fix: handle EPERM when chmod'ing pre-existing mcp-logs directory

src/workdir-setup.test.ts

@@ -11,6 +11,8 @@ jest.mock('./host-env', () => require('./test-helpers/fs-mock-factory.test-utils
 // eslint-disable-next-line @typescript-eslint/no-require-imports
 jest.mock('./host-identity', () => require('./test-helpers/fs-mock-factory.test-utils').hostIdentityMockFactory());
 
+const actualFs = jest.requireActual<typeof import('fs')>('fs');
+
 import { prepareWorkDirectories, workdirSetupTestHelpers } from './workdir-setup';
 import { resolveLogPaths } from './log-paths';
 import { getRealUserHome } from './host-identity';
@@ -138,6 +140,41 @@ describe('prepareWorkDirectories', () => {
       expect(mode).toBe(0o777);
     });
 
+    it('does not throw when chmod on pre-existing mcp-logs dir fails with EPERM', () => {
+      const mcpLogsDir = '/tmp/gh-aw/mcp-logs';
+      fs.mkdirSync(mcpLogsDir, { recursive: true, mode: 0o700 });
+
+      // Simulate EPERM: directory owned by another user (e.g., MCP gateway)
+      const eperm = new Error("EPERM: operation not permitted, chmod '/tmp/gh-aw/mcp-logs'") as NodeJS.ErrnoException;
+      eperm.code = 'EPERM';
+      (fs.chmodSync as jest.Mock).mockImplementation((target: fs.PathLike, mode: fs.Mode) => {
+        if (target === mcpLogsDir) throw eperm;
+        actualFs.chmodSync(target, mode);
+      });
+
+      const config = buildConfig();
+      const logPaths = resolveLogPaths(config);
+
+      expect(() => prepareWorkDirectories(config, logPaths)).not.toThrow();
+    });
+
+    it('rethrows non-EPERM errors when chmod on pre-existing mcp-logs dir fails', () => {
+      const mcpLogsDir = '/tmp/gh-aw/mcp-logs';
+      fs.mkdirSync(mcpLogsDir, { recursive: true, mode: 0o700 });
+
+      const erofs = new Error("EROFS: read-only file system, chmod '/tmp/gh-aw/mcp-logs'") as NodeJS.ErrnoException;
+      erofs.code = 'EROFS';
+      (fs.chmodSync as jest.Mock).mockImplementation((target: fs.PathLike, mode: fs.Mode) => {
+        if (target === mcpLogsDir) throw erofs;
+        actualFs.chmodSync(target, mode);
+      });
+
+      const config = buildConfig();
+      const logPaths = resolveLogPaths(config);
+
+      expect(() => prepareWorkDirectories(config, logPaths)).toThrow(erofs);
+    });
+
     it('falls back to world-writable squid logs when squid chown fails', () => {
       const proxyLogsDir = path.join(fixture.tempDir, 'proxy-logs');
       (fs.chownSync as unknown as jest.Mock).mockImplementation((targetPath: fs.PathLike) => {

src/workdir-setup.ts

@@ -194,9 +194,17 @@ function prepareLogDirectories(logPaths: LogPaths): void {
     fs.chmodSync(mcpLogsDir, 0o777);
     logger.debug(`MCP logs directory created at: ${mcpLogsDir}`);
   } else {
-    // Fix permissions if directory already exists (e.g., created by a previous run)
-    fs.chmodSync(mcpLogsDir, 0o777);
-    logger.debug(`MCP logs directory permissions fixed at: ${mcpLogsDir}`);
+    // Best-effort permission fix if directory already exists (e.g., created by MCP gateway
+    // or a previous run). May fail with EPERM if owned by a different user.
+    try {
+      fs.chmodSync(mcpLogsDir, 0o777);
+      logger.debug(`MCP logs directory permissions fixed at: ${mcpLogsDir}`);
+    } catch (error) {
+      if ((error as NodeJS.ErrnoException).code !== 'EPERM') {
+        throw error;
+      }
+      logger.debug(`MCP logs directory already exists at: ${mcpLogsDir} (chmod skipped, owned by another user)`);
+    }
   }
 }