fix: group drag keeps items on their original tracks

Remove all cross-track logic in multiIds path. Each item only
updates its time position (delta) on its current track. No
merging or track reassignment.

app/static/js/app.precompiled.js

@@ -342,11 +342,7 @@ const handleSweepSelectStart=(trackId,startTime,startY)=>{isSweepingRef.current=
 };// ── 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 rearrangeNewId='sec_dup_'+Date.now()+'_'+Math.random().toString(36).substr(2,5);updatedSections.push({...sec,id:rearrangeNewId,name:sec.name+' (Copy)'});newOriginals[rearrangeNewId]={type:'section',start:sec.start};}}else if(info.type==='midiItem'){var mid=(t.midiItems||[]).find(function(m){return m.id===oid;});if(mid){var rearrangeNewId='midi_dup_'+Date.now()+'_'+Math.random().toString(36).substr(2,5);updatedMidi.push({...mid,id:rearrangeNewId,name:mid.name+' (Copy)'});newOriginals[rearrangeNewId]={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 rearrangeNewId='clip_dup_'+Date.now()+'_'+Math.random().toString(36).substr(2,5);updatedClips.push({...clip,id:rearrangeNewId,startTime:clip.startTime,name:clip.name+' (Copy)'});newOriginals[rearrangeNewId]={type:'clip',start:clip.startTime};}}});return{...t,sections:updatedSections,midiItems:updatedMidi,clips:updatedClips};});});var newItemId=Object.keys(newOriginals)[0]||itemId;setDraggedSectionItem({trackId,itemType,itemId:newItemId,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 rearrangeNewId=itemType+'_dup_'+Date.now();var newItem={...item,id:rearrangeNewId,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:rearrangeNewId,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 ──
-useEffect(()=>{const handleMouseMove=e=>{const drag=draggedSectionItemRef.current;if(!drag)return;const wrapper=timelineWrapperRef.current;if(!wrapper)return;autoScrollTimeline(e.clientX);const rect=wrapper.getBoundingClientRect();const scrollLeft=wrapper.scrollLeft;const mouseX=e.clientX-rect.left+scrollLeft;const time=Math.max(0,mouseX/zoom-leadInMarginRef.current);const beatSec=60.0/(parseInt(bpm)||120);const secondsPerBar=beatSec*4;const marginBar=maxDurationRef.current-secondsPerBar;const rawStart=Math.max(0,Math.min(time-drag.clickOffset,marginBar));const newStart=snapTime(rawStart,snapValueRef.current,bpmRef.current);const itemPx=newStart*zoom;const keepMargin=80;if(itemPx>scrollLeft+rect.width-keepMargin){wrapper.scrollLeft=itemPx-rect.width+keepMargin;setCanvasRedrawCount(n=>n+1);}else if(itemPx<scrollLeft+keepMargin){wrapper.scrollLeft=Math.max(0,itemPx-keepMargin);setCanvasRedrawCount(n=>n+1);}var allTrksNow=activeTracksRef.current||[];var targetTrackId=hoveredTrackIdRef.current||drag.trackId;// Clamp to min track 0 (first track)
-var trkIds=allTrksNow.map(function(x){return x.id;});var targetIdx=trkIds.indexOf(targetTrackId);if(targetIdx<0&&allTrksNow.length>0)targetTrackId=allTrksNow[0].id;// Auto-add track when dragging below the last track
-if(targetIdx<0||targetIdx>=allTrksNow.length-1){var isBelow=e.clientY>rect.top+rect.height;if(isBelow){addNewTrack();var newTrks=activeTracksRef.current||[];targetTrackId=newTrks[newTrks.length-1].id;}}updateActiveTracks(prev=>{let movedItem=null;for(let track of prev){// Search all item types for the dragged item
-const sec=(track.sections||[]).find(it=>it.id===drag.itemId);const mid=(track.midiItems||[]).find(it=>it.id===drag.itemId);if(sec||mid){movedItem=sec||mid;break;}}// Build a live map: where does each multi-drag item currently live?
