test: cancel only the abandoned call so 3.11/3.14 trace the resumption test cleanly

Author: maxisbey

tests/interaction/transports/test_hosting_resume.py

@@ -346,10 +346,18 @@ async def collect(params: LoggingMessageNotificationParams) -> None:
                 anyio.create_task_group() as tg,
             ):
                 await first.initialize()
-                tg.start_soon(first.send_request, call, CallToolResult, None, capture)
+                # The call is abandoned via its own scope so the task group exits cleanly: cancelling
+                # the whole group propagates Cancelled through this frame, which 3.11's tracer mishandles.
+                call_scope = anyio.CancelScope()
+
+                async def issue_call() -> None:
+                    with call_scope:
+                        await first.send_request(call, CallToolResult, metadata=capture)
+
+                tg.start_soon(issue_call)
                 await first_seen.wait()
                 await token_seen.wait()
-                tg.cancel_scope.cancel()
+                call_scope.cancel()
             assert captured == snapshot(["3", "4"])
             assert received == snapshot(["first"])
             # The session id is only observable via the manager (the client transport does not expose it).
@@ -360,7 +368,7 @@ async def collect(params: LoggingMessageNotificationParams) -> None:
             await store.wait_until_stored(6)
             http.headers["mcp-session-id"] = session_id
             http.headers["mcp-protocol-version"] = LATEST_PROTOCOL_VERSION
-            async with (
+            async with (  # pragma: no branch
                 streamable_http_client(f"{BASE_URL}/mcp", http_client=http) as (r2, w2),
                 ClientSession(r2, w2, logging_callback=collect) as second,
             ):