I tried using AI to build an exam system. It worked… until it didn’t.

I didn’t start with the idea of building an exam platform. This actually came from a different problem. We were using AI to generate structured data for APIs, and everything looked fine at first. The responses were correct, nothing obviously wrong. But then things started breaking in production in very strange ways. One example was a value like 120.5 instead of 120.50 . Same number from a human point of view, but the downstream system rejected it because it expected an exact format. These were s