-var currentTrackMap={};if(drag.multiIds){Object.keys(drag.multiIds).forEach(function(mid){var info=drag.multiIds[mid];for(var pi=0;pi<prev.length;pi++){var pt=prev[pi];var foundHere=false;if(info.type==='section')foundHere=(pt.sections||[]).some(function(s){return s.id===mid;});else if(info.type==='midiItem')foundHere=(pt.midiItems||[]).some(function(m){return m.id===mid;});else if(info.type==='clip')foundHere=(pt.clips||[]).some(function(c){return c.id===mid||'default_'+pt.id===mid;});if(foundHere){currentTrackMap[mid]=pt.id;break;}}});}return prev.map(t=>{if(drag.multiIds){var dragOrigStart=drag.multiIds[drag.itemId]?drag.multiIds[drag.itemId].start:0;var delta=newStart-dragOrigStart;var resultSections=(t.sections||[]).slice();var resultMidis=(t.midiItems||[]).slice();var resultClips=(t.clips||[]).slice();var crossTracks=targetTrackId!==drag.trackId;Object.keys(drag.multiIds).forEach(function(mid){var info=drag.multiIds[mid];var newVal=info.start+delta;var currentTid=currentTrackMap.hasOwnProperty(mid)?currentTrackMap[mid]:info.trackId;var onCurrentTrack=currentTid===t.id;if(onCurrentTrack){if(!crossTracks||t.id===targetTrackId){if(info.type==='section'){var idx=resultSections.findIndex(function(s){return s.id===mid;});if(idx>=0)resultSections[idx]={...resultSections[idx],start:Math.max(0,newVal)};}else if(info.type==='midiItem'){var idx=resultMidis.findIndex(function(mx){return mx.id===mid;});if(idx>=0)resultMidis[idx]={...resultMidis[idx],startTime:Math.max(0,newVal)};}else if(info.type==='clip'){var idx=resultClips.findIndex(function(cx){return cx.id===mid||'default_'+t.id===mid;});if(idx>=0)resultClips[idx]={...resultClips[idx],startTime:Math.max(0,newVal)};}}else{if(info.type==='section')resultSections=resultSections.filter(function(s){return s.id!==mid;});else if(info.type==='midiItem')resultMidis=resultMidis.filter(function(mx){return mx.id!==mid;});else if(info.type==='clip'){var cid3='default_'+t.id;resultClips=resultClips.filter(function(cx){return cx.id!==mid&&cx.id!==cid3;});}}}else if(crossTracks&&t.id===targetTrackId){var srcItem=null;for(var pi2=0;pi2<prev.length;pi2++){var tr2=prev[pi2];if(info.type==='section')srcItem=(tr2.sections||[]).find(function(s){return s.id===mid;});else if(info.type==='midiItem')srcItem=(tr2.midiItems||[]).find(function(mx){return mx.id===mid;});else if(info.type==='clip'){var c2=(tr2.clips||[]).find(function(cx){return cx.id===mid||'default_'+tr2.id===mid;});if(c2)srcItem=c2;}if(srcItem)break;}if(srcItem){if(info.type==='section'){resultSections=resultSections.filter(function(s){return s.id!==mid;});resultSections.push({...srcItem,start:Math.max(0,newVal)});}else if(info.type==='midiItem'){resultMidis=resultMidis.filter(function(mx){return mx.id!==mid;});resultMidis.push({...srcItem,startTime:Math.max(0,newVal)});}else if(info.type==='clip'){var cid4='default_'+t.id;resultClips=resultClips.filter(function(cx){return cx.id!==mid&&cx.id!==cid4;});resultClips.push({...srcItem,startTime:Math.max(0,newVal)});}}}});return{...t,sections:resultSections,midiItems:resultMidis,clips:resultClips};}const items=drag.itemType==='section'?t.sections||[]:t.midiItems||[];const updatedItems=items.filter(it=>it.id!==drag.itemId);if(t.id===targetTrackId){if(movedItem){updatedItems.push(drag.itemType==='section'?{...movedItem,start:newStart}:{...movedItem,startTime:newStart});}else{if(drag.itemType==='section'){updatedItems.push({id:drag.itemId,name:'Section',start:newStart,duration:4*secondsPerBar,color:'#06b6d4'});}else{updatedItems.push({id:drag.itemId,name:'MIDI Item',startTime:newStart,duration:4*secondsPerBar,notes:[],color:'#a78bfa'});}}}return drag.itemType==='section'?{...t,sections:updatedItems}:{...t,midiItems:updatedItems};});});if(drag.trackId!