diff --git a/tests/plugins/test_disk_cleanup_plugin.py b/tests/plugins/test_disk_cleanup_plugin.py
index 38fffd5fbf9..52afddc9c46 100644
--- a/tests/plugins/test_disk_cleanup_plugin.py
+++ b/tests/plugins/test_disk_cleanup_plugin.py
@@ -352,13 +352,24 @@ class TestTrackForgetQuick:
         for d in ("logs", "memories", "sessions", "cron", "cache"):
             assert (_isolate_env / d).exists(), f"{d}/ should be preserved"
 
-    def test_quick_does_not_descend_into_protected_top_level_dirs(self, _isolate_env):
+    def test_quick_does_not_descend_into_protected_top_level_dirs(
+        self, _isolate_env, monkeypatch
+    ):
         dg = _load_lib()
         protected_empty = (
             _isolate_env / "hermes-agent" / "node_modules" / "pkg" / "empty"
         )
         protected_empty.mkdir(parents=True)
 
+        original_iterdir = Path.iterdir
+
+        def guarded_iterdir(path):
+            if path == _isolate_env / "hermes-agent":
+                raise AssertionError("quick() descended into protected hermes-agent/")
+            return original_iterdir(path)
+
+        monkeypatch.setattr(Path, "iterdir", guarded_iterdir)
+
         dg.quick()
 
         assert protected_empty.exists()