resolve ruff failures

Author: sreenithi

docs/migration.md

@@ -556,7 +556,7 @@ The session hierarchy now uses a new **runtime-checkable Protocol** called `Abst
 
 Key characteristics of `AbstractBaseSession`:
 1.  **Pure Interface**: It is a structural protocol with no implementation state or `__init__` method.
-2.  **Simplified Type Parameters**: It takes two parameters: `AbstractBaseSession[SendRequestT, SendNotificationT]`. Contravariant variance is used for these parameters to ensure that sessions can be used safely in generic contexts (like `RequestContext`).
+2.  **Simplified Type Parameters**: It takes two parameters: `AbstractBaseSession[SendRequestT_contra, SendNotificationT_contra]`. Contravariant variance is used for these parameters to ensure that sessions can be used safely in generic contexts (like `RequestContext`).
 3.  **BaseSession Implementation**: The concrete implementation logic (state management, response routing) is provided by the `BaseSession` class, which satisfies the protocol.
 
 **Before:**
@@ -580,9 +580,9 @@ class MySession(AbstractBaseSession[...]):
         self._my_state = {}
 ```
 
-#### `SendRequestT` changed to contravariant
+#### `SendRequestT` renamed to `SendRequestT_contra`
 
-The `SendRequestT` TypeVar is now defined as **contravariant** to support its use in the `AbstractBaseSession` Protocol.
+The `SendRequestT` TypeVar is now defined as **contravariant** to support its use in the `AbstractBaseSession` Protocol and renamed accordingly to follow naming conventions for contravariant type variables.
 
 **Before:**
 
@@ -593,12 +593,12 @@ SendRequestT = TypeVar("SendRequestT", ClientRequest, ServerRequest)
 **After:**
 
 ```python
-SendRequestT = TypeVar("SendRequestT", ClientRequest, ServerRequest, contravariant=True)
+SendRequestT_contra = TypeVar("SendRequestT_contra", ClientRequest, ServerRequest, contravariant=True)
 ```
 
-#### `SendNotificationT` changed to contravariant
+#### `SendNotificationT` renamed to `SendNotificationT_contra`
 
-The `SendNotificationT` TypeVar is now defined as **contravariant** to support its use in the `AbstractBaseSession` Protocol.
+The `SendNotificationT` TypeVar is now defined as **contravariant** to support its use in the `AbstractBaseSession` Protocol and renamed accordingly to follow naming conventions for contravariant type variables.
 
 **Before:**
 
@@ -609,14 +609,14 @@ SendNotificationT = TypeVar("SendNotificationT", ClientNotification, ServerNotif
 **After:**
 
 ```python
-SendNotificationT = TypeVar(
-    "SendNotificationT", ClientNotification, ServerNotification, contravariant=True
+SendNotificationT_contra = TypeVar(
+    "SendNotificationT_contra", ClientNotification, ServerNotification, contravariant=True
 )
 ```
 
-#### `ReceiveResultT` changed to covariant
+#### `ReceiveResultT` renamed to `ReceiveResultT_co`
 
-The `ReceiveResultT` TypeVar is now defined as **covariant** to support its use in the `AbstractBaseSession` Protocol.
+The `ReceiveResultT` TypeVar is now defined as **covariant** to support its use in the `AbstractBaseSession` Protocol and renamed accordingly to follow naming conventions for covariant type variables.
 
 **Before:**
 
@@ -627,7 +627,7 @@ ReceiveResultT = TypeVar("ReceiveResultT", bound=BaseModel)
 **After:**
 
