refactor: use FastMCP.http_app() for robust SSE and health check support

src/monarch_mcp_custom/server.py

@@ -13,7 +13,7 @@ from dotenv import load_dotenv
 from fastmcp import FastMCP
 from starlette.applications import Starlette
 from starlette.responses import JSONResponse
-from starlette.routing import Route
+from starlette.routing import Route, Mount
 from mcp.server.sse import SseServerTransport
 import uvicorn
 
@@ -179,28 +179,14 @@ async def health_check(request):
 
 def create_app():
     """Create the Starlette application with MCP at /mcp."""
-    # SSE Transport following the "newer http-streamable" convention:
+    mcp_app = mcp.http_app()
-    # Stream endpoint at /mcp, messages at /mcp/messages
-    sse = SseServerTransport("/mcp/messages")
-
-    async def handle_sse(scope, receive, send):
-        async with sse.connect_sse(scope, receive, send) as (
-            read_stream,
-            write_stream,
-        ):
-            await mcp._mcp_server.run(
-                read_stream,
-                write_stream,
-                mcp._mcp_server.create_initialization_options(),
-            )
 
     routes = [
         Route("/health", health_check, methods=["GET"]),
-        Route("/mcp", endpoint=handle_sse),
+        Mount("/", app=mcp_app),
-        Route("/mcp/messages", endpoint=sse.handle_post_message, methods=["POST"]),
     ]
 
-    return Starlette(routes=routes, lifespan=mcp._lifespan)
+    return Starlette(routes=routes, lifespan=mcp_app.lifespan)
 
 
 app = create_app()