My main Zig project will need over 1,000 edits to get it up there :O I've already had Claude spec out the changes required. I'll just have it or Codex or whatever fork itself into one agent per file and bang on it (for the stuff I can't regex myself) ;)
But the IO thing is frankly a good idea. I/O dependency injection, when I've used it in the past, has made testing quite a bit simpler (such as routing any I/O stream into a string to assert on) and the code much easier to reason about. The extra argument is a bit annoying, but that's the price of purity and it's worth it.