# Chrome MCP Background Proxy — Fix Popups, Focus Stealing & Multi-Agent Conflicts

> Drop-in proxy for Chrome MCP. Solves Chrome 146+ debugging popups, focus stealing, and multi-agent conflicts with persistent CDP connection, request ID remapping, and sessionId-based event routing.

## Install

Merge the JSON below into your `.mcp.json`:

## What It Does

Chrome MCP lets AI agents (Claude Code, Cursor, etc.) control your browser. But it has 3 major pain points:

| Problem | What Happens | This Proxy Fixes It |
|---------|-------------|-------------------|
| **Chrome 146+ popup** | "Allow remote debugging?" pops up every time you start a new session | Persistent connection — popup appears only once |
| **Focus stealing** | Chrome jumps to foreground while agent works | Intercepts focus commands, all tabs open in background |
| **Multi-agent conflicts** | Multiple agents crash each other's browser sessions | Request ID remapping + event routing by sessionId |

## Architecture

```
Claude Code → chrome-mcp-proxy.sh → chrome-devtools-mcp
                                          ↓
                                    cdp-proxy.mjs (port 9401)
                                          ↓
                                    Your Chrome Browser
```

The proxy sits between `chrome-devtools-mcp` and Chrome, maintaining one persistent WebSocket connection.

## Quick Install (3 steps)

### Step 1: Save the 3 scripts

Create `~/scripts/` and save these files there:

<details>
<summary><strong>chrome-mcp-proxy.sh</strong> — MCP entry point (click to expand)</summary>

```bash
#!/bin/bash
# Chrome MCP + 持久 Proxy
# 用法: chrome-mcp-proxy.sh [proxy端口] [chrome端口]
# Proxy 保持和 Chrome 的持久连接，弹窗只出现一次

PROXY_PORT=${1:-9401}
CHROME_PORT=${2:-9222}
PROXY_SCRIPT="$HOME/scripts/cdp-proxy.mjs"
PID_DIR="$HOME/chrome-profiles/pids"
LOG_DIR="$HOME/chrome-profiles/logs"

mkdir -p "$PID_DIR" "$LOG_DIR"

# 本地连接绕过代理
unset http_proxy HTTP_PROXY https_proxy HTTPS_PROXY all_proxy ALL_PROXY
export no_proxy="127.0.0.1,localhost"
export NO_PROXY="127.0.0.1,localhost"

# 如果 Proxy 没跑，启动它（持久运行，不随 Claude Code 退出而死）
if ! lsof -i :${PROXY_PORT} >/dev/null 2>&1; then
    nohup node "${PROXY_SCRIPT}" \
        --port ${PROXY_PORT} \
        --chrome-port ${CHROME_PORT} \
        &>"${LOG_DIR}/proxy-${PROXY_PORT}.log" &
    echo $! > "${PID_DIR}/proxy-${PROXY_PORT}.pid"
    disown
    sleep 2
fi

# 启动 chrome-devtools-mcp，连接到 Proxy
exec npx -y chrome-devtools-mcp@latest --browserUrl "http://127.0.0.1:${PROXY_PORT}"

