I realized that the inheritance of TypedDict does not work as it should.

class BaseAnimal(TypedDict):
     name: str

class Animal(BaseAnimal, total=False):
     voice: str

class Cat(Animal):
     fur_color: str

I would assume that Cat should have required keys name and fur_color and optional voice.
But in reality, it will have required fur_color and optional name and voice, because Animal has total=False

Fixed

• __required_keys__ and __optional_keys__ are copied from base classes
• Own TypedDict annotations are added to __annotations__ after base annotations

https://bugs.python.org/issue39627