fix: recover pnpm symlink loops during workspace install

src/workspace-package-manager.test.ts

@@ -218,6 +218,101 @@ describe('workspace package manager helpers', () => {
     expect(execFileSyncMock).not.toHaveBeenCalled();
   });
 
+  it('repairs a stale pnpm self-referential node_modules tree before install', () => {
+    const repoDir = path.join(tempRoot, 'stale-pnpm');
+    fs.mkdirSync(path.join(repoDir, 'node_modules', '.pnpm'), {
+      recursive: true,
+    });
+    fs.writeFileSync(
+      path.join(repoDir, 'package.json'),
+      JSON.stringify({
+        name: 'stale-pnpm',
+        packageManager: 'pnpm@10.11.0',
+        scripts: { test: 'vitest run' },
+      }),
+    );
+    fs.writeFileSync(
+      path.join(repoDir, 'pnpm-lock.yaml'),
+      'lockfileVersion: 9.0\n',
+    );
+    const selfLoopPath = path.join(
+      repoDir,
+      'node_modules',
+      '.pnpm',
+      'node_modules',
+    );
+    fs.symlinkSync(selfLoopPath, selfLoopPath);
+
+    execFileSyncMock.mockImplementation((_file, _args, options) => {
+      const cwd = (options as { cwd: string }).cwd;
+      expect(fs.existsSync(selfLoopPath)).toBe(false);
+      fs.mkdirSync(path.join(cwd, 'node_modules', '.bin'), { recursive: true });
+      fs.writeFileSync(path.join(cwd, 'node_modules', '.bin', 'vitest'), '');
+      return '';
+    });
+
+    const result = ensureWorkspaceDependenciesInstalled(repoDir);
+
+    expect(result).toMatchObject({
+      installed: true,
+      packageManager: 'pnpm',
+      commandText: 'corepack pnpm install --frozen-lockfile',
+    });
+    expect(execFileSyncMock).toHaveBeenCalledTimes(1);
+    expect(hasInstalledNodeModules(repoDir)).toBe(true);
+  });
+
+  it('retries once after pnpm reports an ELOOP install failure', () => {
+    const repoDir = path.join(tempRoot, 'eloop-retry');
+    fs.mkdirSync(repoDir, { recursive: true });
+    fs.writeFileSync(
+      path.join(repoDir, 'package.json'),
+      JSON.stringify({
+        name: 'eloop-retry',
+        packageManager: 'pnpm@10.11.0',
+        scripts: { test: 'vitest run' },
+      }),
+    );
+    fs.writeFileSync(
+      path.join(repoDir, 'pnpm-lock.yaml'),
+      'lockfileVersion: 9.0\n',
+    );
+
+    execFileSyncMock.mockImplementationOnce((_file, _args, options) => {
+      const cwd = (options as { cwd: string }).cwd;
+      fs.mkdirSync(path.join(cwd, 'node_modules', '.pnpm'), {
+        recursive: true,
+      });
+      const selfLoopPath = path.join(
+        cwd,
+        'node_modules',
+        '.pnpm',
+        'node_modules',
+      );
+      fs.symlinkSync(selfLoopPath, selfLoopPath);
+      throw { stderr: 'ELOOP: too many symbolic links encountered' };
+    });
+    execFileSyncMock.mockImplementationOnce((_file, _args, options) => {
+      const cwd = (options as { cwd: string }).cwd;
+      expect(
+        fs.existsSync(path.join(cwd, 'node_modules', '.pnpm', 'node_modules')),
+      ).toBe(false);
+      fs.mkdirSync(path.join(cwd, 'node_modules', '.bin'), { recursive: true });
+      fs.writeFileSync(path.join(cwd, 'node_modules', '.bin', 'vitest'), '');
+      return '';
+    });
+
+    const result = ensureWorkspaceDependenciesInstalled(repoDir);
+
+    expect(result).toMatchObject({
+      installed: true,
+      packageManager: 'pnpm',
+      commandText: 'corepack pnpm install --frozen-lockfile',
+    });
+    expect(execFileSyncMock).toHaveBeenCalledTimes(2);
+    expect(hasInstalledNodeModules(repoDir)).toBe(true);
+  });
+
   it('disables corepack project specs only for lockfile-selected pnpm workspaces under a conflicting ancestor', () => {
     const parentDir = path.join(tempRoot, 'parent');
     fs.mkdirSync(parentDir, { recursive: true });

