macOS 27 (26A428): Chrome extension installed but desktop app reports it missing; native messaging manifest absent

Problem

The ChatGPT Chrome extension is installed from the Chrome Web Store, but it cannot connect to the desktop app. Its side panel says “Install the app to use ChatGPT in Chrome.” Clicking “open the app” launches ChatGPT but does not change the connection status.

The desktop app's Computer use settings report “Browser extension not installed” for Google Chrome. On the Chrome settings detail page, both “Reinstall extension” and “Remove extension” appear disabled while other permission controls remain available. The reason those buttons are disabled has not been established.

Environment

• macOS 27.0, build 26A428 (verified with sw_vers)
• Apple Silicon / arm64
• Desktop app: /Applications/ChatGPT.app
• App version 26.908.61612, bundle build 9218 (verified from Info.plist)
• Google Chrome 152.0.7977.83
• Chrome extension installed from the Chrome Web Store; exact extension version not captured

Verified diagnostics

• Chrome is running.
• Browser connection attempts return Browser is not available: chrome; browser discovery exposes only the in-app browser.
• Expected user-level native messaging manifest is absent:
  ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.openai.codexextension.json
• A direct stat check reports No such file or directory.
• The user-level NativeMessagingHosts directory exists but is empty.
• The system-level directory /Library/Google/Chrome/NativeMessagingHosts contains only com.apple.passwordmanager.json.
• The bundled extension-enabled diagnostic could not read Chrome's Local State file because it received EPERM. This limits that diagnostic; it does not establish that the extension is disabled.
• User-provided screenshots show the extension's Chrome settings page, its “Install the app” side panel, and the contradictory desktop-app installation status. Screenshots are not attached to this report.

Troubleshooting already attempted

• Reinstalled the Chrome extension from the Chrome Web Store.
• Fully quit ChatGPT with Cmd-Q and reopened it after reinstalling.
• Clicked the extension's “open the app” link: ChatGPT opens but the extension status remains unchanged.
• Rechecked native messaging registration and browser discovery; still unavailable.

No native-host registration was manually created, no browser profile data was edited, and no security protections were disabled.

Expected behavior

The desktop app should recognize the installed extension and complete native messaging registration, or display an actionable error explaining why setup failed. If extension installation/reinstallation controls are disabled, the UI should explain why and provide a supported recovery path.

Related reports

• https://github.com/openai/codex/issues/31904 — same misleading “Install the app” symptom on macOS 27, but that report has an existing manifest with a stale helper path. Here the manifest is absent.
• https://github.com/openai/codex/issues/33248 — missing native-host registration despite installed extension. Its stale-helper diagnosis has not been verified on this machine.

The user recently upgraded macOS. Causation by the OS upgrade is not established. Please advise on a supported repair for missing native messaging registration when the app's reinstall controls are disabled.

Start with the native messaging registration and browser discovery paths for /Applications/ChatGPT.app, using the absent ~/Library/Application Support/Google/Chrome/NativeMessagingHosts/com.openai.codexextension.json as the reproduction point. Compare the behavior with related issues 31904 and 33248; done means the installed extension is recognized or the app presents an actionable supported recovery error.