What an LLM actually does

The finale: teaching PawWalk to understand English

You've built the whole backend: routes, validation, a database, auth, payments, tests. This last stage adds the piece your iOS app teased in Part I — the assistant that turns "walk my dog in Mission tomorrow at 3pm" into a real booking.

That means putting a large language model (LLM) inside the backend. Before we wire one in, you need an honest picture of what an LLM is — because its one surprising weakness shapes every design choice in this stage.