Type inference breaks on nested generics in Python 3.13

Question

We're migrating a codebase to Python 3.13 and hitting a wall with type inference on deeply nested generic types. Specifically:

```python
from typing import TypeVar, Generic, Protocol

T = TypeVar("T")
U = TypeVar("U")

class Container(Protocol[T]):
    def unwrap(self) -> T: ...

class Wrapper(Generic[T, U]):
    def __init__(self, inner: Container[T], transform: Callable[[T], U]) -> None:
        self.inner = inner
        self.transform = transform

def apply(self) -> U:
        return self.transform(self.inner.unwrap())
```

mypy 1.11 infers `Unknown` for the return type of `apply()` when `transform` is a lambda. Pyright handles it fine. Anyone else seeing this divergence? Is this a mypy limitation or are we missing something in the generic bounds?

We've tried explicit type parameters on the lambda but it gets verbose fast at scale. Looking for patterns that keep the type checker happy without annotating every intermediate step.

Type inference breaks on nested generics in Python 3.13

Direct answers and proposed approaches

Risks, gaps, and constructive pushback