixture.RunGit(repo.RepoDir, "commit", "-m", "feat: add feature.txt");
+
+        try { GitRepoFixture.RunGit(repo.RepoDir, "checkout", "main"); }
+        catch { GitRepoFixture.RunGit(repo.RepoDir, "checkout", "master"); }
+
+        var git = new GitService();
+        var (mergeExit, _) = await git.MergeNoFfAsync(repo.RepoDir, "feature/revert", "Merge feature/revert");
+        Assert.Equal(0, mergeExit);
+        var mergeSha = (await git.RevParseHeadAsync(repo.RepoDir)).Trim();
+        Assert.True(File.Exists(Path.Combine(repo.RepoDir, "feature.txt")));
+
+        var (revertExit, _) = await git.RevertMergeCommitAsync(repo.RepoDir, mergeSha);
+
+        Assert.Equal(0, revertExit);
+        Assert.False(File.Exists(Path.Combine(repo.RepoDir, "feature.txt")));
+        Assert.False(await git.IsMidRevertAsync(repo.RepoDir));
+        // History stays intact — both the merge and the new revert commit are reachable.
+        var log = GitRepoFixture.RunGit(repo.RepoDir, "log", "--oneline");
+        Assert.Contains(mergeSha[..7], log);
+    }
+
+    [Fact]
+    public async Task RevertMergeCommitAsync_ConflictingSubsequentEdit_ReturnsNonZero_AndAbortCleansUp()
+    {
+        if (!GitRepoFixture.IsGitAvailable()) return;
+        var repo = NewRepo();
+
+        GitRepoFixture.RunGit(repo.RepoDir, "checkout", "-b", "feature/revert-conflict");
+        File.WriteAllText(Path.Combine(repo.RepoDir, "README.md"), "# test repo\nfeature\n");
+        GitRepoFixture.RunGit(repo.RepoDir, "add", "-A");
+        GitRepoFixture.RunGit(repo.RepoDir, "commit", "-m", "feat: append feature line");
+
+        try { GitRepoFixture.RunGit(repo.RepoDir, "checkout", "main"); }
+        catch { GitRepoFixture.RunGit(repo.RepoDir, "checkout", "master"); }
+
+        var git = new GitService();
+        var (mergeExit, _) = await git.MergeNoFfAsync(repo.RepoDir, "feature/revert-conflict", "Merge feature/revert-conflict");
+        Assert.Equal(0, mergeExit);
+        var mergeSha = (await git.RevParseHeadAsync(repo.RepoDir)).Trim();
+
+        // A direct edit on main to the same line the merge introduced makes the revert conflict.
+        File.WriteAllText(Path.Combine(repo.RepoDir, "README.md"), "# test repo\npost-merge edit\n");
+        GitRepoFixture.RunGit(repo.RepoDir, "add", "-A");
+        GitRepoFixture.RunGit(repo.RepoDir, "commit", "-m", "chore: edit the same line");
+        var headBefore = GitRepoFixture.RunGit(repo.RepoDir, "rev-parse", "HEAD").Trim();
+
+        var (revertExit, _) = await git.RevertMergeCommitAsync(repo.RepoDir, mergeSha);
+
+        Assert.NotEqual(0, revertExit);
+        Assert.True(await git.IsMidRevertAsync(repo.RepoDir));
+        var conflicted = await git.ListConflictedFilesAsync(repo.RepoDir);
+        Assert.Contains("README.md", conflicted);
+
+        await git.RevertAbortAsync(repo.RepoDir);
+
+        Assert.False(await git.IsMidRevertAsync(repo.RepoDir));
+        Assert.Equal(headBefore, GitRepoFixture.RunGit(repo.RepoDir, "rev-parse", "HEAD").Trim());
+        Assert.True(string.IsNullOrWhiteSpace(GitRepoFixture.RunGit(repo.RepoDir, "status", "--porcelain")));
+    }
 }