Yeah for the positive example, I described the syntax of a domain-specific-language, and the AI basically one-shotted the parsing rules, that only needed minor fixes.

For a counterexample, working on any part of a codebase that's 100% application specific business logic, with our custom abstractions, the AI is usually so lost that it's basically not even worth using it, as the chances of writing correct and usable code is next to zero.