ui(sidebar): collapsible Library section with Heaps nested inside

Wraps Views, Folders, Shared-with-me, and Heaps in a single
click-to-toggle Library section with a consistent h-9 eyebrow header
(matching the new Date header). Heaps keeps its own eyebrow
sub-section so it sits alongside Folders, and heap rows now reserve
the same chevron-slot spacer as leaf folder rows so indentation
lines up across hierarchies. ActiveHeapCard moves to the very top
of the sidebar so it stays visible under any panel state.

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

backend/app/routers/photos.py

@@ -422,6 +422,8 @@ async def get_memories(
             Photo.width,
             Photo.height,
             Photo.rating,
+            Photo.color_label,
+            Photo.is_discarded,
         )
         .where(
             Photo.user_id == current_user.id,
@@ -454,6 +456,8 @@ async def get_memories(
             "width": row.width,
             "height": row.height,
             "rating": row.rating,
+            "color_label": row.color_label,
+            "is_discarded": row.is_discarded,
         })
 
     memories = [

frontend/src/App.tsx

@@ -29,6 +29,11 @@ import { TooltipProvider } from '@/components/ui/tooltip'
 function MainApp() {
   const [leftSidebarOpen, setLeftSidebarOpen] = useState(true)
   const [rightSidebarOpen, setRightSidebarOpen] = useState(true)
+  // Respect the user's manual collapse of the metadata panel. Once they
+  // close it explicitly (via `i` hotkey or the sidebar toggle button),
+  // selecting a new photo should NOT force it back open. Cleared when
+  // they open it manually again.
+  const rightCollapsedByUser = useRef(false)
   const viewMode = usePhotoStore((state) => state.viewMode)
   const activePhotoId = usePhotoStore((state) => state.activePhotoId)
   const currentSection = useFilterStore((s) => s.currentSection)
@@ -45,9 +50,24 @@ function MainApp() {
   }, [currentSection])
 
   useEffect(() => {
-    setRightSidebarOpen(!!activePhotoId)
+    if (!activePhotoId) {
+      setRightSidebarOpen(false)
+      return
+    }
+    // User explicitly collapsed the panel — don't undo that just because
+    // they picked a different photo.
+    if (rightCollapsedByUser.current) return
+    setRightSidebarOpen(true)
   }, [activePhotoId])
 
+  const toggleRightSidebar = () => {
+    setRightSidebarOpen((prev) => {
+      const next = !prev
+      rightCollapsedByUser.current = !next
+      return next
+    })
+  }
+
   // Bidirectional sync of filter store with URL query params.
   useFilterUrlSync()
 
@@ -56,11 +76,18 @@ function MainApp() {
   // of what filter key it's stored under.
   const { data: allPhotos } = usePhotosQuery()
 
-  // Set up global keyboard shortcuts
+  // Set up global keyboard shortcuts. Prefer the Timeline's published
+  // visible sequence (which respects per-month ordering) over the raw
+  // backend list — otherwise "Space on a blank selection" would open
+  // the globally first photo, which isn't what the user sees at the
+  // top-left of the grid.
   useKeyboardShortcuts({
     onToggleLeftSidebar: () => setLeftSidebarOpen(!leftSidebarOpen),
-    onToggleRightSidebar: () => setRightSidebarOpen(!rightSidebarOpen),
-    getFirstPhotoId: () => allPhotos?.[0]?.id ?? null,
+    onToggleRightSidebar: toggleRightSidebar,
+    getFirstPhotoId: () =>
+      usePhotoStore.getState().visiblePhotoIds[0] ??
+      allPhotos?.[0]?.id ??
+      null,
   })
 
   // Settings page is a full-page section — hide filter bar, right sidebar,
@@ -96,7 +123,7 @@ function MainApp() {
               leftSidebarOpen={leftSidebarOpen}
               rightSidebarOpen={showRightSidebar}
               onToggleLeftSidebar={() => setLeftSidebarOpen(!leftSidebarOpen)}
-              onToggleRightSidebar={() => setRightSidebarOpen(!rightSidebarOpen)}
+              onToggleRightSidebar={toggleRightSidebar}
             />
           )}
           {!isSettings && <DiscardActionBar />}

frontend/src/components/duplicates/DuplicatesView.tsx

@@ -1,6 +1,7 @@
-import { useMemo, useState, useEffect, useCallback } from 'react'
+import { memo, useMemo, useRef, useState, useEffect, useCallback } from 'react'
 import { Copy, Layers, Sparkles, Trash2, Loader2, Info, Crown } from 'lucide-react'
 import { cn } from '@/lib/utils'
+import { useVirtualizer } from '@tanstack/react-virtual'
 import { useMutation, useQueryClient } from '@tanstack/react-query'
 import { Button } from '@/components/ui/button'
 import { formatApiError } from '../../lib/apiError'
@@ -79,26 +80,50 @@ export function DuplicatesView() {
     () => groups.flatMap((g) => g.members.map((m) => m.id)),
     [groups]
   )
+  // Ref mirror so the stable keyboard handler can reach into the latest
+  // groups without re-binding the listener on every render.
+  const groupsRef = useRef(groups)
+  groupsRef.current = groups
 
   // Track the rendered column count of the duplicates grid so ↑/↓ can
   // skip a row instead of jumping a single cell. The grid uses
-  // `repeat(auto-fill, minmax(180px, 1fr))` so columns = floor(width/180).
+  // `repeat(auto-fill, minmax(160px, 1fr))` so columns = floor(width/160).
   // We measure the FIRST section's grid container — every section uses
   // the same auto-fill rule so any one is representative.
   const [columns, setColumns] = useState(4)
+  // With virtualisation the first section can unmount on scroll and
+  // re-mount on scroll back — track the observer so we can disconnect
+  // cleanly every time the ref detaches (previously this leaked).
+  const sampleObserverRef = useRef<ResizeObserver | null>(null)
   const sampleGridRef = useCallback((el: HTMLDivElement | null) => {
+    sampleObserverRef.current?.disconnect()
+    sampleObserverRef.current = null
     if (!el) return
     const measure = () => {
-      const cols = Math.max(1, Math.floor(el.clientWidth / 180))
+      const cols = Math.max(1, Math.floor(el.clientWidth / 160))
       setColumns(cols)
     }
     measure()
     const ro = new ResizeObserver(measure)
     ro.observe(el)
-    // Caller doesn't get the cleanup hook but ResizeObserver disconnects
-    // when the element unmounts, which is fine for our lifecycle.
+    sampleObserverRef.current = ro
   }, [])
 
+  // Virtualise the group list. Each group has a variable height
+  // (header + dynamic row count), so we let TanStack measure rendered
+  // DOM via `measureElement` and use a conservative estimate for
+  // unmeasured rows. ~360px handles a 2-row, 180px-cell section + header
+  // + group padding without underestimating in most cases.
+  const scrollRef = useRef<HTMLDivElement | null>(null)
+  const virtualizer = useVirtualizer({
+    count: groups.length,
+    getScrollElement: () => scrollRef.current,
+    estimateSize: () => 360,
+    overscan: 2,
+    measureElement: (el) => el.getBoundingClientRect().height,
+    getItemKey: (idx) => groups[idx].group_id,
+  })
+
   // Window-level keyboard nav. Mirrors Timeline's handler but walks
   // `allMemberIds` directly — duplicate groups don't have a uniform row
   // grid so we approximate ↑/↓ via the measured `columns` count and
@@ -135,18 +160,25 @@ export function DuplicatesView() {
       const nextId = allMemberIds[nextIdx]
       if (!nextId) return
       selectPhoto(nextId)
-      // Scroll the now-active cell into view if it's off-screen. The
-      // PhotoThumbnail wrapper carries data-dup-id so we can find it
-      // without threading refs through every cell.
-      const el = document.querySelector<HTMLElement>(
-        `[data-dup-id="${nextId}"]`
+      // With the group list virtualised, the destination cell might not
+      // be mounted yet. Scroll its owning group into view first (cheap
+      // virtualizer op), then scrollIntoView on the cell once it mounts.
+      const currentGroups = groupsRef.current
+      const ownerIdx = currentGroups.findIndex((g) =>
+        g.members.some((m) => m.id === nextId)
       )
-      el?.scrollIntoView({ block: 'nearest', inline: 'nearest' })
+      if (ownerIdx >= 0) virtualizer.scrollToIndex(ownerIdx, { align: 'auto' })
+      requestAnimationFrame(() => {
+        const el = document.querySelector<HTMLElement>(
+          `[data-dup-id="${nextId}"]`
+        )
+        el?.scrollIntoView({ block: 'nearest', inline: 'nearest' })
+      })
     }
 
     window.addEventListener('keydown', onKeyDown)
     return () => window.removeEventListener('keydown', onKeyDown)
-  }, [allMemberIds, activePhotoId, columns, selectPhoto])
+  }, [allMemberIds, activePhotoId, columns, selectPhoto, virtualizer])
 
   if (isLoading) {
     return (
@@ -179,8 +211,27 @@ export function DuplicatesView() {
     )
   }
 
+  // Stable handlers — passed through memoised section + thumbnail so
+  // React.memo is actually effective. The `discardMutation.mutate` and
+  // store actions have stable identity already; we wrap them once so the
+  // closure identity doesn't change per render.
+  const allMemberIdsRef = useRef(allMemberIds)
+  allMemberIdsRef.current = allMemberIds
+  const handleKeepBest = useCallback(
+    (discardIds: string[]) => discardMutation.mutate(discardIds),
+    [discardMutation]
+  )
+  const handlePreviewMember = useCallback(
+    (memberId: string) => openPreview(memberId, allMemberIdsRef.current),
+    [openPreview]
+  )
+  const handleSelectMember = useCallback(
+    (memberId: string) => selectPhoto(memberId),
+    [selectPhoto]
+  )
+
   return (
-    <div className="h-full overflow-auto bg-bg p-4 pb-20">
+    <div ref={scrollRef} className="h-full overflow-auto bg-bg p-4 pb-20">
       <div className="mb-4 flex items-center gap-2 text-xs text-text-muted">
         <Info className="h-3.5 w-3.5" />
         <span>
@@ -191,22 +242,43 @@ export function DuplicatesView() {
         </span>
       </div>
 
-      <div className="space-y-6">
-        {groups.map((group, idx) => (
-          <DuplicateGroupSection
-            key={group.group_id}
-            group={group}
-            onKeepBest={(discardIds) => discardMutation.mutate(discardIds)}
-            onPreviewMember={(memberId) => openPreview(memberId, allMemberIds)}
-            onSelectMember={(memberId) => selectPhoto(memberId)}
-            selectedPhotos={selectedPhotos}
-            isPending={discardMutation.isPending}
-            // Hand the column-measurement ref to the first section only
-            // — every section's grid uses the same auto-fill rule so any
-            // one is representative of the rendered column count.
-            gridRef={idx === 0 ? sampleGridRef : undefined}
-          />
-        ))}
+      <div
+        style={{
+          height: virtualizer.getTotalSize(),
+          position: 'relative',
+          width: '100%',
+        }}
+      >
+        {virtualizer.getVirtualItems().map((vItem) => {
+          const group = groups[vItem.index]
+          return (
+            <div
+              key={group.group_id}
+              data-index={vItem.index}
+              ref={virtualizer.measureElement}
+              style={{
+                position: 'absolute',
+                top: 0,
+                left: 0,
+                width: '100%',
+                transform: `translateY(${vItem.start}px)`,
+                paddingBottom: 24,
+              }}
+            >
+              <DuplicateGroupSection
+                group={group}
+                onKeepBest={handleKeepBest}
+                onPreviewMember={handlePreviewMember}
+                onSelectMember={handleSelectMember}
+                selectedPhotos={selectedPhotos}
+                isPending={discardMutation.isPending}
+                // First section feeds the column-count sample ref —
+                // every section uses the same auto-fill rule.
+                gridRef={vItem.index === 0 ? sampleGridRef : undefined}
+              />
+            </div>
+          )
+        })}
       </div>
     </div>
   )
@@ -225,7 +297,7 @@ interface DuplicateGroupSectionProps {
   gridRef?: (el: HTMLDivElement | null) => void
 }
 
