SSIA. Here's a repro:
$ nvim typed_dict_closed_inheritence.py
$ python3.13 -Im venv some-venv-py313
$ some-venv-py313/bin/pip install mypy==1.18.2 typing_extensions==4.15.0
$ some-venv-py313/bin/mypy typed_dict_closed_inheritence.py
typed_dict_closed_inheritence.py:6: error: Unexpected keyword argument "closed" for "__init_subclass__" of "TypedDict" [call-arg]
typed_dict_closed_inheritence.py:
import typing_extensions as _te
class TypedBase(_te.TypedDict):
...
class TypedChild(TypedBase, closed=True):
...
SSIA. Here's a repro:
typed_dict_closed_inheritence.py: