Construction

generator/acoustic.py

@@ -162,12 +162,12 @@ def validate_comping(document: dict) -> None:
       raise ValueError('acoustic comping requires quarter/eighth notes or authored sustains')
     events.append((start, end))
   events.sort()
-  # Distinct lanes can overlap. The physical validator still checks sounding
-  # strings and grip span, including staggered releases after voice merging.
+  # A combined attack is one interval with both lanes. Separate attacks must
+  # be sequential, including bass/upper alternation and cross-bar ties.
   for i, a in enumerate(events):
     for b in events[i + 1:]:
-      if a[1] > b[0] and groups[a] & groups[b]:
-        raise ValueError('acoustic attacks overlap within the same lane')
+      if a[1] > b[0]:
+        raise ValueError('acoustic sound must release before the next attack')
   spans = []
   for span in generator.harmonic_time.read(document['staves'][0]):
     if spans and generator.accompaniment.same_chord(spans[-1].chord, span.chord):