 ```python
-ReceiveResultT = TypeVar("ReceiveResultT", bound=BaseModel, covariant=True)
+ReceiveResultT_co = TypeVar("ReceiveResultT_co", bound=BaseModel, covariant=True)
 ```
 
 #### `BaseClientSession` is now a Protocol

src/mcp/shared/_context.py

@@ -1,17 +1,16 @@
 """Request context for MCP handlers."""
 
 from dataclasses import dataclass
-from typing import TYPE_CHECKING, Generic, Any
+from typing import TYPE_CHECKING, Any, Generic
+
 from typing_extensions import TypeVar
 
 if TYPE_CHECKING:
     from mcp.shared.session import AbstractBaseSession
 
 from mcp.types import RequestId, RequestParamsMeta
 
-SessionT_co = TypeVar(
-    "SessionT_co", bound="AbstractBaseSession[Any, Any]", covariant=True
-)
+SessionT_co = TypeVar("SessionT_co", bound="AbstractBaseSession[Any, Any]", covariant=True)
 
 
 @dataclass(kw_only=True)

src/mcp/shared/session.py

@@ -4,12 +4,11 @@
 from collections.abc import Callable
 from contextlib import AsyncExitStack
 from types import TracebackType
-from typing import Any, Generic, Protocol, TypeVar
+from typing import Any, Generic, Protocol, Self, TypeVar, runtime_checkable
 
 import anyio
 from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
 from pydantic import BaseModel, TypeAdapter
-from typing_extensions import Protocol, Self, runtime_checkable
 
 from mcp.shared.exceptions import MCPError
 from mcp.shared.message import MessageMetadata, ServerMessageMetadata, SessionMessage
@@ -35,13 +34,13 @@
     ServerResult,
 )
 
-SendRequestT = TypeVar("SendRequestT", ClientRequest, ServerRequest, contravariant=True)
+SendRequestT_contra = TypeVar("SendRequestT_contra", ClientRequest, ServerRequest, contravariant=True)
 SendResultT = TypeVar("SendResultT", ClientResult, ServerResult)
-SendNotificationT = TypeVar(
-    "SendNotificationT", ClientNotification, ServerNotification, contravariant=True
+SendNotificationT_contra = TypeVar(
+    "SendNotificationT_contra", ClientNotification, ServerNotification, contravariant=True
 )
 ReceiveRequestT = TypeVar("ReceiveRequestT", ClientRequest, ServerRequest)
-ReceiveResultT = TypeVar("ReceiveResultT", bound=BaseModel, covariant=True)
+ReceiveResultT_co = TypeVar("ReceiveResultT_co", bound=BaseModel, covariant=True)
 ReceiveNotificationT = TypeVar("ReceiveNotificationT", ClientNotification, ServerNotification)
 
 RequestId = str | int
@@ -76,7 +75,9 @@ def __init__(
         request_id: RequestId,
         request_meta: RequestParamsMeta | None,
         request: ReceiveRequestT,
-        session: BaseSession[SendRequestT, SendNotificationT, SendResultT, ReceiveRequestT, ReceiveNotificationT],
+        session: BaseSession[
+            SendRequestT_contra, SendNotificationT_contra, SendResultT, ReceiveRequestT, ReceiveNotificationT
+        ],
         on_complete: Callable[[RequestResponder[ReceiveRequestT, SendResultT]], Any],
         message_metadata: MessageMetadata = None,
     ) -> None:
@@ -160,8 +161,8 @@ def cancelled(self) -> bool:
 class AbstractBaseSession(
     Protocol,
     Generic[
-        SendRequestT,
-        SendNotificationT,
+        SendRequestT_contra,
+        SendNotificationT_contra,
     ],
 ):
     """Pure abstract interface for MCP sessions.
@@ -172,12 +173,12 @@ class AbstractBaseSession(
 
     async def send_request(
         self,
-        request: SendRequestT,
-        result_type: type[ReceiveResultT],
+        request: SendRequestT_contra,
+        result_type: type[ReceiveResultT_co],
         request_read_timeout_seconds: float | None = None,
         metadata: MessageMetadata = None,
         progress_callback: ProgressFnT | None = None,
-    ) -> ReceiveResultT:
+    ) -> ReceiveResultT_co:
         """Sends a request and wait for a response.
 
         Raises an MCPError if the response contains an error. If a request read timeout is provided, it will take
@@ -189,7 +190,7 @@ async def send_request(
 
     async def send_notification(
         self,
-        notification: SendNotificationT,
+        notification: SendNotificationT_contra,
         related_request_id: RequestId | None = None,
     ) -> None:
         """Emits a notification, which is a one-way message that does not expect a response."""
@@ -208,12 +209,12 @@ async def send_progress_notification(
 
 class BaseSession(
     AbstractBaseSession[
-        SendRequestT,
-        SendNotificationT,
+        SendRequestT_contra,
+        SendNotificationT_contra,
     ],
     Generic[
-        SendRequestT,
-        SendNotificationT,
+        SendRequestT_contra,
+        SendNotificationT_contra,
         SendResultT,
         ReceiveRequestT,
         ReceiveNotificationT,
@@ -287,12 +288,12 @@ async def __aexit__(
 
     async def send_request(
         self,
-        request: SendRequestT,
-        result_type: type[ReceiveResultT],
+        request: SendRequestT_contra,
+        result_type: type[ReceiveResultT_co],
         request_read_timeout_seconds: float | None = None,
         metadata: MessageMetadata = None,
         progress_callback: ProgressFnT | None = None,
-    ) -> ReceiveResultT:
+    ) -> ReceiveResultT_co:
         """Sends a request and wait for a response.
 
         Raises an MCPError if the response contains an error. If a request read timeout is provided, it will take
@@ -346,7 +347,7 @@ async def send_request(
 
     async def send_notification(
         self,
-        notification: SendNotificationT,
+        notification: SendNotificationT_contra,
         related_request_id: RequestId | None = None,
     ) -> None:
         """Emits a notification, which is a one-way message that does not expect a response."""