-function DuplicateGroupSection({
+const DuplicateGroupSection = memo(function DuplicateGroupSection({
   group,
   onKeepBest,
   onPreviewMember,
@@ -251,6 +323,25 @@ function DuplicateGroupSection({
   const discardCount = group.member_count - 1
   const isExact = group.reason === 'exact'
 
+  // Adapt members to Photo once per group (group.members reference is
+  // stable across renders as long as the query data doesn't change),
+  // so PhotoThumbnail's memo doesn't re-render on parent tick.
+  const photoByMemberId = useMemo(() => {
+    const map = new Map<string, Photo>()
+    for (const m of group.members) map.set(m.id, memberToPhoto(m))
+    return map
+  }, [group.members])
+
+  const handleClick = useCallback(
+    (p: Photo) => onSelectMember(p.id),
+    [onSelectMember]
+  )
+  const handleDoubleClick = useCallback(
+    (p: Photo) => onPreviewMember(p.id),
+    [onPreviewMember]
+  )
+  const selectedSet = useMemo(() => new Set(selectedPhotos), [selectedPhotos])
+
   return (
     <section className="rounded-lg border border-border bg-surface">
       <header className="flex items-center justify-between gap-3 border-b border-border px-3 py-2">
@@ -295,7 +386,7 @@ function DuplicateGroupSection({
         className="grid gap-1 p-2"
         style={{
           gridTemplateColumns:
-            'repeat(auto-fill, minmax(180px, 1fr))',
+            'repeat(auto-fill, 160px)',
         }}
       >
         {group.members.map((member) => {
@@ -307,12 +398,12 @@ function DuplicateGroupSection({
               className="group/dup relative"
             >
               <PhotoThumbnail
-                photo={memberToPhoto(member)}
-                size={180}
+                photo={photoByMemberId.get(member.id)!}
+                size={160}
                 fill
-                isSelected={selectedPhotos.includes(member.id)}
-                onClick={(p) => onSelectMember(p.id)}
-                onDoubleClick={(p) => onPreviewMember(p.id)}
+                isSelected={selectedSet.has(member.id)}
+                onClick={handleClick}
+                onDoubleClick={handleDoubleClick}
               />
               {/* BEST pill — top-right, pick-coloured. Composes the same
                *  THUMB_BADGE_* family used by PhotoThumbnail so the full
@@ -373,7 +464,7 @@ function DuplicateGroupSection({
       </div>
     </section>
   )
-}
+})
 
