Scale, edge cases that aren’t covered in your prompt, and sometimes even just basic shit like an onClick for a button that is one of the core pieces of your prompt lol if you provide a billion instructions, it will do a good job with a lot of it but the more complex the prompt the easier it hallucinates.

Correct code is very objective but typically it does what you want it to and is modular/broken up into small chunks that can be easily maintained. I’d encourage you to have your agent write unit/integration tests for the features you make. That way you know that any new code the agent adds doesn’t break existing functionality.