fix: resolve push_files commit action per file

CHANGELOG.md

@@ -6,6 +6,10 @@ Generated by [`auto-changelog`](https://github.com/CookPete/auto-changelog).
 
 #### Unreleased
 
+##### Fixed
+
+- `push_files` can now update files that already exist. Every commit action was hardcoded to `create`, and GitLab rejects that for a tracked path with `400 A file with this name already exists` — so the tool could only ever add new files. The action is now resolved per file with a `HEAD` request against the Repository Files API: `update` when the path exists in the target branch, `create` when it does not.
+
 ##### Added
 
 - Add `list_group_members` tool for searching group members by name or username ([#631](https://github.com/zereight/gitlab-mcp/issues/631))

README.md

@@ -559,7 +559,7 @@ Register the skill directory in your AI client to get optimal tool usage guidanc
 10. `create_repository` - Create a new GitLab project
 11. `create_group` - Create a new GitLab group or subgroup (name, path, description, visibility, and optional parent_id)
 12. `get_file_contents` - Get the contents of a file or directory from a GitLab project
-13. `push_files` - Push multiple files to a GitLab project in a single commit
+13. `push_files` - Create or update multiple files in a GitLab project in a single commit
 14. `create_issue` - Create a new issue in a GitLab project
 15. `create_merge_request` - Create a new merge request in a GitLab project
 16. `fork_repository` - Fork a GitLab project to your account or specified namespace

docs/tools/index.md

@@ -74,7 +74,7 @@ Project search/creation/fork plus the Files API for reading and writing reposito
 | [`search_repositories`](repositories.md#search_repositories) | Search for GitLab projects | 📖 |
 | [`create_repository`](repositories.md#create_repository) | Create a new GitLab project | ✏️ |
 | [`get_file_contents`](repositories.md#get_file_contents) | Get contents of a file or directory from a GitLab project | 📖 |
-| [`push_files`](repositories.md#push_files) | Push multiple files in a single commit | ✏️ |
+| [`push_files`](repositories.md#push_files) | Create or update multiple files in a single commit | ✏️ |
 | [`create_or_update_file`](repositories.md#create_or_update_file) | Create or update a file in a GitLab project | ✏️ |
 | [`fork_repository`](repositories.md#fork_repository) | Fork a project to your account or specified namespace | ✏️ |
 | [`get_repository_tree`](repositories.md#get_repository_tree) | List files and directories in a repository | 📖 |

docs/tools/repositories.md

@@ -64,7 +64,7 @@ Get contents of a file or directory from a GitLab project
 
 *✏️ Writes*
 
-Push multiple files in a single commit
+Create or update multiple files in a single commit
 
 **Parameters**
 

index.ts

@@ -4786,6 +4786,42 @@ function encodeRepoFilePayloadContent(content: string): string {
   return content;
 }
 
+/**
+ * Check whether a path already exists in a branch.
+ *
+ * Uses HEAD on the Repository Files API so the check costs headers rather than the
+ * whole blob — a commit may carry several files, and their content is irrelevant here.
+ * A missing branch answers 404 just like a missing file, which is the right answer:
+ * a commit that also creates the branch has to use `create`.
+ *
+ * @param {string} projectId - The ID or URL-encoded path of the project
+ * @param {string} filePath - The path to look for, relative to the repository root
+ * @param {string} ref - The branch the commit targets
+ * @returns {Promise<boolean>} Whether the path is already tracked in that ref
+ */
+async function repositoryFileExists(
+  projectId: string,
+  filePath: string,
+  ref: string
+): Promise<boolean> {
+  const url = new URL(
+    `${getEffectiveApiUrl()}/projects/${encodeURIComponent(getEffectiveProjectId(projectId))}/repository/files/${encodeURIComponent(filePath)}`
+  );
+  url.searchParams.append("ref", ref);
+
+  const response = await fetch(url.toString(), {
+    ...getFetchConfig(),
+    method: "HEAD",
+  });
+
+  if (response.status === 404) {
+    return false;
+  }
+
+  await handleGitLabError(response);
+  return true;
+}
+
 /**
  * Create or update a file in a GitLab project
  * 파일 생성 또는 업데이트
@@ -4894,18 +4930,25 @@ async function createCommit(
     `${getEffectiveApiUrl()}/projects/${encodeURIComponent(getEffectiveProjectId(projectId))}/repository/commits`
   );
 
