fix: Bug 2 mastering — chainSignature order-sensitive (reorder rebuild graph); applyMasteringSettings sig gom chain; limiter/compressor default neutral (limThreshold 0, compThreshold 0 ratio 1) — them module khong tu cat volume (T2)

app/static/js/app.jsx

@@ -639,7 +639,7 @@ function applyMasteringSettings(s) {
   // Re-applying identical values in rapid bursts is "fast parameter automation"
   // and makes Chromium flag the biquad EQ filters as unstable ("state is bad").
   // Only touch the graph when a value actually changed.
-  const sig = [s.masterConnected, s.isBypassed, s.eqActive, s.eqLowGain, s.eqMid1Gain, s.eqMid2Gain, s.eqHighGain, s.imagerActive, s.w1, s.w2, s.w3, s.w4, s.maximizerActive, s.maxGain, s.maxSoftClip, s.maxUpward, s.ceiling, s.compActive, s.compThreshold, s.compRatio, s.compMakeup, s.limActive, s.limThreshold, s.excActive, s.excDrive, s.rebalActive, s.rebalMid, s.rebalSide].join('|');
+  const sig = [s.masterConnected, s.isBypassed, s.eqActive, s.eqLowGain, s.eqMid1Gain, s.eqMid2Gain, s.eqHighGain, s.imagerActive, s.w1, s.w2, s.w3, s.w4, s.maximizerActive, s.maxGain, s.maxSoftClip, s.maxUpward, s.ceiling, s.compActive, s.compThreshold, s.compRatio, s.compMakeup, s.limActive, s.limThreshold, s.excActive, s.excDrive, s.rebalActive, s.rebalMid, s.rebalSide, chainSignature(s.chain)].join('|');
   if (sig === _lastMasteringSig) return;
   _lastMasteringSig = sig;
 
@@ -1093,7 +1093,8 @@ const DEFAULT_MASTER_CHAIN = [
 ];
 
 function chainSignature(chainArray) {
-  return (chainArray || []).map(m => (m.type || '') + (m.active ? '1' : '0')).join(',');
+  // Order-sensitive: reorder phai lam doi signature -> rebuild graph dung thu tu.
+  return (chainArray || []).map((m, i) => i + ':' + (m.type || '') + (m.active ? '1' : '0')).join(',');
 }
 
 // ── Track FX module factory (mastering_expand.md §II.4) ──
@@ -6446,8 +6447,8 @@ const ProfileModal = ({
                 ceiling: -0.1,
                 isBypassed: false,
                 chain: DEFAULT_MASTER_CHAIN.map(m => ({ ...m })),
-                compActive: false, compThreshold: -16, compRatio: 3, compMakeup: 0,
-                limActive: false, limThreshold: -1.0,
+                compActive: false, compThreshold: 0, compRatio: 1, compMakeup: 0, // neutral-then-apply: them module khong tu cat volume
+                limActive: false, limThreshold: 0, // neutral: limiter khong tu clip -1dB khi bat
                 excActive: false, excDrive: 40,
                 rebalActive: false, rebalMid: 0, rebalSide: 0,
               });