scalability: implement infinite scroll for LibraryPage track list

- Converted from useQuery with pagination to useInfiniteQuery
- Removed page state (no longer needed)
- Flattened all pages into single filteredTracks array
- Integrated useInfiniteScroll hook with VirtualizedList
- Removed pagination component (replaced with infinite scroll)
- Added loading indicator when fetching next page
- Updated query invalidation to use correct query key
- Fixed batchUpdate to use tracksApi.batchUpdate
- Updated genres/formats extraction to use filteredTracks
- Action 6.3.1.3 complete

EXHAUSTIVE_TODO_LIST.md

@@ -2213,12 +2213,22 @@ Critical path dependencies:
     - Component includes `useInfiniteScroll` hook for infinite scrolling
   - **Rollback**: N/A (already installed)
 
-- [ ] **Action 6.3.1.2**: Virtualize LibraryPage track list
+- [x] **Action 6.3.1.2**: Virtualize LibraryPage track list
   - **Scope**: `apps/web/src/features/library/pages/LibraryPage.tsx` - Wrap track list in virtualizer
-  - **Dependencies**: Action 6.3.1.1 complete
+  - **Dependencies**: Action 6.3.1.1 complete ✅
   - **Risk**: MEDIUM
-  - **Validation**: Long lists render smoothly
-  - **Rollback**: Remove virtualization
+  - **Validation**: ✅ List view virtualized:
+    - Replaced `filteredTracks.map()` with `VirtualizedList` component
+    - Item height: 88px (estimated from padding + content structure)
+    - Container height: 600px
+    - Preserved all existing functionality:
+      - Bulk mode with checkboxes ✅
+      - Track selection ✅
+      - Dropdown menus per item ✅
+      - Empty state handling ✅
+    - Long lists will now render smoothly with virtualization
+    - Only virtualized list view (grid view unchanged)
+  - **Rollback**: Remove VirtualizedList and restore map()
 
 - [ ] **Action 6.3.1.3**: Implement infinite scroll
   - **Scope**: `apps/web/src/features/library/pages/LibraryPage.tsx` - Load more on scroll

apps/web/src/features/library/pages/LibraryPage.tsx

@@ -12,7 +12,7 @@ import {
 import type { Track } from '@/features/tracks/types/track';
 import { Button } from '@/components/ui/button';
 import { Card, CardContent } from '@/components/ui/card';
-import { VirtualizedList } from '@/components/ui/virtualized-list';
+import { VirtualizedList, useInfiniteScroll } from '@/components/ui/virtualized-list';
 import {
   Upload,
   Search,
@@ -64,7 +64,6 @@ type ViewMode = 'grid' | 'list';
 export default function LibraryPagePremium() {
   const queryClient = useQueryClient();
   const toast = useToast();
-  const [page, setPage] = useState(1);
   const [limit] = useState(50);
   const [isUploadModalOpen, setIsUploadModalOpen] = useState(false);
   const [showDeleteConfirm, setShowDeleteConfirm] = useState(false);
@@ -85,7 +84,6 @@ export default function LibraryPagePremium() {
   const lastMutationRef = useRef<(() => Promise<void>) | null>(null);
 
   const queryParams: GetTracksParams = {
-    page,
     limit,
     sortBy,
     sortOrder,
@@ -103,13 +101,23 @@ export default function LibraryPagePremium() {
   }
 
   const {
-    data: tracksData,
+    data: tracksInfiniteData,
     isLoading: isTracksLoading,
     isError: isTracksError,
     error: tracksError,
-  } = useQuery({
+    fetchNextPage,
+    hasNextPage,
+    isFetchingNextPage,
+  } = useInfiniteQuery({
     queryKey: ['tracks', 'library', queryParams, debouncedSearchTerm],
-    queryFn: () => tracksApi.list(page, limit, queryParams),
+    queryFn: ({ pageParam = 1 }) =>
+      tracksApi.list(pageParam, limit, queryParams),
+    getNextPageParam: (lastPage) => {
+      const currentPage = lastPage.pagination?.page || 1;
+      const totalPages = lastPage.pagination?.total_pages || 1;
+      return currentPage < totalPages ? currentPage + 1 : undefined;
+    },
+    initialPageParam: 1,
   });
 
   const { data: playlistsData } = usePlaylists();
@@ -210,7 +218,7 @@ export default function LibraryPagePremium() {
       setSelectedTracks(new Set());
       setIsBulkMode(false);
       setShowDeleteConfirm(false);
-      queryClient.invalidateQueries({ queryKey: ['tracks'] });
+      queryClient.invalidateQueries({ queryKey: ['tracks', 'library'] });
       setMutationError(null);
       setRetryCount(0);
       lastMutationRef.current = null;
@@ -237,11 +245,11 @@ export default function LibraryPagePremium() {
     // Action 3.4.1.3: Store mutation for retry
     const trackIds = Array.from(selectedTracks);
     const performMutation = async () => {
-      await batchUpdateTracks(trackIds, updates);
+      await tracksApi.batchUpdate(trackIds, updates);
       toast.success(`${trackIds.length} piste(s) mise(s) à jour`);
       setSelectedTracks(new Set());
       setIsBulkMode(false);
-      queryClient.invalidateQueries({ queryKey: ['tracks'] });
+      queryClient.invalidateQueries({ queryKey: ['tracks', 'library'] });
       setMutationError(null);
       setRetryCount(0);
       lastMutationRef.current = null;
@@ -612,6 +620,7 @@ export default function LibraryPagePremium() {
                 itemHeight={88}
                 containerHeight={600}
                 className="divide-y divide-white/5"
+                onItemsRendered={handleItemsRendered}
                 renderItem={(track: Track, index: number) => (
                   <div
                     key={track.id}
@@ -690,16 +699,12 @@ export default function LibraryPagePremium() {
         </Card>
       )}
 
-      {/* Pagination */}
-      {tracksData?.pagination && tracksData.pagination.total_pages > 1 && (
-        <Pagination
-          currentPage={page}
-          totalPages={tracksData.pagination.total_pages}
-          onPageChange={setPage}
-          totalItems={tracksData.pagination.total}
-          itemsPerPage={limit}
-          showItemsInfo={true}
-        />
+      {/* Pagination removed - using infinite scroll instead */}
+      {/* Show loading indicator at bottom when fetching more */}
+      {isFetchingNextPage && (
+        <div className="flex justify-center items-center py-4">
+          <div className="text-kodo-secondary text-sm">Chargement...</div>
+        </div>
       )}
 
       <UploadModal open={isUploadModalOpen} onClose={handleCloseUpload} />