+  // The action has to be resolved per file: GitLab rejects `create` for a path that
+  // already exists ("A file with this name already exists") and `update` for one that
+  // does not. Assuming `create` made push_files unable to change any tracked file.
+  const resolvedActions = await Promise.all(
+    actions.map(async action => ({
+      action: (await repositoryFileExists(projectId, action.path, branch)) ? "update" : "create",
+      file_path: action.path,
+      content: encodeRepoFilePayloadContent(action.content),
+      encoding: GITLAB_REPO_FILE_ENCODING,
+    }))
+  );
+
   const response = await fetch(url.toString(), {
     ...getFetchConfig(),
     method: "POST",
     body: JSON.stringify({
       branch,
       commit_message: message,
-      actions: actions.map(action => ({
-        action: "create",
-        file_path: action.path,
-        content: encodeRepoFilePayloadContent(action.content),
-        encoding: GITLAB_REPO_FILE_ENCODING,
-      })),
+      actions: resolvedActions,
     }),
   });
 

test/test-push-files.ts

@@ -0,0 +1,172 @@
+import { describe, test } from "node:test";
+import assert from "node:assert";
+import { spawn } from "child_process";
+import { MockGitLabServer, findMockServerPort } from "./utils/mock-gitlab-server.js";
+
+const MOCK_TOKEN = "mock-token-push-files";
+const PROJECT_ID = "42";
+const BRANCH = "feature/update";
+
+const MOCK_COMMIT = {
+  id: "0123456789abcdef0123456789abcdef01234567",
+  short_id: "01234567",
+  title: "Update files",
+  author_name: "Tester",
+  author_email: "tester@example.com",
+  authored_date: "2025-01-01T00:00:00.000Z",
+  committer_name: "Tester",
+  committer_email: "tester@example.com",
+  committed_date: "2025-01-01T00:00:00.000Z",
+  web_url: "https://gitlab.example.com/group/project/-/commit/01234567",
+  parent_ids: [],
+};
+
+interface CommitAction {
+  action: string;
+  file_path: string;
+  content: string;
+}
+
+async function callPushFiles(
+  args: Record<string, unknown>,
+  env: NodeJS.ProcessEnv
+): Promise<unknown> {
+  return new Promise((resolve, reject) => {
+    const proc = spawn("node", ["build/index.js"], {
+      stdio: ["pipe", "pipe", "pipe"],
+      env: { ...process.env, ...env },
+    });
+
+    let output = "";
+    let errorOutput = "";
+    proc.stdout?.on("data", (d: Buffer) => (output += d));
+    proc.stderr?.on("data", (d: Buffer) => (errorOutput += d));
+
+    proc.on("close", code => {
+      if (code !== 0) {
+        return reject(new Error(`Process exited with code ${code}: ${errorOutput}`));
+      }
+
+      const line = output.split("\n").find(l => l.startsWith("{"));
+      if (!line) return reject(new Error("No JSON output found"));
+
+      try {
+        const response = JSON.parse(line);
+        if (response.error) {
+          reject(new Error(response.error?.message ?? String(response.error)));
+        } else {
+          const content = response.result?.content?.[0]?.text;
+          resolve(content ? JSON.parse(content) : response.result);
+        }
+      } catch (e) {
+        reject(e);
+      }
+    });
+
+    proc.stdin?.end(
+      JSON.stringify({
+        jsonrpc: "2.0",
+        id: 1,
+        method: "tools/call",
+        params: { name: "push_files", arguments: args },
+      }) + "\n"
+    );
+  });
+}
+
+/**
+ * Starts a mock GitLab where `existingPaths` are already tracked in the branch and
+ * everything else 404s, then runs one push_files call and returns the commit actions
+ * the server received.
+ */
+async function actionsForPush(
+  existingPaths: string[],
+  files: { file_path: string; content: string }[]
