In a large codebase there will still be bugs in how these components interoperate with each other, bugs involving complex chaining of api logic or a temporal element. These are the kind of bugs fuzzers generally struggle at finding. I would be a little freaked out if LLMs started to get good at finding these. Everything I've seen so far seems similar to fuzzer finds.

I think there is already papers and presentations on integrating these kind of iterative code understanding/verificaiton loops in harnesses. There may be some advantages over fuzzing alone. But I think the cost-benefit analysis is a lot more mixed/complex than anthropic would like people to believe. Sure you need human engineers but it's not like insurmountably hard for a non-expert to figure out