very naive. the runtime behavior of a rewrite should be significantly different in all kinds of unpredictable ways nobody see coming or might expect. It is a combination of language semantics, compiler behavior, operating system behavior, file system behavior, driver behavior, ..
yea, I found LLMs poor at reasoning through system-wide behaviors. Good luck to the vibers when they try to rootcause a rare data-corruption problem. They will hand it off to fable which will attempt trial-and-error bug fixes which will eventually muck up the code. What happens then ?