Merge branch 'main' into ihrpr/memory-stream-item-type

Author: ihrpr

src/mcp/server/lowlevel/server.py

@@ -480,11 +480,11 @@ async def run(
         # but also make tracing exceptions much easier during testing and when using
         # in-process servers.
         raise_exceptions: bool = False,
-        # When True, the server runs in standalone mode for stateless deployments where
+        # When True, the server as stateless deployments where
         # clients can perform initialization with any node. The client must still follow
         # the initialization lifecycle, but can do so with any available node
         # rather than requiring initialization for each connection.
-        standalone_mode: bool = False,
+        stateless: bool = False,
     ):
         async with AsyncExitStack() as stack:
             lifespan_context = await stack.enter_async_context(self.lifespan(self))
@@ -493,7 +493,7 @@ async def run(
                     read_stream,
                     write_stream,
                     initialization_options,
-                    standalone_mode=standalone_mode,
+                    stateless=stateless,
                 )
             )
 

src/mcp/server/session.py

@@ -86,15 +86,17 @@ def __init__(
         read_stream: MemoryObjectReceiveStream[SessionMessage | Exception],
         write_stream: MemoryObjectSendStream[SessionMessage],
         init_options: InitializationOptions,
-        standalone_mode: bool = False,
+        stateless: bool = False,
     ) -> None:
         super().__init__(
             read_stream, write_stream, types.ClientRequest, types.ClientNotification
         )
-        if standalone_mode:
-            self._initialization_state = InitializationState.Initialized
-        else:
-            self._initialization_state = InitializationState.NotInitialized
+        self._initialization_state = (
+            InitializationState.Initialized
+            if stateless
+            else InitializationState.NotInitialized
+        )
+
         self._init_options = init_options
         self._incoming_message_stream_writer, self._incoming_message_stream_reader = (
             anyio.create_memory_object_stream[ServerRequestResponder](0)

src/mcp/server/streamable_http.py

@@ -520,7 +520,7 @@ async def sse_writer():
             )
             await response(scope, receive, send)
             if writer:
-                await writer.send(Exception(err))
+                await writer.send(err)
             return
 
     async def _handle_get_request(self, request: Request, send: Send) -> None:
@@ -551,11 +551,9 @@ async def _handle_get_request(self, request: Request, send: Send) -> None:
         if not await self._validate_session(request, send):
             return
         # Handle resumability: check for Last-Event-ID header
-        if self._event_store:
-            last_event_id = request.headers.get(LAST_EVENT_ID_HEADER)
-            if last_event_id:
-                await self._replay_events(last_event_id, request, send)
-                return
+        if last_event_id := request.headers.get(LAST_EVENT_ID_HEADER):
+            await self._replay_events(last_event_id, request, send)
+            return
 
         headers = {
             "Cache-Control": "no-cache, no-transform",