Windows: Chrome extension installed and native host registered, but extension backend is unavailable

Summary

On Windows, the Codex in-app browser works after enabling js_repl and --disable-sandbox, but the Chrome backend remains unavailable even though the Codex Chrome extension is installed, enabled, and the native host registry entry exists.

Expected behavior

agent.browsers.list() should include the Chrome extension backend, and agent.browsers.get("extension") should succeed.

Actual behavior

• In-app browser (iab) works
• agent.browsers.list() only returns the in-app browser
• agent.browsers.get("extension") fails with Browser is not available: extension

Reproduction

1. Install/enable the Codex Chrome Extension on Windows
2. Confirm native host manifest and registry are present
3. Start Codex Desktop and use the Browser/Chrome workflows
4. Observe that only iab is available in runtime

Environment

• Codex desktop release: 26.519.81530
• Windows Store build
• OS: Windows 10.0.26200
• Chrome runtime seen in logs: 148.0.7778.97

Verified local state

• Chrome extension installed and enabled
• Native host registry exists: HKCU\Software\Google\Chrome\NativeMessagingHosts\com.openai.codexextension
• Manifest exists: C:\Users\liuka\AppData\Local\OpenAI\extension\com.openai.codexextension.json
• Bundled marketplace contains chrome and logs show chrome_native_host_install_requested

Relevant observations from logs

• bundled_plugins_runtime_marketplace_written pluginNames=["browser","chrome","latex"]
• chrome_native_host_install_requested ... nativeHostName=com.openai.codexextension
• browser_use_availability_resolved available=true browserPane=true platform=Windows reason=available
• There are browser_use_iab_backend_startup_ready entries
• There are no corresponding extension/chrome backend startup ready entries

Workaround

• In-app browser works
• Chrome backend remains unavailable

Notes

This does not appear to be a simple extension install issue. The bridge files and registry are present, but the runtime still does not expose the extension backend.