PEP 695, which is implemented in the upcoming Python 3.12, adds a new syntax for defining generic classes:

class Sequence[T]:
     def __getitem__(self, idx: int) -> T: ...

I would like to document generic classes with e.g. .. class:: Sequence[T], but that doesn't render correctly (the class introduction doesn't appear):

Presumably the parser for the class directive needs to be taught to recognize this syntax. (Cross-ref: python/cpython#104642 (comment).)