Drop AbstractAsyncContextManager for proper type hints (modelcontextprotocol#257)

Author: Kludex

src/mcp/shared/session.py

@@ -8,6 +8,7 @@
 import httpx
 from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
 from pydantic import BaseModel
+from typing_extensions import Self
 
 from mcp.shared.exceptions import McpError
 from mcp.types import (
@@ -60,7 +61,7 @@ def __init__(
  request_id: RequestId,
  request_meta: RequestParams.Meta | None,
  request: ReceiveRequestT,
- session: "BaseSession",
+ session: "BaseSession[SendRequestT, SendNotificationT, SendResultT, ReceiveRequestT, ReceiveNotificationT]",
  on_complete: Callable[["RequestResponder[ReceiveRequestT, SendResultT]"], Any],
  ) -> None:
  self.request_id = request_id
@@ -134,7 +135,6 @@ def cancelled(self) -> bool:
 
 
 class BaseSession(
- AbstractAsyncContextManager,
  Generic[
  SendRequestT,
  SendNotificationT,
@@ -183,7 +183,7 @@ def __init__(
  ]()
  )
 
- async def __aenter__(self):
+ async def __aenter__(self) -> Self:
  self._task_group = anyio.create_task_group()
  await self._task_group.__aenter__()
  self._task_group.start_soon(self._receive_loop)