refactor: move StreamableHTTPASGIApp to streamable_http_manager module

Move StreamableHTTPASGIApp from streamable_http.py to streamable_http_manager.py
since it directly depends on StreamableHTTPSessionManager.

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Author: maxisbey

src/mcp/server/lowlevel/server.py

@@ -97,8 +97,8 @@ async def main():
 from mcp.server.lowlevel.helper_types import ReadResourceContents
 from mcp.server.models import InitializationOptions
 from mcp.server.session import ServerSession
-from mcp.server.streamable_http import EventStore, StreamableHTTPASGIApp
-from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
+from mcp.server.streamable_http import EventStore
+from mcp.server.streamable_http_manager import StreamableHTTPASGIApp, StreamableHTTPSessionManager
 from mcp.server.transport_security import TransportSecuritySettings
 from mcp.shared.context import RequestContext
 from mcp.shared.exceptions import McpError, UrlElicitationRequiredError

src/mcp/server/streamable_http.py

@@ -14,10 +14,7 @@
 from contextlib import asynccontextmanager
 from dataclasses import dataclass
 from http import HTTPStatus
-from typing import TYPE_CHECKING, Any
-
-if TYPE_CHECKING:
-    from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
+from typing import Any
 
 import anyio
 from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
@@ -1057,13 +1054,3 @@ async def message_router():  # pragma: no cover
                 except Exception as e:  # pragma: no cover
                     # During cleanup, we catch all exceptions since streams might be in various states
                     logger.debug(f"Error closing streams: {e}")
-
-
-class StreamableHTTPASGIApp:
-    """ASGI application for Streamable HTTP server transport."""
-
-    def __init__(self, session_manager: "StreamableHTTPSessionManager"):
-        self.session_manager = session_manager
-
-    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:  # pragma: no cover
-        await self.session_manager.handle_request(scope, receive, send)

src/mcp/server/streamable_http_manager.py

@@ -292,3 +292,13 @@ async def run_server(*, task_status: TaskStatus[None] = anyio.TASK_STATUS_IGNORE
                 media_type="application/json",
             )
             await response(scope, receive, send)
+
+
+class StreamableHTTPASGIApp:
+    """ASGI application for Streamable HTTP server transport."""
+
+    def __init__(self, session_manager: StreamableHTTPSessionManager):
+        self.session_manager = session_manager
+
+    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:  # pragma: no cover
+        await self.session_manager.handle_request(scope, receive, send)