This doesn't sound good to me, you end up with a large codebase that no human has actually laid eyes on. When you get a bug weird enough that you can't reason the LLM through it, then what? What if a bug is because of interactions between two systems, and you don't own one of them? What if there's an issue due to convoluted business process failures, that just end in a bug report like "my data is missing!"? I honestly think in the latter case, the LLM will just fix a 'bug' and miss the forest for the trees.

I prefer the idea of the other comment reply where you use AI as a tool to explore a codebase and assist you, not something you instruct to do the work. It can accelerate you building that experience and intuition at a level we've never been able to do before.