Preserve request-stream ownership during server cleanup

docs/run/legacy-clients.md

@@ -66,6 +66,11 @@ On one worker that is invisible. On two, it is the whole problem: a request that
     events to a client reconnecting to the *same* session), not a session store. It never makes a
     session reachable from another process.
 
+!!! note "Request cleanup preserves newer streams"
+    Closing an HTTP request releases its own streams, including during cancellation.
+    If you reuse a JSON-RPC request ID after the previous request completes, cleanup from an
+    older connection does not close the newer request's streams. This does not reserve request IDs.
+
 ## Session lifetime and limits
 
 A legacy session does not live forever, and one process does not hold an unlimited number of

src/mcp/server/sse.py

@@ -192,7 +192,15 @@ async def sse_writer():
                     )
 
         try:
-            async with anyio.create_task_group() as tg:
+            async with (
+                read_stream_writer,
+                read_stream,
+                write_stream,
+                write_stream_reader,
+                sse_stream_writer,
+                sse_stream_reader,
+                anyio.create_task_group() as tg,
+            ):
 
                 async def response_wrapper(scope: Scope, receive: Receive, send: Send):
                     """The EventSourceResponse returning signals a client close / disconnect.