From c72d0320f40562c6da2fcd3fc71c6cf8d9386e4c Mon Sep 17 00:00:00 2001
From: Yury Semikhatsky <yurys@chromium.org>
Date: Thu, 24 Jul 2025 10:25:13 -0700
Subject: [PATCH] chore(extension): use free port (#735)

---
 src/browserContextFactory.ts | 2 +-
 src/extension/cdpRelay.ts    | 6 +++---
 src/extension/main.ts        | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/browserContextFactory.ts b/src/browserContextFactory.ts
index c548bba..7e17b78 100644
--- a/src/browserContextFactory.ts
+++ b/src/browserContextFactory.ts
@@ -217,7 +217,7 @@ async function injectCdpPort(browserConfig: FullConfig['browser']) {
     (browserConfig.launchOptions as any).cdpPort = await findFreePort();
 }
 
-async function findFreePort() {
+async function findFreePort(): Promise<number> {
   return new Promise((resolve, reject) => {
     const server = net.createServer();
     server.listen(0, () => {
diff --git a/src/extension/cdpRelay.ts b/src/extension/cdpRelay.ts
index 5366167..d14fdda 100644
--- a/src/extension/cdpRelay.ts
+++ b/src/extension/cdpRelay.ts
@@ -28,10 +28,10 @@ import { WebSocket, WebSocketServer } from 'ws';
 import debug from 'debug';
 import * as playwright from 'playwright';
 import { httpAddressToString, startHttpServer } from '../transport.js';
-import { BrowserContextFactory } from '../browserContextFactory.js';
 // @ts-ignore
 const { registry } = await import('playwright-core/lib/server/registry/index');
 
+import type { BrowserContextFactory } from '../browserContextFactory.js';
 import type websocket from 'ws';
 
 const debugLogger = debug('pw:mcp:relay');
@@ -324,8 +324,8 @@ class ExtensionContextFactory implements BrowserContextFactory {
   }
 }
 
-export async function startCDPRelayServer(port: number, browserChannel: string) {
-  const httpServer = await startHttpServer({ port });
+export async function startCDPRelayServer(browserChannel: string) {
+  const httpServer = await startHttpServer({});
   const cdpRelayServer = new CDPRelayServer(httpServer, browserChannel);
   process.on('exit', () => cdpRelayServer.stop());
   debugLogger(`CDP relay server started, extension endpoint: ${cdpRelayServer.extensionEndpoint()}.`);
diff --git a/src/extension/main.ts b/src/extension/main.ts
index 1e20cbd..c3fc6f6 100644
--- a/src/extension/main.ts
+++ b/src/extension/main.ts
@@ -22,7 +22,7 @@ import { filteredTools } from '../tools.js';
 import type { FullConfig } from '../config.js';
 
 export async function runWithExtension(config: FullConfig) {
-  const contextFactory = await startCDPRelayServer(9225, config.browser.launchOptions.channel || 'chrome');
+  const contextFactory = await startCDPRelayServer(config.browser.launchOptions.channel || 'chrome');
   const server = new Server(config, filteredTools(config), contextFactory);
   server.setupExitWatchdog();