refactor: remove piano roll AI prompt, reuse Copilot for MIDI gen

- Removed aiPrompt/aiLoading state and handleAIPrompt from PianoRollTabEditor
- Removed AI prompt input UI from piano roll toolbar
- handleAISend now detects active piano roll tab and routes
  prompts to MIDI note generation, appends notes to the tab

app/static/js/app.jsx

@@ -5469,8 +5469,6 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
   snapToScaleRef.current = snapToScale;
   const [scaleMenuPos, setScaleMenuPos] = React.useState(null);
   const scaleMenuOriginRef = React.useRef(null);
-  const [aiPrompt, setAiPrompt] = React.useState('');
-  const [aiLoading, setAiLoading] = React.useState(false);
   const [showCC, setShowCC] = React.useState(true);
   const [ccHeight, setCcHeight] = React.useState(80);
 
@@ -5485,52 +5483,6 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
     return octave * 12 + best;
   };
 
-  const handleAIPrompt = async () => {
-    const prompt = aiPrompt.trim();
-    if (!prompt || !window.AIGateway) return;
-    setAiLoading(true);
-    try {
-      const result = await window.AIGateway.executeAIPrompt({
-        prompt: 'Generate MIDI notes for a piano roll. Return ONLY a JSON array: [{pitch(0-127), start_beat, duration_beats, velocity(0.0-1.0)}]. ' + prompt,
-        provider: 'openai',
-        model: 'gpt-4o',
-        systemInstruction: 'You are a MIDI composer. Output ONLY valid JSON array of notes. No markdown, no explanation. Use 4/4 time. pitch=C4=60, D4=62, E4=64, F4=65, G4=67, A4=69, B4=71, C5=72.'
-      });
-      let notesData = null;
-      if (result.textResponse) {
-        try {
-          const cleaned = result.textResponse.replace(/```json?\s*/g, '').replace(/```/g, '').trim();
-          notesData = JSON.parse(cleaned);
-        } catch (e1) {}
-      }
-      if (!notesData && result.functionCalls) {
-        for (const fc of result.functionCalls) {
-          if (fc.arguments && fc.arguments.notes) { notesData = fc.arguments.notes; break; }
-        }
-      }
-      if (Array.isArray(notesData) && notesData.length > 0) {
-        const newNotes = notesData.map((n, i) => ({
-          id: 'note_ai_' + Date.now() + '_' + i,
-          pitch: Math.max(0, Math.min(127, n.pitch || 60)),
-          start_beat: Math.max(0, parseFloat(n.start_beat) || 0),
-          duration_beats: Math.max(0.125, parseFloat(n.duration_beats) || 0.25),
-          velocity: Math.max(0.1, Math.min(1.0, n.velocity ?? 0.8)),
-          pan: 0.0
-        }));
-        pushToUndo(notes);
-        setNotes(prev => [...prev, ...newNotes]);
-        setSelectedNoteIds(newNotes.map(n => n.id));
-        if (window.SonicSF && newNotes.length > 0) {
-          const ctx = getAudioContext();
-          newNotes.forEach(n => window.SonicSF.playNote(n.pitch, n.velocity * 127, 300, ctx.currentTime + (n.start_beat * 0.01), st.instrumentProgram, null));
-        }
-      }
-    } catch (err) {
-      console.error('AI Piano Roll error:', err);
-    }
-    setAiLoading(false);
-  };
-
   const renderScaleContextMenu = () => {
     const closeMenu = () => setScaleMenuPos(null);
     const origin = scaleMenuOriginRef.current || scaleMenuPos;
@@ -5652,19 +5604,6 @@ const PianoRollTabEditor = ({ st, zoom, bpm, viewportWidth, onClose, onUpdateNot
     onClick: () => setShowCC(!showCC),
     className: `px-2 py-1 rounded text-xs ${showCC ? 'bg-purple-900/60 text-purple-300 border border-purple-700' : 'text-zinc-500 hover:text-zinc-300'}`
   }, ccMode === 'pan' ? 'Pan' : 'Vel'), /*#__PURE__*/React.createElement("div", {
-    className: "flex items-center gap-1 flex-1 max-w-[300px] ml-2"
-  }, /*#__PURE__*/React.createElement("input", {
-    type: "text",
-    value: aiPrompt,