 // ── Helpers ──────────────────────────────────────────────────────────────
 

frontend/src/components/filter/DateRangePicker.tsx

@@ -0,0 +1,489 @@
+import { memo, useCallback, useEffect, useMemo, useRef, useState } from 'react'
+import { Filter, X } from 'lucide-react'
+import { DayPicker } from 'react-day-picker'
+import { useVirtualizer } from '@tanstack/react-virtual'
+import { cn } from '@/lib/utils'
+import { usePhotosQuery } from '../../hooks/usePhotosQuery'
+import { usePhotoStore } from '../../store/photoStore'
+import {
+  Popover,
+  PopoverContent,
+  PopoverTrigger,
+} from '@/components/ui/popover'
+import { buttonVariants } from '@/components/ui/button'
+
+// Fixed month height so snap points are uniform regardless of whether
+// a given month lays out as 5 or 6 weeks. Sized to fit the tallest
+// (6-week) case: caption ~18px + weekday head ~14px + 6 rows × 24px +
+// padding ~12px.
+const MONTH_HEIGHT = 200
+
+/**
+ * Continuous vertical calendar. Renders one DayPicker per month from
+ * the earliest booked year up to next month, stacked in a scrollable
+ * column. As the user scrolls the Timeline, the calendar
+ * programmatically scrolls the matching month into view — so the date
+ * picker is always showing "what the user is looking at."
+ *
+ * Clicking days does nothing here (no range selection); range setting
+ * lives in the popover reachable via the Filter button.
+ */
+export function DateRangePicker({
+  from,
+  to,
+  onFromChange,
+  onToChange,
+}: {
+  from: string | null
+  to: string | null
+  onFromChange: (v: string | null) => void
+  onToChange: (v: string | null) => void
+}) {
+  const { data: photos = [] } = usePhotosQuery()
+
+  // Photo count per yyyy-mm-dd — drives a GitHub-contribution-style
+  // intensity heatmap on the calendar. Slicing the ISO string verbatim
+  // avoids timezone drift (Date round-trips would shift photos near
+  // midnight into the adjacent day).
+  const countByDay = useMemo(() => {
+    const m = new Map<string, number>()
+    for (const p of photos) {
+      if (!p.taken_at) continue
+      const key = p.taken_at.slice(0, 10)
+      if (!/^\d{4}-\d{2}-\d{2}$/.test(key)) continue
+      m.set(key, (m.get(key) ?? 0) + 1)
+    }
+    return m
+  }, [photos])
+
+  // Thresholds picked from the count distribution so the heatmap adapts
+  // to the library: a 100k-photo archive and a 200-photo album both get
+  // meaningful contrast. Quartiles of non-zero day counts, with a
+  // floor so a very flat distribution still buckets into 4 steps.
+  const levelThresholds = useMemo(() => {
+    const counts = Array.from(countByDay.values()).sort((a, b) => a - b)
+    if (counts.length === 0) return [1, 2, 4, 8]
+    const q = (p: number) =>
+      counts[Math.min(counts.length - 1, Math.floor(counts.length * p))]
+    // 4 buckets: [≥1, ≥q50, ≥q75, ≥q95]
+    const t1 = 1
+    const t2 = Math.max(2, q(0.5))
+    const t3 = Math.max(t2 + 1, q(0.75))
+    const t4 = Math.max(t3 + 1, q(0.95))
+    return [t1, t2, t3, t4]
+  }, [countByDay])
+
+  // Oldest year in the cache — drives the top of the month list.
+  const currentDate = new Date()
+  const earliestYear = useMemo(() => {
+    let min = currentDate.getFullYear()
+    for (const k of countByDay.keys()) {
+      const y = parseInt(k.slice(0, 4), 10)
+      if (!Number.isNaN(y) && y < min) min = y
+    }
+    return min
+  }, [countByDay, currentDate])
+
+  // Flat list of yyyy-mm keys from earliest year's January up through
+  // (and including) next month, newest first — matches the default
+  // timeline sort order (desc), so scroll direction feels consistent.
+  const monthKeys = useMemo(() => {
+    const end = new Date(currentDate.getFullYear(), currentDate.getMonth() + 1, 1)
+    const start = new Date(earliestYear, 0, 1)
+    const out: string[] = []
+    const cursor = new Date(end)
+    while (cursor >= start) {
+      const y = cursor.getFullYear()
+      const m = String(cursor.getMonth() + 1).padStart(2, '0')
+      out.push(`${y}-${m}`)
+      cursor.setMonth(cursor.getMonth() - 1)
+    }
+    return out
+  }, [earliestYear, currentDate])
+
+  // O(1) id→taken_at map so activePhotoId lookups don't linear-scan
+  // the whole library on every selection change.
+  const takenAtById = useMemo(() => {
+    const m = new Map<string, string | null | undefined>()
+    for (const p of photos) m.set(p.id, p.taken_at)
+    return m
+  }, [photos])
+
+  // Month the calendar should currently centre on. Priority:
+  //   1. The currently focused photo's taken_at (follows click/arrow
+  //      navigation — lets the calendar land on the right month even
+  //      before any scroll has happened).
+  //   2. The Timeline's published anchor date (live scroll tracking).
+  //   3. A picked from/to bound (so opening the picker with a saved
+  //      filter doesn't snap back to today).
+  //   4. Current month, as a final fallback.
+  const visibleAnchorDate = usePhotoStore((s) => s.visibleAnchorDate)
+  const activePhotoId = usePhotoStore((s) => s.activePhotoId)
+  const activePhotoDate = useMemo(() => {
+    if (!activePhotoId) return null
+    const iso = takenAtById.get(activePhotoId)?.slice(0, 10)
+    return iso && /^\d{4}-\d{2}-\d{2}$/.test(iso) ? iso : null
+  }, [activePhotoId, takenAtById])
+  const anchorMonthKey = useMemo(() => {
+    const src = activePhotoDate ?? visibleAnchorDate ?? from ?? to
+    if (src && /^\d{4}-\d{2}/.test(src)) return src.slice(0, 7)
+    return `${currentDate.getFullYear()}-${String(
+      currentDate.getMonth() + 1,
+    ).padStart(2, '0')}`
+  }, [activePhotoDate, visibleAnchorDate, from, to, currentDate])
+
+  // Index-in-monthKeys of the anchor month — needed both to drive the
+  // virtualizer's scrollToIndex and as the O(1) lookup for the month
+  // list below (avoids a linear indexOf per render).
+  const monthIndex = useMemo(() => {
+    const m = new Map<string, number>()
+    for (let i = 0; i < monthKeys.length; i++) m.set(monthKeys[i], i)
+    return m
+  }, [monthKeys])
+
+  // Virtualise the month list. Mounting 100+ DayPickers up-front was
+  // the dominant cost of opening the calendar; with the viewport fixed
+  // to MONTH_HEIGHT we only keep ~1 mounted at any moment (+overscan).
+  const scrollRef = useRef<HTMLDivElement | null>(null)
+  const virtualizer = useVirtualizer({
+    count: monthKeys.length,
+    getScrollElement: () => scrollRef.current,
+    estimateSize: () => MONTH_HEIGHT,
+    overscan: 1,
+    getItemKey: (idx) => monthKeys[idx],
+  })
+
+  // Jump instantly to the anchor on first mount; smooth-scroll for
+  // subsequent moves so a click-through-sidebar feels natural while
+  // the initial paint lands on the right month without animation.
+  //
+  // Only depend on `anchorMonthKey` — `virtualizer` gets a new object
+  // identity on most renders, so including it would refire this effect
+  // constantly and fight the user's own wheel/drag scroll in the
+  // calendar viewport. We read the latest virtualizer via a ref.
+  const virtualizerRef = useRef(virtualizer)
+  virtualizerRef.current = virtualizer
+  const didInitialScrollRef = useRef(false)
+  useEffect(() => {
+    const idx = monthIndex.get(anchorMonthKey)
+    if (idx === undefined) return
+    virtualizerRef.current.scrollToIndex(idx, {
+      align: 'start',
+      behavior: didInitialScrollRef.current ? 'smooth' : 'auto',
+    })
+    didInitialScrollRef.current = true
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [anchorMonthKey, monthIndex])
+
+  const hasSelection = !!(from || to)
+
+  // Precomputed (time, id) array sorted ascending, so "closest photo
+  // to a clicked date" is an O(log n) binary search instead of a
+  // linear scan that allocates a Date per photo on every click.
+  const photosByDate = useMemo(() => {
+    const out: { t: number; id: string }[] = []
+    for (const p of photos) {
+      if (!p.taken_at) continue
+      const d = parseIsoDate(p.taken_at.slice(0, 10)).getTime()
+      if (!Number.isFinite(d)) continue
+      out.push({ t: d, id: p.id })
+    }
+    out.sort((a, b) => a.t - b.t)
+    return out
+  }, [photos])
+
+  // Click a day → find the photo whose taken_at is closest and jump
+  // the timeline to it. Empty days still jump to the nearest neighbour
+  // so a click never no-ops.
+  const jumpToPhoto = usePhotoStore((s) => s.jumpToPhoto)
+  // Stable identity so MonthGrid's memo actually skips unchanged months.
+  const onDayClick = useCallback(
+    (iso: string) => {
+      if (photosByDate.length === 0) return
+      const target = parseIsoDate(iso).getTime()
+      // Binary search for the insertion point.
+      let lo = 0
+      let hi = photosByDate.length
+      while (lo < hi) {
+        const mid = (lo + hi) >> 1
+        if (photosByDate[mid].t < target) lo = mid + 1
+        else hi = mid
+      }
+      // Compare the two neighbours and pick whichever is closer.
+      const prev = photosByDate[lo - 1]
+      const next = photosByDate[lo]
+      const best =
+        !prev ? next
+        : !next ? prev
+        : target - prev.t <= next.t - target ? prev
+        : next
+      if (best) jumpToPhoto(best.id)
+    },
+    [photosByDate, jumpToPhoto]
+  )
+
+  return (
+    <div className="space-y-1.5">
+      <div className="flex items-center justify-end gap-1">
+        <DateFilterPopover
+          from={from}
+          to={to}
+          onFromChange={onFromChange}
+          onToChange={onToChange}
+        />
+        {hasSelection && (
+          <button
+            onClick={() => {
+              onFromChange(null)
+              onToChange(null)
+            }}
+            className="shrink-0 rounded px-1.5 py-0.5 text-[10px] uppercase tracking-wider text-text-muted hover:bg-surface-2 hover:text-text"
+          >
+            Clear
+          </button>
+        )}
+      </div>
+      {/* Single-month viewport — container height matches exactly one
+       *  month so the previous / next months stay off-screen. Uses
+       *  scroll-snap so a wheel tick or drag settles on a whole month
+       *  rather than an awkward halfway position. Each month wrapper
+       *  is fixed-height (padded to fit the 6-row calendar layout)
+       *  so the snap points are evenly spaced. */}
+      {/* Virtualised single-month viewport. `overflow: hidden` keeps
+       *  the user from scrolling the calendar manually — month-changes
+       *  are always driven from outside (timeline scroll / active
+       *  photo / filter bounds). Programmatic `scrollToIndex` still
+       *  sets scrollTop even when overflow is hidden. */}
+      <div
+        ref={scrollRef}
+        className="overflow-hidden rounded border border-border bg-bg"
+        style={{ height: MONTH_HEIGHT }}
+      >
+        <div
+          style={{
+            height: virtualizer.getTotalSize(),
+            width: '100%',
+            position: 'relative',
+          }}
+        >
+          {virtualizer.getVirtualItems().map((vItem) => {
+            const k = monthKeys[vItem.index]
+            const [y, m] = k.split('-').map(Number)
+            return (
+              <div
+                key={k}
+                className="flex items-start justify-center px-1 py-1"
+                style={{
+                  position: 'absolute',
+                  top: 0,
+                  left: 0,
+                  width: '100%',
+                  height: MONTH_HEIGHT,
+                  transform: `translateY(${vItem.start}px)`,
+                }}
+              >
+                <MonthGrid
+                  year={y}
+                  month={m - 1}
+                  countByDay={countByDay}
+                  levels={levelThresholds}
+                  focusedIso={activePhotoDate}
+                  fromIso={from}
+                  toIso={to}
+                  onDayClick={onDayClick}
+                />
+              </div>
+            )
+          })}
+        </div>
+      </div>
+    </div>
+  )
+}
+
+/** Single month calendar — read-only, no nav buttons, no selection
+ *  handler. Colours each day by photo count (GitHub-contributions
+ *  style) and highlights any day inside the currently-filtered range. */
+const MonthGrid = memo(function MonthGrid({
+  year,
+  month,
+  countByDay,
+  levels,
+  focusedIso,
+  fromIso,
+  toIso,
+  onDayClick,
+}: {
+  year: number
+  month: number
+  countByDay: Map<string, number>
+  levels: number[]
+  focusedIso: string | null
+  fromIso: string | null
+  toIso: string | null
+  onDayClick: (iso: string) => void
+}) {
+  const from = fromIso ? parseIsoDate(fromIso) : undefined
+  const to = toIso ? parseIsoDate(toIso) : undefined
+  const monthDate = new Date(year, month, 1)
+  const [t1, t2, t3, t4] = levels
+  const dayLevel = (d: Date): 0 | 1 | 2 | 3 | 4 => {
+    const n = countByDay.get(formatIsoDate(d)) ?? 0
+    if (n >= t4) return 4
+    if (n >= t3) return 3
+    if (n >= t2) return 2
+    if (n >= t1) return 1
+    return 0
+  }
+  return (
+    <DayPicker
+      mode="default"
+      month={monthDate}
+      disableNavigation
+      showOutsideDays={false}
+      className="p-1"
+      classNames={{
+        months: 'flex flex-col',
+        month: 'flex flex-col gap-1',
+        caption: 'flex items-center justify-center px-1 pt-0.5',
+        caption_label: 'text-[11px] font-semibold uppercase tracking-wide text-text',
+        nav: 'hidden',
+        table: 'w-full border-collapse',
+        head_row: 'flex',
+        head_cell:
+          'text-text-muted rounded w-6 font-normal text-[9px] uppercase tracking-wide',
+        row: 'flex w-full mt-0.5',
+        cell: 'relative p-0 text-center text-xs',
+        day: cn(
+          buttonVariants({ variant: 'ghost' }),
+          'h-6 w-6 p-0 text-xs font-normal cursor-pointer',
+        ),
+        day_today: 'text-star ring-1 ring-star/60',
+      }}
+      modifiers={{
+        level1: (d) => dayLevel(d) === 1,
+        level2: (d) => dayLevel(d) === 2,
+        level3: (d) => dayLevel(d) === 3,
+        level4: (d) => dayLevel(d) === 4,
+        inRange: (d) => isInRange(d, from, to),
+        focused: (d) => !!focusedIso && formatIsoDate(d) === focusedIso,
+      }}
+      modifiersClassNames={{
+        // GitHub-contributions-style intensity shades. Each level tints
+        // the cell's background with an increasing primary opacity
+        // while keeping text readable.
+        level1: 'bg-primary/15 text-text',
+        level2: 'bg-primary/30 text-text',
+        level3: 'bg-primary/55 text-bg',
+        level4: 'bg-primary/85 text-bg font-semibold',
+        // Filter-range highlight composes on top with a subtle ring
+        // instead of a background so the intensity heatmap stays
+        // legible.
+        inRange: 'ring-1 ring-primary',
+        // Focused day — the taken_at of the currently active photo.
+        // Stronger ring + offset so it pops above the range highlight
+        // without fighting the heatmap fill underneath.
+        focused:
+          'ring-2 ring-star ring-offset-1 ring-offset-bg font-semibold',
+      }}
+      title="Daily photo count"
+      onDayClick={(d) => onDayClick(formatIsoDate(d))}
+    />
+  )
+})
+
+/** Compact popover with two native date inputs for setting a range
+ *  explicitly. Lives behind the "Filter" button next to the calendar. */
+function DateFilterPopover({
+  from,
+  to,
+  onFromChange,
+  onToChange,
+}: {
+  from: string | null
+  to: string | null
+  onFromChange: (v: string | null) => void
+  onToChange: (v: string | null) => void
+}) {
+  const [open, setOpen] = useState(false)
+  const active = !!(from || to)
+  return (
+    <Popover open={open} onOpenChange={setOpen}>
+      <PopoverTrigger
+        className={cn(
+          'flex items-center gap-1 rounded border px-1.5 py-0.5 text-[10px] uppercase tracking-wider',
+          active
+            ? 'border-primary/60 bg-primary/10 text-primary'
+            : 'border-border text-text-muted hover:bg-surface-2 hover:text-text',
+        )}
+      >
+        <Filter className="h-3 w-3" />
+        Filter
+      </PopoverTrigger>
+      <PopoverContent className="w-56 space-y-2 p-3" side="bottom" align="end">
+        <div className="flex items-center justify-between">
+          <h3 className="text-[11px] font-semibold uppercase tracking-wide text-text">
+            Date range
+          </h3>
+          {active && (
+            <button
+              onClick={() => {
+                onFromChange(null)
+                onToChange(null)
+              }}
+              className="flex items-center gap-0.5 rounded px-1 py-0.5 text-[10px] text-text-muted hover:bg-surface-2 hover:text-text"
+              title="Clear range"
+            >
+              <X className="h-3 w-3" />
+              Clear
+            </button>
+          )}
+        </div>
+        <label className="block space-y-0.5">
+          <span className="text-[10px] uppercase tracking-wider text-text-muted">
+            From
+          </span>
+          <input
+            type="date"
+            value={from ?? ''}
+            onChange={(e) => onFromChange(e.target.value || null)}
+            max={to ?? undefined}
+            className="w-full rounded border border-border bg-bg px-2 py-1 text-xs text-text"
+          />
+        </label>
+        <label className="block space-y-0.5">
+          <span className="text-[10px] uppercase tracking-wider text-text-muted">
+            To
+          </span>
+          <input
+            type="date"
+            value={to ?? ''}
+            onChange={(e) => onToChange(e.target.value || null)}
+            min={from ?? undefined}
+            className="w-full rounded border border-border bg-bg px-2 py-1 text-xs text-text"
+          />
+        </label>
+      </PopoverContent>
+    </Popover>
+  )
+}
+
+function isInRange(d: Date, from?: Date, to?: Date): boolean {
+  if (!from && !to) return false
+  const t = d.getTime()
+  if (from && t < from.getTime()) return false
+  if (to && t > to.getTime()) return false
+  return true
+}
+
+function parseIsoDate(s: string): Date {
+  const [y, m, d] = s.split('-').map(Number)
+  return new Date(y, (m ?? 1) - 1, d ?? 1)
+}
+
+function formatIsoDate(d: Date): string {
+  const y = d.getFullYear()
+  const m = String(d.getMonth() + 1).padStart(2, '0')
+  const day = String(d.getDate()).padStart(2, '0')
+  return `${y}-${m}-${day}`
+}

frontend/src/components/filter/FilterBar.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useMemo, useRef, useState } from 'react'
+import { useEffect, useRef, useState } from 'react'
 import {
   Star,
   X,
@@ -18,7 +18,6 @@ import {
   type SortField,
 } from '../../store/filterStore'
 import { useTagsQuery } from '../../hooks/useTagsQuery'
-import { usePhotosQuery } from '../../hooks/usePhotosQuery'
 import { FilterPill } from './FilterPill'
 import { COLOR_LABEL_OPTIONS } from '../../constants/colorLabels'
 import { Input } from '@/components/ui/input'
@@ -31,7 +30,6 @@ import {
   SelectValue,
 } from '@/components/ui/select'
 import { MultiSelect } from '@/components/ui/multi-select'
-import { Calendar } from '@/components/ui/calendar'
 
 const SEARCH_DEBOUNCE_MS = 300
 
@@ -70,8 +68,6 @@ export function FilterBar({
   onToggleRightSidebar,
 }: FilterBarProps) {
   const filterState = useFilterStore()
-  const dateFrom = useFilterStore((s) => s.dateFrom)
-  const dateTo = useFilterStore((s) => s.dateTo)
   const mediaTypes = useFilterStore((s) => s.mediaTypes)
   const ratingMin = useFilterStore((s) => s.ratingMin)
   const colorLabel = useFilterStore((s) => s.colorLabel)
@@ -90,8 +86,6 @@ export function FilterBar({
   // them further (ratingMin >= 3, restrict to specific tag ids).
   const hideFlagPill = currentSection === 'discarded'
 
