I took a peek at the implementation - I think this only works for a case where the typing explicitly contains the string "Promise". For example, I don't think it would work if I use `SomeInterface["some_promise_key"]` or might incorrectly add an async if I use `Awaited<Promise<...>>`.

I think what you're trying to build might be best served by Typescript's VFS - https://www.npmjs.com/package/@typescript/vfs. You can load the local files into an in-memory type system, and quickly extract async/await hints that might be more useful for a typical TS developer. I think there's a lot of really interesting static analysis you could do to improve async/await safety, as it certainly leads to issues from time to time.

Is this a problem that people actually have?

I do not want to be mean but I think you'd be much better served with ESLint rules to yell at you when you don't await when you should or do when you shouldn't.

This should _not_ be an automatic operation since it can change behavior in ways that will be unclear to the developer (completely undoing any gain from them being added automatically).

Fun side project man!