chore: import upstream snapshot with attribution

examples/stories/middleware/client.py

@@ -0,0 +1,27 @@
+"""Prove the middleware wrapped both `tools/list` and the in-flight `tools/call`."""
+
+from mcp.client import Client
+from stories._harness import Target, run_client
+
+
+async def main(target: Target, *, mode: str = "auto") -> None:
+    async with Client(target, mode=mode) as client:
+        listed = await client.list_tools()
+        assert [t.name for t in listed.tools] == ["audit_log"]
+
+        result = await client.call_tool("audit_log", {})
+        assert not result.is_error
+        assert result.structured_content is not None, result
+
+        # Era-neutral: legacy adds initialize + notifications/initialized; modern HTTP
+        # adds server/discover; modern in-memory adds nothing. Filter to the methods
+        # this client drove.
+        seen = [m for m in result.structured_content["result"] if m.startswith("tools/")]
+        # The tail ends at tools/call with no :done — the handler ran inside the
+        # middleware frame. Assert the tail (not the whole list) so a re-run against
+        # a long-lived server, whose log accumulates across clients, still passes.
+        assert seen[-3:] == ["tools/list", "tools/list:done", "tools/call"], seen
+
+
+if __name__ == "__main__":
+    run_client(main)