-  const setDateFrom = useFilterStore((s) => s.setDateFrom)
-  const setDateTo = useFilterStore((s) => s.setDateTo)
   const toggleMediaType = useFilterStore((s) => s.toggleMediaType)
   const setRatingMin = useFilterStore((s) => s.setRatingMin)
   const setColorLabel = useFilterStore((s) => s.setColorLabel)
@@ -124,11 +118,6 @@ export function FilterBar({
   }, [searchQuery, storeQ, setStoreQ])
 
   // Pre-compute pill values + active flags so the JSX stays terse.
-  const dateActive = dateFrom !== null || dateTo !== null
-  const dateValue = dateActive
-    ? `${dateFrom ?? '…'} → ${dateTo ?? '…'}`
-    : null
-
   const typeActive = mediaTypes.length > 0
   const typeValue = typeActive
     ? mediaTypes.map((t) => t.toUpperCase()).join(', ')
@@ -184,23 +173,8 @@ export function FilterBar({
 
       {/* Pills — left side, scroll horizontally if they overflow. */}
       <div className="flex min-w-0 flex-1 items-center gap-1.5 overflow-x-auto">
-        {/* Date */}
-        <FilterPill
-          label="Date"
-          value={dateValue}
-          isActive={dateActive}
-          onClear={() => {
-            setDateFrom(null)
-            setDateTo(null)
-          }}
-        >
-          <DateRangePicker
-            from={dateFrom}
-            to={dateTo}
-            onFromChange={setDateFrom}
-            onToChange={setDateTo}
-          />
-        </FilterPill>
+        {/* Date filter is rendered inline at the top of the right
+         *  sidebar (always visible) — no pill needed here. */}
 
         {/* Type */}
         <FilterPill
@@ -486,111 +460,3 @@ export function FilterBar({
   )
 }
 
-/** Date range picker used inside the Date FilterPill. A single
- *  shadcn/react-day-picker Calendar in `range` mode — first click picks
- *  the start, second click picks the end. Writes both bounds to the
- *  store as yyyy-mm-dd ISO strings.
- *
- *  Days without matching photos are disabled + visually dimmed
- *  ("booked days" pattern from shadcn docs), so the user can see at a
- *  glance which dates are worth clicking. The booked set is derived
- *  from the currently-cached photos — reflects every other active
- *  filter, which is the intended UX: "which days have 5★ photos of
- *  screenshots" etc. The caption uses the dropdown layout so the user
- *  can jump across months/years without clicking the arrows. */
-function DateRangePicker({
-  from,
-  to,
-  onFromChange,
-  onToChange,
-}: {
-  from: string | null
-  to: string | null
-  onFromChange: (v: string | null) => void
-  onToChange: (v: string | null) => void
-}) {
-  // Unique yyyy-mm-dd keys of every cached photo's taken_at. Derived
-  // from the shared photos cache so opening the calendar doesn't fire
-  // another network request.
-  const { data: photos = [] } = usePhotosQuery()
-  const bookedSet = useMemo(() => {
-    const s = new Set<string>()
-    for (const p of photos) {
-      if (!p.taken_at) continue
-      const d = new Date(p.taken_at)
-      if (Number.isNaN(d.getTime())) continue
-      s.add(formatIsoDate(d))
-    }
-    return s
-  }, [photos])
-
-  const currentYear = new Date().getFullYear()
-  const earliestYear = useMemo(() => {
-    let min = currentYear
-    for (const k of bookedSet) {
-      const y = parseInt(k.slice(0, 4), 10)
-      if (!Number.isNaN(y) && y < min) min = y
-    }
-    return min
-  }, [bookedSet, currentYear])
-
-  const selected = {
-    from: from ? parseIsoDate(from) : undefined,
-    to: to ? parseIsoDate(to) : undefined,
-  }
-  const handleSelect = (range: { from?: Date; to?: Date } | undefined) => {
-    onFromChange(range?.from ? formatIsoDate(range.from) : null)
-    onToChange(range?.to ? formatIsoDate(range.to) : null)
-  }
-  const label =
-    from && to
-      ? from === to
-        ? from
-        : `${from} → ${to}`
-      : from
-        ? `From ${from}`
-        : to
-          ? `Until ${to}`
-          : 'Click to pick a start date, then an end date'
-
-  return (
-    <div className="space-y-2">
-      <div className="text-[11px] text-text-muted">{label}</div>
-      <Calendar
-        mode="range"
-        selected={selected}
-        onSelect={handleSelect}
-        numberOfMonths={1}
-        defaultMonth={selected.from ?? selected.to ?? new Date()}
-        captionLayout="dropdown"
-        fromYear={earliestYear}
-        toYear={currentYear + 1}
-        modifiers={{
-          booked: (d) => bookedSet.has(formatIsoDate(d)),
-        }}
-        modifiersClassNames={{
-          // Days that DO have matching photos get a small primary dot
-          // below the number; unmatched days stay visible and
-          // clickable so the user can still pick any bound they want.
-          booked:
-            'relative font-semibold text-text after:absolute after:bottom-0.5 after:left-1/2 after:h-1 after:w-1 after:-translate-x-1/2 after:rounded-full after:bg-primary after:content-[""]',
-        }}
-        className="rounded-md border border-border bg-bg p-2"
-      />
-    </div>
-  )
-}
-
-function parseIsoDate(s: string): Date {
-  // yyyy-mm-dd → Date with local components so a user's "2024-01-15"
-  // never rolls back to 2024-01-14 in a pacific timezone.
-  const [y, m, d] = s.split('-').map(Number)
-  return new Date(y, (m ?? 1) - 1, d ?? 1)
-}
-
-function formatIsoDate(d: Date): string {
-  const y = d.getFullYear()
-  const m = String(d.getMonth() + 1).padStart(2, '0')
-  const day = String(d.getDate()).padStart(2, '0')
-  return `${y}-${m}-${day}`
-}

frontend/src/components/heaps/HeapsPanel.tsx

@@ -44,13 +44,27 @@ import {
  *  - filter heapId: which heap is currently filtered to (visual)
  *  - heap.is_active: which heap T adds to (server-side, single per row)
  */
-export function HeapsPanel() {
+interface HeapsPanelProps {
+  /** Controlled expand state. When both props are supplied the panel
+   *  defers to the parent for collapse/expand, so the sidebar's pane
+   *  sizing layer can flex the Heaps pane only when it is open. */
+  expanded?: boolean
+  onExpandedChange?: (expanded: boolean) => void
+}
+
+export function HeapsPanel({ expanded: expandedProp, onExpandedChange }: HeapsPanelProps = {}) {
   const { data: heaps = [] } = useHeapsQuery()
   const navigateToSection = useFilterStore((s) => s.navigateToSection)
   const currentSection = useFilterStore((s) => s.currentSection)
   const queryClient = useQueryClient()
 
-  const [expanded, setExpanded] = useState(true)
+  const [expandedInternal, setExpandedInternal] = useState(true)
+  const expanded = expandedProp ?? expandedInternal
+  const setExpanded = (next: boolean | ((prev: boolean) => boolean)) => {
+    const resolved = typeof next === 'function' ? (next as (p: boolean) => boolean)(expanded) : next
+    if (onExpandedChange) onExpandedChange(resolved)
+    else setExpandedInternal(resolved)
+  }
   const [creating, setCreating] = useState(false)
   const [newName, setNewName] = useState('')
   // Which heap row is currently being hovered with a drag — used to render
@@ -174,13 +188,23 @@ export function HeapsPanel() {
 
   return (
     <div>
-      {/* Section header — eyebrow style to match the LeftSidebar
-       *  library/folders headers. */}
+      {/* Section header — mirrors the Folders section eyebrow in
+       *  LeftSidebar so Heaps sits alongside it at the same visual
+       *  tier, with heap rows indented the same as folder rows. */}
       <div
         className="group mt-2 flex cursor-pointer items-center gap-1 px-3 py-1 text-[10px] font-semibold uppercase tracking-[0.14em] text-text-muted hover:text-text"
         onClick={() => setExpanded((v) => !v)}
+        aria-expanded={expanded}
+        role="button"
       >
-        <button className="rounded p-0.5 hover:bg-surface-offset">
+        <button
+          className="rounded p-0.5 hover:bg-surface-offset"
+          onClick={(e) => {
+            e.stopPropagation()
+            setExpanded((v) => !v)
+          }}
+          aria-label="Toggle heaps"
+        >
           {expanded ? (
             <ChevronDown className="h-3 w-3" />
           ) : (
@@ -209,6 +233,7 @@ export function HeapsPanel() {
               className="flex items-center gap-1 px-2 py-0.5"
               style={{ paddingLeft: '20px' }}
             >
+              <div className="h-4 w-4 flex-shrink-0" aria-hidden="true" />
               <Input
                 autoFocus
                 type="text"
@@ -237,10 +262,11 @@ export function HeapsPanel() {
 
           {heaps.length === 0 && !creating && (
             <div
-              className="px-2 py-0.5 text-[11px] text-text-faint"
+              className="flex items-center gap-1 px-2 py-0.5 text-[11px] text-text-faint"
               style={{ paddingLeft: '20px' }}
             >
-              No heaps yet
+              <div className="h-4 w-4 flex-shrink-0" aria-hidden="true" />
+              <span>No heaps yet</span>
             </div>
           )}
 
@@ -308,6 +334,10 @@ export function HeapsPanel() {
                   }
                 }}
               >
+                {/* Chevron-slot spacer — heap rows don't expand, but this
+                 *  reserves the same width that leaf folder rows use so
+                 *  icons and labels line up across the two hierarchies. */}
+                <div className="h-4 w-4 flex-shrink-0" aria-hidden="true" />
                 <ShoppingBasket
                   className={cn(
                     'h-3.5 w-3.5 flex-shrink-0',

frontend/src/components/layout/LeftSidebar.tsx

@@ -1,4 +1,4 @@
-import { useState } from 'react'
+import { useEffect, useState } from 'react'
 import {
   ChevronRight,
   ChevronDown,
@@ -26,6 +26,7 @@ import {
   Upload as UploadIcon,
   Download as DownloadIcon,
 } from 'lucide-react'
+import { DateRangePicker } from '../filter/DateRangePicker'
 import { cn } from '@/lib/utils'
 import { sourceFolders, photos as photosApi, downloads, type FolderTreeNode } from '../../services/api'
 import { useMutation, useQueryClient } from '@tanstack/react-query'
@@ -81,6 +82,9 @@ export function LeftSidebar() {
   const { user, isAdmin, logout } = useAuth()
   const scanActivity = useScanActivity()
   const [expandedItems, setExpandedItems] = useState<Set<string>>(new Set(['library', 'folders', 'heaps']))
+  // Library pane collapse. Its body holds Views, Folders, Shared, and
+  // Heaps, so a single toggle hides the whole navigation area.
+  const [libraryPaneOpen, setLibraryPaneOpen] = useState(true)
   // Inline rename state for source-root rows. Stores the id being edited
   // and the draft name. Double-click a folder row to start.
   const [renamingId, setRenamingId] = useState<string | null>(null)
@@ -834,15 +838,40 @@ export function LeftSidebar() {
 