==targetTrackId){setDraggedSectionItem(prev=>({...prev,trackId:targetTrackId}));}};const handleMouseUp=()=>{const drag=draggedSectionItemRef.current;if(!drag)return;setDraggedSectionItem(null);showToast(`Đã di chuyển ${drag.itemType==='section'?'section':'MIDI item'}.`,'success');};document.addEventListener('mousemove',handleMouseMove);document.addEventListener('mouseup',handleMouseUp);return()=>{document.removeEventListener('mousemove',handleMouseMove);document.removeEventListener('mouseup',handleMouseUp);};},[zoom,activeTab,sessionTabs]);// ── Pending drag: Ctrl+click toggles selection; mousemove > threshold starts copy-drag ──
+useEffect(()=>{const handleMouseMove=e=>{const drag=draggedSectionItemRef.current;if(!drag)return;const wrapper=timelineWrapperRef.current;if(!wrapper)return;autoScrollTimeline(e.clientX);const rect=wrapper.getBoundingClientRect();const scrollLeft=wrapper.scrollLeft;const mouseX=e.clientX-rect.left+scrollLeft;const time=Math.max(0,mouseX/zoom-leadInMarginRef.current);const beatSec=60.0/(parseInt(bpm)||120);const secondsPerBar=beatSec*4;const marginBar=maxDurationRef.current-secondsPerBar;const rawStart=Math.max(0,Math.min(time-drag.clickOffset,marginBar));const newStart=snapTime(rawStart,snapValueRef.current,bpmRef.current);const itemPx=newStart*zoom;const keepMargin=80;if(itemPx>scrollLeft+rect.width-keepMargin){wrapper.scrollLeft=itemPx-rect.width+keepMargin;setCanvasRedrawCount(n=>n+1);}else if(itemPx<scrollLeft+keepMargin){wrapper.scrollLeft=Math.max(0,itemPx-keepMargin);setCanvasRedrawCount(n=>n+1);}updateActiveTracks(prev=>{let movedItem=null;for(let track of prev){const sec=(track.sections||[]).find(it=>it.id===drag.itemId);const mid=(track.midiItems||[]).find(it=>it.id===drag.itemId);if(sec||mid){movedItem=sec||mid;break;}}if(drag.multiIds){var dragOrigStart=drag.multiIds[drag.itemId]?drag.multiIds[drag.itemId].start:0;var delta=newStart-dragOrigStart;return prev.map(t=>{var resultSections=(t.sections||[]).slice();var resultMidis=(t.midiItems||[]).slice();var resultClips=(t.clips||[]).slice();Object.keys(drag.multiIds).forEach(function(mid){var info=drag.multiIds[mid];var newVal=info.start+delta;if(info.type==='section'){var idx=resultSections.findIndex(function(s){return s.id===mid;});if(idx>=0)resultSections[idx]={...resultSections[idx],start:Math.max(0,newVal)};}else if(info.type==='midiItem'){var idx=resultMidis.findIndex(function(mx){return mx.id===mid;});if(idx>=0)resultMidis[idx]={...resultMidis[idx],startTime:Math.max(0,newVal)};}else if(info.type==='clip'){var idx=resultClips.findIndex(function(cx){return cx.id===mid||'default_'+t.id===mid;});if(idx>=0)resultClips[idx]={...resultClips[idx],startTime:Math.max(0,newVal)};}});return{...t,sections:resultSections,midiItems:resultMidis,clips:resultClips};});}const items=drag.itemType==='section'?t.sections||[]:t.midiItems||[];const updatedItems=items.filter(it=>it.id!==drag.itemId);if(movedItem){updatedItems.push(drag.itemType==='section'?{...movedItem,start:newStart}:{...movedItem,startTime:newStart});}return prev.map(t=>drag.itemType==='section'?{...t,sections:updatedItems}:{...t,midiItems:updatedItems});});if(drag.trackId!==targetTrackId){setDraggedSectionItem(prev=>({...prev,trackId:targetTrackId}));}};const handleMouseUp=()=>{const drag=draggedSectionItemRef.current;if(!drag)return;setDraggedSectionItem(null);showToast(`Đã di chuyển ${drag.itemType==='section'?'section':'MIDI item'}.`,'success');};document.addEventListener('mousemove',handleMouseMove);document.addEventListener('mouseup',handleMouseUp);return()=>{document.removeEventListener('mousemove',handleMouseMove);document.removeEventListener('mouseup',handleMouseUp);};},[zoom,activeTab,sessionTabs]);// ── Pending drag: Ctrl+click toggles selection; mousemove > threshold starts copy-drag ──
