If I were to inject CoroutineScope everywhere, do you bother to make sure nobody calls cancel on you? Is there some base interface so I dont need to compose myself?

What is the reason to inject it everywhere? The most common use case is that the 'edges' of your program define their CoroutineScopes, based on their lifecycl, and everything 'down' from there is just plain suspend funs.

yes and the scope instancr can be either private withing that edge, or shared across layer i.e userScope tldr; even the first case, someone might call cancel, im trying to model it away, or ask if others not care