```

</details>

<details>
<summary><strong>cdp-proxy.mjs</strong> — CDP persistent proxy with multi-agent isolation (click to expand)</summary>

```javascript
#!/usr/bin/env node
/**
 * CDP Background Proxy v3 — 持久连接 + 多 Agent 隔离
 *
 * 1. 持久 WebSocket 连接到 Chrome（弹窗只出现一次）
 * 2. 拦截 Target.activateTarget / Page.bringToFront（防抢焦点）
 * 3. 强制 createTarget background=true
 * 4. 请求 ID 重映射（防多客户端 ID 冲突）
 * 5. 事件按 sessionId 路由到对应客户端（防多 Agent 互扰）
 * 6. 自动重连
 *
 * 用法: node cdp-proxy.mjs [--port 9401] [--chrome-port 9222]
 */

import http from 'http';
import fs from 'fs';
import path from 'path';
import os from 'os';
import { WebSocketServer, WebSocket } from 'ws';

const args = process.argv.slice(2);
const getArg = (name, def) => {
    const i = args.indexOf(name);
    return i >= 0 ? args[i + 1] : def;
};

const PROXY_PORT = parseInt(getArg('--port', '9401'));
const CHROME_PORT = parseInt(getArg('--chrome-port', '9222'));
const CHROME_HOST = getArg('--chrome-host', '127.0.0.1');

const DEVTOOLS_PORT_FILE = getArg('--devtools-port-file',
    path.join(os.homedir(), 'Library/Application Support/Google/Chrome/DevToolsActivePort'));

// ═══════════════════════════════════════════
// 持久 Chrome 连接
// ═══════════════════════════════════════════

let chromeWs = null;
let chromeReady = false;
let reconnecting = false;

const BLOCKED_METHODS = new Set([
    'Target.activateTarget',
    'Page.bringToFront',
]);

function safeSend(ws, data) {
    if (ws && ws.readyState === WebSocket.OPEN) {
        ws.send(typeof data === 'string' ? data : JSON.stringify(data));
    }
}

function readDevToolsActivePort() {
    try {
        const content = fs.readFileSync(DEVTOOLS_PORT_FILE, 'utf-8').trim();
        const lines = content.split('\n');
        if (lines.length >= 2) {
            return { port: parseInt(lines[0]), wsPath: lines[1] };
        }
    } catch (e) { /* ignore */ }
    return null;
}

function getChromeWsUrl() {
    const portInfo = readDevToolsActivePort();
    if (portInfo) {
        return `ws://${CHROME_HOST}:${portInfo.port}${portInfo.wsPath}`;
    }
    return null;
}

// ═══════════════════════════════════════════
// 多客户端隔离
// ═══════════════════════════════════════════

// 全局自增 ID，保证唯一
let globalIdCounter = 1;

// proxyId → { clientWs, originalId, method, createdAt }
const pendingRequests = new Map();

// 每30秒清理超过60秒未响应的 pending requests
setInterval(() => {
    const now = Date.now();
    let cleaned = 0;
    for (const [proxyId, req] of pendingRequests) {
        if (now - req.createdAt > 60000) {
            // 给客户端返回超时错误，避免它也卡住
            safeSend(req.clientWs, { id: req.originalId, error: { code: -32000, message: 'CDP request timeout (60s)' } });
            pendingRequests.delete(proxyId);
            const state = clientState.get(req.clientWs);
            if (state) state.proxyIds.delete(proxyId);
            cleaned++;
        }
    }
    if (cleaned > 0) {
        console.log(`[Proxy] 清理 ${cleaned} 个超时请求 (剩 ${pendingRequests.size} 个)`);
    }
}, 30000);

// sessionId → clientWs（哪个客户端 attach 了这个 session）
const sessionOwners = new Map();

// clientWs → { tabs: Set, sessions: Set, proxyIds: Set }
const clientState = new Map();

function getOrCreateState(clientWs) {
    if (!clientState.has(clientWs)) {
        clientState.set(clientWs, { tabs: new Set(), sessions: new Set(), proxyIds: new Set() });
    }
    return clientState.get(clientWs);
}

// ═══════════════════════════════════════════
// Chrome 连接管理
// ═══════════════════════════════════════════

function connectToChrome() {
    if (reconnecting) return;
    reconnecting = true;

    const wsUrl = getChromeWsUrl();
    if (!wsUrl) {
        console.error('[Proxy] Chrome 未运行，5秒后重试...');
        setTimeout(() => { reconnecting = false; connectToChrome(); }, 5000);
        return;
    }

    console.log(`[Proxy] 连接 Chrome: ${wsUrl}`);
    chromeWs = new WebSocket(wsUrl);

    chromeWs.on('open', () => {
        console.log('[Proxy] ✓ Chrome 已连接');
        chromeReady = true;
        reconnecting = false;
    });

    chromeWs.on('message', (rawData) => {
        try {
            const msg = JSON.parse(rawData.toString());

            // ── 响应消息（有 id）→ 路由到发起者 ──
            if (msg.id !== undefined && pendingRequests.has(msg.id)) {
                const { clientWs, originalId, method } = pendingRequests.get(msg.id);
                pendingRequests.delete(msg.id);

                const state = clientState.get(clientWs);

                // 追踪 createTarget
                if (method === 'Target.createTarget' && msg.result?.targetId) {
                    if (state) state.tabs.add(msg.result.targetId);
                    console.log(`[Proxy] 新 tab: ${msg.result.targetId}`);
                }

                // 追踪 attachToTarget → 记录 session 归属
