Yeah, don‘t rely on the LLM finding all the issues. Complex code like Swift concurrency tooling is just riddled with issues. I usually need to increase to 100% line coverage and then let it loop on hanging tests until everything _seems_ to work.

(It’s been said that Swift concurrency is too hard for humans as well though)

I don't trust programmers to find all the issues either and in several shops I've been in "we should have tests" was a controversial argument.

A good software engineering system built around the top LLMs today is definitely competitive in quality to a mediocre software shop and 100x faster and 1000x cheaper.