feat: "On this day" memories — photos from previous years

Add a Memories view that surfaces photos taken on the current date in
previous years (like Google Photos / Immich). Only uses EXIF-sourced
dates to avoid false matches from filesystem timestamps.

- Backend: GET /api/v1/photos/memories returns groups by year, up to
  12 photos each, filtered to non-discarded/non-hidden EXIF dates
- Frontend: MemoriesView with year-grouped thumbnail grid
- Sidebar: new "Memories" nav item with clock icon

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

backend/app/routers/photos.py

@@ -352,6 +352,74 @@ async def list_photos_with_gps(
     ]
 
 
+@router.get("/memories")
+async def get_memories(
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """'On this day' — photos taken on this date in previous years.
+
+    Returns groups keyed by year, each with up to 12 photos. Only
+    considers non-discarded, non-hidden photos with an EXIF-sourced
+    taken_at (no filesystem-guessed dates to avoid false matches).
+    """
+    from sqlalchemy import extract
+
+    today = datetime.now().date()
+
+    result = await db.execute(
+        select(
+            Photo.id,
+            Photo.filename,
+            Photo.taken_at,
+            Photo.thumb_small,
+            Photo.thumb_medium,
+            Photo.media_type,
+            Photo.width,
+            Photo.height,
+            Photo.rating,
+        )
+        .where(
+            Photo.user_id == current_user.id,
+            Photo.is_discarded.is_(False),
+            Photo.is_hidden.is_(False),
+            Photo.taken_at.is_not(None),
+            Photo.taken_at_source == "exif",
+            extract("month", Photo.taken_at) == today.month,
+            extract("day", Photo.taken_at) == today.day,
+            extract("year", Photo.taken_at) < today.year,
+        )
+        .order_by(Photo.taken_at.desc())
+    )
+    rows = result.all()
+
+    # Group by year
+    years: dict[int, list] = {}
+    for row in rows:
+        year = row.taken_at.year
+        group = years.setdefault(year, [])
+        if len(group) >= 12:
+            continue
+        group.append({
+            "id": row.id,
+            "filename": row.filename,
+            "taken_at": row.taken_at.isoformat(),
+            "thumb_small": row.thumb_small,
+            "thumb_medium": row.thumb_medium,
+            "media_type": row.media_type,
+            "width": row.width,
+            "height": row.height,
+            "rating": row.rating,
+        })
+
+    memories = [
+        {"year": year, "years_ago": today.year - year, "photos": photos}
+        for year, photos in sorted(years.items())
+    ]
+
+    return {"date": today.isoformat(), "memories": memories}
+
+
 @router.get("/{photo_id}")
 async def get_photo(
     photo_id: str,

frontend/src/App.tsx

@@ -2,6 +2,7 @@ import { useState } from 'react'
 import { Timeline } from './components/timeline/Timeline'
 import { DuplicatesView } from './components/duplicates/DuplicatesView'
 import { MapView } from './components/map/MapView'
+import { MemoriesView } from './components/memories/MemoriesView'
 import { PeopleView } from './components/people/PeopleView'
 import { TagsView } from './components/tags/TagsView'
 import { ColorsView } from './components/colors/ColorsView'
@@ -87,6 +88,8 @@ function MainApp() {
               <SettingsPage />
             ) : currentSection === 'map' ? (
               <MapView />
+            ) : currentSection === 'memories' ? (
+              <MemoriesView />
             ) : currentSection === 'duplicates' ? (
               <DuplicatesView />
             ) : currentSection === 'people' ? (

frontend/src/components/layout/LeftSidebar.tsx

@@ -23,6 +23,7 @@ import {
   User as UserIcon,
   LogOut,
   Shield,
+  Clock,
 } from 'lucide-react'
 import clsx from 'clsx'
 import { sourceFolders, photos as photosApi, type FolderTreeNode } from '../../services/api'
@@ -407,6 +408,7 @@ export function LeftSidebar({ onCollapse }: LeftSidebarProps) {
         { id: 'people', label: 'People', icon: <Users className="h-4 w-4" />, count: peopleTotalCount },
         { id: 'colors', label: 'Colors', icon: <Palette className="h-4 w-4" />, count: stats?.colored ?? 0 },
         { id: 'map', label: 'Map', icon: <MapPin className="h-4 w-4" />, count: stats?.with_gps ?? 0 },
+        { id: 'memories', label: 'Memories', icon: <Clock className="h-4 w-4" /> },
         { id: 'duplicates', label: 'Duplicates', icon: <Copy className="h-4 w-4" />, count: stats?.duplicates ?? 0 },
         { id: 'discarded', label: 'Discarded', icon: <Trash2 className="h-4 w-4" />, count: stats?.discarded ?? 0 },
       ],