-    onChange: e => setAiPrompt(e.target.value),
-    onKeyDown: e => { if (e.key === 'Enter') handleAIPrompt(); },
-    placeholder: "AI: tạo 8 bars MIDI...",
-    className: "flex-1 bg-zinc-900 border border-zinc-700 text-zinc-200 text-[10px] rounded px-2 py-1 outline-none focus:border-amber-500 min-w-0"
-  }), /*#__PURE__*/React.createElement("button", {
-    onClick: handleAIPrompt,
-    disabled: aiLoading,
-    className: "px-2 py-1 text-[10px] bg-purple-700 hover:bg-purple-600 disabled:bg-zinc-700 text-white rounded flex items-center gap-1 transition"
-  }, aiLoading ? "..." : "AI")), /*#__PURE__*/React.createElement("div", {
     className: "flex items-center gap-1"
   }, /*#__PURE__*/React.createElement("button", {
     onClick: () => onSaveNotes(st.id, st.trackId, st.target_id, notes),
@@ -12296,6 +12235,53 @@ const App = () => {
   const handleAISend = async () => {
     const prompt = aiPrompt.trim();
     if (!prompt) { showToast('Vui lòng nhập nội dung prompt.', 'warning'); return; }
+
+    // Check if piano roll tab is active → route prompt to MIDI generation
+    const activePianoRoll = subTabs.find(s => s.id === activeTab && s.type === 'PIANO_ROLL');
+    if (activePianoRoll) {
+      setAiProcessing(true);
+      setAiActionLog(prev => [...prev, { type: 'status', text: ` ⏳ Đang gửi prompt đến AI cho Piano Roll...`, time: Date.now() }]);
+      try {
+        const result = await window.AIGateway.executeAIPrompt({
+          prompt: 'Generate MIDI notes for a piano roll. Return ONLY a JSON array: [{pitch(0-127), start_beat, duration_beats, velocity(0.0-1.0)}]. ' + prompt,
+          provider: 'openai',
+          model: 'gpt-4o',
+          systemInstruction: 'You are a MIDI composer. Output ONLY valid JSON array of notes. No markdown, no explanation. Use 4/4 time. pitch=C4=60, D4=62, E4=64, F4=65, G4=67, A4=69, B4=71, C5=72.'
+        });
+        let notesData = null;
+        if (result.textResponse) {
+          try {
+            const cleaned = result.textResponse.replace(/```json?\s*/g, '').replace(/```/g, '').trim();
+            notesData = JSON.parse(cleaned);
+          } catch (e1) {}
+        }
+        if (!notesData && result.functionCalls) {
+          for (const fc of result.functionCalls) {
+            if (fc.arguments && fc.arguments.notes) { notesData = fc.arguments.notes; break; }
+          }
+        }
+        if (Array.isArray(notesData) && notesData.length > 0) {
+          const newNotes = notesData.map((n, i) => ({
+            id: 'note_ai_' + Date.now() + '_' + i,
+            pitch: Math.max(0, Math.min(127, n.pitch || 60)),
+            start_beat: Math.max(0, parseFloat(n.start_beat) || 0),
+            duration_beats: Math.max(0.125, parseFloat(n.duration_beats) || 0.25),
+            velocity: Math.max(0.1, Math.min(1.0, n.velocity ?? 0.8)),
+            pan: 0.0
+          }));
+          setSubTabs(prev => prev.map(s => s.id === activePianoRoll.id ? { ...s, notes: [...(s.notes || []), ...newNotes], isDirty: true } : s));
+          setAiActionLog(prev => [...prev, { type: 'status', text: ` ✅ Đã thêm ${newNotes.length} notes vào Piano Roll`, time: Date.now() }]);
+          setCanvasRedrawCount(n => n + 1);
+        } else {
+          setAiActionLog(prev => [...prev, { type: 'error', text: ` ❌ AI không trả về notes hợp lệ.`, time: Date.now() }]);
+        }
+      } catch (err) {
+        setAiActionLog(prev => [...prev, { type: 'error', text: ` ❌ Lỗi: ${err.message}`, time: Date.now() }]);
+      }
+      setAiProcessing(false);
+      return;
+    }
+
     if (window.DAWCommandDispatcher) {
       window.DAWCommandDispatcher.currentSelectedTrackId = selectedTrackId;
       window.DAWCommandDispatcher.currentTracks = activeTracks;