fix: CC note detection with Y-aware stem matching

app/static/js/app.jsx

@@ -5381,6 +5381,30 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
   const rightClickDragRef = React.useRef({ active: false, startX: 0, startY: 0 });
   const swallowContextMenuRef = React.useRef(false);
 
+  const findCCNoteIndex = (b, mouseY, ccH) => {
+    const snapped = getSnapBeat(b, snapVal);
+    const hits = [];
+    notes.forEach((n, idx) => {
+      if (snapped >= n.start_beat && snapped <= n.start_beat + n.duration_beats) {
+        const nv = ccMode === 'pan' ? ((n.pan || 0) * 0.5 + 0.5) : (n.velocity !== undefined ? n.velocity : 0.8);
+        const stemTop = ccH - (nv * (ccH - 20) + 10);
+        hits.push({ idx, dist: Math.abs(stemTop - mouseY) });
+      }
+    });
+    if (hits.length > 0) {
+      hits.sort((a, b) => a.dist - b.dist);
+      return hits[0].idx;
+    }
+    let nearest = -1;
+    let minDist = Infinity;
+    notes.forEach((n, idx) => {
+      const center = n.start_beat + n.duration_beats / 2;
+      const d = Math.abs(center - snapped);
+      if (d < minDist) { minDist = d; nearest = idx; }
+    });
+    return nearest;
+  };
+
   const handleCCMouseDown = (e) => {
     const canvas = ccCanvasRef.current;
     if (!canvas) return;
@@ -5390,33 +5414,12 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
     const h = rect.height;
     const beat = x / pixelsPerBeat;
 
-    const snappedBeat = getSnapBeat(beat, snapVal);
-    let noteIdx = notes.findIndex(n => snappedBeat >= n.start_beat && snappedBeat <= n.start_beat + n.duration_beats);
-    if (noteIdx === -1) {
-      let minDistance = Infinity;
-      notes.forEach((n, idx) => {
-        const center = n.start_beat + n.duration_beats / 2;
-        const dist = Math.abs(center - snappedBeat);
-        if (dist < minDistance) {
-          minDistance = dist;
-          noteIdx = idx;
-        }
-      });
-    }
-
+    const noteIdx = findCCNoteIndex(beat, y, h);
     const val = Math.max(0, Math.min(1, (h - y) / h));
 
     if (e.ctrlKey) {
       if (selectedNoteIds.length > 0) {
-        let cursorNoteIdx = notes.findIndex(n => beat >= n.start_beat && beat <= n.start_beat + n.duration_beats);
-        if (cursorNoteIdx === -1) {
-          let minDist = Infinity;
-          notes.forEach((n, idx) => {
-            const center = n.start_beat + n.duration_beats / 2;
-            const dist = Math.abs(center - beat);
-            if (dist < minDist) { minDist = dist; cursorNoteIdx = idx; }
-          });
-        }
+        const cursorNoteIdx = findCCNoteIndex(beat, y, h);
         if (cursorNoteIdx !== -1 && selectedNoteIds.includes(notes[cursorNoteIdx] ? notes[cursorNoteIdx].id : -1)) {
           const currentNote = notes[cursorNoteIdx];
           const currentVal = ccMode === 'pan' ? ((currentNote.pan || 0) / 2.0 + 0.5) : (currentNote.velocity !== undefined ? currentNote.velocity : 0.8);
@@ -5464,15 +5467,7 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
     const painted = drag.lastPainted || [];
 
     if (drag.selectedMode && selectedNoteIds.length > 0) {
-      let cursorNoteIdx = notes.findIndex(n => beat >= n.start_beat && beat <= n.start_beat + n.duration_beats);
-      if (cursorNoteIdx === -1) {
-        let minDist = Infinity;
-        notes.forEach((n, idx) => {
-          const center = n.start_beat + n.duration_beats / 2;
-          const dist = Math.abs(center - beat);
-          if (dist < minDist) { minDist = dist; cursorNoteIdx = idx; }
-        });
-      }
+      const cursorNoteIdx = findCCNoteIndex(beat, y, h);
       if (cursorNoteIdx !== -1) {
         const cursorNote = notes[cursorNoteIdx];
         if (cursorNote && selectedNoteIds.includes(cursorNote.id) && !painted.includes(cursorNoteIdx)) {
@@ -5490,9 +5485,7 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
       return;
     }
 
-    const snappedBeat = getSnapBeat(beat, snapVal);
-    const candidateIdx = notes.findIndex(n => snappedBeat >= n.start_beat && snappedBeat <= n.start_beat + n.duration_beats);
-
+    const candidateIdx = findCCNoteIndex(beat, y, h);
     if (candidateIdx !== -1 && !painted.includes(candidateIdx)) {
       const currentVal = ccMode === 'pan' ? ((notes[candidateIdx].pan || 0) / 2.0 + 0.5) : (notes[candidateIdx].velocity !== undefined ? notes[candidateIdx].velocity : 0.8);
       if (Math.abs(currentVal - val) > 0.001) {
@@ -5503,25 +5496,6 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
         }));
       }
       drag.lastPainted = [...painted, candidateIdx];
-    } else if (candidateIdx === -1) {
-      let nearest = -1;
-      let minDist = Infinity;
-      notes.forEach((n, idx) => {
-        const center = n.start_beat + n.duration_beats / 2;
-        const d = Math.abs(center - snappedBeat);
-        if (d < minDist) { minDist = d; nearest = idx; }
-      });
-      if (nearest !== -1 && !painted.includes(nearest)) {
-        const currentVal = ccMode === 'pan' ? ((notes[nearest].pan || 0) / 2.0 + 0.5) : (notes[nearest].velocity !== undefined ? notes[nearest].velocity : 0.8);
-        if (Math.abs(currentVal - val) > 0.001) {
-          setNotes(prev => prev.map((n, i) => {
-            if (i !== nearest) return n;
-            if (ccMode === 'pan') return { ...n, pan: (val - 0.5) * 2.0 };
-            return { ...n, velocity: val };
-          }));
-        }
-        drag.lastPainted = [...painted, nearest];
-      }
     }
   };
 

wiki.md

@@ -210,3 +210,8 @@
 - **Tóm tắt thay đổi:** Thay `!visited.includes(snappedPitch)` bằng `snappedPitch !== lastDrawnPitch`. Bug cũ: khi vẽ C→D→C, visited.includes(C) = true → không tạo note mới → note D cũ bị extend. Fix: so sánh với pitch của note cuối cùng, cho phép vẽ tiếp khi pitch thay đổi dù đã visit trước đó. Bỏ `visitedPitches` (không còn dùng).
 - **Các file ảnh hưởng:** `app/static/js/app.jsx`
 - **Ghi chú/Test (nếu có):** `npm run build` pass.
+
+### [2026-07-26 10:58] Task: Fix CC note detection with Y-aware stem matching
+- **Tóm tắt thay đổi:** Thêm `findCCNoteIndex(beat, mouseY, ccH)` helper — tìm note trong CC lane dựa trên cả X (beat) và Y (vị trí stem top). Khi nhiều note cùng beat (chord), so sánh `mouseY` với stem top của từng note, chọn note có stem gần nhất. Dùng helper này thay thế tất cả `notes.findIndex` và nearest-fallback trong `handleCCMouseDown` và `handleCCMouseMove`. Fix lỗi không detect được note khi velocity gần nhau hoặc cùng beat.
+- **Các file ảnh hưởng:** `app/static/js/app.jsx`
+- **Ghi chú/Test (nếu có):** `npm run build` pass.