How does API builder work?

I love the Lightning studio experience so far, but don’t quite understand the API builder auto-start / enabled feature:

My development workflow is that I want to start an app from the shell (via VS Code, say, a FastAPI app), and then I want to submit requests to it from a remote endpoint. This works with the API Builder, except for one thing: The API seems to be active only when “Auto start” is enabled. When that’s enabled, Studio tries to start another instance of my app.

I would like to create an active / enabled API without auto-start. Is that possible?

Otherwise, I Autostart is very cool, in that it can automatically start the studio upon incoming calls.