Browser Use broken after today update: no node_repl/js or no Codex IAB backend discovered

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

• #20248
• #19463
• #19667
• #19766
• #20417

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same

I can reproduce this on Windows after restarting Codex Desktop.

Environment:

• Platform: Windows x64
• Codex Desktop package observed locally: OpenAI.Codex_26.429.2026.0_x64__2p2nqsd0c76g0
• Browser Use plugin: openai-bundled/browser-use/0.1.0-alpha1
• Backend requested: iab

What happened:

1. The in-app browser was open and could manually load an external page.
2. Before restart, Browser Use could not run because the Node REPL js entrypoint was not actually usable (unsupported call: mcp__node_repl__js).
3. After restarting Codex Desktop, the Node REPL js tool became available, but Browser Use still failed during setupAtlasRuntime({ globals: globalThis, backend: "iab" }).

Actual error after restart:

Failed to connect to browser-use backend "iab". No Codex IAB backends were discovered. Discovery diagnostics: listedPipes=2, candidates=4, browsers=0, iabBrowsers=0, failures=["discovered/timeout","discovered/timeout","legacy-iab/timeout","legacy-chrome/timeout"], pipeListingError=none.

Expected:
Browser Use should discover the currently open Codex in-app browser backend and allow selecting/screenshotting the current tab.

Notes:

• This does not appear to be a website-specific problem; the page was already open manually in the in-app browser.
• The failure happens before tab selection or screenshot.

I can reproduce the "no node_repl/js tool exposed" variant on macOS.

Environment:

• Platform: Darwin 25.3.0 arm64 arm
• Codex CLI: codex-cli 0.128.0
• ~/.codex/version.json: latest_version 0.128.0
• Browser Use plugin: openai-bundled/browser-use/0.1.0-alpha1

Observed:

• ~/.codex/config.toml has [plugins."browser-use@openai-bundled"] enabled = true
• The Browser Use skill requires mcp__node_repl__js
• Tool discovery for node_repl js, mcp__node_repl__js, js, and js_reset did not expose a Node REPL execution tool
• codex mcp list does not show a node_repl server
• codex mcp get node_repl returns:

Error: No MCP server named 'node_repl' found.

Additional note:
The installed Browser Use plugin bundle has no .mcp.json, so enabling Browser Use does not appear to start/provide the Node REPL MCP server itself. It seems to rely on a platform-provided Node REPL tool, but that tool is not available in this session.

when fixed?

I reproduced the Browser Use side of this on Codex Desktop macOS with openai-bundled/browser-use/0.1.0-alpha1.

The Browser Use bootstrap attempted:

setupAtlasRuntime({ globals: globalThis, backend: "iab" })

It failed before navigation with:

Failed to connect to browser-use backend "iab". No Codex IAB backends were discovered.

In the same run, falling back to plain Playwright could open the local app at http://127.0.0.1:5123/, so the local server/page itself was reachable. This looks like IAB backend discovery/registration rather than a local app or network problem.

I can still reproduce this on macOS after reinstalling the Browser Use plugin and restarting Codex Desktop.

Environment:

• Codex Desktop on macOS
• Browser Use plugin: openai-bundled/browser-use/0.1.0-alpha1
• Backend requested: iab
• Local app manually open in the Codex in-app browser: http://localhost:8080/#/

Observed sequence:

1. Before restarting, Browser Use could not run because the Node REPL execution tools were not exposed in the current request:

• mcp__node_repl__js unavailable
• mcp__node_repl__js_reset unavailable

1. After restarting Codex, tool discovery exposed Node REPL again:

• mcp__node_repl__.js
• mcp__node_repl__.js_reset

1. After resetting the JS kernel and running the normal Browser Use bootstrap, IAB discovery still failed before tab selection/navigation.

Bootstrap attempted:

const { setupAtlasRuntime } = await import('/Users/ylp/.codex/plugins/cache/openai-bundled/browser-use/0.1.0-alpha1/scripts/browser-client.mjs');
const backend = 'iab';
await setupAtlasRuntime({ globals: globalThis, backend });

Actual error:

Failed to connect to browser-use backend "iab". No Codex IAB backends were discovered. Discovery diagnostics: listedPipes=4, candidates=6, browsers=0, iabBrowsers=0, failures=["discovered/timeout","discovered/timeout","discovered/timeout","discovered/timeout","legacy-iab/timeout","legacy-chrome/timeout"], pipeListingError=none.

Notes:

• The in-app browser itself was visible and could manually load the local app.
• The failure happens during IAB backend discovery, before agent.browser.tabs.selected() can read the current tab.
• As a workaround, chrome_devtools could open and inspect http://localhost:8080/#/device-group, so the local frontend server and page were reachable. This looks specific to Codex IAB backend discovery/registration rather than the target URL.

Hi,
Any update here? I am also facing the same issue.

browserAgentAvailable = inAppBrowserEnabled && statsigGate && browserUseFeatureEnabled && RUN_CODEX_IN_WSL !== true
These are the conditions specified in the source code. browseruse can only be used if all of them are satisfied.