Wrap JSONRPC messages with SessionMessage for metadata support (#590)

src/mcp/server/lowlevel/server.py

@@ -84,6 +84,7 @@ from mcp.server.session import ServerSession
 from mcp.server.stdio import stdio_server as stdio_server
 from mcp.shared.context import RequestContext
 from mcp.shared.exceptions import McpError
+from mcp.shared.message import SessionMessage
 from mcp.shared.session import RequestResponder
 
 logger = logging.getLogger(__name__)
@@ -471,8 +472,8 @@ class Server(Generic[LifespanResultT]):
 
     async def run(
         self,
-        read_stream: MemoryObjectReceiveStream[types.JSONRPCMessage | Exception],
-        write_stream: MemoryObjectSendStream[types.JSONRPCMessage],
+        read_stream: MemoryObjectReceiveStream[SessionMessage | Exception],
+        write_stream: MemoryObjectSendStream[SessionMessage],
         initialization_options: InitializationOptions,
         # When False, exceptions are returned as messages to the client.
         # When True, exceptions are raised, which will cause the server to shut down