fix: Ctrl+S in SECTION-TAB stale closure, saveSectionTab uses initial sessionTabs

Keyboard handler (useEffect [] deps) captures handleSaveSectionTab
from first render, which has sessionTabs = []. When section tab
is opened later, saved handleSaveSectionTab finds no tab and
returns silently. Added handleSaveSectionTabRef, updated on
every render, used in keyboard handler via ref.current.

app/static/js/app.precompiled.js

@@ -231,10 +231,10 @@ const handleUndoRef=useRef(handleUndo);const handleRedoRef=useRef(handleRedo);ha
 const segmentData=data.subarray(startSample,endSample);const addedSamples=len*(loopCount-1);const newBuffer=ctx.createBuffer(1,data.length+addedSamples,sr);const newData=newBuffer.getChannelData(0);let idx=0;for(let i=0;i<endSample;i++)newData[idx++]=data[i];for(let n=0;n<loopCount-1;n++){for(let i=0;i<len;i++)newData[idx++]=segmentData[i];}for(let i=endSample;i<data.length;i++)newData[idx++]=data[i];setSubTabs(prev=>prev.map(s=>s.id===tabId?{...s,buffer:newBuffer,selectionStart:null,selectionEnd:null}:s));showToast(`Đã lặp vùng chọn ${loopCount} lần.`,'success');};useEffect(()=>{const handler=e=>{// Bypass global hotkeys when typing inside input/textarea/contentEditable elements
 if(e.target&&(e.target.tagName==='INPUT'||e.target.tagName==='TEXTAREA'||e.target.isContentEditable)){return;}const ctrl=e.ctrlKey||e.metaKey;const alt=e.altKey;// Global space play/pause shortcut for transport
 if(e.key===' '||e.code==='Space'){e.preventDefault();if(recordingState==='RECORDING'||recordingState==='COUNT_IN'){handleRecordClick();return;}if(handlePlayPauseRef.current)handlePlayPauseRef.current();return;}if(activeTabRef.current!=='main'&&!activeTabRef.current.startsWith('session_')){// Sub-Tab keyboard shortcuts mapping
-const curTabId=activeTabRef.current;if(ctrl&&alt&&e.key==='n'){e.preventDefault();handleSubTabNormalize(curTabId);return;}if(e.key==='f'||e.key==='F'){e.preventDefault();handleSubTabFade(curTabId,'in');return;}if(e.key==='g'||e.key==='G'){e.preventDefault();handleSubTabFade(curTabId,'out');return;}if(ctrl&&e.key==='l'){e.preventDefault();handleSubTabLoop(curTabId,4);return;}if(e.key==='v'||e.key==='V'){e.preventDefault();const val=prompt("Nhập Gain điều chỉnh (dB):","0");if(val)handleSubTabGain(curTabId,parseFloat(val)||0);return;}if(ctrl&&e.key==='x'){e.preventDefault();handleSubTabCut(curTabId);return;}if(ctrl&&e.key==='c'){e.preventDefault();handleSubTabCopy(curTabId);return;}if(ctrl&&e.key==='v'){e.preventDefault();handleSubTabPaste(curTabId);return;}if(e.key==='Delete'||e.key==='Backspace'||e.key==='Del'){e.preventDefault();if(subTabSelectedNodeTimeRef.current!==null){const selTime=subTabSelectedNodeTimeRef.current;setSubTabs(prev=>prev.map(s=>{if(s.id!==curTabId)return s;const curNodes=s.graphMode==='pan'?s.panningNodes||[]:s.volumeNodes||[];const updated=curNodes.filter(n=>n.time!==selTime);return{...s,[s.graphMode==='pan'?'panningNodes':'volumeNodes']:updated};}));setSubTabSelectedNodeTime(null);}else{handleSubTabDelete(curTabId);}return;}return;}if(ctrl&&e.key==='z'&&!e.shiftKey){e.preventDefault();handleUndoRef.current();return;}if(ctrl&&(e.key==='y'||e.key==='z'&&e.shiftKey)){e.preventDefault();handleRedoRef.current();return;}if(ctrl&&!alt&&e.key==='o'){e.preventDefault();handleImportSFS();return;}if(ctrl&&!alt&&e.key==='n'){e.preventDefault();setTracks([{id:'1',name:'Track 01',buffer:null,startTime:0,volumeDb:0,pan:0,muted:false,solo:false,color:'#0f766e',markers:[],serverFileId:null},{id:'2',name:'Track 02',buffer:null,startTime:0,volumeDb:0,pan:0,muted:false,solo:false,color:'#1d4ed8',markers:[],serverFileId:null}]);setSelectedTrackId('1');showToast('New project created','info');return;}if(ctrl&&!alt&&!e.shiftKey&&e.key==='a'){e.preventDefault();const curTab=activeTabRef.current;if(curTab!