"""Excluding names from limited API can break existing code that use them with defined Py_LIMITED_API."""

How is that different? Right now, the code would break at compile time,
because the macros are accessing opaque type fields. Excluding them has
the same effect but is much cleaner.

My current first approach is conservative, because it only makes things
work that didn't work before.
Core that is clearly meant as macro is obviously not meant for the limited
API. And if it should be better included, I'm all open for it.

Right now I want to remove quickly the breakage that was a showstopper.
Maybe I misunderstood you and did exactly what you proposed?

Please let us start a discussion on python-dev. I think there is more to
do to make the limited API really usable in large projects.