enable http headers in sse in the context

src/mcp/server/lowlevel/server.py

@@ -525,7 +525,7 @@ async def _handle_message(
 
     async def _handle_request(
         self,
-        message: RequestResponder,
+        message: RequestResponder[types.ClientRequest, types.ServerResult],
         req: Any,
         session: ServerSession,
         lifespan_context: LifespanResultT,
@@ -546,6 +546,7 @@ async def _handle_request(
                         message.request_meta,
                         session,
                         lifespan_context,
+                        message.request.root.headers or {},
                     )
                 )
                 response = await handler(req)

src/mcp/server/sse.py

@@ -160,7 +160,8 @@ async def handle_post_message(
         logger.debug(f"Received JSON: {json}")
 
         try:
-            message = types.JSONRPCMessage.model_validate(json)
+            message_with_headers = {**json, "headers": dict(request.headers)}
+            message = types.JSONRPCMessage.model_validate(message_with_headers)
             logger.debug(f"Validated client message: {message}")
         except ValidationError as err:
             logger.error(f"Failed to parse message: {err}")

src/mcp/shared/context.py

@@ -1,4 +1,4 @@
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from typing import Generic, TypeVar
 
 from mcp.shared.session import BaseSession
@@ -14,3 +14,4 @@ class RequestContext(Generic[SessionT, LifespanContextT]):
     meta: RequestParams.Meta | None
     session: SessionT
     lifespan_context: LifespanContextT
+    headers: dict[str, str] = field(default_factory=dict)

src/mcp/types.py

@@ -74,6 +74,7 @@ class Request(BaseModel, Generic[RequestParamsT, MethodT]):
 
     method: MethodT
     params: RequestParamsT
+    headers: dict[str, str] | None = None
     model_config = ConfigDict(extra="allow")