fix: address CodeRabbit review on download_job_artifacts traversal fix

- validate local_path before the GitLab fetch, not after
- reject Windows drive-relative paths (e.g. "C:foo") via path.parse().root
- update job-artifact tests to use relative fixture dirs, add traversal
  and absolute-path rejection test cases

Author: brennanneoh

index.ts

@@ -7466,6 +7466,19 @@ async function downloadJobArtifacts(
   jobId: string,
   localPath?: string
 ): Promise<string> {
+  if (localPath) {
+    const normalizedLocalPath = path.normalize(localPath);
+    if (
+      path.isAbsolute(normalizedLocalPath) ||
+      path.parse(normalizedLocalPath).root !== "" ||
+      normalizedLocalPath === ".." ||
+      normalizedLocalPath.startsWith(".." + path.sep) ||
+      normalizedLocalPath.includes(path.sep + ".." + path.sep)
+    ) {
+      throw new Error("Invalid local_path: directory traversal is not allowed.");
+    }
+  }
+
   projectId = decodeURIComponent(projectId);
   const effectiveProjectId = getEffectiveProjectId(projectId);
 
@@ -7486,21 +7499,7 @@ async function downloadJobArtifacts(
   await handleGitLabError(response);
 
   const filename = `artifacts_job_${encodeGitLabPathSegment(jobId)}.zip`;
-  let savePath: string;
-  if (localPath) {
-    const normalizedLocalPath = path.normalize(localPath);
-    if (
-      path.isAbsolute(normalizedLocalPath) ||
-      normalizedLocalPath === ".." ||
-      normalizedLocalPath.startsWith(".." + path.sep) ||
-      normalizedLocalPath.includes(path.sep + ".." + path.sep)
-    ) {
-      throw new Error("Invalid local_path: directory traversal is not allowed.");
-    }
-    savePath = path.join(normalizedLocalPath, filename);
-  } else {
-    savePath = filename;
-  }
+  const savePath = localPath ? path.join(path.normalize(localPath), filename) : filename;
   fs.mkdirSync(path.dirname(savePath), { recursive: true });
 
   if (!response.body) {

test/test-job-artifacts.ts

@@ -4,7 +4,6 @@ import { spawn } from 'child_process';
 import { MockGitLabServer, findMockServerPort } from './utils/mock-gitlab-server.js';
 import fs from 'node:fs';
 import path from 'node:path';
-import os from 'node:os';
 
 const MOCK_TOKEN = 'glpat-mock-token-12345';
 const TEST_PROJECT_ID = '123';
@@ -143,8 +142,12 @@ describe('job artifacts tools', () => {
     await mockGitLab.start();
     mockGitLabUrl = mockGitLab.getUrl();
 
-    // Create a temp directory for download tests
-    tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'gitlab-mcp-test-'));
+    // Create a temp directory for download tests. Must be relative to the
+    // process cwd — download_job_artifacts rejects absolute local_path
+    // values as directory traversal (see downloadJobArtifacts/downloadAttachment).
+    tmpDir = `gitlab-mcp-test-artifacts-${process.pid}`;
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+    fs.mkdirSync(tmpDir, { recursive: true });
   });
 
   after(async () => {
@@ -210,6 +213,44 @@ describe('job artifacts tools', () => {
     assert.ok(fs.existsSync(nestedLocalPath), `Directory should be created at ${nestedLocalPath}`);
   });
 
+  test('download_job_artifacts rejects local_path directory traversal', async () => {
+    try {
+      await callTool(
+        'download_job_artifacts',
+        { project_id: TEST_PROJECT_ID, job_id: TEST_JOB_ID, local_path: '../../../tmp' },
+        {
+          GITLAB_API_URL: `${mockGitLabUrl}/api/v4`,
+          GITLAB_PERSONAL_ACCESS_TOKEN: MOCK_TOKEN,
+        }
+      );
+      assert.fail('Expected download_job_artifacts to reject a traversal local_path');
+    } catch (error: any) {
+      assert.ok(
+        typeof error?.message === 'string' && error.message.toLowerCase().includes('traversal'),
+        `Expected a traversal error, got: ${error?.message}`
+      );
+    }
+  });
+
+  test('download_job_artifacts rejects absolute local_path', async () => {
+    try {
+      await callTool(
+        'download_job_artifacts',
+        { project_id: TEST_PROJECT_ID, job_id: TEST_JOB_ID, local_path: '/tmp' },
+        {
+          GITLAB_API_URL: `${mockGitLabUrl}/api/v4`,
+          GITLAB_PERSONAL_ACCESS_TOKEN: MOCK_TOKEN,
+        }
+      );
+      assert.fail('Expected download_job_artifacts to reject an absolute local_path');
+    } catch (error: any) {
+      assert.ok(
+        typeof error?.message === 'string' && error.message.toLowerCase().includes('traversal'),
+        `Expected a traversal error, got: ${error?.message}`
+      );
+    }
+  });
+
   test('get_job_artifact_file returns file content', async () => {
     const result = await callTool(
       'get_job_artifact_file',