codex - 💡(How to fix) Fix Codex Chrome Plugin: extension-host not running, node_repl MCP tool unavailable in session

What version of the Codex App are you using (From “About Codex” dialog)?

26.527.31326 (3390)

What subscription do you have?

free

What platform is your computer?

macOS m1

What issue are you seeing?

The @chrome plugin cannot establish communication with Chrome. All static checks pass (Chrome running, extension installed & enabled, native host manifest correct), but the runtime communication chain never completes:

extension-host (native messaging host binary) is never spawned as a process node_repl MCP tool is not available in the session, preventing browser-client.mjs from setting up the connection Environment Codex desktop app (latest, bundled plugins) Chrome 148.0.7778.181 on macOS ARM64 Codex Chrome Extension: hehggadaopoacecdllhhajmbjkdcmajg v1.1.5_0, installed & enabled in Default profile Plugin: [email protected] (OpenAI bundled) Session type: Projectless chat thread Diagnostics All static checks pass:

chrome-is-running.js --check → ✅ Chrome running check-extension-installed.js --json → ✅ installed, enabled, registered check-native-host-manifest.js --json → ✅ manifest exists, path correct, origin allowed Runtime checks fail:

extension-host process → ❌ not running (checked via pgrep -f extension-host) node_repl MCP tool → ❌ not listed in available MCP tools; globalThis.nodeRepl is undefined open-chrome-window.js → ❌ fails with kLSServerCommunicationErr (LaunchServices not available in sandbox) CDP remote debugging port → ❌ no port open (scanned 9222-9230) browser-client.mjs setup → ❌ fails with privileged native pipe bridge is not available; browser-client is not trusted Binary status:

node_repl → ✅ exists at /Applications/Codex.app/Contents/Resources/node_repl, properly code-signed (Team ID: 2DC432GLL2) extension-host → ✅ exists, executable, correct path in manifest Root Cause The communication chain is:

Chrome Tab ⇄ Chrome Extension (Native Messaging) → extension-host (stdio) → native pipe → node_repl (MCP server) → Codex Session It breaks at two points:

extension-host never starts. Chrome should launch it on demand for native messaging, but it never does. The Chrome extension appears enabled in preferences but may not have its background service worker actively running, or the handshake never initiates.

node_repl MCP tool is unavailable. The binary exists but the MCP server it provides is not registered for the current session. Without it, browser-client.mjs cannot access globalThis.nodeRepl?.nativePipe or call agent.browsers.get("extension").

Workarounds Tried (all no change) Restart Chrome completely Reinstall Codex Chrome Extension from Chrome Web Store Remove & reinstall Chrome plugin from Codex plugin UI Restart Codex desktop app entirely Create new chat thread Suspected Areas node_repl MCP server may only be started for workspace-based sessions, not projectless threads Chrome extension may be registered/enabled but its background.service_worker not actively running The browser plugin (which has node-repl keyword) is not installed, while the chrome plugin depends on its MCP server sandbox_approval: false and rules: false in session approval policy may block process spawning No --remote-debugging-port flag used, so CDP fallback path is unavailable

What steps can reproduce the bug?

Since I installed the CodeX and Chrome extensions, I haven't been able to use them successfully

What is the expected behavior?

No response

Additional information

No response