This is true, but: it’s far easier to get there once you have gotten types in place in the first place—because that kind of domain modeling very often entails n

This is true, but: it’s far easier to get there once you have gotten types in place in the first place—because that kind of domain modeling very often entails non-trivial refactoring work. Our guidance to folks when I was at LinkedIn was that as much as PRs possible adding types should not change the runtime code at all, only describe what was already there (even if it was really dumb!). That meant TS conversions were never going to be at fault for prod issues, only for fixing prod issues; and it therefore also meant that those PRs were much less likely to get reverted… which is super important since a revert would then have knock-on effects on any other modules which relied on the types from the reverted PR.