Looked into it a lot. There are deterministic refactoring tools for things like convert for into foreach, or create constructor based on list of fields, but they still don't cover a lot of use cases.

I tried using a refactoring tool for reordering function arguments. The problem is, clicking through various GUI to get your point across is again too distracting. And there are still too many details. You can't say something like "new argument should be zero for callers that ignore the return value". It's not deterministic, and each case is slightly different from others. But LLMs handle this surprisingly well, and the mistakes they make are easy to spot.

What I'm really hoping to do some day is a "formal mode" where the LLM would write a mini-program to mutate the abstract syntax tree based on a textual refactoring request, thus guaranteeing determinism. But that's a whole new dimension of work, and there are numerous easier use cases to tackle before that.