Shift + 드래그시 포함되는 카드들의 선택 상태가 토글되도록 수정

src/renderer/handlers/selection.js

@@ -8,6 +8,7 @@ let _rafPending   = false;
 let _lastMoveEvent = null;
 
 let lastSelectedIdx = null;
+let _rbStartSelection = new Set(); // 러버밴드 시작 시점의 선택 스냅샷
 
 export function resetAnchor() {
   lastSelectedIdx = null;
@@ -95,8 +96,10 @@ function _onStart(e) {
   });
 
   const preserve = e.shiftKey || e.ctrlKey || e.metaKey;
+  _rbStartSelection = new Set(_state.selectedIdxs); // 토글 기준점 스냅샷
   if (!preserve) {
     _state.selectedIdxs.clear();
+    _rbStartSelection.clear();
     lastSelectedIdx = null;
     _cb.refreshCardSelection();
   }
@@ -127,12 +130,20 @@ function _processMove() {
   });
 
   const sel = { left, top, right: left + width, bottom: top + height };
-  const preserve = e.shiftKey || e.ctrlKey || e.metaKey;
+  const shiftToggle = e.shiftKey && !e.ctrlKey && !e.metaKey;
+  const preserve    = e.ctrlKey || e.metaKey;
   Array.from(_grid.children).forEach((card, i) => {
     const r = card.getBoundingClientRect();
     const overlaps = !(r.right < sel.left || r.left > sel.right ||
                        r.bottom < sel.top  || r.top  > sel.bottom);
-    if (overlaps) {
+    if (shiftToggle) {
+      // 러버밴드 안: 시작 시점 기준으로 토글 (밖: 시작 시점 상태 복원)
+      if (overlaps ? !_rbStartSelection.has(i) : _rbStartSelection.has(i)) {
+        _state.selectedIdxs.add(i);
+      } else {
+        _state.selectedIdxs.delete(i);
+      }
+    } else if (overlaps) {
       _state.selectedIdxs.add(i);
     } else if (!preserve) {
       _state.selectedIdxs.delete(i);