Fix looping on synth_bass and synth_lead

Both use pluck envelopes that decay to silence — removed from
LOOP_INSTRUMENTS. Audited all remaining loop instruments to confirm
only sustained envelopes (organ, pad, strings, bowed) are looped.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

generate.py

@@ -192,7 +192,7 @@ LOOP_INSTRUMENTS = {
     # Mellotron (tape playback, sustained)
     "mellotron", "mellotron_strings", "mellotron_flute", "mellotron_choir",
     # Sustained synths
-    "synth_pad", "synth_lead", "synth_bass", "acid_bass", "808_bass",
+    "synth_pad", "acid_bass", "808_bass",
     "choir", "vocal", "granular_pad", "granular_texture",
     "analog_pad", "drift_saw", "drift_square", "wavefold_warm",
     # Continuous

opxy-samples/pytheory/synth_bass.preset/patch.json

@@ -43,9 +43,9 @@
   "envelope": {
     "amp": {
       "attack": 0,
-      "decay": 2457,
-      "release": 14395,
-      "sustain": 32767
+      "decay": 20295,
+      "release": 16383,
+      "sustain": 14989
     },
     "filter": {
       "attack": 0,
@@ -90,8 +90,9 @@
       "hikey": 42,
       "lokey": 0,
       "loop.crossfade": 0,
+      "loop.enabled": false,
       "loop.end": 11189,
-      "loop.onrelease": true,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 36,
       "reverse": false,
@@ -104,8 +105,9 @@
       "hikey": 54,
       "lokey": 0,
       "loop.crossfade": 0,
+      "loop.enabled": false,
       "loop.end": 11189,
-      "loop.onrelease": true,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 48,
       "reverse": false,
@@ -118,8 +120,9 @@
       "hikey": 64,
       "lokey": 0,
       "loop.crossfade": 0,
+      "loop.enabled": false,
       "loop.end": 11187,
-      "loop.onrelease": true,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 60,
       "reverse": false,
@@ -132,8 +135,9 @@
       "hikey": 70,
       "lokey": 0,
       "loop.crossfade": 0,
+      "loop.enabled": false,
       "loop.end": 11179,
-      "loop.onrelease": true,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 69,
       "reverse": false,
@@ -146,8 +150,9 @@
       "hikey": 78,
       "lokey": 0,
       "loop.crossfade": 0,
+      "loop.enabled": false,
       "loop.end": 11224,
-      "loop.onrelease": true,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 72,
       "reverse": false,
@@ -160,8 +165,9 @@
       "hikey": 127,
       "lokey": 0,
       "loop.crossfade": 0,
+      "loop.enabled": false,
       "loop.end": 11207,
-      "loop.onrelease": true,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 84,
       "reverse": false,

opxy-samples/pytheory/synth_lead.preset/patch.json

@@ -43,9 +43,9 @@
   "envelope": {
     "amp": {
       "attack": 0,
-      "decay": 2457,
-      "release": 14395,
-      "sustain": 32767
+      "decay": 20295,
+      "release": 16383,
+      "sustain": 14989
     },
     "filter": {
       "attack": 0,
@@ -86,31 +86,33 @@
   "platform": "OP-XY",
   "regions": [
     {
-      "framecount": 43777,
+      "framecount": 43767,
       "hikey": 42,
       "lokey": 0,
       "loop.crossfade": 0,
-      "loop.end": 43777,
-      "loop.onrelease": true,
+      "loop.enabled": false,
+      "loop.end": 43767,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 36,
       "reverse": false,
       "sample": "c2.wav",
-      "sample.end": 43777,
+      "sample.end": 43767,
       "tune": 0
     },
     {
-      "framecount": 43955,
+      "framecount": 43959,
       "hikey": 54,
       "lokey": 0,
       "loop.crossfade": 0,
-      "loop.end": 43955,
-      "loop.onrelease": true,
+      "loop.enabled": false,
+      "loop.end": 43959,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 48,
       "reverse": false,
       "sample": "c3.wav",
-      "sample.end": 43955,
+      "sample.end": 43959,
       "tune": 0
     },
     {
@@ -118,8 +120,9 @@
       "hikey": 64,
       "lokey": 0,
       "loop.crossfade": 0,
+      "loop.enabled": false,
       "loop.end": 43835,
-      "loop.onrelease": true,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 60,
       "reverse": false,
@@ -132,8 +135,9 @@
       "hikey": 70,
       "lokey": 0,
       "loop.crossfade": 0,
+      "loop.enabled": false,
       "loop.end": 43889,
-      "loop.onrelease": true,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 69,
       "reverse": false,
@@ -142,17 +146,18 @@
       "tune": 0
     },
     {
-      "framecount": 43978,
+      "framecount": 43976,
       "hikey": 78,
       "lokey": 0,
       "loop.crossfade": 0,
-      "loop.end": 43978,
-      "loop.onrelease": true,
+      "loop.enabled": false,
+      "loop.end": 43976,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 72,
       "reverse": false,
       "sample": "c5.wav",
-      "sample.end": 43978,
+      "sample.end": 43976,
       "tune": 0
     },
     {
@@ -160,8 +165,9 @@
       "hikey": 127,
       "lokey": 0,
       "loop.crossfade": 0,
+      "loop.enabled": false,
       "loop.end": 43873,
-      "loop.onrelease": true,
+      "loop.onrelease": false,
       "loop.start": 0,
       "pitch.keycenter": 84,
       "reverse": false,