CodexAuthPlugin loads but OAuth login methods not presented in auth CLI #13231

Bug

opencode auth login → select OpenAI → goes straight to "Enter your API key" instead of showing the login method selector with OAuth options.

Environment

• opencode v1.1.56 (Homebrew, macOS arm64)
• Also reproduced on dev branch built from source

Investigation

1. The built-in CodexAuthPlugin from src/plugin/codex.ts does load (confirmed via debug logging in plugin/index.ts — prints auth.provider=openai)
2. The "(ChatGPT Plus/Pro or API key)" hint in the provider selector is hardcoded in src/cli/cmd/auth.ts line ~297 — not from the plugin
3. After selecting OpenAI, Plugin.list().findLast(x => x.auth?.provider === provider) at line ~310 should find the CodexAuthPlugin, but the code falls through to the plain "Enter your API key" prompt
4. The third-party opencode-openai-codex-auth npm plugin is explicitly blocked at plugin/index.ts line ~56

Expected

After selecting OpenAI, a "Login method" selector should appear with options:

• ChatGPT Pro/Plus (browser)
• ChatGPT Pro/Plus (headless)
• Manually enter API Key

(Same pattern as Anthropic's "Claude Pro/Max" login method selector)

Steps to Reproduce

1. opencode auth login
2. Select "OpenAI"
3. Observe: jumps straight to "Enter your API key" — no login method options

Notes

• Anthropic auth works correctly (shows Claude Max vs API Key selector) because it uses the opencode-anthropic-auth BUILTIN npm package
• The third-party plugin skip at line 56 means users can't work around this by installing the npm plugin