Bug: `Provide` fails to detect generator methods on callable instances

[enrico-stauss]

Description

The Provide class cannot properly detect when a callable instance's __call__ method is a generator function. This breaks the dependency injection with cleanup pattern when using stateful callable instances.

Reproduction

from typing import Generator, Any
from uuid import UUID, uuid4
from litestar.di import Provide

class SessionSchedulerFactory:
    """A callable factory that maintains state across calls."""
    def __init__(self):
        self._sessions: dict[UUID, object] = {}
    
    def __call__(self) -> Generator[object, Any, None]:
        """Generator method that should be detected by Provide."""
        try:
            yield uuid4()
        finally:
            pass

def session_scheduler_factory() -> Generator[object, Any, None]: 
    try:
        yield uuid4()
    finally:
        pass

# Function works correctly
Provide(session_scheduler_factory, sync_to_thread=False).has_sync_generator_dependency  # True

# Callable instance fails to be detected
Provide(SessionSchedulerFactory(), sync_to_thread=False).has_sync_generator_dependency  # False

Note: This example is simplified for reproducibility. The real use case involves maintaining a cache of sessions across multiple dependency injections, which requires instance state.

Root Cause

In Provide.__init__, isclass(instance) returns False for callable instances, so the code checks isgeneratorfunction(instance) instead of isgeneratorfunction(instance.__call__):

is_class_dependency = isclass(dependency)
self.has_sync_generator_dependency = isgeneratorfunction(
    dependency if not is_class_dependency else dependency.__call__
)

Proposed Fix

Check callable instances the same way as classes:

is_class_dependency = isclass(dependency)
is_callable_instance = not is_class_dependency and hasattr(dependency, '__call__')

check_target = dependency.__call__ if (is_class_dependency or is_callable_instance) else dependency
self.has_sync_generator_dependency = isgeneratorfunction(check_target)
self.has_async_generator_dependency = isasyncgenfunction(check_target)

Litestar Version

litestar==2.18.0

[provinzkraut]

The fix sounds reasonable, would you like to provide a PR?