feat(mq_editor): sort partials by amplitude, keep% slider for reconstruction

- Sort extracted partials by decreasing peak amplitude
- Add Keep% range slider (1-100%) to toolbar
- Viewer draws omitted partials at 50% opacity (live on slider input)
- synthesizeMQ uses only the top-N% partials

handoff(Claude): partial amplitude filtering complete

2 files changed, 38 insertions, 3 deletions

diff --git a/tools/mq_editor/index.html b/tools/mq_editor/index.html
index 27eba2a..e8386c2 100644
--- a/tools/mq_editor/index.html
+++ b/tools/mq_editor/index.html
@@ -83,6 +83,10 @@
 
       <label>Threshold (dB):</label>
       <input type="number" id="threshold" value="-60" step="any">
+
+      <label style="margin-left:16px;">Keep:</label>
+      <input type="range" id="keepPct" min="1" max="100" value="100" style="width:100px; vertical-align:middle;">
+      <span id="keepPctLabel" style="margin-left:4px;">100%</span>
     </div>
   </div>
 
@@ -120,8 +124,17 @@
 
     const hopSize = document.getElementById('hopSize');
     const threshold = document.getElementById('threshold');
+    const keepPct = document.getElementById('keepPct');
+    const keepPctLabel = document.getElementById('keepPctLabel');
     const fftSize = 1024; // Fixed
 
+    keepPct.addEventListener('input', () => {
+      keepPctLabel.textContent = keepPct.value + '%';
+      if (viewer && extractedPartials) {
+        viewer.setKeepCount(Math.max(1, Math.ceil(extractedPartials.length * parseInt(keepPct.value) / 100)));
+      }
+    });
+
     // Initialize audio context
     function initAudioContext() {
       if (!audioContext) {
@@ -190,10 +203,18 @@
 
           const result = extractPartials(params, stftCache);
 
+          // Sort by decreasing peak amplitude
+          result.partials.sort((a, b) => {
+            const peakA = a.amps.reduce((m, v) => Math.max(m, v), 0);
+            const peakB = b.amps.reduce((m, v) => Math.max(m, v), 0);
+            return peakB - peakA;
+          });
+
           extractedPartials = result.partials;
           viewer.setFrames(result.frames);
           setStatus(`Extracted ${result.partials.length} partials`, 'info');
           viewer.setPartials(result.partials);
+          viewer.setKeepCount(Math.max(1, Math.ceil(result.partials.length * parseInt(keepPct.value) / 100)));
 
         } catch (err) {
           setStatus('Extraction error: ' + err.message, 'error');
@@ -286,10 +307,13 @@
 
       setStatus('Synthesizing...', 'info');
 
-      // Synthesize PCM from partials
+      // Synthesize PCM from top-N% partials by amplitude
       const sampleRate = audioBuffer.sampleRate;
       const duration = audioBuffer.duration;
-      const pcm = synthesizeMQ(extractedPartials, sampleRate, duration);
+      const keepCount = Math.max(1, Math.ceil(extractedPartials.length * parseInt(keepPct.value) / 100));
+      const partialsToUse = extractedPartials.slice(0, keepCount);
+      setStatus(`Synthesizing ${keepCount}/${extractedPartials.length} partials (${keepPct.value}%)...`, 'info');
+      const pcm = synthesizeMQ(partialsToUse, sampleRate, duration);
 
       // Create audio buffer
       const synthBuffer = audioContext.createBuffer(1, pcm.length, sampleRate);
@@ -311,7 +335,7 @@
 
       playBtn.disabled = true;
       stopBtn.disabled = false;
-      setStatus('Playing synthesized...', 'info');
+      setStatus(`Playing synthesized (${keepCount}/${extractedPartials.length} partials, ${keepPct.value}%)...`, 'info');
 
       // Animate playhead
       function updatePlayhead() {
diff --git a/tools/mq_editor/viewer.js b/tools/mq_editor/viewer.js
index 5065498..e8780e7 100644
--- a/tools/mq_editor/viewer.js
+++ b/tools/mq_editor/viewer.js
@@ -30,6 +30,9 @@ class SpectrogramViewer {
     // Tooltip
     this.tooltip = document.getElementById('tooltip');
 
+    // Partial keep count (Infinity = all kept)
+    this.keepCount = Infinity;
+
     // Playhead
     this.playheadTime = -1; // -1 = not playing
 
@@ -59,6 +62,11 @@ class SpectrogramViewer {
     this.render();
   }
 
+  setKeepCount(n) {
+    this.keepCount = n;
+    this.render();
+  }
+
   setFrames(frames) {
     this.frames = frames;
   }
@@ -216,6 +224,7 @@ class SpectrogramViewer {
     for (let p = 0; p < partials.length; ++p) {
       const partial = partials[p];
       const color = colors[p % colors.length];
+      ctx.globalAlpha = p < this.keepCount ? 1.0 : 0.5;
 
       // Draw raw trajectory
       ctx.strokeStyle = color + '44';
@@ -281,6 +290,8 @@ class SpectrogramViewer {
         this.drawControlPoint(curve.t3, curve.v3);
       }
     }
+
+    ctx.globalAlpha = 1.0;
   }
 
   // Render raw peaks from mq_extract (before partial tracking)