src/workspace-package-manager.ts

@@ -226,11 +226,63 @@ function writeInstallFingerprint(
   );
 }
 
+function hasRecoverableSymlinkLoopAt(symlinkPath: string): boolean {
+  let stat: fs.Stats;
+  try {
+    stat = fs.lstatSync(symlinkPath);
+  } catch (error) {
+    return (
+      typeof error === 'object' &&
+      error !== null &&
+      'code' in error &&
+      (error as { code?: unknown }).code === 'ELOOP'
+    );
+  }
+
+  if (!stat.isSymbolicLink()) {
+    return false;
+  }
+
+  const target = fs.readlinkSync(symlinkPath);
+  const resolvedTarget = path.resolve(path.dirname(symlinkPath), target);
+  if (resolvedTarget === symlinkPath) {
+    return true;
+  }
+
+  try {
+    fs.realpathSync(symlinkPath);
+    return false;
+  } catch (error) {
+    return (
+      typeof error === 'object' &&
+      error !== null &&
+      'code' in error &&
+      (error as { code?: unknown }).code === 'ELOOP'
+    );
+  }
+}
+
+function hasRecoverableNodeModulesLoop(repoDir: string): boolean {
+  return hasRecoverableSymlinkLoopAt(
+    path.join(repoDir, 'node_modules', '.pnpm', 'node_modules'),
+  );
+}
+
+function removeNodeModulesTree(repoDir: string): void {
+  fs.rmSync(path.join(repoDir, 'node_modules'), {
+    recursive: true,
+    force: true,
+  });
+}
+
 function hasRunnableNodeModulesTree(repoDir: string): boolean {
   const nodeModulesDir = path.join(repoDir, 'node_modules');
   if (!fs.existsSync(nodeModulesDir)) {
     return false;
   }
+  if (hasRecoverableNodeModulesLoop(repoDir)) {
+    return false;
+  }
 
   try {
     return fs
@@ -383,6 +435,42 @@ export function hasInstalledNodeModules(repoDir: string): boolean {
   return readInstallFingerprint(repoDir) === expectedFingerprint;
 }
 
+function getInstallErrorDetail(error: unknown): string {
+  const stderr =
+    typeof error === 'object' &&
+    error !== null &&
+    'stderr' in error &&
+    typeof (error as { stderr?: unknown }).stderr === 'string'
+      ? (error as { stderr: string }).stderr.trim()
+      : '';
+  const stdout =
+    typeof error === 'object' &&
+    error !== null &&
+    'stdout' in error &&
+    typeof (error as { stdout?: unknown }).stdout === 'string'
+      ? (error as { stdout: string }).stdout.trim()
+      : '';
+  return (
+    stderr || stdout || (error instanceof Error ? error.message : String(error))
+  );
+}
+
+function isRecoverableNodeModulesLoopInstallFailure(detail: string): boolean {
+  return /\bELOOP\b|too many symbolic links/i.test(detail);
+}
+
+function runWorkspaceInstallCommand(
+  repoDir: string,
+  command: WorkspaceCommandSpec,
+): void {
+  execFileSync(command.file, command.args, {
+    cwd: repoDir,
+    env: buildWorkspaceCommandEnvironment(repoDir, command.packageManager),
+    encoding: 'utf-8',
+    stdio: ['ignore', 'pipe', 'pipe'],
+  });
+}
+
 export function ensureWorkspaceDependenciesInstalled(
   repoDir: string,
 ): WorkspaceDependencyInstallResult {
@@ -403,35 +491,29 @@ export function ensureWorkspaceDependenciesInstalled(
     return { installed: false, packageManager };
   }
 
+  if (hasRecoverableNodeModulesLoop(repoDir)) {
+    removeNodeModulesTree(repoDir);
+  }
+
   try {
-    execFileSync(command.file, command.args, {
+    runWorkspaceInstallCommand(repoDir, command);
-      cwd: repoDir,
-      env: buildWorkspaceCommandEnvironment(repoDir, command.packageManager),
-      encoding: 'utf-8',
-      stdio: ['ignore', 'pipe', 'pipe'],
-    });
   } catch (error) {
-    const stderr =
+    const detail = getInstallErrorDetail(error);
-      typeof error === 'object' &&
+    if (isRecoverableNodeModulesLoopInstallFailure(detail)) {
-      error !== null &&
+      removeNodeModulesTree(repoDir);
-      'stderr' in error &&
+      try {
-      typeof (error as { stderr?: unknown }).stderr === 'string'
+        runWorkspaceInstallCommand(repoDir, command);
-        ? (error as { stderr: string }).stderr.trim()
+      } catch (retryError) {
-        : '';
+        const retryDetail = getInstallErrorDetail(retryError);
-    const stdout =
+        throw new Error(
-      typeof error === 'object' &&
+          `Failed to install workspace dependencies with "${command.commandText}" in ${repoDir} after cleaning node_modules: ${retryDetail}`,
-      error !== null &&
+        );
-      'stdout' in error &&
+      }
-      typeof (error as { stdout?: unknown }).stdout === 'string'
+    } else {
-        ? (error as { stdout: string }).stdout.trim()
+      throw new Error(
-        : '';
+        `Failed to install workspace dependencies with "${command.commandText}" in ${repoDir}: ${detail}`,
-    const detail =
+      );
-      stderr ||
+    }
-      stdout ||
-      (error instanceof Error ? error.message : String(error));
-    throw new Error(
-      `Failed to install workspace dependencies with "${command.commandText}" in ${repoDir}: ${detail}`,
-    );
   }
 
   const fingerprint = computeInstallFingerprint(repoDir);