Is typing.Protocol the only way to concatenate the keyword-only arguments in ParamSpec?

[McDic]

Hello, I wrote a decorator code adds custom keyword-only argument on the function using typing.Protocol and generics.

import typing

P = typing.ParamSpec("P")
Ret = typing.TypeVar("Ret", covariant=True)  # Mypy complains this should be covariant


class CustomFunctionProtocol(typing.Protocol[P, Ret]):
    def __call__(
        self,
        *args: P.args,
        special_kwarg: str,
        **kwargs: P.kwargs,
    ) -> Ret: ...


def decorator(f: typing.Callable[P, Ret]) -> CustomFunctionProtocol[P, Ret]:

    def inner_func(*args: P.args, special_kwarg: str, **kwargs: P.kwargs) -> Ret:
        print("Special kwarg given: ", special_kwarg)
        return f(*args, **kwargs)

    return inner_func


@decorator
def example_function(a: int, b: int, c: int) -> int:
    return a + b + c


typing.reveal_type(example_function)

In this example code, decorator adds a keyword-only argument special_kwarg to a decorated function, type hint provided by CustomFunctionProtocol.

When I run mypy for this Python code, there is no error. I see reveal_type(example_function) is also working well.

Type of "example_function" is "CustomFunctionProtocol[(a: int, b: int, c: int), int]" [Pylance]

Revealed type is "typing_test_20241224.CustomFunctionProtocol[[a: builtins.int, b: builtins.int, c: builtins.int], builtins.int]" [Mypy]

However, running pyright will report an error regarding special_kwarg;

typing_test_20241224.py:11:9 - error: Keyword parameter "special_kwarg" cannot appear in signature after ParamSpec args parameter (reportGeneralTypeIssues)
typing_test_20241224.py:18:35 - error: Keyword parameter "special_kwarg" cannot appear in signature after ParamSpec args parameter (reportGeneralTypeIssues)
typing_test_20241224.py:30:20 - information: Type of "example_function" is "CustomFunctionProtocol[(a: int, b: int, c: int), int]"

When I try to use that function on code, VSCode intellisense does not reflect the ParamSpec variable properly, it shows example_function(*args, special_kwarg: str, **kwargs) instead. I installed Mypy type checker, Pylance and Python extensions.

Perhaps showing correct intellisense for generic Protocol's __call__ is not implemented yet. I do not know where to ask or complain this, neither I know how to make this intellisense do the correct behavior, so I am seeking if there is any other way to give a type hint for "kwargs" version of typing.Concatenate.