   return (
     <div className="flex h-full flex-col bg-surface">
-      {/* Header with collapse button. Matches the right sidebar header
-       *  so both panels have symmetric affordances. */}
-      <div className="flex h-9 flex-shrink-0 items-center justify-between border-b border-border px-3">
-        <h2 className="text-[11px] font-semibold uppercase tracking-[0.14em] text-text-muted">
-          Library
-        </h2>
-        <div className="flex items-center gap-1">
+      {/* Active heap card — pinned at the very top so it stays visible
+       *  even when the date filter is expanded into a tall calendar.
+       *  Returns null when no heap is active, so the layout collapses
+       *  cleanly. */}
+      <ActiveHeapCard />
+
+      {/* Date range filter — always visible, collapsible. Drives the
+       *  global dateFrom/dateTo on the filter store, so it applies to
+       *  every section regardless of which tree item is selected. */}
+      <DateFilterSection />
+
+      {/* Resizable two-pane region: Library (Views + Folders + Shared)
+       *  on top, Heaps on the bottom. Each pane collapses to its
+       *  header; when both are expanded a drag divider splits the
+       *  vertical space between them (persisted to localStorage). */}
+      {/* Library pane — the sole navigation section. Contains Views,
+       *  Folders, Shared-with-me, and Heaps in a single scroll area;
+       *  collapses to its header when hidden. */}
+      <div
+        className="flex min-h-0 flex-col"
+        style={{ flex: libraryPaneOpen ? '1 1 0' : '0 0 auto' }}
+      >
+        <div
+          className="group flex h-9 flex-shrink-0 cursor-pointer items-center gap-2 border-b border-border px-3 text-[11px] font-semibold uppercase tracking-[0.14em] text-text-muted hover:text-text"
+          onClick={() => setLibraryPaneOpen((v) => !v)}
+          aria-expanded={libraryPaneOpen}
+          role="button"
+        >
+          <span className="flex-1 truncate">Library</span>
           <button
-            onClick={() => setUploadTarget({ open: true, folderId: null })}
+            onClick={(e) => {
+              e.stopPropagation()
+              setUploadTarget({ open: true, folderId: null })
+            }}
             className="rounded p-0.5 text-text-muted hover:bg-surface-2 hover:text-text"
             title="Upload photos"
             aria-label="Upload photos"
@@ -850,63 +879,61 @@ export function LeftSidebar() {
             <UploadIcon className="h-3.5 w-3.5" />
           </button>
         </div>
-      </div>
-      {/* Active heap card — pinned just below the Library header so
-       *  toasts (bottom-left fixed) can't cover it. Returns null when
-       *  no heap is active, so the layout collapses cleanly. */}
-      <ActiveHeapCard />
+        {libraryPaneOpen && (
+          <div className="min-h-0 flex-1 overflow-y-auto pb-2">
+            {libraryTree.map((item) => renderTreeItem(item))}
 
-      {/* Tree View */}
-      <div className="flex-1 overflow-y-auto pb-2">
-        {libraryTree.map((item) => renderTreeItem(item))}
-
-        {/* Shared with me — folders shared by other users */}
-        {sharedFolders.length > 0 && (
-          <div className="mt-1">
-            <div className="px-3 py-1 text-[10px] font-semibold uppercase tracking-[0.14em] text-text-muted">
-              Shared with me
-            </div>
-            {sharedFolders.map((sf) => {
-              const isSelected = currentSection === `folder-${sf.id}`
-              return (
-                <div
-                  key={sf.id}
-                  className={cn(
-                    'flex h-[24px] cursor-pointer items-center gap-1 rounded px-2 text-[12px] leading-none',
-                    isSelected ? 'bg-primary/20 text-primary' : 'text-text hover:bg-surface-2',
-                  )}
-                  style={{ paddingLeft: '20px' }}
-                  onClick={() =>
-                    navigateToSection(`folder-${sf.id}`, { folderId: sf.id })
-                  }
-                >
-                  <Users
-                    className={cn(
-                      'h-3.5 w-3.5 flex-shrink-0',
-                      isSelected ? 'text-primary' : 'text-text-muted'
-                    )}
-                  />
-                  <span className="truncate" title={sf.name}>
-                    {sf.name}
-                  </span>
-                  <span className="ml-0.5 truncate text-[10px] text-text-faint">
-                    {sf.owner_username}
-                  </span>
-                  <span className="ml-auto rounded bg-surface-offset px-1 text-[9px] uppercase text-text-faint">
-                    {sf.permission}
-                  </span>
-                  {sf.photo_count > 0 && (
-                    <span className="flex h-4 min-w-[20px] flex-shrink-0 items-center justify-center rounded bg-surface-offset px-1 text-[10px] tabular-nums text-text-muted">
-                      {sf.photo_count}
-                    </span>
-                  )}
+            {/* Shared with me — folders shared by other users */}
+            {sharedFolders.length > 0 && (
+              <div className="mt-1">
+                <div className="px-3 py-1 text-[10px] font-semibold uppercase tracking-[0.14em] text-text-muted">
+                  Shared with me
                 </div>
-              )
-            })}
+                {sharedFolders.map((sf) => {
+                  const isSelected = currentSection === `folder-${sf.id}`
+                  return (
+                    <div
+                      key={sf.id}
+                      className={cn(
+                        'flex h-[24px] cursor-pointer items-center gap-1 rounded px-2 text-[12px] leading-none',
+                        isSelected ? 'bg-primary/20 text-primary' : 'text-text hover:bg-surface-2',
+                      )}
+                      style={{ paddingLeft: '20px' }}
+                      onClick={() =>
+                        navigateToSection(`folder-${sf.id}`, { folderId: sf.id })
+                      }
+                    >
+                      <Users
+                        className={cn(
+                          'h-3.5 w-3.5 flex-shrink-0',
+                          isSelected ? 'text-primary' : 'text-text-muted'
+                        )}
+                      />
+                      <span className="truncate" title={sf.name}>
+                        {sf.name}
+                      </span>
+                      <span className="ml-0.5 truncate text-[10px] text-text-faint">
+                        {sf.owner_username}
+                      </span>
+                      <span className="ml-auto rounded bg-surface-offset px-1 text-[9px] uppercase text-text-faint">
+                        {sf.permission}
+                      </span>
+                      {sf.photo_count > 0 && (
+                        <span className="flex h-4 min-w-[20px] flex-shrink-0 items-center justify-center rounded bg-surface-offset px-1 text-[10px] tabular-nums text-text-muted">
+                          {sf.photo_count}
+                        </span>
+                      )}
+                    </div>
+                  )
+                })}
+              </div>
+            )}
+
+            {/* Heaps — nested inside the Library section; HeapsPanel owns
+             *  its own eyebrow header + collapse state. */}
+            <HeapsPanel />
           </div>
         )}
-
-        <HeapsPanel />
       </div>
 
       {/* Bottom panel — user identity + settings, pinned below the tree. */}
@@ -972,3 +999,70 @@ export function LeftSidebar() {
   )
 }
 
+/** Collapsible date-range filter block. Lives at the top of the left
+ *  sidebar and drives the global dateFrom/dateTo filter-store fields,
+ *  so it applies across every section. The calendar component itself
+ *  supports range selection and decorates days that have photos.
+ *  Open state persists across sessions via localStorage. */
+const DATE_FILTER_OPEN_KEY = 'mulita:dateFilterOpen'
+function DateFilterSection() {
+  const dateFrom = useFilterStore((s) => s.dateFrom)
+  const dateTo = useFilterStore((s) => s.dateTo)
+  const setDateFrom = useFilterStore((s) => s.setDateFrom)
+  const setDateTo = useFilterStore((s) => s.setDateTo)
+  const active = dateFrom !== null || dateTo !== null
+  // Default open; remembered across sessions. localStorage is read
+  // lazily inside the initialiser so SSR / disabled-storage fall back
+  // cleanly to the default.
+  const [open, setOpen] = useState<boolean>(() => {
+    try {
+      const v = localStorage.getItem(DATE_FILTER_OPEN_KEY)
+      if (v === null) return true
+      return v === '1'
+    } catch {
+      return true
+    }
+  })
+  useEffect(() => {
+    try {
+      localStorage.setItem(DATE_FILTER_OPEN_KEY, open ? '1' : '0')
+    } catch {
+      // Ignore — quota / disabled storage is non-fatal.
+    }
+  }, [open])
+  const summary = active
+    ? dateFrom && dateTo && dateFrom === dateTo
+      ? dateFrom
+      : `${dateFrom ?? '…'} → ${dateTo ?? '…'}`
+    : 'Any date'
+  return (
+    <div className="flex-shrink-0">
+      <div
+        onClick={() => setOpen((v) => !v)}
+        className="group flex h-9 cursor-pointer items-center gap-2 border-b border-border px-3 text-[11px] font-semibold uppercase tracking-[0.14em] text-text-muted hover:text-text"
+        aria-expanded={open}
+        role="button"
+      >
+        <span className="flex-1 truncate">
+          {active ? summary : 'Date'}
+        </span>
+        {active && (
+          <span className="rounded bg-primary/20 px-1 py-px text-[9px] uppercase tracking-wider text-primary">
+            Filtering
+          </span>
+        )}
+      </div>
+      {open && (
+        <div className="border-b border-border px-3 py-3">
+          <DateRangePicker
+            from={dateFrom}
+            to={dateTo}
+            onFromChange={setDateFrom}
+            onToChange={setDateTo}
+          />
+        </div>
+      )}
+    </div>
+  )
+}
+

frontend/src/components/layout/RightSidebar.tsx

@@ -213,6 +213,7 @@ export function RightSidebar() {
     </div>
   )
 
+
   if (selectedPhotos.length === 0) {
     return (
       <div

frontend/src/components/memories/MemoriesView.tsx

@@ -1,4 +1,4 @@
-import { useCallback, useEffect, useMemo, useRef } from 'react'
+import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import { useQuery } from '@tanstack/react-query'
 import { Loader2 } from 'lucide-react'
 import {
@@ -10,10 +10,15 @@ import type { Photo } from '../../types/photo'
 import { usePhotoStore } from '../../store/photoStore'
 import { useFilterStore } from '../../store/filterStore'
 import { PhotoThumbnail } from '../timeline/PhotoThumbnail'
+import { useActiveHeapMembers } from '../../hooks/useActiveHeapMembersQuery'
+import { useGridKeyNav } from '../../hooks/useGridKeyNav'
 
-const CELL_SIZE = 180
+// Match Timeline's THUMBNAIL_SIZE / GAP so memories cells line up
+// visually with what the user sees in the main grid.
+const THUMBNAIL_SIZE = 160
 const GAP = 4
 
+
 /**
  * "On this day" view. Same visual + interaction grid as Timeline —
  * PhotoThumbnail cells wired up to the shared photo store, so selection,
@@ -46,7 +51,9 @@ export function MemoriesView() {
   const togglePhotoSelection = usePhotoStore((s) => s.togglePhotoSelection)
   const selectRange = usePhotoStore((s) => s.selectRange)
   const openPreview = usePhotoStore((s) => s.openPreview)
+  const viewMode = usePhotoStore((s) => s.viewMode)
   const searchQuery = useFilterStore((s) => s.q)
+  const { memberIds: activeHeapMembers } = useActiveHeapMembers()
 
   const visibleSequenceRef = useRef<string[]>([])
   visibleSequenceRef.current = visibleSequence
@@ -66,6 +73,87 @@ export function MemoriesView() {
     [openPreview],
   )
 
