You're right that Callable[[P], int] is invalid, so a flat representation isn't currently ambiguous. But a flat representation would foist the responsibility for checking that to all users of `__args__`. If your code isn't ParamSpec aware, your failures will probably be less obvious or even silent.

The flat representation trades off a) implementation complexity with b) usability / aesthetics, c) future proof-ness. I'm not morally opposed to such a tradeoff / am happy to defer to people with more experience in making such tradeoffs.