Comment by szhu

I think that's actually just an example of either ask culture or guess culture, depending on the context.

If the friend should only say yes if they really want to, then that's ask culture.

If the friend should feel obligated to say yes, then that's guess culture.

The only difference here is that the request is worded differently (as a statement rather than as a question), which is simply close friends adopting their own language conventions, a slightly-related but independent concept.