FIX: sửa lỗi khi quét chọn duration để loop và khi bật nút loop thì tự động giãn ra bar 18

app/static/js/app.jsx

@@ -17610,6 +17610,9 @@ const App = () => {
     setSelectedTrackId(trackId);
     captureSelectionUndo();
     clearLocalSelection();
+    // A fresh region selection re-enables selection-looping (a previous
+    // Ctrl+click "clear selection" must not keep blocking the new region).
+    setSelectionCleared(false);
     localSelectionAnchorRef.current = time;
     setSelectionMode('local');
     setLocalSelectionTrackId(trackId);
@@ -22525,24 +22528,31 @@ const App = () => {
               setSubTabs(prev => prev.map(s => s.id === activeTab ? { ...s, selectionStart: 0, selectionEnd: loopEndTime } : s));
             }
           } else {
-            // Main timeline: auto-derive loop end from tracks
-            const bpmVal = parseInt(bpm) || 120;
-            const secPerBar = (60.0 / bpmVal) * 4;
-            let maxEnd = 0;
-            activeTracks.forEach(t => {
-              (t.clips || []).forEach(c => {
-                const end = (c.startTime || 0) + (c.duration || 0);
-                if (end > maxEnd) maxEnd = end;
+            // Main timeline / section tab: if the user already selected a loop
+            // region, KEEP it — only auto-derive (0 → content end) when no
+            // selection exists yet. Previously this always overwrote the
+            // selection with 0 → (contentEnd + 2 bars).
+            const hasSel = (selectionMode === 'local' && selLeft !== null && selRight !== null && selRight > selLeft)
+              || (selectionStart !== null && selectionEnd !== null && selectionEnd > selectionStart);
+            if (!hasSel) {
+              const bpmVal = parseInt(bpm) || 120;
+              const secPerBar = (60.0 / bpmVal) * 4;
+              let maxEnd = 0;
+              activeTracks.forEach(t => {
+                (t.clips || []).forEach(c => {
+                  const end = (c.startTime || 0) + (c.duration || 0);
+                  if (end > maxEnd) maxEnd = end;
+                });
+                (t.items || []).forEach(it => {
+                  const end = (it.start || 0) + (it.duration || 4);
+                  if (end > maxEnd) maxEnd = end;
+                });
               });
-              (t.items || []).forEach(it => {
-                const end = (it.start || 0) + (it.duration || 4);
-                if (end > maxEnd) maxEnd = end;
-              });
-            });
-            if (maxEnd > 0) {
-              const loopEnd = maxEnd + secPerBar * 2;
-              setSelectionStart(0);
-              setSelectionEnd(loopEnd);
+              if (maxEnd > 0) {
+                const loopEnd = maxEnd + secPerBar * 2;
+                setSelectionStart(0);
+                setSelectionEnd(loopEnd);
+              }
             }
           }
         },