fix(browser): avoid selecting non-server playwright cli paths (#74)

Co-authored-by: root <root@localhost.localdomain>

src/browser.test.ts

@@ -1,4 +1,6 @@
 import { afterEach, describe, it, expect, vi } from 'vitest';
+import * as os from 'node:os';
+import * as path from 'node:path';
 import { PlaywrightMCP, __test__ } from './browser/index.js';
 
 afterEach(() => {
@@ -248,6 +250,27 @@ describe('browser helpers', () => {
       });
     }
   });
+
+  it('ignores non-server playwright cli paths discovered from fallback scans', () => {
+    const wrongCli = '/root/.npm/_npx/e41f203b7505f1fb/node_modules/playwright/lib/mcp/terminal/cli.js';
+    const npxCacheBase = path.join(os.homedir(), '.npm', '_npx');
+
+    const existsSync = vi.fn((candidate: any) => {
+      const value = String(candidate);
+      return value === npxCacheBase || value === wrongCli;
+    });
+
+    const execSync = vi.fn((command: string) => {
+      if (String(command).includes('npm root -g')) return '/missing/global/node_modules\n' as any;
+      if (String(command).includes('--package=@playwright/mcp which mcp-server-playwright')) return `${wrongCli}\n` as any;
+      if (String(command).includes('which mcp-server-playwright')) return '' as any;
+      if (String(command).includes(`find "${npxCacheBase}"`)) return `${wrongCli}\n` as any;
+      throw new Error(`unexpected command: ${String(command)}`);
+    });
+    __test__.setMcpDiscoveryTestHooks({ existsSync, execSync: execSync as any });
+
+    expect(__test__.findMcpServerPath()).toBeNull();
+  });
 });
 
 describe('PlaywrightMCP state', () => {

src/browser/discover.ts

@@ -12,6 +12,19 @@ let _cachedMcpServerPath: string | null | undefined;
 let _existsSync = fs.existsSync;
 let _execSync = execSync;
 
+function isSupportedMcpEntrypoint(candidate: string): boolean {
+  const normalized = candidate.replace(/\\/g, '/').toLowerCase();
+  return normalized.endsWith('/@playwright/mcp/cli.js') ||
+    normalized.endsWith('/mcp-server-playwright') ||
+    normalized.endsWith('/mcp-server-playwright.js');
+}
+
+function resolveSupportedMcpPath(candidate: string | null | undefined): string | null {
+  const trimmed = candidate?.trim();
+  if (!trimmed || !_existsSync(trimmed)) return null;
+  return isSupportedMcpEntrypoint(trimmed) ? trimmed : null;
+}
+
 export function resetMcpServerPathCache(): void {
   _cachedMcpServerPath = undefined;
 }
@@ -80,8 +93,9 @@ export function findMcpServerPath(): string | null {
   // Try npx resolution (legacy package name)
   try {
     const result = _execSync('npx -y --package=@playwright/mcp which mcp-server-playwright 2>/dev/null', { encoding: 'utf-8', timeout: 10000 }).trim();
-    if (result && _existsSync(result)) {
-      _cachedMcpServerPath = result;
+    const resolved = resolveSupportedMcpPath(result);
+    if (resolved) {
+      _cachedMcpServerPath = resolved;
       return _cachedMcpServerPath;
     }
   } catch {}
@@ -89,8 +103,9 @@ export function findMcpServerPath(): string | null {
   // Try which
   try {
     const result = _execSync('which mcp-server-playwright 2>/dev/null', { encoding: 'utf-8', timeout: 5000 }).trim();
-    if (result && _existsSync(result)) {
-      _cachedMcpServerPath = result;
+    const resolved = resolveSupportedMcpPath(result);
+    if (resolved) {
+      _cachedMcpServerPath = resolved;
       return _cachedMcpServerPath;
     }
   } catch {}
@@ -99,9 +114,10 @@ export function findMcpServerPath(): string | null {
   for (const base of candidates) {
     if (!_existsSync(base)) continue;
     try {
-      const found = _execSync(`find "${base}" -name "cli.js" -path "*playwright*mcp*" 2>/dev/null | head -1`, { encoding: 'utf-8', timeout: 5000 }).trim();
-      if (found) {
-        _cachedMcpServerPath = found;
+      const found = _execSync(`find "${base}" -type f -path "*/@playwright/mcp/cli.js" 2>/dev/null | head -1`, { encoding: 'utf-8', timeout: 5000 }).trim();
+      const resolved = resolveSupportedMcpPath(found);
+      if (resolved) {
+        _cachedMcpServerPath = resolved;
         return _cachedMcpServerPath;
       }
     } catch {}