Server fallback

Requests the policy routes to server run on your own OpenAI-compatible endpoint. Nothing ships with this demo, no shared key, ever. The key is stored only in this browser (localStorage on this origin) and is sent only to the endpoint you set here. localStorage is readable by any script on this origin, so treat this as a developer convenience, not end-user secret storage. The endpoint must allow browser CORS from this origin (direct browser call, no proxy). Saving takes effect on your next message, no reload.