+): Promise<CommitAction[]> {
+  const mockPort = await findMockServerPort();
+  const mockServer = new MockGitLabServer({ port: mockPort, validTokens: [MOCK_TOKEN] });
+  let receivedActions: CommitAction[] = [];
+
+  for (const path of existingPaths) {
+    mockServer.addMockHandler(
+      "head",
+      `/projects/${PROJECT_ID}/repository/files/${encodeURIComponent(path)}`,
+      (req, res) => {
+        assert.strictEqual(req.query.ref, BRANCH);
+        res.status(200).end();
+      }
+    );
+  }
+
+  mockServer.addMockHandler("post", `/projects/${PROJECT_ID}/repository/commits`, (req, res) => {
+    receivedActions = (req.body as { actions: CommitAction[] }).actions;
+    res.status(201).json(MOCK_COMMIT);
+  });
+
+  await mockServer.start();
+
+  try {
+    await callPushFiles(
+      {
+        project_id: PROJECT_ID,
+        branch: BRANCH,
+        commit_message: "Update files",
+        files,
+      },
+      {
+        GITLAB_API_URL: `${mockServer.getUrl()}/api/v4`,
+        GITLAB_PERSONAL_ACCESS_TOKEN: MOCK_TOKEN,
+      }
+    );
+  } finally {
+    await mockServer.stop();
+  }
+
+  return receivedActions;
+}
+
+describe("When push_files commits a file that already exists", () => {
+  test("should send action 'update' instead of 'create'", async () => {
+    // Regression: every action was hardcoded to "create", and GitLab answers
+    // `400 A file with this name already exists` for a tracked path — so push_files
+    // could only ever add new files.
+    const actions = await actionsForPush(
+      ["src/index.ts"],
+      [{ file_path: "src/index.ts", content: "export const x = 1;\n" }]
+    );
+
+    assert.strictEqual(actions.length, 1);
+    assert.strictEqual(actions[0].action, "update");
+    assert.strictEqual(actions[0].file_path, "src/index.ts");
+  });
+});
+
+describe("When push_files commits a file that does not exist", () => {
+  test("should send action 'create'", async () => {
+    const actions = await actionsForPush(
+      [],
+      [{ file_path: "docs/new-page.md", content: "# New\n" }]
+    );
+
+    assert.strictEqual(actions.length, 1);
+    assert.strictEqual(actions[0].action, "create");
+  });
+});
+
+describe("When push_files commits a mix of new and existing files", () => {
+  test("should resolve the action per file", async () => {
+    const actions = await actionsForPush(
+      ["src/index.ts"],
+      [
+        { file_path: "src/index.ts", content: "export const x = 2;\n" },
+        { file_path: "src/new-module.ts", content: "export const y = 3;\n" },
+      ]
+    );
+
+    const byPath = Object.fromEntries(actions.map(a => [a.file_path, a.action]));
+    assert.deepStrictEqual(byPath, {
+      "src/index.ts": "update",
+      "src/new-module.ts": "create",
+    });
+  });
+});

test/utils/mock-gitlab-server.ts

@@ -75,7 +75,11 @@ export class MockGitLabServer {
     this.setupRoutes();
   }
 
-  public addMockHandler(method: "get" | "post" | "put" | "delete", path: string, handler: Handler) {
+  public addMockHandler(
+    method: "get" | "post" | "put" | "delete" | "head",
+    path: string,
+    handler: Handler
+  ) {
     // Note: path should be relative to /api/v4
     const key = `${method.toUpperCase()}:${path}`;
     console.log(`[MockServer] Adding custom handler: ${key}`);

tools/registry.ts

@@ -296,7 +296,7 @@ export const allTools = [
   },
   {
     name: "push_files",
-    description: "Push multiple files in a single commit",
+    description: "Create or update multiple files in a single commit",
     inputSchema: toJSONSchema(PushFilesSchema),
   },
   {