+  // Measure the scroll container directly and subtract its padding to
+  // get the real grid width. A ResizeObserver on the container itself
+  // always fires on width changes — sentinel elements can miss changes
+  // in some edge cases (zero-height, detached during loading states).
+  const [containerWidth, setContainerWidth] = useState(0)
+  const roRef = useRef<ResizeObserver | null>(null)
+  const scrollRef = useCallback((el: HTMLDivElement | null) => {
+    roRef.current?.disconnect()
+    roRef.current = null
+    scrollElRef.current = el
+    if (!el) return
+    const measure = () => {
+      const style = window.getComputedStyle(el)
+      const padX =
+        parseFloat(style.paddingLeft) + parseFloat(style.paddingRight)
+      setContainerWidth(Math.max(0, el.clientWidth - padX))
+    }
+    measure()
+    const ro = new ResizeObserver(measure)
+    ro.observe(el)
+    roRef.current = ro
+  }, [])
+  const scrollElRef = useRef<HTMLDivElement | null>(null)
+  useEffect(() => () => roRef.current?.disconnect(), [])
+  // Fixed-size cells — always exactly THUMBNAIL_SIZE px, regardless of
+  // container width. See Timeline's column-math comment for the
+  // tradeoff (may leave a small gap on the right edge).
+  const { columns, cellSize } = useMemo(() => {
+    if (containerWidth === 0) return { columns: 4, cellSize: THUMBNAIL_SIZE }
+    const cols = Math.max(
+      1,
+      Math.floor((containerWidth + GAP) / (THUMBNAIL_SIZE + GAP)),
+    )
+    return { columns: cols, cellSize: THUMBNAIL_SIZE }
+  }, [containerWidth])
+
+  // Break each year's photos into rows of `columns` ids — matches the
+  // shape useGridKeyNav expects. Arrow-nav crosses year boundaries
+  // naturally because rows flow in visual order across groups.
+  const gridNavRows = useMemo(() => {
+    const rows: { cells: { id: string }[] }[] = []
+    for (const group of memories) {
+      const cells = group.photos.map((m) => ({ id: m.id }))
+      for (let i = 0; i < cells.length; i += columns) {
+        rows.push({ cells: cells.slice(i, i + columns) })
+      }
+    }
+    return rows
+  }, [memories, columns])
+
+  const scrollRowIntoView = useCallback((rowIdx: number) => {
+    const firstId = gridNavRowsRef.current[rowIdx]?.cells[0]?.id
+    if (!firstId) return
+    const scrollEl = scrollElRef.current
+    if (!scrollEl) return
+    const cellEl = scrollEl.querySelector<HTMLElement>(
+      `[data-photo-id="${firstId}"]`,
+    )
+    if (!cellEl) return
+    const peek = Math.round(cellSize * 0.35)
+    const cellTop = cellEl.offsetTop
+    const cellBottom = cellTop + cellEl.offsetHeight
+    const viewTop = scrollEl.scrollTop
+    const viewBottom = viewTop + scrollEl.clientHeight
+    if (cellTop - peek < viewTop) {
+      scrollEl.scrollTo({ top: Math.max(0, cellTop - peek) })
+    } else if (cellBottom + peek > viewBottom) {
+      scrollEl.scrollTo({ top: cellBottom + peek - scrollEl.clientHeight })
+    }
+  }, [])
+  // Rows change on resize / data load — read via ref so the callback
+  // identity stays stable.
+  const gridNavRowsRef = useRef(gridNavRows)
+  gridNavRowsRef.current = gridNavRows
+
+  useGridKeyNav({
+    rows: gridNavRows,
+    enabled: viewMode === 'grid',
+    scrollRowIntoView,
+  })
+
   if (isLoading) {
     return (
       <div className="flex h-full items-center justify-center text-text-muted">
@@ -90,6 +178,7 @@ export function MemoriesView() {
 
   return (
     <div
+      ref={scrollRef}
       className="h-full overflow-auto bg-bg p-4"
       role="grid"
       aria-label="Memories"
@@ -112,22 +201,24 @@ export function MemoriesView() {
             <div
               className="grid"
               style={{
-                gridTemplateColumns: `repeat(auto-fill, minmax(${CELL_SIZE}px, 1fr))`,
-                gridAutoRows: `${CELL_SIZE}px`,
+                gridTemplateColumns: `repeat(${columns}, ${cellSize}px)`,
+                gridAutoRows: `${cellSize}px`,
                 gap: `${GAP}px`,
               }}
             >
               {group.photos.map((m) => (
-                <PhotoThumbnail
-                  key={m.id}
-                  photo={memoryToPhoto(m)}
-                  size={CELL_SIZE}
-                  fill
-                  isSelected={selectedPhotos.includes(m.id)}
-                  searchQuery={searchQuery}
-                  onClick={handleCellClick}
-                  onDoubleClick={handleCellDoubleClick}
-                />
+                <div key={m.id} data-photo-id={m.id}>
+                  <PhotoThumbnail
+                    photo={memoryToPhoto(m)}
+                    size={cellSize}
+                    fill
+                    isSelected={selectedPhotos.includes(m.id)}
+                    isInActiveHeap={activeHeapMembers.has(m.id)}
+                    searchQuery={searchQuery}
+                    onClick={handleCellClick}
+                    onDoubleClick={handleCellDoubleClick}
+                  />
+                </div>
               ))}
             </div>
           </section>
@@ -151,7 +242,8 @@ function memoryToPhoto(m: MemoryPhoto): Photo {
     height: m.height,
     taken_at: m.taken_at,
     rating: m.rating,
-    is_discarded: false,
+    color_label: m.color_label,
+    is_discarded: m.is_discarded,
     is_duplicate: false,
     file_hash: '',
     folder_id: null,

frontend/src/components/preview/PreviewFilmstrip.tsx

@@ -1,4 +1,5 @@
-import { useEffect, useRef, useState } from 'react'
+import { useEffect, useLayoutEffect, useRef, useState } from 'react'
+import { useVirtualizer } from '@tanstack/react-virtual'
 import { cn } from '@/lib/utils'
 import type { Photo } from '../../types/photo'
 import { photos as photosApi } from '../../services/api'
@@ -11,48 +12,87 @@ interface PreviewFilmstripProps {
 }
 
 const CELL_SIZE = 72
+const GAP = 4
 
-export function PreviewFilmstrip({ photos, currentIndex, onSelect }: PreviewFilmstripProps) {
-  const activeRef = useRef<HTMLButtonElement>(null)
+/**
+ * Horizontal virtualised filmstrip. Mounting thousands of `<button>`
+ * nodes on preview open used to dominate the perceived open latency
+ * for large libraries — with virtualisation only a viewport's worth
+ * (~15-20 cells) ever hits the DOM.
+ */
+export function PreviewFilmstrip({
+  photos,
+  currentIndex,
+  onSelect,
+}: PreviewFilmstripProps) {
+  const scrollRef = useRef<HTMLDivElement>(null)
   const { memberIds: activeHeapMembers } = useActiveHeapMembers()
 
-  useEffect(() => {
-    activeRef.current?.scrollIntoView({
-      block: 'nearest',
-      inline: 'center',
-      behavior: 'smooth',
-    })
-  }, [currentIndex])
+  const virtualizer = useVirtualizer({
+    horizontal: true,
+    count: photos.length,
+    getScrollElement: () => scrollRef.current,
+    estimateSize: () => CELL_SIZE + GAP,
+    overscan: 10,
+    getItemKey: (idx) => photos[idx].id,
+  })
+
+  // Centre the active cell when the index changes. Using layout-effect
+  // so the scroll happens before paint — avoids a visible jump.
+  useLayoutEffect(() => {
+    if (currentIndex < 0 || currentIndex >= photos.length) return
+    virtualizer.scrollToIndex(currentIndex, { align: 'center' })
+  }, [currentIndex, photos.length, virtualizer])
 
   return (
-    <div className="flex h-24 shrink-0 items-center gap-1 overflow-x-auto border-t border-border bg-surface px-2 py-2">
-      {photos.map((photo, index) => {
-        const isActive = index === currentIndex
-        const isInActiveHeap = activeHeapMembers.has(photo.id)
-        return (
-          <button
-            key={photo.id}
-            ref={isActive ? activeRef : null}
-            onClick={() => onSelect(photo.id)}
-            className={cn(
-              'relative shrink-0 overflow-hidden rounded-sm will-change-transform transition-[transform,box-shadow,opacity] duration-300 ease-[cubic-bezier(0.34,1.56,0.64,1)]',
-              isActive && 'scale-90 opacity-100 ring-2 ring-blue-500 ring-offset-2 ring-offset-surface',
-              !isActive && isInActiveHeap && 'opacity-100',
-              !isActive && !isInActiveHeap && 'opacity-60 hover:opacity-100 hover:ring-1 hover:ring-text-muted/70'
-            )}
-            style={{ width: CELL_SIZE, height: CELL_SIZE }}
-            title={photo.filename}
-          >
-            <FilmstripThumb photo={photo} />
-            {isInActiveHeap && (
-              <div className="pointer-events-none absolute inset-0 bg-emerald-500/40" />
-            )}
-            {isActive && (
-              <div className="pointer-events-none absolute inset-0 bg-blue-500/50" />
-            )}
-          </button>
-        )
-      })}
+    <div
+      ref={scrollRef}
+      className="relative h-24 shrink-0 overflow-x-auto overflow-y-hidden border-t border-border bg-surface py-2"
+    >
+      <div
+        style={{
+          width: virtualizer.getTotalSize(),
+          height: '100%',
+          position: 'relative',
+          paddingLeft: 8,
+          paddingRight: 8,
+        }}
+      >
+        {virtualizer.getVirtualItems().map((vItem) => {
+          const photo = photos[vItem.index]
+          const isActive = vItem.index === currentIndex
+          const isInActiveHeap = activeHeapMembers.has(photo.id)
+          return (
+            <button
+              key={photo.id}
+              onClick={() => onSelect(photo.id)}
+              className={cn(
+                'absolute top-0 overflow-hidden rounded-sm will-change-transform transition-[transform,box-shadow,opacity] duration-300 ease-[cubic-bezier(0.34,1.56,0.64,1)]',
+                isActive &&
+                  'scale-90 opacity-100 ring-2 ring-blue-500 ring-offset-2 ring-offset-surface',
+                !isActive && isInActiveHeap && 'opacity-100',
+                !isActive &&
+                  !isInActiveHeap &&
+                  'opacity-60 hover:opacity-100 hover:ring-1 hover:ring-text-muted/70'
+              )}
+              style={{
+                width: CELL_SIZE,
+                height: CELL_SIZE,
+                transform: `translateX(${vItem.start}px)`,
+              }}
+              title={photo.filename}
+            >
+              <FilmstripThumb photo={photo} />
+              {isInActiveHeap && (
+                <div className="pointer-events-none absolute inset-0 bg-emerald-500/40" />
+              )}
+              {isActive && (
+                <div className="pointer-events-none absolute inset-0 bg-blue-500/50" />
+              )}
+            </button>
+          )
+        })}
+      </div>
     </div>
   )
 }

frontend/src/components/timeline/Timeline.tsx

@@ -1,18 +1,19 @@
 import { useRef, useEffect, useMemo, useState, useCallback } from 'react'
 import { useVirtualizer } from '@tanstack/react-virtual'
-import { format, parseISO } from 'date-fns'
+import { format } from 'date-fns'
 import { cn } from '@/lib/utils'
 import { usePhotoStore } from '../../store/photoStore'
 import { useFilterStore, hasActiveFilters } from '../../store/filterStore'
 import { PhotoThumbnail } from './PhotoThumbnail'
 import { usePhotosQuery } from '../../hooks/usePhotosQuery'
 import { useActiveHeapMembers } from '../../hooks/useActiveHeapMembersQuery'
+import { useGridKeyNav } from '../../hooks/useGridKeyNav'
 import { Button } from '@/components/ui/button'
 import { ImageOff } from 'lucide-react'
 import type { Photo } from '../../types/photo'
 
 // Layout constants for the grid + grouped headers.
-const THUMBNAIL_SIZE = 200
+const THUMBNAIL_SIZE = 160
 const GAP = 4
 const PADDING = 16
 const HEADER_HEIGHT = 36
@@ -39,7 +40,6 @@ type TimelineItem =
 function buildItems(
   photos: Photo[],
   columns: number,
-  rowHeight: number,
   sortBy: string,
   groupBy: string,
 ): TimelineItem[] {
@@ -47,7 +47,9 @@ function buildItems(
 
   const items: TimelineItem[] = []
 