                if (method === 'Target.attachToTarget' && msg.result?.sessionId) {
                    const sid = msg.result.sessionId;
                    sessionOwners.set(sid, clientWs);
                    if (state) state.sessions.add(sid);
                    console.log(`[Proxy] session ${sid.slice(0, 8)}... → 客户端`);
                }

                // 还原原始 ID
                msg.id = originalId;
                safeSend(clientWs, msg);
                return;
            }

            // ── 事件消息（无 id）→ 按 sessionId 路由 ──
            if (msg.method) {
                // 带 sessionId 的事件：发给对应客户端
                if (msg.sessionId && sessionOwners.has(msg.sessionId)) {
                    safeSend(sessionOwners.get(msg.sessionId), msg);
                    return;
                }

                // Target 域的全局事件：按 targetId 路由或广播
                if (msg.method.startsWith('Target.')) {
                    const targetId = msg.params?.targetInfo?.targetId || msg.params?.targetId;
                    if (targetId) {
                        // 找到拥有这个 tab 的客户端
                        for (const [ws, state] of clientState) {
                            if (state.tabs.has(targetId)) {
                                safeSend(ws, msg);
                                return;
                            }
                        }
                    }
                    // 找不到归属，广播
                    for (const [ws] of clientState) {
                        safeSend(ws, msg);
                    }
                    return;
                }

                // 其他无 sessionId 的事件，广播
                for (const [ws] of clientState) {
                    safeSend(ws, msg);
                }
                return;
            }

            // 其他消息，广播
            for (const [ws] of clientState) {
                safeSend(ws, rawData);
            }
        } catch (e) {
            for (const [ws] of clientState) {
                safeSend(ws, rawData);
            }
        }
    });

    chromeWs.on('close', () => {
        console.log('[Proxy] Chrome 断开，5秒后重连...');
        chromeReady = false;
        chromeWs = null;
        reconnecting = false;
        // 清理所有 session 归属（Chrome 重启后 session 失效）
        sessionOwners.clear();
        setTimeout(() => connectToChrome(), 5000);
    });

    chromeWs.on('error', (err) => {
        console.error('[Proxy] Chrome 错误:', err.message);
        chromeReady = false;
        chromeWs = null;
        reconnecting = false;
        setTimeout(() => connectToChrome(), 5000);
    });
}

// ═══════════════════════════════════════════
// HTTP 端点
// ═══════════════════════════════════════════

function cdpRequest(method, params = {}) {
    return new Promise((resolve, reject) => {
        if (!chromeReady) return reject(new Error('Chrome not connected'));
        const proxyId = globalIdCounter++;
        const timeout = setTimeout(() => {
            pendingRequests.delete(proxyId);
            reject(new Error('timeout'));
        }, 5000);
        const fakeClient = {
            send: (data) => {
                clearTimeout(timeout);
                resolve(typeof data === 'string' ? JSON.parse(data) : data);
            },
            readyState: WebSocket.OPEN,
        };
        pendingRequests.set(proxyId, { clientWs: fakeClient, originalId: proxyId, method });
        chromeWs.send(JSON.stringify({ id: proxyId, method, params }));
    });
}

const server = http.createServer(async (req, res) => {
    try {
        if (req.url === '/json/version') {
            const portInfo = readDevToolsActivePort();
            const wsUrl = portInfo
                ? `ws://${CHROME_HOST}:${PROXY_PORT}${portInfo.wsPath}`
                : `ws://${CHROME_HOST}:${PROXY_PORT}/devtools/browser/proxy`;
            res.writeHead(200, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify({ Browser: 'Chrome (via CDP Proxy v3)', webSocketDebuggerUrl: wsUrl }));
            return;
        }

        if (req.url === '/json/list' || req.url === '/json') {
            if (!chromeReady) { res.writeHead(503); res.end('Chrome not connected'); return; }
            try {
                const result = await cdpRequest('Target.getTargets');
                const targets = (result.result?.targetInfos || []).map(t => ({
                    ...t,
                    webSocketDebuggerUrl: `ws://${CHROME_HOST}:${PROXY_PORT}/devtools/page/${t.targetId}`,
                }));
                res.writeHead(200, { 'Content-Type': 'application/json' });
                res.end(JSON.stringify(targets));
            } catch (e) { res.writeHead(500); res.end(e.message); }
            return;
        }

        if (req.url === '/json/new') {
