fix: VCA zeroes on live CV connect + visual feedback for envelope control

VCA fix:
- connectWire now zeros VCA base gain immediately when CV is connected
  (previously only rebuildGraph did this, missing live-connect case)
- disconnectWire restores base gain from params when CV is removed

Visual modulation feedback:
- ModuleNode RAF loop now handles envelope sources (not just LFO)
- Reads actual Tone.js gain node value for real-time display
- VCA gain knob shows live envelope value during playback
- LFO visualization unchanged (simulated waveform as before)

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

src/components/ModuleNode.jsx

@@ -1,7 +1,7 @@
 import React, { useCallback, useState, useEffect, useRef } from 'react';
 import { getModuleDef } from '../engine/moduleRegistry.js';
 import { state, removeModule, updateModuleParam, isPortConnected, emit } from '../engine/state.js';
-import { updateParam } from '../engine/audioEngine.js';
+import { updateParam, getAudioNode } from '../engine/audioEngine.js';
 import Knob from './Knob.jsx';
 import ScopeDisplay from './ScopeDisplay.jsx';
 import KeyboardWidget from './KeyboardWidget.jsx';
@@ -60,7 +60,7 @@ export default function ModuleNode({ mod, zoom, onStartConnect, onPortPosition }
     }
   }
 
-  // ==================== Live LFO modulation visualization ====================
+  // ==================== Live modulation visualization (LFO + Envelope + any CV) ====================
   const [liveValues, setLiveValues] = useState({});
   const rafRef = useRef(null);
   const startTimeRef = useRef(performance.now() / 1000);
@@ -75,7 +75,6 @@ export default function ModuleNode({ mod, zoom, onStartConnect, onPortPosition }
     const tick = () => {
       frameCount++;
       rafRef.current = requestAnimationFrame(tick);
-      // Throttle to ~15fps (every 4th frame) to reduce main thread pressure
       if (frameCount % 4 !== 0) return;
 
       const t = performance.now() / 1000 - startTimeRef.current;
@@ -87,26 +86,34 @@ export default function ModuleNode({ mod, zoom, onStartConnect, onPortPosition }
         if (!paramName) continue;
 
         const srcMod = state.modules.find(m => m.id === conn.from.moduleId);
-        if (!srcMod || srcMod.type !== 'lfo') continue;
+        if (!srcMod) continue;
 
-        // Read LFO params from state
-        const lfoDef = getModuleDef('lfo');
-        const lfoP = { ...Object.fromEntries(Object.entries(lfoDef.params).map(([k, v]) => [k, v.default])), ...srcMod.params };
-        const freq = lfoP.frequency;
-        const amp = lfoP.amplitude;
-        const waveform = lfoP.waveform;
-        const phase = (t * freq) % 1;
-        const lfoVal = simulateLFO(waveform, phase) * amp;
+        if (srcMod.type === 'lfo') {
+          // LFO: simulate waveform for smooth visual
+          const lfoDef = getModuleDef('lfo');
+          const lfoP = { ...Object.fromEntries(Object.entries(lfoDef.params).map(([k, v]) => [k, v.default])), ...srcMod.params };
+          const freq = lfoP.frequency;
+          const amp = lfoP.amplitude;
+          const waveform = lfoP.waveform;
+          const phase = (t * freq) % 1;
+          const lfoVal = simulateLFO(waveform, phase) * amp;
 
-        // Compute modulated value (same scaling as audioEngine)
-        const baseValue = params[paramName];
-        let scale;
-        if (mod.type === 'oscillator' && paramName === 'frequency') scale = baseValue * 0.5;
-        else if (mod.type === 'filter' && paramName === 'frequency') scale = baseValue;
-        else if (mod.type === 'vca' && paramName === 'gain') scale = 1;
-        else scale = baseValue || 1;
+          const baseValue = params[paramName];
+          let scale;
+          if (mod.type === 'oscillator' && paramName === 'frequency') scale = baseValue * 0.5;
+          else if (mod.type === 'filter' && paramName === 'frequency') scale = baseValue;
+          else if (mod.type === 'vca' && paramName === 'gain') scale = 1;
+          else scale = baseValue || 1;
 
-        newValues[paramName] = baseValue + lfoVal * scale;
+          newValues[paramName] = baseValue + lfoVal * scale;
+        } else if (srcMod.type === 'envelope') {
+          // Envelope: read the actual audio node gain value for real-time display
+          const audioEntry = getAudioNode(mod.id);
+          if (audioEntry?.node?.gain) {
+            const currentGain = audioEntry.node.gain.value;
+            newValues[paramName] = currentGain;
+          }
+        }
       }
 
       setLiveValues(newValues);

src/engine/audioEngine.js

@@ -327,6 +327,11 @@ export function connectWire(conn) {
   } catch (e) {
     console.warn('connect error', e);
   }
+
+  // When CV is connected to VCA, zero the base gain so only envelope controls it
+  if (toMod?.type === 'vca' && conn.to.port === 'cv') {
+    toEntry.node.gain.value = 0;
+  }
 }
 
 export function disconnectWire(conn) {
@@ -345,6 +350,12 @@ export function disconnectWire(conn) {
   } catch (e) {
     // Tone.js may throw if not connected
   }
+
+  // When CV is disconnected from VCA, restore base gain from params
+  const toMod = state.modules.find(m => m.id === conn.to.moduleId);
+  if (toMod?.type === 'vca' && conn.to.port === 'cv') {
+    toEntry.node.gain.value = toMod.params?.gain ?? 0.8;
+  }
 }
 
 export function updateParam(moduleId, paramName, value) {