revert: drop By Date sidebar node and supporting code

Tried it, didn't add value beyond what the date-grouped timeline
already gives. The grouped, sticky-headered timeline (which kicks
in by default whenever sortBy is taken_at) is the better
affordance for date navigation — duplicating that as a sidebar
drilldown was just clutter.

Removes the full stack:
- LeftSidebar: by-date tree node, byDateChildren computation,
  date-year-/date-month- handlers in applyLibraryNode, isItemActive
  branches that matched a date-range filter, the now-unused
  setDateFrom/setDateTo/filterDateFrom/filterDateTo selectors, and
  the Calendar icon import.
- frontend/src/hooks/useDateBucketsQuery.ts deleted entirely.
- api.ts: library.dateBuckets helper and DateBucketYear/Month types.
- backend/app/routers/library.py: GET /library/date_buckets endpoint
  and its strftime aggregation query.

The dateFrom/dateTo filter state stays in filterStore — the
FilterBar still uses it for the "Date" range inputs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/routers/library.py

@@ -47,50 +47,6 @@ async def trigger_scan():
     
     return {"status": "success", "message": "Library scan started"}
 
-@router.get("/date_buckets")
-async def get_date_buckets(db: AsyncSession = Depends(get_db)):
-    """Aggregate non-discarded photos by year and month based on taken_at.
-    Used by the LeftSidebar 'By Date' subtree to render a year-then-month
-    drilldown without fetching every photo. Returns:
-        [{ year: 2026, count: 5, months: [{ month: 4, count: 5 }] }]
-    """
-    year_expr = func.strftime('%Y', Photo.taken_at)
-    month_expr = func.strftime('%m', Photo.taken_at)
-
-    result = await db.execute(
-        select(
-            year_expr.label('year'),
-            month_expr.label('month'),
-            func.count(Photo.id).label('count'),
-        )
-        .where(
-            Photo.is_discarded == False,  # noqa: E712
-            Photo.taken_at.is_not(None),
-        )
-        .group_by(year_expr, month_expr)
-        .order_by(year_expr.desc(), month_expr.desc())
-    )
-    rows = result.all()
-
-    years: dict[int, dict] = {}
-    for year_str, month_str, count in rows:
-        if not year_str or not month_str:
-            continue
-        try:
-            year = int(year_str)
-            month = int(month_str)
-        except ValueError:
-            continue
-        bucket = years.setdefault(
-            year, {'year': year, 'count': 0, 'months': []}
-        )
-        bucket['count'] += int(count)
-        bucket['months'].append({'month': month, 'count': int(count)})
-
-    # Already ordered by the SQL ORDER BY (newest first), preserve insertion.
-    return list(years.values())
-
-
 @router.get("/scan/status")
 async def get_scan_status(db: AsyncSession = Depends(get_db)):
     """Get current scan status"""

frontend/src/components/layout/LeftSidebar.tsx

@@ -4,7 +4,6 @@ import {
   ChevronDown,
   Folder,
   Image,
-  Calendar,
   Star,
   Trash2,
   Plus,
@@ -16,12 +15,10 @@ import clsx from 'clsx'
 import { AddSourceFolderDialog } from '../dialogs/AddSourceFolderDialog'
 import { sourceFolders, library, photos as photosApi } from '../../services/api'
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query'
-import { format } from 'date-fns'
 import { toast } from '../ToastContainer'
 import { useFilterStore } from '../../store/filterStore'
 import { HeapsPanel } from '../heaps/HeapsPanel'
 import { PHOTO_DRAG_MIME } from '../timeline/PhotoThumbnail'
-import { useDateBucketsQuery } from '../../hooks/useDateBucketsQuery'
 
 interface TreeItem {
   id: string
@@ -43,12 +40,7 @@ export function LeftSidebar() {
   const setRatingMin = useFilterStore((s) => s.setRatingMin)
   const setFlag = useFilterStore((s) => s.setFlag)
   const setFolderId = useFilterStore((s) => s.setFolderId)
-  const setDateFrom = useFilterStore((s) => s.setDateFrom)
-  const setDateTo = useFilterStore((s) => s.setDateTo)
   const filterFolderId = useFilterStore((s) => s.folderId)
-  const filterDateFrom = useFilterStore((s) => s.dateFrom)
-  const filterDateTo = useFilterStore((s) => s.dateTo)
-  const { data: dateBuckets = [] } = useDateBucketsQuery()
   const [dropTargetId, setDropTargetId] = useState<string | null>(null)
 
