Complete D&D NPC interaction integration

docs/integrations/dnd-npc-artifacts.md

@@ -5,6 +5,10 @@ the selectable production NPC pipeline. The normalized JSON payload can be
 passed explicitly to the spell extractor as an optional caster-name registry
 or to the combat extractor and normalizer as an actor registry. It
 remains a reference, not spell or combat evidence.
+The NPC interaction extractor and normalizer also consume this registry for
+canonical identity; registry source references remain provenance and never
+become interaction evidence. Their occurrence contract is defined in the
+[D&D NPC interaction artifact](dnd-npc-interaction-artifacts.md).
 
 ## Identity