=='main'&&!curTab.startsWith('session_'))return;const allIds=new Set();(activeTracksRef.current||[]).forEach(t=>{(t.sections||[]).forEach(s=>allIds.add(s.id));(t.midiItems||[]).forEach(m=>allIds.add(m.id));(t.clips||[]).forEach(c=>allIds.add(c.id==='default'?'default_'+t.id:c.id));});setSelectedItemIds(allIds);return;}if(ctrl&&!alt&&e.key==='s'){e.preventDefault();var curTab=activeTabRef.current;if(curTab.startsWith('session_')){handleSaveSectionTab(curTab);showToast('Đã lưu Section','success');}else{handleExportSFS();}return;}if(ctrl&&alt&&e.key==='s'||ctrl&&e.shiftKey&&e.key==='s'){e.preventDefault();handleExportSFS();return;}if(ctrl&&!alt&&e.key==='i'){e.preventDefault();addNewTrack();return;}if(ctrl&&alt&&e.key==='i'){e.preventDefault();showToast('Import audio','info');return;}if(ctrl&&!alt&&e.key==='e'){e.preventDefault();openTempTab();return;}if(ctrl&&!alt&&e.key==='m'){e.preventDefault();handleMergeTracks();return;}if(ctrl&&!alt&&e.key==='c'){e.preventDefault();handleCopyTrack();return;}if(ctrl&&!alt&&e.key==='x'){e.preventDefault();handleCutTrack();return;}if(ctrl&&!alt&&e.key==='v'){e.preventDefault();handlePasteTrack();return;}if(e.key==='Delete'||e.key==='Backspace'||e.key==='Del'){const selClip=selectedClipIdRef.current;if(selClip){e.preventDefault();const{trackId,clipId}=selClip;setTracks(prev=>{const track=prev.find(t=>t.id===trackId);if(!track)return prev;const beforeSnap=captureTrackSnapshotRef.current?captureTrackSnapshotRef.current(trackId):null;const updatedClips=(track.clips||[]).filter(c=>c.id!==clipId);const updatedTracks=prev.map(t=>{if(t.id===trackId){return{...t,clips:updatedClips,buffer:updatedClips.length>0?updatedClips[0].buffer:null,startTime:updatedClips.length>0?updatedClips[0].startTime:0,name:updatedClips.length>0?updatedClips[0].name:`Track ${t.id}`};}return t;});setTimeout(()=>{const afterSnap=captureTrackSnapshotRef.current?captureTrackSnapshotRef.current(trackId):null;pushAction('DELETE_CLIP',trackId,beforeSnap,afterSnap);},50);return updatedTracks;});setSelectedClipId(null);showToast('Đã xóa clip.','info');return;}else{e.preventDefault();handleDeleteTrack();return;}}if(ctrl&&!alt&&e.key==='s'){e.preventDefault();const curTab=activeTabRef.current;if(curTab==='main'){// Main session: save project + save all dirty sub-tabs
+const curTabId=activeTabRef.current;if(ctrl&&alt&&e.key==='n'){e.preventDefault();handleSubTabNormalize(curTabId);return;}if(e.key==='f'||e.key==='F'){e.preventDefault();handleSubTabFade(curTabId,'in');return;}if(e.key==='g'||e.key==='G'){e.preventDefault();handleSubTabFade(curTabId,'out');return;}if(ctrl&&e.key==='l'){e.preventDefault();handleSubTabLoop(curTabId,4);return;}if(e.key==='v'||e.key==='V'){e.preventDefault();const val=prompt("Nhập Gain điều chỉnh (dB):","0");if(val)handleSubTabGain(curTabId,parseFloat(val)||0);return;}if(ctrl&&e.key==='x'){e.preventDefault();handleSubTabCut(curTabId);return;}if(ctrl&&e.key==='c'){e.preventDefault();handleSubTabCopy(curTabId);return;}if(ctrl&&e.key==='v'){e.preventDefault();handleSubTabPaste(curTabId);return;}if(e.key==='Delete'||e.key==='Backspace'||e.key==='Del'){e.preventDefault();if(subTabSelectedNodeTimeRef.current!==null){const selTime=subTabSelectedNodeTimeRef.current;setSubTabs(prev=>prev.map(s=>{if(s.id!