-  // Helper: split a flat array of cells into rows of `columns` cells.
+  // Row items carry a placeholder `height: 0` — the virtualizer reads
+  // the live cellSize off a ref at render time (see `estimateSize`),
+  // so resizing the main column doesn't force items to rebuild.
   const pushRowsForGroup = (groupKey: string, cells: PhotoCell[]) => {
     for (let i = 0; i < cells.length; i += columns) {
       const slice = cells.slice(i, i + columns)
@@ -55,7 +57,7 @@ function buildItems(
         type: 'row',
         key: `${groupKey}::row::${i}`,
         cells: slice,
-        height: rowHeight + GAP,
+        height: 0,
       })
     }
   }
@@ -89,6 +91,23 @@ function buildItems(
       label: currentLabel,
       height: HEADER_HEIGHT,
     })
+    // Sort the current month's photos ascending (day 1 → day 31) so
+    // each month reads chronologically start-to-end regardless of the
+    // global sortOrder. Month buckets themselves stay in the order the
+    // backend returned them (honours `sortOrder` for the month-level
+    // axis). Stable on equal timestamps via the globalIndex tiebreak.
+    bucket.sort((a, b) => {
+      const aKey =
+        (sortBy === 'taken_at'
+          ? a.photo.taken_at
+          : a.photo.added_at ?? a.photo.taken_at) ?? ''
+      const bKey =
+        (sortBy === 'taken_at'
+          ? b.photo.taken_at
+          : b.photo.added_at ?? b.photo.taken_at) ?? ''
+      if (aKey === bKey) return a.globalIndex - b.globalIndex
+      return aKey < bKey ? -1 : 1
+    })
     pushRowsForGroup(`${bucketIndex}::${currentLabel}`, bucket)
     bucketIndex++
     bucket = []
@@ -99,9 +118,21 @@ function buildItems(
       sortBy === 'taken_at' ? photo.taken_at : photo.added_at ?? photo.taken_at
     let label: string
     if (dateStr) {
-      try {
-        label = format(parseISO(dateStr), 'MMMM yyyy')
-      } catch {
+      // Same slice-first strategy the scroll-date chip uses — the
+      // date portion is trusted verbatim so local timezones can't
+      // drag an early/late-day photo into the wrong month bucket.
+      const iso = dateStr.slice(0, 10)
+      const match = /^(\d{4})-(\d{2})-(\d{2})$/.exec(iso)
+      if (match) {
+        const y = Number(match[1])
+        const mth = Number(match[2])
+        const day = Number(match[3])
+        try {
+          label = format(new Date(y, mth - 1, day), 'MMMM yyyy')
+        } catch {
+          label = 'Unknown date'
+        }
+      } else {
         label = 'Unknown date'
       }
     } else {
@@ -119,7 +150,7 @@ function buildItems(
 }
 
 export function Timeline() {
-  const parentRef = useRef<HTMLDivElement>(null)
+  const parentRef = useRef<HTMLDivElement | null>(null)
   // Sentinel placed inside the inner virtualizer wrapper at the exact
   // position rows will render. We measure THIS instead of parentRef,
   // because parentRef has padding and we'd otherwise have to subtract
@@ -133,7 +164,6 @@ export function Timeline() {
     selectPhoto,
     togglePhotoSelection,
     selectRange,
-    clearSelection,
     openPreview,
   } = usePhotoStore()
   // Pulled via a focused selector so the publisher subscription doesn't
@@ -149,33 +179,20 @@ export function Timeline() {
   const searchQuery = useFilterStore((s) => s.q)
   const viewMode = usePhotoStore((s) => s.viewMode)
 
-  // Calculate number of columns + actual cell size based on container
-  // width. Treat THUMBNAIL_SIZE as a *minimum* and let cells grow to
-  // fill the remaining space, so we never leave a horizontal gap on
-  // the right side of the grid.
-  //
-  // Column math: with N columns there are N-1 inter-cell gaps, so the
-  // width needed is N*T + (N-1)*G. Solving for the largest N that fits
-  // in the available width gives N = floor((available + G) / (T + G)).
-  // The previous formula floor((available) / (T + G)) was off-by-one
-  // and lost a whole column whenever the remainder almost fit.
+  // Number of columns that fit at the FIXED THUMBNAIL_SIZE. Cells no
+  // longer stretch to absorb the remaining width — we prefer a stable
+  // cell size across sidebar-open / sidebar-closed states over a
+  // perfectly-flush right edge. A small gap may remain on the right
+  // when containerWidth isn't an integer multiple of (T+G).
   const { columns, cellSize } = useMemo(() => {
     if (containerWidth === 0) {
       return { columns: 4, cellSize: THUMBNAIL_SIZE }
     }
-    // containerWidth here is the sentinel's actual rendered width — no
-    // padding subtraction needed, the sentinel already lives inside the
-    // padded scroll container.
-    const available = containerWidth
     const cols = Math.max(
       1,
-      Math.floor((available + GAP) / (THUMBNAIL_SIZE + GAP))
+      Math.floor((containerWidth + GAP) / (THUMBNAIL_SIZE + GAP))
     )
-    // Exact float — no floor. cellSize × cols + (cols-1) × gap == available
-    // by construction, so the row fills edge-to-edge without any
-    // sub-pixel rounding gap.
-    const cell = (available - (cols - 1) * GAP) / cols
-    return { columns: cols, cellSize: cell }
+    return { columns: cols, cellSize: THUMBNAIL_SIZE }
   }, [containerWidth])
 
   // Shared photos query — both Timeline and PreviewView use the same hook so
@@ -192,6 +209,12 @@ export function Timeline() {
   // explicitly clears the selection (Escape), we don't re-focus, so
   // the metadata sidebar can collapse and stay collapsed.
   const didAutoFocusRef = useRef(false)
+  // visibleSequence isn't in scope yet (derived below from items). Read
+  // it through a ref so this effect can focus the first *visually*
+  // ordered photo — matters now that months sort ascending while the
+  // photos array from the backend is still globally desc, i.e. the
+  // top-left cell the user actually sees isn't photos[0] anymore.
+  const visibleSequenceRef = useRef<string[]>([])
   useEffect(() => {
     if (didAutoFocusRef.current) return
     if (viewMode !== 'grid') return
@@ -199,9 +222,10 @@ export function Timeline() {
       didAutoFocusRef.current = true
       return
     }
-    if (photos.length === 0) return
+    const firstVisible = visibleSequenceRef.current[0]
+    if (!firstVisible) return
     didAutoFocusRef.current = true
-    selectPhoto(photos[0].id)
+    selectPhoto(firstVisible)
   }, [viewMode, activePhotoId, photos, selectPhoto])
 
   // Membership in the active heap (drives the green tint on each
@@ -212,9 +236,8 @@ export function Timeline() {
   // Stable cell handlers. PhotoThumbnail is wrapped in React.memo so
   // identity-stable callbacks let it skip re-render on unrelated store
   // churn (e.g. heap membership invalidation). visibleSequence is read
-  // through a ref at click time so scrolling doesn't rebind the
-  // double-click handler.
-  const visibleSequenceRef = useRef<string[]>([])
+  // through the ref declared above at click time so scrolling doesn't
+  // rebind the double-click handler.
   const handleCellClick = useCallback(
     (photo: Photo, e: React.MouseEvent) => {
       if (e.shiftKey) selectRange(photo.id)
@@ -232,11 +255,28 @@ export function Timeline() {
 
   // Build the flat virtualizer items: a mix of group headers and rows of
   // photos. Date headers appear only in the main timeline (groupBy='date').
+  //
+  // Notably NOT dependent on `cellSize` — row heights are read off a ref
+  // at virtualizer-measurement time instead. This stops `items` (and
+  // every downstream memo) from rebuilding on every sub-pixel tick of
+  // the sidebar CSS transition, which used to cause visible jank in
+  // timelines with thousands of photos.
   const items = useMemo(
-    () => buildItems(photos, columns, cellSize, sortBy, groupBy),
-    [photos, columns, cellSize, sortBy, groupBy]
+    () => buildItems(photos, columns, sortBy, groupBy),
+    [photos, columns, sortBy, groupBy]
   )
 
+  // Live cell size, consumed by the virtualizer's estimateSize so row
+  // heights stay accurate as the column fluidly resizes.
+  const cellSizeRef = useRef(cellSize)
+  cellSizeRef.current = cellSize
+
+  // Row items carry a placeholder height of 0 (see buildItems). Any
+  // code walking `items` for scroll offsets must resolve it against the
+  // current cellSize; headers carry their fixed height verbatim.
+  const effectiveHeight = (it: TimelineItem) =>
+    it.type === 'header' ? it.height : cellSizeRef.current + GAP
+
   // Used by the sticky header, the row-date index, and the floating
   // scrollbar chip — all three only make sense in date-sorted views.
   const isDateSort = sortBy === 'taken_at' || sortBy === 'added_at'
@@ -246,27 +286,43 @@ export function Timeline() {
   const headerOffsets = useMemo(() => {
     const result: { offset: number; label: string }[] = []
     let cumulative = 0
+    // Row items carry a placeholder height of 0 (see buildItems) so
+    // that the items array stays stable across cellSize changes. We
+    // resolve it here against the live cellSize so header offsets line
+    // up with the virtualizer's coordinate space.
+    const rowH = cellSize + GAP
     for (const item of items) {
       if (item.type === 'header') {
         result.push({ offset: cumulative, label: item.label })
+        cumulative += item.height
+      } else {
+        cumulative += rowH
       }
-      cumulative += item.height
     }
     return result
-  }, [items])
+  }, [items, cellSize])
 
   // Virtual scrolling setup with per-item heights.
   const virtualizer = useVirtualizer({
     count: items.length,
     getScrollElement: () => parentRef.current,
-    estimateSize: (index) => items[index]?.height ?? cellSize,
+    estimateSize: (index) => {
+      const it = items[index]
+      if (!it) return cellSizeRef.current + GAP
+      // Row items carry `height: 0` as a placeholder — always resolved
+      // to the current cellSize via the ref. Headers carry their own
+      // fixed height.
+      return it.type === 'header' ? it.height : cellSizeRef.current + GAP
+    },
     overscan: 5,
   })
 
-  // Re-measure when items change (column count, group structure).
+  // Re-measure when items change (column count, group structure) or
+  // cellSize shifts (sidebar collapse, window resize). Cheap — it just
+  // walks the item list and recomputes heights.
   useEffect(() => {
     virtualizer.measure()
-  }, [items, virtualizer])
+  }, [items, cellSize, virtualizer])
 
   // Track scroll position so we can (a) show the current group label as
   // a pinned overlay at the top of the scroll container and (b) drive
@@ -338,6 +394,12 @@ export function Timeline() {
     if (!isDateSort) return [] as { offset: number; raw: string | null }[]
     const out: { offset: number; raw: string | null }[] = []
     let cum = 0
+    // Row items carry a placeholder `height: 0` (resolved at render
+    // time from cellSize via effectiveHeight). Sum the live height here
+    // so cumulative offsets match the virtualizer's coordinate space —
+    // otherwise every row lands at offset 0 and the scroll chip /
+    // sidebar calendar freeze on the last photo regardless of scroll.
+    const rowH = cellSize + GAP
     for (const item of items) {
       if (item.type === 'row') {
         const first = item.cells[0]?.photo
@@ -346,11 +408,13 @@ export function Timeline() {
             ? first?.added_at ?? first?.taken_at ?? null
             : first?.taken_at ?? null
         out.push({ offset: cum, raw })
+        cum += rowH
+      } else {
+        cum += item.height
       }
-      cum += item.height
     }
     return out
-  }, [items, sortBy, isDateSort])
+  }, [items, sortBy, isDateSort, cellSize])
 