frontend/src/components/memories/MemoriesView.tsx

@@ -0,0 +1,70 @@
+import { useQuery } from '@tanstack/react-query'
+import { photos } from '../../services/api'
+import type { MemoryGroup } from '../../services/api'
+
+export function MemoriesView() {
+  const { data, isLoading } = useQuery({
+    queryKey: ['memories'],
+    queryFn: () => photos.memories(),
+    staleTime: 60_000 * 30, // 30 min — date doesn't change often
+  })
+
+  if (isLoading) {
+    return (
+      <div className="flex items-center justify-center h-64 text-neutral-500">
+        Loading memories...
+      </div>
+    )
+  }
+
+  const memories = data?.memories ?? []
+
+  if (memories.length === 0) {
+    return (
+      <div className="flex flex-col items-center justify-center h-64 text-neutral-500 gap-2">
+        <p className="text-lg font-medium">No memories for today</p>
+        <p className="text-sm">Photos taken on this date in previous years will appear here.</p>
+      </div>
+    )
+  }
+
+  return (
+    <div className="p-6 space-y-8 max-w-5xl mx-auto">
+      <h2 className="text-xl font-semibold text-neutral-200">
+        On This Day &mdash; {data?.date}
+      </h2>
+
+      {memories.map((group: MemoryGroup) => (
+        <section key={group.year} className="space-y-3">
+          <h3 className="text-sm font-medium text-neutral-400 uppercase tracking-wide">
+            {group.year} &middot; {group.years_ago} year{group.years_ago !== 1 ? 's' : ''} ago
+          </h3>
+          <div className="grid grid-cols-2 sm:grid-cols-3 md:grid-cols-4 lg:grid-cols-6 gap-2">
+            {group.photos.map((photo) => (
+              <div
+                key={photo.id}
+                className="aspect-square rounded-lg overflow-hidden bg-neutral-800 relative group"
+              >
+                {photo.thumb_small ? (
+                  <img
+                    src={`/api/v1/photos/${photo.id}/thumb/small`}
+                    alt={photo.filename}
+                    className="w-full h-full object-cover"
+                    loading="lazy"
+                  />
+                ) : (
+                  <div className="w-full h-full flex items-center justify-center text-neutral-600 text-xs">
+                    No thumb
+                  </div>
+                )}
+                <div className="absolute bottom-0 left-0 right-0 bg-gradient-to-t from-black/60 to-transparent px-2 py-1 opacity-0 group-hover:opacity-100 transition-opacity">
+                  <p className="text-xs text-white truncate">{photo.filename}</p>
+                </div>
+              </div>
+            ))}
+          </div>
+        </section>
+      ))}
+    </div>
+  )
+}

frontend/src/services/api.ts

@@ -328,6 +328,12 @@ export const photos = {
   getProxyUrl: (photoId: string) => {
     return `${API_BASE_URL}/photos/${photoId}/proxy`
   },
+
+  /** "On this day" memories — photos taken on this date in previous years. */
+  memories: async (): Promise<MemoriesResponse> => {
+    const response = await api.get('/photos/memories')
+    return response.data
+  },
 }
 
 // Library API
@@ -577,6 +583,31 @@ export interface DuplicateGroupsResponse {
   total_members: number
 }
 
+// ── Memories ("On this day") ────────────────────────────────────────────
+
+export interface MemoryPhoto {
+  id: string
+  filename: string
+  taken_at: string
+  thumb_small: string | null
+  thumb_medium: string | null
+  media_type: string
+  width: number | null
+  height: number | null
+  rating: number
+}
+
+export interface MemoryGroup {
+  year: number
+  years_ago: number
+  photos: MemoryPhoto[]
+}
+
+export interface MemoriesResponse {
+  date: string
+  memories: MemoryGroup[]
+}
+
 export interface LibraryStats {
   all_photos: number
   rated: number