[Hammershaft]

As opposed to decades of companies and governments arguing in court what constitutes a monopoly? I mean, composability would just be the intended net result, not a part of the legal framework of the mandate.

I think you could also avoid using the word API entirely. I could see the end result being similiar to how default app selection works in Android.

That said, I still haven't sat down and thought through the unintended side effects.