[JoeyJoJoJr]

I get the impression you either don’t have much experience with Typescript or haven’t fully grokked it’s workflow, and have prematurely made up your mind. Your autocomplete comment for instance shows you aren’t aware of the extent to which Typescript vastly improves autocomplete.

Regarding typing at the boundaries, this is precisely where typescript shines. The types exist whether they are documented explicitly in your code (in the form of interfaces, types, protocols, etc), or not. This is where the documentation aspect come in to play - it is far easier to read a type definition than having to chase up API documentation, mentally parse tests, or console logging out api responses, to understand your boundary. Your refactoring argument is a strawman, because you wouldn’t just go and refactor names of things at the boundaries of your code in typescript, or any other language, without understanding the API spec. What typescript gives you is precisely the ability to refactor at the boundary when the spec changes and be much more confident that your changes aren’t going to break a whole bunch of thing, especially when it comes to the “class of bugs” that literally every JavaScript developer has dealt with, whether you are aware of them or not.