One reference draw per render in both views: a repeat iteration draws anew, a group option draws apart, and one fence refuses what a render's draws cannot answer for

graph.go

@@ -196,6 +196,9 @@ func checkRenders(s nodeScope) error {
 	if err := s(heldCheck); err != nil {
 		return err
 	}
+	if err := s((&drawCheck{}).check); err != nil {
+		return err
+	}
 	return s((&valueProof{}).checkDatatype)
 }