==curTabId)return s;const curNodes=s.graphMode==='pan'?s.panningNodes||[]:s.volumeNodes||[];const updated=curNodes.filter(n=>n.time!==selTime);return{...s,[s.graphMode==='pan'?'panningNodes':'volumeNodes']:updated};}));setSubTabSelectedNodeTime(null);}else{handleSubTabDelete(curTabId);}return;}return;}if(ctrl&&e.key==='z'&&!e.shiftKey){e.preventDefault();handleUndoRef.current();return;}if(ctrl&&(e.key==='y'||e.key==='z'&&e.shiftKey)){e.preventDefault();handleRedoRef.current();return;}if(ctrl&&!alt&&e.key==='o'){e.preventDefault();handleImportSFS();return;}if(ctrl&&!alt&&e.key==='n'){e.preventDefault();setTracks([{id:'1',name:'Track 01',buffer:null,startTime:0,volumeDb:0,pan:0,muted:false,solo:false,color:'#0f766e',markers:[],serverFileId:null},{id:'2',name:'Track 02',buffer:null,startTime:0,volumeDb:0,pan:0,muted:false,solo:false,color:'#1d4ed8',markers:[],serverFileId:null}]);setSelectedTrackId('1');showToast('New project created','info');return;}if(ctrl&&!alt&&!e.shiftKey&&e.key==='a'){e.preventDefault();const curTab=activeTabRef.current;if(curTab!=='main'&&!curTab.startsWith('session_'))return;const allIds=new Set();(activeTracksRef.current||[]).forEach(t=>{(t.sections||[]).forEach(s=>allIds.add(s.id));(t.midiItems||[]).forEach(m=>allIds.add(m.id));(t.clips||[]).forEach(c=>allIds.add(c.id==='default'?'default_'+t.id:c.id));});setSelectedItemIds(allIds);return;}if(ctrl&&!alt&&e.key==='s'){e.preventDefault();var curTab=activeTabRef.current;if(curTab.startsWith('session_')){handleSaveSectionTabRef.current(curTab);showToast('Đã lưu Section','success');}else{handleExportSFS();}return;}if(ctrl&&alt&&e.key==='s'||ctrl&&e.shiftKey&&e.key==='s'){e.preventDefault();handleExportSFS();return;}if(ctrl&&!alt&&e.key==='i'){e.preventDefault();addNewTrack();return;}if(ctrl&&alt&&e.key==='i'){e.preventDefault();showToast('Import audio','info');return;}if(ctrl&&!alt&&e.key==='e'){e.preventDefault();openTempTab();return;}if(ctrl&&!alt&&e.key==='m'){e.preventDefault();handleMergeTracks();return;}if(ctrl&&!alt&&e.key==='c'){e.preventDefault();handleCopyTrack();return;}if(ctrl&&!alt&&e.key==='x'){e.preventDefault();handleCutTrack();return;}if(ctrl&&!alt&&e.key==='v'){e.preventDefault();handlePasteTrack();return;}if(e.key==='Delete'||e.key==='Backspace'||e.key==='Del'){const selClip=selectedClipIdRef.current;if(selClip){e.preventDefault();const{trackId,clipId}=selClip;setTracks(prev=>{const track=prev.find(t=>t.id===trackId);if(!track)return prev;const beforeSnap=captureTrackSnapshotRef.current?captureTrackSnapshotRef.current(trackId):null;const updatedClips=(track.clips||[]).filter(c=>c.id!==clipId);const updatedTracks=prev.map(t=>{if(t.id===trackId){return{...t,clips:updatedClips,buffer:updatedClips.length>0?updatedClips[0].buffer:null,startTime:updatedClips.length>0?updatedClips[0].startTime:0,name:updatedClips.length>0?updatedClips[0].name:`Track ${t.id}`};}return t;});setTimeout(()=>{const afterSnap=captureTrackSnapshotRef.current?captureTrackSnapshotRef.current(trackId):null;pushAction('DELETE_CLIP',trackId,beforeSnap,afterSnap);},50);return updatedTracks;});setSelectedClipId(null);showToast('Đã xóa clip.','info');return;}else{e.preventDefault();handleDeleteTrack();return;}}if(ctrl&&!alt&&e.key==='s'){e.preventDefault();const curTab=activeTabRef.current;if(curTab==='main'){// Main session: save project + save all dirty sub-tabs
 handleSaveProject();subTabsRef.current.filter(s=>s.isDirty).forEach(st=>{if(st.type==='PIANO_ROLL'){handleSaveMidiNotes(st.id,st.trackId,st.target_id,st.notes||[]);}else if(st.type==='SECTION'){handleSaveSectionTab(st.id);}else if(st.buffer){// Audio clip sub-tab: save buffer to track