            if (!chromeReady) { res.writeHead(503); res.end('Chrome not connected'); return; }
            try {
                const result = await cdpRequest('Target.createTarget', { url: 'about:blank', background: true });
                res.writeHead(200, { 'Content-Type': 'application/json' });
                res.end(JSON.stringify(result.result || {}));
            } catch (e) { res.writeHead(500); res.end(e.message); }
            return;
        }

        if (req.url === '/proxy/status') {
            const clientList = [];
            for (const [, state] of clientState) {
                clientList.push({ tabs: state.tabs.size, sessions: state.sessions.size });
            }
            res.writeHead(200, { 'Content-Type': 'application/json' });
            res.end(JSON.stringify({
                chromeConnected: chromeReady,
                clients: clientState.size,
                sessions: sessionOwners.size,
                pendingRequests: pendingRequests.size,
                clientDetails: clientList,
            }, null, 2));
            return;
        }

        res.writeHead(404);
        res.end('Not found');
    } catch (e) { res.writeHead(500); res.end(e.message); }
});

// ═══════════════════════════════════════════
// WebSocket 客户端处理
// ═══════════════════════════════════════════

const wss = new WebSocketServer({ server });

wss.on('connection', (clientWs, req) => {
    const state = getOrCreateState(clientWs);
    console.log(`[Proxy] 客户端连接 (共 ${clientState.size} 个)`);

    clientWs.on('message', (data) => {
        if (!chromeReady) {
            try {
                const msg = JSON.parse(data.toString());
                if (msg.id !== undefined) {
                    safeSend(clientWs, { id: msg.id, error: { code: -1, message: 'Chrome not connected' } });
                }
            } catch (e) { /* ignore */ }
            return;
        }

        try {
            const msg = JSON.parse(data.toString());

            // 拦截抢焦点命令
            if (BLOCKED_METHODS.has(msg.method)) {
                console.log(`[Proxy] 拦截: ${msg.method}`);
                const reply = { id: msg.id, result: {} };
                if (msg.sessionId) reply.sessionId = msg.sessionId;
                safeSend(clientWs, reply);
                return;
            }

            // 强制后台创建 tab
            if (msg.method === 'Target.createTarget') {
                if (!msg.params) msg.params = {};
                msg.params.background = true;
                console.log(`[Proxy] 后台创建 tab: ${msg.params.url || 'about:blank'}`);
            }

            // ── ID 重映射 ──
            if (msg.id !== undefined) {
                const proxyId = globalIdCounter++;
                pendingRequests.set(proxyId, {
                    clientWs,
                    originalId: msg.id,
                    method: msg.method,
                    createdAt: Date.now(),
                });
                state.proxyIds.add(proxyId);
                msg.id = proxyId;
            }

            safeSend(chromeWs, msg);
        } catch (e) {
            safeSend(chromeWs, data);
        }
    });

    const cleanup = () => {
        // 清理这个客户端的 session 归属
        for (const sid of state.sessions) {
            sessionOwners.delete(sid);
        }
        // 清理未完成的请求
        for (const pid of state.proxyIds) {
            pendingRequests.delete(pid);
        }
        clientState.delete(clientWs);
        console.log(`[Proxy] 客户端断开 (剩 ${clientState.size} 个, 释放 ${state.tabs.size} tab, ${state.sessions.size} session)`);
    };

    clientWs.on('close', cleanup);
    clientWs.on('error', cleanup);
});

// ═══════════════════════════════════════════
// 启动
// ═══════════════════════════════════════════

process.on('uncaughtException', (err) => {
    console.error('[Proxy] 异常（已恢复）:', err.message);
});
process.on('unhandledRejection', (reason) => {
    console.error('[Proxy] Promise 拒绝（已恢复）:', reason);
});

server.listen(PROXY_PORT, () => {
    console.log(`
╔══════════════════════════════════════════════════════╗
║   CDP Background Proxy v3 — 持久连接 + 多Agent隔离  ║
║                                                      ║
║   Proxy:  http://127.0.0.1:${PROXY_PORT}                    ║
║                                                      ║
║   ✓ 持久连接（弹窗只出现一次）                       ║
║   ✓ 拦截 activateTarget / bringToFront               ║
║   ✓ 强制 createTarget background=true                ║
║   ✓ 请求 ID 重映射（防多客户端冲突）                 ║
║   ✓ 事件按 sessionId 路由（防多 Agent 互扰）         ║
║   ✓ 自动重连                                         ║
║                                                      ║
║   状态: http://127.0.0.1:${PROXY_PORT}/proxy/status          ║
╚══════════════════════════════════════════════════════╝
`);
    connectToChrome();
});

