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Codex Issues / #30904

Codex Desktop on Windows does not expose mcp__node_repl__js / node_repl js, so Browser Use cannot control the in-app browser

Open 💬 2 comments Opened Jul 2, 2026 by deepicemint
💡 Likely answer: A maintainer (github-actions[bot], contributor) responded on this thread — see the highlighted reply below.

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

Unknown; Windows Codex Desktop app

What subscription do you have?

Plus

What platform is your computer?

Windows x64

What issue are you seeing?

Codex Desktop on Windows repeatedly does not expose mcp__node_repl__js / node_repl js in fresh chats.

I have already tried:

  • restarting Codex Desktop
  • fully closing/reopening the app
  • creating multiple new chats
  • invoking the bundled Browser skill first
  • searching tool discovery for:
  • node_repl js
  • mcp__node_repl__js
  • js
  • node_repl js JavaScript execution

Result:
The required JS execution tool is never exposed. Browser Use cannot bootstrap through scripts/browser-client.mjs, so the in-app browser cannot be controlled.

Observed impact:

  • The bundled Browser skill can be read.
  • The skill requires bootstrapping through mcp__node_repl__js using browser-client.mjs.
  • Because mcp__node_repl__js / node_repl js is not exposed, Codex cannot open or control the in-app browser.
  • Repeated restarts and new chats do not change the result.

This appears similar to:

Please check whether mcp__node_repl__js / node_repl js is currently enabled for my account/build, or whether this Windows build is failing to expose the Node REPL tool surface.

What steps can reproduce the bug?

  1. Open Codex Desktop on Windows.
  2. Start a fresh chat.
  3. Ask Codex to use the bundled Browser skill.
  4. Have Codex search for:
  • node_repl js
  • mcp__node_repl__js
  • js
  • node_repl js JavaScript execution
  1. Observe that no Node REPL JavaScript execution tool is exposed.
  2. Browser Use cannot bootstrap through browser-client.mjs.

What is the expected behavior?

When the bundled Browser plugin is available, Codex should expose the Node REPL JavaScript execution tool, typically mcp__node_repl__js, so Browser Use can import scripts/browser-client.mjs and control the in-app browser.

Additional information

This has been tried across multiple restarts and fresh chats. The issue appears to be tool exposure/registration, not a specific website or browser page.

View original on GitHub ↗

2 Comments

github-actions[bot] contributor · 1 month ago

Potential duplicates detected. Please review them and close your issue if it is a duplicate.

  • #30562
  • #30486
  • #30026

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deepicemint · 1 month ago

Thanks for the duplicate check. I reviewed #30562, #30486, and #30026.

#30486 / #30026 look like the closest matches. This issue appears to be in the same failure family: Browser/Chrome/In-app Browser skills are present, but the Node REPL JavaScript execution tool required by the official browser runtime is not exposed to the agent turn.

Current fresh-session confirmation:

  • control-in-app-browser skill is readable
  • browser-client.mjs exists
  • tool discovery for node_repl js, mcp__node_repl__js, and js JavaScript execution node repl runtime tool does not expose a usable Node REPL JS execution tool
  • only unrelated Canva / Notion / Slack / GitHub / Data Analytics tools are returned
  • because the JS execution tool is missing, the browser runtime cannot be initialized and no page-level click/input verification can be performed
  • Chrome launch or URL opening is not a valid substitute for this failure mode

So this may be a duplicate of #30486 / #30026, but the issue still reproduces in a fresh Windows Desktop session. Happy to close/consolidate wherever maintainers prefer.