fix(ui): improve drag selection scroll behavior, add right-click to unpin sidebar items, close preview on back navigation, fix shared files alignment

frontend/src/components/FileExplorer.tsx

@@ -220,6 +220,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
     const handlePopState = (e: PopStateEvent) => {
       if (e.state && e.state.path) setCurrentPath(e.state.path);
       else setCurrentPath(new URLSearchParams(window.location.search).get('path') || '.');
+      setPreviewFile(null);
     };
     window.addEventListener('popstate', handlePopState);
     return () => window.removeEventListener('popstate', handlePopState);
@@ -273,7 +274,9 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
   const [pinnedOrder, setPinnedOrder] = useState<string[]>([]);
   const [dragOverPinnedItem, setDragOverPinnedItem] = useState<string | null>(null);
   const [pinnedRefreshCounter, setPinnedRefreshCounter] = useState(0);
+  const [selectedFiles, setSelectedFiles] = useState<Set<string>>(new Set());
   const [selectionBox, setSelectionBox] = useState<{ startX: number; startY: number; currentX: number; currentY: number } | null>(null);
+  const lastMousePos = useRef<{clientX: number, clientY: number} | null>(null);
   const [initialSelectedFiles, setInitialSelectedFiles] = useState<Set<string>>(new Set());
   const searchTimeoutRef = useRef<NodeJS.Timeout | undefined>(undefined);
   const [downloadToken, setDownloadToken] = useState<string>('');
@@ -527,12 +530,18 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
     if (target.closest('button') || target.closest('input') || target.closest('[data-file-item]')) {
       return;
     }
+    const rect = mainContainerRef.current!.getBoundingClientRect();
+    const scrollLeft = mainContainerRef.current!.scrollLeft;
+    const scrollTop = mainContainerRef.current!.scrollTop;
+
     setSelectionBox({
-      startX: e.clientX,
-      startY: e.clientY,
-      currentX: e.clientX,
-      currentY: e.clientY,
+      startX: e.clientX - rect.left + scrollLeft,
+      startY: e.clientY - rect.top + scrollTop,
+      currentX: e.clientX - rect.left + scrollLeft,
+      currentY: e.clientY - rect.top + scrollTop,
     });
+    lastMousePos.current = { clientX: e.clientX, clientY: e.clientY };
+
     if (e.shiftKey || e.ctrlKey || e.metaKey) {
       setInitialSelectedFiles(new Set(selectedFiles));
     } else {
@@ -541,26 +550,35 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
     }
   }
 
-  function handlePointerMove(e: React.PointerEvent) {
-    if (!selectionBox) return;
-    setSelectionBox(prev => prev ? { ...prev, currentX: e.clientX, currentY: e.clientY } : null);
+  function updateSelection(clientX: number, clientY: number) {
+    setSelectionBox(prev => {
+      if (!prev || !mainContainerRef.current) return null;
+      const rect = mainContainerRef.current.getBoundingClientRect();
+      const scrollLeft = mainContainerRef.current.scrollLeft;
+      const scrollTop = mainContainerRef.current.scrollTop;
+      
+      const next = { ...prev, currentX: clientX - rect.left + scrollLeft, currentY: clientY - rect.top + scrollTop };
 
-    if (mainContainerRef.current) {
-      const boxLeft = Math.min(selectionBox.startX, e.clientX);
-      const boxRight = Math.max(selectionBox.startX, e.clientX);
-      const boxTop = Math.min(selectionBox.startY, e.clientY);
-      const boxBottom = Math.max(selectionBox.startY, e.clientY);
+      const boxLeft = Math.min(next.startX, next.currentX);
+      const boxRight = Math.max(next.startX, next.currentX);
+      const boxTop = Math.min(next.startY, next.currentY);
+      const boxBottom = Math.max(next.startY, next.currentY);
+
+      const viewportBoxLeft = boxLeft + rect.left - scrollLeft;
+      const viewportBoxRight = boxRight + rect.left - scrollLeft;
+      const viewportBoxTop = boxTop + rect.top - scrollTop;
+      const viewportBoxBottom = boxBottom + rect.top - scrollTop;
 
       const fileNodes = mainContainerRef.current.querySelectorAll('[data-file-item]');
       const newSelected = new Set(initialSelectedFiles);
 
       fileNodes.forEach(node => {
-        const rect = node.getBoundingClientRect();
+        const fileRect = node.getBoundingClientRect();
         const intersects = !(
-          rect.right < boxLeft ||
-          rect.left > boxRight ||
-          rect.bottom < boxTop ||
-          rect.top > boxBottom
+          fileRect.right < viewportBoxLeft ||
+          fileRect.left > viewportBoxRight ||
+          fileRect.bottom < viewportBoxTop ||
+          fileRect.top > viewportBoxBottom
         );
 
         const filePath = node.getAttribute('data-file-path');
@@ -574,6 +592,19 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
       });
 
       setSelectedFiles(newSelected);
+      return next;
+    });
+  }
+
+  function handlePointerMove(e: React.PointerEvent) {
+    if (!selectionBox) return;
+    lastMousePos.current = { clientX: e.clientX, clientY: e.clientY };
+    updateSelection(e.clientX, e.clientY);
+  }
+
+  function handleScroll(e: React.UIEvent) {
+    if (selectionBox && lastMousePos.current) {
+      updateSelection(lastMousePos.current.clientX, lastMousePos.current.clientY);
     }
   }
 
@@ -1270,6 +1301,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
                           borderTop: dragOverPinnedItem === file.path ? '2px solid var(--color-accent)' : '2px solid transparent',
                         }}
                         onClick={() => { setActiveSection('files'); navigateTo(file.path); }}
+                        onContextMenu={(e) => handleContextMenu(e, file)}
                       >
                         <div className="w-4 h-4 flex items-center justify-center flex-shrink-0 [&>svg]:w-4 [&>svg]:h-4">
                           {getFileIcon(file)}
@@ -1490,10 +1522,11 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
               onPointerMove={handlePointerMove}
               onPointerUp={handlePointerUp}
               onPointerLeave={handlePointerUp}
+              onScroll={handleScroll}
             >
           {selectionBox && (
             <div
-              className="fixed z-50 pointer-events-none"
+              className="absolute z-50 pointer-events-none"
               style={{
                 left: Math.min(selectionBox.startX, selectionBox.currentX),
                 top: Math.min(selectionBox.startY, selectionBox.currentY),