chore: import upstream snapshot with attribution

examples/stories/starlette_mount/server.py

@@ -0,0 +1,47 @@
+"""Mount an MCPServer in an existing Starlette app at a sub-path, alongside non-MCP routes; exports `build_app()`."""
+
+import contextlib
+from collections.abc import AsyncIterator
+
+from starlette.applications import Starlette
+from starlette.requests import Request
+from starlette.responses import JSONResponse
+from starlette.routing import Mount, Route
+
+from mcp.server.mcpserver import MCPServer
+from stories._hosting import NO_DNS_REBIND, run_app_from_args
+
+
+def build_app() -> Starlette:
+    mcp = MCPServer("starlette-mount-example")
+
+    @mcp.tool()
+    def greet(name: str) -> str:
+        """Return a greeting."""
+        return f"Hello, {name}! (served from a Starlette sub-mount)"
+
+    # streamable_http_path="/" so Mount("/api", ...) serves the MCP endpoint at
+    # /api itself, not /api/mcp. The returned sub-app has its own lifespan, but
+    # Starlette does not run nested lifespans under Mount — the parent app below
+    # must enter mcp.session_manager.run() itself.
+    mcp_app = mcp.streamable_http_app(streamable_http_path="/", transport_security=NO_DNS_REBIND)
+
+    async def health(_request: Request) -> JSONResponse:
+        return JSONResponse({"status": "ok"})
+
+    @contextlib.asynccontextmanager
+    async def lifespan(_app: Starlette) -> AsyncIterator[None]:
+        async with mcp.session_manager.run():
+            yield
+
+    return Starlette(
+        routes=[
+            Route("/health", health),
+            Mount("/api", app=mcp_app),
+        ],
+        lifespan=lifespan,
+    )
+
+
+if __name__ == "__main__":
+    run_app_from_args(build_app)