fix: brush drawing smooth - track pitch + beat delta

app/static/js/app.jsx

@@ -5119,7 +5119,8 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
         drawDuration: initialDur,
         visitedPitches: snapToScaleRef.current ? [snapPitchToScale(pitch, selectedScaleRef.current)] : [pitch],
         initialBeat: start,
-        initialPitch: snapToScaleRef.current ? snapPitchToScale(pitch, selectedScaleRef.current) : pitch
+        initialPitch: snapToScaleRef.current ? snapPitchToScale(pitch, selectedScaleRef.current) : pitch,
+        lastDrawBeat: start
       });
       // Play the note with SoundFont
       if (window.SonicSF) {
@@ -5215,14 +5216,16 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
         }));
       }
       const snappedPitch = snapToScaleRef.current ? snapPitchToScale(pitch, selectedScaleRef.current) : pitch;
-      if (!visited.includes(snappedPitch)) {
-        const newPitches = [...visited, snappedPitch];
+      const lastDrawBeat = draggedNote.lastDrawBeat !== undefined ? draggedNote.lastDrawBeat : draggedNote.startOffsetBeat;
+      const minBeatStep = Math.max(0.03125, getSnapDuration(snapVal) * 0.25);
+      const pitchChanged = !visited.includes(snappedPitch);
+      const beatChanged = Math.abs(beat - lastDrawBeat) >= minBeatStep;
+      if (pitchChanged || (beatChanged && visited.length > 0)) {
         const brushIds = draggedNote.brushIds || [];
-        const snappedBeat = getSnapBeat(beat, snapVal);
         const newNote = {
-          id: 'note_' + Date.now() + Math.random().toString(36).substr(2, 8) + '_' + newPitches.length,
+          id: 'note_' + Date.now() + Math.random().toString(36).substr(2, 8) + '_' + (visited.length + 1),
           pitch: snappedPitch,
-          start_beat: snappedBeat,
+          start_beat: beat,
           duration_beats: getSnapDuration(snapVal),
           velocity: brushVelocityRef.current,
           pan: 0.0
@@ -5230,7 +5233,10 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
         setNotes(prev => [...prev, newNote]);
         setSelectedNoteIds(prev => [...prev, newNote.id]);
         draggedNote.brushIds = [...brushIds, newNote.id];
-        draggedNote.visitedPitches = newPitches;
+        draggedNote.lastDrawBeat = beat;
+        if (pitchChanged) {
+          draggedNote.visitedPitches = [...visited, snappedPitch];
+        }
       }
       const container = gridScrollRef.current;
       if (container) {

wiki.md

@@ -190,3 +190,8 @@
 - **Tóm tắt thay đổi:** (1) Brush drawing: thay vì redistribute notes evenly, append từng note mới tại beat position thực tế (`getSnapBeat(beat, snapVal)`) — notes theo đúng hình dạng brush stroke. (2) Xóa transport controls (back/play/stop/record/forward) khỏi MIDI tab toolbar — chỉ dùng global transport. (3) Loop repeat: thêm `schedulePianoRollMidi` helper — reschedule MIDI notes qua SonicSF mỗi khi loop repeat, fix lỗi notes trong vùng chọn không có âm thanh khi play lặp lại.
 - **Các file ảnh hưởng:** `app/static/js/app.jsx`
 - **Ghi chú/Test (nếu có):** `npm run build` pass.
+
+### [2026-07-26 10:44] Task: Fix brush drawing smooth - track pitch + beat delta
+- **Tóm tắt thay đổi:** Brush drawing: theo dõi cả `lastDrawBeat` và `visitedPitches`. Tạo note mới khi pitch thay đổi HOẶC beat di chuyển >= minBeatStep (25% của grid duration). Dùng raw `beat` thay vì `getSnapBeat` để note theo sát vị trí chuột. Khởi tạo `lastDrawBeat: start` trong draggedNote. Fix lỗi draw bị ngắt quãng do chỉ tạo note khi pitch thay đổi.
+- **Các file ảnh hưởng:** `app/static/js/app.jsx`
+- **Ghi chú/Test (nếu có):** `npm run build` pass.