diff --git a/masque/utils/ports2data.py b/masque/utils/ports2data.py
index 889425e..c7f42e1 100644
--- a/masque/utils/ports2data.py
+++ b/masque/utils/ports2data.py
@@ -86,6 +86,8 @@ def data_to_ports(
     if visited is None:
         visited = set()
 
+    # Note: visited uses id(pattern) to detect cycles and avoid redundant processing.
+    # This may not catch identical patterns if they are loaded as separate object instances.
     if id(pattern) in visited:
         return pattern
     visited.add(id(pattern))