 const subTrack=activeTracksRef.current.find(t=>t.id===st.trackId);if(subTrack){updateActiveTracks(prev=>prev.map(t=>t.id===st.trackId?{...t,buffer:st.buffer}:t));}}showToast('Đã lưu','success');});}else if(curTab.startsWith('session_')){// Section tab: save section
-handleSaveSectionTab(curTab);showToast('Đã lưu Section','success');}else{// Sub-tab: save current tab
+handleSaveSectionTabRef.current(curTab);showToast('Đã lưu Section','success');}else{// Sub-tab: save current tab
 const st=subTabsRef.current.find(s=>s.id===curTab);if(st){if(st.type==='PIANO_ROLL'){handleSaveMidiNotes(st.id,st.trackId,st.target_id,st.notes||[]);showToast('Đã lưu Piano Roll','success');}else if(st.type==='SECTION'){handleSaveSectionTab(st.id);showToast('Đã lưu Section Tab','success');}else if(st.buffer){const subTrack=activeTracksRef.current.find(t=>t.id===st.trackId);if(subTrack){updateActiveTracks(prev=>prev.map(t=>t.id===st.trackId?{...t,buffer:st.buffer}:t));}showToast('Đã lưu Audio Tab','success');}}}return;}if(!ctrl&&!alt&&e.key==='s'){e.preventDefault();handleSplitTrack(selectedTrackId);return;}};window.addEventListener('keydown',handler,{capture:true});return()=>window.removeEventListener('keydown',handler,{capture:true});},[]);// ── Temp Tab: draw isolated waveform ──
 useEffect(()=>{if(!tempTabActive||!tempTabBuffer||!tempTabCanvasRef.current)return;const canvas=tempTabCanvasRef.current;const ctx=canvas.getContext('2d');const dpr=window.devicePixelRatio||1;const rect=canvas.getBoundingClientRect();canvas.width=rect.width*dpr;canvas.height=rect.height*dpr;ctx.scale(dpr,dpr);const w=rect.width;const h=rect.height;ctx.fillStyle='#181818';ctx.fillRect(0,0,w,h);const data=tempTabBuffer.getChannelData(0);const sr=tempTabBuffer.sampleRate;const totalSamples=data.length;if(totalSamples===0)return;ctx.strokeStyle='#6ee7b7';ctx.lineWidth=1;for(let px=0;px<w;px++){const startSample=Math.floor(px/w*totalSamples);const endSample=Math.floor((px+1)/w*totalSamples);let maxVal=0;for(let i=startSample;i<endSample&&i<totalSamples;i++){const abs=Math.abs(data[i]);if(abs>maxVal)maxVal=abs;}const mid=h/2;const peakHeight=maxVal*(h*0.4);ctx.beginPath();ctx.moveTo(px,mid-peakHeight);ctx.lineTo(px,mid+peakHeight);ctx.stroke();}},[tempTabActive,tempTabBuffer]);// ── Sub Tab: open as new tab instead of modal (LOOP_EDITOR_2.md §1) ──
 const openTempTab=()=>{const useLocal=selectionMode==='local'&&localSelectionTrackId;const trackId=useLocal?localSelectionTrackId:selectedTrackId;const t=tracks.find(x=>x.id===trackId);if(!t||!t.buffer){showToast('Vui lòng chọn track có dữ liệu âm thanh.','warning');return;}if(selLeft===null||selRight===null||selRight<=selLeft){showToast('Vui lòng chọn một khoảng thời gian trên sóng âm.','warning');return;}// Check if a subtab for this track+range already exists
@@ -330,7 +330,7 @@ if(t.id===drag.trackId&&drag.trackId!==targetTrackId){const updatedClips=(t.clip
 if(t.id===targetTrackId){const existingClips=t.clips&&t.clips.length>0?t.clips:t.buffer?[{id:'default_'+t.id,buffer:t.buffer,startTime:t.startTime||0,name:t.name}]:[];const hasClip=existingClips.some(c=>c.id===drag.clipId);let updatedClips;if(hasClip){updatedClips=existingClips.map(c=>c.id===drag.clipId?{...c,startTime:newStart}:c);}else{updatedClips=[...existingClips,{id:drag.clipId,buffer:drag.buffer,startTime:newStart,name:drag.name}];}return{...t,clips:updatedClips,buffer:updatedClips[0].buffer,startTime:updatedClips[0].startTime,name:updatedClips[0].name};}return t;}));if(drag.trackId!