Fix #355: Fix type error with lifespan context (#368)

Co-authored-by: Marcelo Trylesinski <marcelotryle@gmail.com>

src/mcp/server/fastmcp/server.py

@@ -652,9 +652,9 @@ class Context(BaseModel, Generic[ServerSessionT, LifespanContextT]):
         Returns:
             The resource content as either text or bytes
         """
-        assert self._fastmcp is not None, (
-            "Context is not available outside of a request"
-        )
+        assert (
+            self._fastmcp is not None
+        ), "Context is not available outside of a request"
         return await self._fastmcp.read_resource(uri)
 
     async def log(

src/mcp/shared/context.py

@@ -7,7 +7,7 @@ from mcp.shared.session import BaseSession
 from mcp.types import RequestId, RequestParams
 
 SessionT = TypeVar("SessionT", bound=BaseSession[Any, Any, Any, Any, Any])
-LifespanContextT = TypeVar("LifespanContextT", default=None)
+LifespanContextT = TypeVar("LifespanContextT")
 
 
 @dataclass

src/mcp/shared/progress.py

@@ -5,7 +5,7 @@ from typing import Generic
 
 from pydantic import BaseModel
 
-from mcp.shared.context import RequestContext
+from mcp.shared.context import LifespanContextT, RequestContext
 from mcp.shared.session import (
     BaseSession,
     ReceiveNotificationT,
@@ -60,7 +60,8 @@ def progress(
             SendResultT,
             ReceiveRequestT,
             ReceiveNotificationT,
-        ]
+        ],
+        LifespanContextT,
     ],
     total: float | None = None,
 ) -> Generator[