VS Code Codex browser plugin installed, but no session-owned browser route is registered

Summary

In VS Code Codex on Windows, the Browser plugin appears installed and enabled, but no browser backend is exposed to the active Codex session. Browser discovery returns an empty list, and direct browser lookups fail.

The same machine has a working Codex Desktop session where the in-app browser works correctly, so this appears specific to the VS Code Codex session/browser route registration.

Environment

• OS: Windows
• Host: VS Code Codex extension
• Codex extension binary path observed:

c:\Users\Mikke\.vscode\extensions\openai.chatgpt-26.527.31454-win32-x64\bin\windows-x86_64\codex.exe

• Browser plugin enabled in C:\Users\Mikke\.codex\config.toml:

browser@openai-bundled

• Browser plugin versions present:
• 26.519.31651
• 26.527.31326
• Feature flags observed:
• browser_use = true
• browser_use_external = true
• in_app_browser = true

What works elsewhere

In Codex Desktop on the same machine, the in-app browser works:

• Browser surface: Codex In-app Browser
• Browser client type/id: iab
• Working plugin path:

C:\Users\Mikke\.codex\plugins\cache\openai-bundled\browser\26.527.31326\

• Browser client module:

C:\Users\Mikke\.codex\plugins\cache\openai-bundled\browser\26.527.31326\scripts\browser-client.mjs

• Smoke test passed there:
• Opened https://example.com/
• Read title: Example Domain
• Read URL: https://example.com/
• Inspected DOM/text content
• Found the "Learn more" link target

What fails in VS Code Codex

Using the Browser plugin bootstrap pattern in VS Code Codex:

const { setupBrowserRuntime } = await import('file:///C:/Users/Mikke/.codex/plugins/cache/openai-bundled/browser/26.527.31326/scripts/browser-client.mjs');
await setupBrowserRuntime({ globals: globalThis });
const browsers = await agent.browsers.list();

Observed result:

{
  "browsers": []
}

Trying direct browser IDs also fails:

agent.browsers.get('iab')       -> Browser is not available: iab
agent.browsers.get('chrome')    -> Browser is not available: chrome
agent.browsers.get('extension') -> Browser is not available: extension
agent.browsers.get('cdp')       -> Browser is not available: cdp

Using the newer browser plugin bundle gives this more specific error:

IAB_DISCOVERY no session-owned iab browser
No Codex browser route is available for browser session ...
reason: no-iab-backends

Expected behavior

Since the Browser plugin is installed/enabled and the same machine can run the Codex Desktop in-app browser, VS Code Codex should either:

1. register a session-owned iab browser route, or
2. expose a clear setup/error message explaining how to create/attach the browser route for the VS Code session.

Actual behavior

The VS Code Codex session has no registered browser backend. The plugin is present and loads, but agent.browsers.list() returns [].

Impact

This prevents Codex in VS Code from visually opening, testing, or screenshotting local web pages even though the Browser plugin appears enabled and available.