==targetTrackId){setDraggedClip(prev=>({...prev,trackId:targetTrackId}));}};const handleMouseUp=()=>{const drag=draggedClipRef.current;if(!drag)return;const afterSnap=captureTrackSnapshotRef.current(drag.trackId);pushAction('MOVE_CLIP',drag.trackId,drag.beforeSnap,afterSnap);setDraggedClip(null);showToast('Đã di chuyển clip.','success');};document.addEventListener('mousemove',handleMouseMove);document.addEventListener('mouseup',handleMouseUp);return()=>{document.removeEventListener('mousemove',handleMouseMove);document.removeEventListener('mouseup',handleMouseUp);};},[zoom]);// Document-level mousemove/mouseup for clip stretching
 useEffect(()=>{const handleMouseMove=e=>{const stretch=stretchedClipRef.current;if(!stretch)return;autoScrollTimeline(e.clientX);const wrapper=timelineWrapperRef.current;if(!wrapper)return;const rect=wrapper.getBoundingClientRect();const scrollLeft=wrapper.scrollLeft;const mouseX=e.clientX-rect.left+scrollLeft;const time=mouseX/zoom;const secPerBar=60.0/(parseInt(bpmRef.current)||120)*4;const marginBar=maxDurationRef.current-secPerBar;const maxEnd=Math.min(time,marginBar);const newDuration=Math.max(0.1,maxEnd-stretch.startTime);const speedRatio=stretch.originalDuration/newDuration;updateActiveTracks(prev=>prev.map(t=>{if(t.id===stretch.trackId){const updatedClips=(t.clips||[]).map(c=>{if(c.id===stretch.clipId){return{...c,speed:speedRatio};}return c;});return{...t,clips:updatedClips,buffer:updatedClips[0]?.buffer,startTime:updatedClips[0]?.startTime||0,speed:updatedClips[0]?.speed||1.0};}return t;}));};const handleMouseUp=()=>{const stretch=stretchedClipRef.current;if(!stretch)return;const afterSnap=captureTrackSnapshotRef.current(stretch.trackId);pushAction('STRETCH_CLIP',stretch.trackId,stretch.beforeSnap,afterSnap);setStretchedClip(null);showToast('Đã giãn thời gian clip.','success');};document.addEventListener('mousemove',handleMouseMove);document.addEventListener('mouseup',handleMouseUp);return()=>{document.removeEventListener('mousemove',handleMouseMove);document.removeEventListener('mouseup',handleMouseUp);};},[zoom]);// ── Deselect single item ──
 const handleDeselectItem=itemId=>{setSelectedItemIds(prev=>{var next=new Set(prev);next.delete(itemId);return next;});};// ── Add item to selectedItemIds ──
-const handleAddToSelection=itemId=>{setSelectedItemIds(prev=>{var next=new Set(prev);next.add(itemId);return next;});};const handleSetPendingDrag=(trackId,itemType,itemId,clickOffset,e,preToggleSnapshot)=>{pendingDragRef.current={trackId,itemType,itemId,clickOffset,startX:e.clientX,startY:e.clientY,selectedIds:preToggleSnapshot||new Set(selectedItemIds)};};// ── Sweep Select ──
+const handleSaveSectionTabRef=useRef(handleSaveSectionTab);handleSaveSectionTabRef.current=handleSaveSectionTab;const handleAddToSelection=itemId=>{setSelectedItemIds(prev=>{var next=new Set(prev);next.add(itemId);return next;});};const handleSetPendingDrag=(trackId,itemType,itemId,clickOffset,e,preToggleSnapshot)=>{pendingDragRef.current={trackId,itemType,itemId,clickOffset,startX:e.clientX,startY:e.clientY,selectedIds:preToggleSnapshot||new Set(selectedItemIds)};};// ── Sweep Select ──
 const handleSweepSelectStart=(trackId,startTime)=>{isSweepingRef.current=true;sweepStartRef.current=startTime;sweepTrackIdRef.current=trackId;var init={startTime,endTime:startTime};sweepSelectRef.current=init;setSweepSelect(init);setSelectedItemIds(new Set());};// ── Section / MIDI Item Drag Start ──
