Yeah, this is something we tried!

And yea, from an IDE perspective, it seems like maybe a sensible default would be to run `mypy ${CURRENT_FILE}` on save or something -- I've tried this manually myself, and it's decent, but it's not good enough to use constantly. I don't remember specific issues since I haven't done this in a long time.

Pre-commits are painful (on purpose!), but preventing people from shipping seemed like the wrong call. So we ended up dropping them.

Running mypy as a pre-commit hook is a bad idea for many reasons, primarily being a relatively really heavy runtime cost, plus you're running it on the entire codebase since it's going to follow your imports.

Many people, including myself, also like making atomic commits that may not be fully typed yet. Conditioning people to skip the hook(s), doubly so during a gradual typing rollout, just conditions them to skip them always. Leave it in CI where it's checked at a point in time where it actually matters.