Hey @Benjamin_Mossier, thanks for the detailed write-up. What you’re seeing is expected behavior on the Free Hobby plan, not something broken in your setup.
On the Free plan, the model picker is locked, and using your own API key BYOK with Agent and Chat is only available on a paid plan. Seeing Secret saved, having the toggle enabled, and having Claude Opus 5 and Sonnet 5 checked in Settings > Models doesn’t unlock it by itself. On the Free plan, requests to the agent using your own key are gated on the server regardless of those settings. That’s why the picker stays on Cursor Grok 4.6 Medium.
To use your Anthropic key with Claude models, you’ll need a paid plan Pro. After upgrading, the picker will unlock and you’ll be able to select your BYOK models.
If you upgrade to Pro and it still won’t switch, reply here with a screenshot of the picker and the Request ID (top right of the chat > Copy Request ID) and we’ll take a look.