   // Bulk discard mutation for the drag-onto-Discarded interaction.
@@ -122,26 +114,6 @@ export function LeftSidebar() {
           const folderId = id.slice('folder-'.length)
           clearAllFilters()
           setFolderId(folderId)
-        } else if (id.startsWith('date-year-')) {
-          const year = parseInt(id.slice('date-year-'.length), 10)
-          if (Number.isFinite(year)) {
-            clearAllFilters()
-            setDateFrom(`${year}-01-01`)
-            setDateTo(`${year}-12-31`)
-          }
-        } else if (id.startsWith('date-month-')) {
-          // Format: date-month-YYYY-MM
-          const parts = id.slice('date-month-'.length).split('-')
-          const year = parseInt(parts[0], 10)
-          const month = parseInt(parts[1], 10)
-          if (Number.isFinite(year) && Number.isFinite(month)) {
-            const lastDay = new Date(year, month, 0).getDate()
-            const mm = String(month).padStart(2, '0')
-            const dd = String(lastDay).padStart(2, '0')
-            clearAllFilters()
-            setDateFrom(`${year}-${mm}-01`)
-            setDateTo(`${year}-${mm}-${dd}`)
-          }
         }
     }
   }
@@ -211,22 +183,6 @@ export function LeftSidebar() {
     setExpandedItems(newExpanded)
   }
   
-  // Build the dynamic By Date subtree from the date_buckets aggregation.
-  // Year nodes contain month nodes; clicking either sets the date range
-  // filter (handled in applyLibraryNode). Sorted newest-first by the
-  // backend already.
-  const byDateChildren: TreeItem[] = dateBuckets.map((year) => ({
-    id: `date-year-${year.year}`,
-    label: String(year.year),
-    icon: <Calendar className="h-4 w-4" />,
-    count: year.count,
-    children: year.months.map((m) => ({
-      id: `date-month-${year.year}-${m.month}`,
-      label: format(new Date(year.year, m.month - 1, 1), 'MMMM'),
-      count: m.count,
-    })),
-  }))
-
   const libraryTree: TreeItem[] = [
     {
       id: 'library',
@@ -234,12 +190,6 @@ export function LeftSidebar() {
       icon: <HardDrive className="h-4 w-4" />,
       children: [
         { id: 'all-photos', label: 'All Photos', icon: <Image className="h-4 w-4" />, count: 0 },
-        {
-          id: 'by-date',
-          label: 'By Date',
-          icon: <Calendar className="h-4 w-4" />,
-          children: byDateChildren,
-        },
         { id: 'rated', label: 'Rated', icon: <Star className="h-4 w-4" />, count: 0 },
         { id: 'discarded', label: 'Discarded', icon: <Trash2 className="h-4 w-4" />, count: 0 },
       ],
@@ -261,7 +211,7 @@ export function LeftSidebar() {
   // Derive whether a tree item is currently the "active" filter target.
   // Folder rows are selected when the filter store's folderId matches; the
   // library "All Photos" virtual node is selected when no folder/heap filter
-  // is set; year/month nodes when their date range matches.
+  // is set.
   const isItemActive = (id: string): boolean => {
     if (id.startsWith('folder-')) {
       return filterFolderId === id.slice('folder-'.length)
@@ -269,18 +219,6 @@ export function LeftSidebar() {
     if (id === 'all-photos') {
       return filterFolderId === null && selectedItem === 'all-photos'
     }
-    if (id.startsWith('date-year-')) {
-      const year = id.slice('date-year-'.length)
-      return filterDateFrom === `${year}-01-01` && filterDateTo === `${year}-12-31`
-    }
-    if (id.startsWith('date-month-')) {
-      const parts = id.slice('date-month-'.length).split('-')
-      const year = parseInt(parts[0], 10)
-      const month = parseInt(parts[1], 10)
-      if (!Number.isFinite(year) || !Number.isFinite(month)) return false
-      const mm = String(month).padStart(2, '0')
-      return filterDateFrom === `${year}-${mm}-01` && filterDateTo?.startsWith(`${year}-${mm}-`) === true
-    }
     return selectedItem === id
   }
 

frontend/src/hooks/useDateBucketsQuery.ts

@@ -1,12 +0,0 @@
-import { useQuery } from '@tanstack/react-query'
-import { library, type DateBucketYear } from '../services/api'
-
-export const DATE_BUCKETS_QUERY_KEY = ['library', 'date_buckets'] as const
-
-export function useDateBucketsQuery() {
-  return useQuery<DateBucketYear[]>({
-    queryKey: DATE_BUCKETS_QUERY_KEY,
-    queryFn: library.dateBuckets,
-    staleTime: 60_000,
-  })
-}

frontend/src/services/api.ts

@@ -113,16 +113,6 @@ export const photos = {
 }
 
 // Library API
-export interface DateBucketMonth {
-  month: number
-  count: number
-}
-export interface DateBucketYear {
-  year: number
-  count: number
-  months: DateBucketMonth[]
-}
-
 export const library = {
   scan: async () => {
     const response = await api.post('/library/scan')
@@ -138,12 +128,6 @@ export const library = {
     const response = await api.get('/library/stats')
     return response.data
   },
-
-  /** Year/month aggregation for the sidebar By Date drilldown. */
-  dateBuckets: async (): Promise<DateBucketYear[]> => {
-    const response = await api.get('/library/date_buckets')
-    return response.data
-  },
 }
 
 // Heaps API