refactor(examples): migrate all HTTP examples to streamable_http_app() (#2291)

examples/servers/simple-streamablehttp-stateless/README.md

@@ -7,7 +7,6 @@ A stateless MCP server example demonstrating the StreamableHttp transport withou
 - Uses the StreamableHTTP transport in stateless mode (mcp_session_id=None)
 - Each request creates a new ephemeral connection
 - No session state maintained between requests
-- Task lifecycle scoped to individual requests
 - Suitable for deployment in multi-node environments
 
 ## Usage

examples/servers/simple-streamablehttp-stateless/mcp_simple_streamablehttp_stateless/server.py

@@ -1,17 +1,11 @@
-import contextlib
 import logging
-from collections.abc import AsyncIterator
 
 import anyio
 import click
 import uvicorn
 from mcp import types
 from mcp.server import Server, ServerRequestContext
-from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
-from starlette.applications import Starlette
 from starlette.middleware.cors import CORSMiddleware
-from starlette.routing import Mount
-from starlette.types import Receive, Scope, Send
 
 logger = logging.getLogger(__name__)
 
@@ -104,39 +98,17 @@ def main(
         on_call_tool=handle_call_tool,
     )
 
-    # Create the session manager with true stateless mode
-    session_manager = StreamableHTTPSessionManager(
-        app=app,
-        event_store=None,
+    starlette_app = app.streamable_http_app(
+        stateless_http=True,
         json_response=json_response,
-        stateless=True,
-    )
-
-    async def handle_streamable_http(scope: Scope, receive: Receive, send: Send) -> None:
-        await session_manager.handle_request(scope, receive, send)
-
-    @contextlib.asynccontextmanager
-    async def lifespan(app: Starlette) -> AsyncIterator[None]:
-        """Context manager for session manager."""
-        async with session_manager.run():
-            logger.info("Application started with StreamableHTTP session manager!")
-            try:
-                yield
-            finally:
-                logger.info("Application shutting down...")
-
-    # Create an ASGI application using the transport
-    starlette_app = Starlette(
         debug=True,
-        routes=[Mount("/mcp", app=handle_streamable_http)],
-        lifespan=lifespan,
     )
 
     # Wrap ASGI application with CORS middleware to expose Mcp-Session-Id header
     # for browser-based clients (ensures 500 errors get proper CORS headers)
     starlette_app = CORSMiddleware(
         starlette_app,
-        allow_origins=["*"],  # Allow all origins - adjust as needed for production
+        allow_origins=["*"],  # Note: streamable_http_app() enforces localhost-only Origin by default
         allow_methods=["GET", "POST", "DELETE"],  # MCP streamable HTTP methods
         expose_headers=["Mcp-Session-Id"],
     )