AI coding tools are not reliable out of the box. Anyone who has used them on a real production project knows this. They work great on greenfield code. They fall apart on a codebase with history.
I learned this the hard way.
The Problem
We have a fintech project that has been running for nearly three years. Two React frontends, an admin panel and a client-facing app, sitting on top of a FastAPI backend with a complex relational database. Multiple tables, heavy joins, financial and personal user data that has to be handled carefully.
Adding new features should be simple. Most tasks are straightforward: new frontend page, new API route, new integration with an external financial data provider. But it was taking longer than it should. The database structure was only fully understood by one person. Every new query, every new table join, needed that person in the loop.
