[macOS][Chrome extension] Chrome Dev is not detected and native host is registered only for stable Chrome

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

ChatGPT desktop 26.818.21641 (build 6849), bundled Chrome plugin 26.818.21641

What subscription do you have?

Not relevant to this local browser-discovery issue.

What platform is your computer?

macOS 26.5.2 (25F84), arm64

What issue are you seeing?

The ChatGPT/Codex Chrome integration on macOS does not detect Google Chrome Dev.

The ChatGPT Chrome extension is installed and enabled in Chrome Dev's active Default profile, but Settings → Computer Use reports that the browser extension is not installed, and the browser runtime returns:

Browser is not available: chrome

Environment:

• Google Chrome Dev 154.0.8013.2
• Chrome Dev bundle ID: com.google.Chrome.dev
• ChatGPT Chrome extension: 1.2.27268.51612_0
• Stable Google Chrome is not installed

Diagnostics:

• Running the bundled extension check against ~/Library/Application Support/Google/Chrome Dev reports installed: true and enabled: true for the Default profile.
• ~/Library/Application Support/Google/Chrome Dev/NativeMessagingHosts/ exists, but it does not contain com.openai.codexextension.json.
• A valid com.openai.codexextension.json is instead installed under the stable-Chrome support directory, even though stable Chrome is not installed.
• The bundled macOS browser diagnostics recognize only Google Chrome.app, bundle ID com.google.Chrome, and the stable Chrome user-data directory. They do not include Google Chrome Dev.app, com.google.Chrome.dev, or the Chrome Dev user-data directory.

This appears to be a channel-detection/native-host installation gap rather than a problem with the Web Store extension itself.

What steps can reproduce the bug?

1. Install Google Chrome Dev on macOS without installing stable Google Chrome.
2. Install and enable the ChatGPT Chrome extension in the Chrome Dev Default profile.
3. Install or enable the bundled Chrome plugin in the ChatGPT desktop app.
4. Restart Chrome Dev and ChatGPT, then open the extension side panel.
5. Open Settings → Computer Use or request a Chrome task from Codex.
6. Observe that the UI reports the extension as not installed and the Chrome backend is unavailable.

What is the expected behavior?

The integration should support official Chrome release channels on macOS, including Chrome Dev, by:

• detecting Google Chrome Dev.app / com.google.Chrome.dev;
• checking the Chrome Dev profile directory;
• installing the native messaging host manifest in the location used by Chrome Dev; and
• exposing the connected Chrome backend without requiring stable Chrome to be installed.

If Chrome Dev is intentionally unsupported, the installer and Computer Use UI should state that explicitly instead of reporting that the already-installed extension is missing.

Related but not duplicate: #26585 covers a Windows profile/status mismatch where a Chrome Dev extension backend is actually usable. In this macOS case, the backend is unavailable because the Dev-channel native-host registration is missing.

Additional information

No manual copying or modification of native-host manifests was attempted.

Start by locating the bundled macOS browser diagnostics and native-messaging installer, then compare their handling of Google Chrome.app, com.google.Chrome, and the stable user-data directory with the Chrome Dev values in the report. Reproduce with only Chrome Dev installed and verify that the extension is detected, com.openai.codexextension.json is placed under the Chrome Dev support directory, and Computer Use exposes the Chrome backend.