 const handleSectionItemDragStart=(trackId,itemType,itemId,clickOffset,isDuplicate,pendingSelectedIds)=>{var curTracks=activeTracksRef.current||activeTracks;var multiIds=null;var selIds=pendingSelectedIds||selectedItemIds;if(selIds&&selIds.size>0&&selIds.has(itemId)){var selArr=Array.from(selIds);var originals={};curTracks.forEach(function(t){(t.sections||[]).forEach(function(s){if(selArr.indexOf(s.id)>=0)originals[s.id]={type:'section',start:s.start};});(t.midiItems||[]).forEach(function(m){if(selArr.indexOf(m.id)>=0)originals[m.id]={type:'midiItem',start:m.startTime};});(t.clips||[]).forEach(function(c){var cid=c.id==='default'?'default_'+t.id:c.id;if(selArr.indexOf(cid)>=0)originals[cid]={type:'clip',start:c.startTime};});});if(Object.keys(originals).length>0)multiIds=originals;}if(isDuplicate){var track=curTracks.find(function(t){return t.id===trackId;});if(!track)return;if(multiIds){var newOriginals={};updateActiveTracks(function(prev){return prev.map(function(t){var updatedSections=t.sections?t.sections.slice():[];var updatedMidi=t.midiItems?t.midiItems.slice():[];var updatedClips=t.clips?t.clips.slice():[];Object.keys(multiIds).forEach(function(oid){var info=multiIds[oid];if(info.type==='section'){var sec=(t.sections||[]).find(function(s){return s.id===oid;});if(sec){var newId='sec_dup_'+Date.now()+'_'+Math.random().toString(36).substr(2,5);updatedSections.push({...sec,id:newId,name:sec.name+' (Copy)'});newOriginals[newId]={type:'section',start:sec.start};}}else if(info.type==='midiItem'){var mid=(t.midiItems||[]).find(function(m){return m.id===oid;});if(mid){var newId='midi_dup_'+Date.now()+'_'+Math.random().toString(36).substr(2,5);updatedMidi.push({...mid,id:newId,name:mid.name+' (Copy)'});newOriginals[newId]={type:'midiItem',start:mid.startTime};}}else if(info.type==='clip'){var clip=(t.clips||[]).find(function(c){return c.id===oid||'default_'+t.id===oid;});if(clip){var newId='clip_dup_'+Date.now()+'_'+Math.random().toString(36).substr(2,5);updatedClips.push({...clip,id:newId,startTime:clip.startTime,name:clip.name+' (Copy)'});newOriginals[newId]={type:'clip',start:clip.startTime};}}});return{...t,sections:updatedSections,midiItems:updatedMidi,clips:updatedClips};});});setDraggedSectionItem({trackId,itemType,itemId,clickOffset,multiIds:newOriginals});}else{var items=itemType==='section'?track.sections||[]:track.midiItems||[];var item=items.find(function(it){return it.id===itemId;});if(!item)return;var newId=itemType+'_dup_'+Date.now();var newItem={...item,id:newId,name:item.name+' (Copy)'};updateActiveTracks(function(prev){return prev.map(function(t){if(t.id!==trackId)return t;var updated=itemType==='section'?[...(t.sections||[]),newItem]:[...(t.midiItems||[]),newItem];return itemType==='section'?{...t,sections:updated}:{...t,midiItems:updated};});});setDraggedSectionItem({trackId,itemType,itemId:newId,clickOffset,isDuplicate:false});}return;}setDraggedSectionItem({trackId,itemType,itemId,clickOffset,multiIds});};handleSectionItemDragStartRef.current=handleSectionItemDragStart;// ── Section / MIDI Item Resize Start ──
 const handleSectionItemResizeStart=(trackId,itemType,itemId,side,clickTime)=>{const curTracks=activeTracks;const track=curTracks.find(t=>t.id===trackId);if(!track)return;const items=itemType==='section'?track.sections:track.midiItems;const item=(items||[]).find(it=>it.id===itemId);if(!item)return;const start=itemType==='section'?item.start:item.startTime;setResizedSectionItem({trackId,itemType,itemId,side,originalStart:start,originalDuration:item.duration});};// ── Document-level mousemove/mouseup for Section/MIDI item drag ──