```

</details>

<details>
<summary><strong>kill-old-chrome-mcp.sh</strong> — Safe process cleanup (click to expand)</summary>

```bash
#!/bin/bash
# kill-old-chrome-mcp.sh
# 只杀旧的 Chrome MCP 进程，保留最新的（当前 Claude Code session 的）
#
# 用法：bash ~/scripts/kill-old-chrome-mcp.sh

PIDS=$(ps aux | grep "[c]hrome-devtools-mcp" | grep -v watchdog | grep -v "npm exec" | awk '{print $2}')

if [ -z "$PIDS" ]; then
    echo "没有找到 chrome-devtools-mcp 进程"
    exit 0
fi

COUNT=$(echo "$PIDS" | wc -l | tr -d ' ')

if [ "$COUNT" -le 1 ]; then
    echo "只有 1 个 Chrome MCP 进程 (PID: $PIDS)，无需清理"
    exit 0
fi

# 保留最新的（PID最大的），杀掉其他所有
NEWEST=$(echo "$PIDS" | sort -n | tail -1)
OLD_PIDS=$(echo "$PIDS" | sort -n | head -n -1)

echo "发现 $COUNT 个 Chrome MCP 进程"
echo "保留最新: PID $NEWEST"
echo "杀掉旧的: $OLD_PIDS"

for pid in $OLD_PIDS; do
    # 同时杀掉关联的 npm exec 和 watchdog 进程
    PARENT_PIDS=$(ps aux | grep -E "npm exec.*chrome-devtools|watchdog.*parent-pid=$pid" | grep -v grep | awk '{print $2}')
    kill $pid $PARENT_PIDS 2>/dev/null
    echo "  已杀: PID $pid (及关联进程)"
done

echo "✅ 清理完成，保留 PID $NEWEST"

```

</details>

Then make them executable:

```bash
mkdir -p ~/scripts ~/chrome-profiles/pids ~/chrome-profiles/logs
chmod +x ~/scripts/chrome-mcp-proxy.sh ~/scripts/kill-old-chrome-mcp.sh
```

### Step 2: Add to your `.mcp.json`

```json
{
  "chrome": {
    "command": "bash",
    "args": ["~/scripts/chrome-mcp-proxy.sh", "9401", "9222"]
  }
}
```

> **Important:** Do NOT add `http_proxy` or `https_proxy` env vars to the chrome config. The script handles proxy bypass internally.

### Step 3: Enable Chrome Remote Debugging

Open `chrome://inspect/#remote-debugging` in Chrome and check **"Allow remote debugging for this browser instance"** (one-time setup).

Start Claude Code. Click "Allow" on the Chrome popup **once**. Done — future sessions won't prompt again.

## Troubleshooting

| Symptom | Fix |
|---------|-----|
| "Could not connect to Chrome" | Check Chrome is running: `pgrep -x "Google Chrome"` |
| Proxy not responding | `curl -s --noproxy '*' http://127.0.0.1:9401/proxy/status` |
| Multiple MCP processes piling up | `bash ~/scripts/kill-old-chrome-mcp.sh` |
| Chrome popup keeps appearing | Proxy may have died — it auto-restarts, just click "Allow" once |

## Requirements

- Node.js 18+
- macOS (uses `DevToolsActivePort` file path; Linux users: adjust the path in `cdp-proxy.mjs`)
- Chrome with remote debugging enabled


---
Source: https://tokrepo.com/en/workflows/29944683-2033-4e30-9449-6d18dffa60f5
Author: henuwangkai