The contract loop

The loop that runs this whole backend

Here's the idea the whole FastAPI stage is building toward: change a Pydantic model → /docs changes with it → both mobile clients follow the new contract. No separate documentation to update, no Postman collection to keep in sync — the model is the source of truth, and docs/API-CONTRACT.md is just the human-readable mirror of it.

You're about to make that loop happen with your own hands: add one rule to a real field, and watch the docs update live.