Part 2 was about the scaffold breaking in four different ways before it worked. This one is about the day the app actually started talking back and about three more bugs, quieter than the ones before. Postgres, and a client that shouldn’t be reborn every request Wiring up Postgres was the easy part: a table for exchanges (prompt, response, timestamp) and a DatabaseClient wrapping a SQLAlchemy connection. The first version created a new client and a new connection on every single request. It worked, but it’s the wrong shape: a real app should open one connection when it starts and reuse it, not pay connection overhead on every prompt. ...