 useEffect(()=>{const handleMouseMove=e=>{var pd=pendingDragRef.current;if(!pd)return;var dx=e.clientX-pd.startX;if(Math.abs(dx)>5){var pdSnap=pendingDragRef.current;pendingDragRef.current=null;if(handleSectionItemDragStartRef.current)handleSectionItemDragStartRef.current(pdSnap.trackId,pdSnap.itemType,pdSnap.itemId,pdSnap.clickOffset,true,pdSnap.selectedIds);}};document.addEventListener('mousemove',handleMouseMove);var handleMouseUp=function(){pendingDragRef.current=null;};document.addEventListener('mouseup',handleMouseUp);return function(){document.removeEventListener('mousemove',handleMouseMove);document.removeEventListener('mouseup',handleMouseUp);pendingDragRef.current=null;};},[]);// ── Document-level mousemove/mouseup for Section/MIDI item resize ──
 useEffect(()=>{const handleMouseMove=e=>{const resize=resizedSectionItemRef.current;if(!resize)return;const wrapper=timelineWrapperRef.current;if(!wrapper)return;autoScrollTimeline(e.clientX);const rect=wrapper.getBoundingClientRect();const scrollLeft=wrapper.scrollLeft;const mouseX=e.clientX-rect.left+scrollLeft;const time=Math.max(0,mouseX/zoom-leadInMarginRef.current);updateActiveTracks(prev=>prev.map(t=>{if(t.id!==resize.trackId)return t;const items=resize.itemType==='section'?[...(t.sections||[])]:[...(t.midiItems||[])];const idx=items.findIndex(it=>it.id===resize.itemId);if(idx===-1)return t;const item=items[idx];if(resize.side==='left'){const beatSec=60.0/(parseInt(bpm)||120);const newStart=Math.max(0,Math.min(time,resize.originalStart+resize.originalDuration-0.1));const end=resize.originalStart+resize.originalDuration;const newDuration=end-newStart;if(newDuration<0.1)return t;items[idx]=resize.itemType==='section'?{...item,start:newStart,duration:newDuration}:{...item,startTime:newStart,duration:newDuration};}else{const secondsPerBar=60.0/(parseInt(bpm)||120)*4;const marginBar=maxDurationRef.current-secondsPerBar;const clampedTime=Math.min(time,marginBar);const snappedDuration=snapValueRef.current!=='free'?snapTime(clampedTime-resize.originalStart,snapValueRef.current,bpm):clampedTime-resize.originalStart;const newDuration=Math.max(0.1,snappedDuration);items[idx]={...item,duration:newDuration};}return resize.itemType==='section'?{...t,sections:items}:{...t,midiItems:items};}));setCanvasRedrawCount(n=>n+1);const edgePx=(resize.side==='left'?Math.max(0,time):time)*zoom;const keepMargin=80;if(edgePx>scrollLeft+rect.width-keepMargin){wrapper.scrollLeft=edgePx-rect.width+keepMargin;setCanvasRedrawCount(n=>n+1);}else if(edgePx<scrollLeft+keepMargin){wrapper.scrollLeft=Math.max(0,edgePx-keepMargin);setCanvasRedrawCount(n=>n+1);}};const handleMouseUp=()=>{const resize=resizedSectionItemRef.current;if(!resize)return;setResizedSectionItem(null);};document.addEventListener('mousemove',handleMouseMove);document.addEventListener('mouseup',handleMouseUp);return()=>{document.removeEventListener('mousemove',handleMouseMove);document.removeEventListener('mouseup',handleMouseUp);};},[zoom,activeTab,sessionTabs]);// ── Sweep Select mousemove/mouseup ──
 useEffect(()=>{const handleMouseMove=e=>{if(!isSweepingRef.current)return;const wrapper=timelineWrapperRef.current;if(!wrapper)return;const rect=wrapper.getBoundingClientRect();const scrollLeft=wrapper.scrollLeft;const mouseX=e.clientX-rect.left+scrollLeft;const time=Math.max(0,mouseX/zoom-leadInMarginRef.current);setSweepSelect(prev=>{var updated=prev?{...prev,endTime:time}:null;sweepSelectRef.current=updated;return updated;});};const handleMouseUp=()=>{if(!isSweepingRef.current)return;isSweepingRef.current=false;sweepTrackIdRef.current=null;const sweep=sweepSelectRef.current;sweepSelectRef.current=null;if(sweep){const start=Math.min(sweep.startTime,sweep.endTime);const end=Math.max(sweep.startTime,sweep.endTime);// Small movement (no real drag) → deselect all