   // Date shown in the floating chip next to the scrollbar. Finds the
   // deepest row whose offset is at/above the viewport top (plus a
@@ -358,11 +422,10 @@ export function Timeline() {
   // photo's capture date. Null when not date-sorted, not scrolling, or
   // when the topmost row has no date — we'd rather hide the chip than
   // show an unhelpful "Unknown".
-  const scrollDateLabel = useMemo(() => {
+  const scrollRaw = useMemo(() => {
     if (!isDateSort || rowDateIndex.length === 0) return null
     const target = scrollMetrics.top + 20
     let raw: string | null = null
-    // Binary search: largest offset ≤ target.
     let lo = 0
     let hi = rowDateIndex.length - 1
     while (lo <= hi) {
@@ -374,13 +437,36 @@ export function Timeline() {
         hi = mid - 1
       }
     }
-    if (!raw) return null
+    return raw
+  }, [rowDateIndex, scrollMetrics.top, isDateSort])
+  const scrollDateLabel = useMemo(() => {
+    if (!scrollRaw) return null
+    // Take the date portion straight from the ISO string and build a
+    // local-midnight Date for formatting — avoids parseISO's timezone
+    // conversion shifting the displayed day.
+    const iso = scrollRaw.slice(0, 10)
+    if (!/^\d{4}-\d{2}-\d{2}$/.test(iso)) return null
+    const [y, m, d] = iso.split('-').map(Number)
     try {
-      return format(parseISO(raw), 'MMM d, yyyy')
+      return format(new Date(y, m - 1, d), 'MMM d, yyyy')
     } catch {
       return null
     }
-  }, [rowDateIndex, scrollMetrics.top, isDateSort])
+  }, [scrollRaw])
+
+  // Publish the anchor date (yyyy-mm-dd) so the left-sidebar Date
+  // picker can track which month the user is scrolled to. The leading
+  // 10 chars of the ISO string are taken verbatim — no Date round-trip
+  // — so timezones can't shift the visible day by one.
+  const setVisibleAnchorDate = usePhotoStore((s) => s.setVisibleAnchorDate)
+  useEffect(() => {
+    if (!scrollRaw) {
+      setVisibleAnchorDate(null)
+      return
+    }
+    const iso = scrollRaw.slice(0, 10)
+    setVisibleAnchorDate(/^\d{4}-\d{2}-\d{2}$/.test(iso) ? iso : null)
+  }, [scrollRaw, setVisibleAnchorDate])
 
   // Vertical position of the floating chip in scroll-viewport pixels.
   // Tracks the scrollbar thumb's position by mapping scroll progress
@@ -411,41 +497,29 @@ export function Timeline() {
     return current
   }, [headerOffsets, scrollTop])
 
-  // Measure the sentinel's actual rendered width on mount, window
-  // resize, and any layout change driven by the sidebar collapse /
-  // right panel toggle. ResizeObserver picks up everything window
-  // resize misses (sidebar collapse doesn't fire window resize).
-  //
-  // Uses a callback ref (not useRef + useEffect) because Timeline
-  // early-returns a loading/empty state before the sentinel exists,
-  // so a mount-only effect would see a null ref and never install
-  // the observer. The callback ref fires whenever the sentinel
-  // actually attaches, which is the moment we can measure it.
+  // Measure the scroll container directly and subtract its padding to
+  // get the real grid width. Observing the scroll container itself (vs
+  // a sentinel child) reliably fires on every sidebar toggle and
+  // window resize — no edge cases with zero-height observers or
+  // early-returned loading states detaching the sentinel.
   const roRef = useRef<ResizeObserver | null>(null)
-  const measureElRef = useRef<HTMLDivElement | null>(null)
-  const widthSentinelRef = useCallback((el: HTMLDivElement | null) => {
+  const scrollContainerRef = useCallback((el: HTMLDivElement | null) => {
     roRef.current?.disconnect()
     roRef.current = null
-    measureElRef.current = el
+    parentRef.current = el
     if (!el) return
-    const measure = () => setContainerWidth(el.clientWidth)
+    const measure = () => {
+      const style = window.getComputedStyle(el)
+      const padX =
+        parseFloat(style.paddingLeft) + parseFloat(style.paddingRight)
+      setContainerWidth(Math.max(0, el.clientWidth - padX))
+    }
     measure()
     const ro = new ResizeObserver(measure)
     ro.observe(el)
     roRef.current = ro
   }, [])
-  useEffect(() => {
-    const onResize = () => {
-      const el = measureElRef.current
-      if (el) setContainerWidth(el.clientWidth)
-    }
-    window.addEventListener('resize', onResize)
-    return () => {
-      window.removeEventListener('resize', onResize)
-      roRef.current?.disconnect()
-      roRef.current = null
-    }
-  }, [])
+  useEffect(() => () => roRef.current?.disconnect(), [])
 
   // Photo rows in visual order — drops the header items so navigation
   // walks the grid as the user sees it. Each row has cells of length
@@ -490,8 +564,8 @@ export function Timeline() {
     const scrollEl = parentRef.current
     if (itemIdx === undefined || !scrollEl) return
     let rowTop = 0
-    for (let i = 0; i < itemIdx; i++) rowTop += items[i].height
-    const rowHeight = items[itemIdx].height
+    for (let i = 0; i < itemIdx; i++) rowTop += effectiveHeight(items[i])
+    const rowHeight = effectiveHeight(items[itemIdx])
     const viewTop = scrollEl.scrollTop
     const viewBottom = viewTop + scrollEl.clientHeight
     if (rowTop >= viewTop && rowTop + rowHeight <= viewBottom) return
@@ -505,6 +579,45 @@ export function Timeline() {
     scrollEl.scrollTo({ top: target })
   }, [viewMode, activePhotoId, photoRows, photoRowItemIndex, items])
 
+  // Handle explicit jump requests from outside the grid (e.g. the
+  // sidebar calendar clicking a date). Same centring math as the
+  // preview-close path but uses smooth scroll so the jump is visually
+  // connected to the click, and always fires regardless of viewport
+  // state. Clears the target after scrolling so the next click on the
+  // same id still fires a fresh scroll.
+  const jumpTargetId = usePhotoStore((s) => s.jumpTargetId)
+  const clearJumpTarget = usePhotoStore((s) => s.clearJumpTarget)
+  useEffect(() => {
+    if (!jumpTargetId) return
+    if (viewMode !== 'grid') return
+    let rowIdx = -1
+    for (let r = 0; r < photoRows.length; r++) {
+      if (photoRows[r].cells.some((c) => c.photo.id === jumpTargetId)) {
+        rowIdx = r
+        break
+      }
+    }
+    if (rowIdx < 0) {
+      clearJumpTarget()
+      return
+    }
+    const itemIdx = photoRowItemIndex[rowIdx]
+    const scrollEl = parentRef.current
+    if (itemIdx === undefined || !scrollEl) {
+      clearJumpTarget()
+      return
+    }
+    let rowTop = 0
+    for (let i = 0; i < itemIdx; i++) rowTop += effectiveHeight(items[i])
+    const rowHeight = effectiveHeight(items[itemIdx])
+    const target = Math.max(
+      0,
+      rowTop - scrollEl.clientHeight / 2 + rowHeight / 2,
+    )
+    scrollEl.scrollTo({ top: target, behavior: 'smooth' })
+    clearJumpTarget()
+  }, [jumpTargetId, viewMode, photoRows, photoRowItemIndex, items, clearJumpTarget])
+
   // Flat visible-order id sequence — exactly the order the user reads
   // off the grid (top-to-bottom, left-to-right within each row).
   // Includes duplicates from tag-grouping; landing on the same photo's
@@ -520,197 +633,63 @@ export function Timeline() {
     return ids
   }, [photoRows])
 
+  // Mirror visibleSequence into a ref synchronously so the auto-focus
+  // effect (which runs earlier and references this ref) sees the
+  // current sequence on the same render the data loads. Updating the
+  // ref inside an effect would lag by one render.
+  visibleSequenceRef.current = visibleSequence
+
   // Publish to the photo store so PreviewView's arrow nav and filmstrip
   // can walk the same order even when opened from a non-click path
   // (e.g. the global Space hotkey).
   useEffect(() => {
     setVisiblePhotoIds(visibleSequence)
-    visibleSequenceRef.current = visibleSequence
   }, [visibleSequence, setVisiblePhotoIds])
 
-  // Locate the active photo in the visual grid. Returns the FIRST
-  // Handle keyboard shortcuts for photo navigation. Operates on the
-  // grouped grid the user sees, so a half-full last row of a group
-  // doesn't make ArrowDown skip into the wrong place.
+  // Keyboard grid nav (arrows / Ctrl+A / Escape) is shared with
+  // MemoriesView via useGridKeyNav. Timeline provides its own scroll
+  // callback because row geometry comes from the TanStack virtualizer's
+  // item heights; MemoriesView reads DOM offsets instead.
   //
-  // Inert in preview mode — PreviewView mounts its own arrow handlers,
-  // and a window-level grid handler firing alongside them used to race
-  // against PreviewView's setActivePhoto, landing the user on the wrong
-  // photo. The grid handler stays attached so it can re-engage the
-  // moment the user closes preview.
-  //
-  // The handler reads its inputs through a ref so the listener can bind
-  // once per (viewMode, currentSection) — every other dep used to be in
-  // the array and triggered an unbind/rebind on every state tick (eight
-  // values, several with new identity each render).
-  const navStateRef = useRef({
-    photoRows,
-    photos,
-    selectedPhotos,
-    activePhotoId,
-    photoRowItemIndex,
-    items,
-    cellSize,
+  // Inert in preview mode (PreviewView has its own arrow handlers) and
+  // in the duplicates section (DuplicatesView manages its own grouped
+  // nav against a different snapshot of the visible grid).
+  const gridNavRows = useMemo(
+    () =>
+      photoRows.map((row) => ({
+        cells: row.cells.map((c) => ({ id: c.photo.id })),
+      })),
+    [photoRows]
+  )
+  const scrollRowIntoView = useCallback(
+    (rowIdx: number) => {
+      const itemIdx = photoRowItemIndex[rowIdx]
+      const scrollEl = parentRef.current
+      if (itemIdx === undefined || !scrollEl) return
+      // Sum item heights up to itemIdx to get this row's offset in the
+      // virtualizer's coordinate space. Cheap enough at O(items) and
+      // avoids reaching into virtualizer.measurementsCache internals.
+      let rowTop = 0
+      for (let i = 0; i < itemIdx; i++) rowTop += effectiveHeight(items[i])
+      const rowHeight = effectiveHeight(items[itemIdx])
+      const peek = Math.round(cellSize * 0.35)
+      const viewTop = scrollEl.scrollTop
+      const viewBottom = viewTop + scrollEl.clientHeight
+      if (rowTop - peek < viewTop) {
+        scrollEl.scrollTo({ top: Math.max(0, rowTop - peek) })
+      } else if (rowTop + rowHeight + peek > viewBottom) {
+        scrollEl.scrollTo({
+          top: rowTop + rowHeight + peek - scrollEl.clientHeight,
+        })
+      }
+    },
+    [photoRowItemIndex, items, cellSize]
+  )
+  useGridKeyNav({
+    rows: gridNavRows,
+    enabled: viewMode === 'grid' && currentSection !== 'duplicates',
+    scrollRowIntoView,
   })
-  navStateRef.current = {
-    photoRows,
-    photos,
-    selectedPhotos,
-    activePhotoId,
-    photoRowItemIndex,
-    items,
-    cellSize,
-  }
-  useEffect(() => {
-    if (viewMode !== 'grid') return
-    // The duplicates section mounts its own grouped view (DuplicatesView)
-    // with its own keyboard nav — bail out so we don't double-handle
-    // arrow keys and try to navigate against a photoRows snapshot that
-    // doesn't match what the user actually sees on screen.
-    if (currentSection === 'duplicates') return
-    const handleKeyDown = (e: KeyboardEvent) => {
-      const {
-        photoRows,
-        photos,
-        selectedPhotos,
-        photoRowItemIndex,
-        items,
-        cellSize,
-      } = navStateRef.current
-      if (photoRows.length === 0) return
-      const target = e.target as HTMLElement | null
-      if (target && (target.tagName === 'INPUT' || target.tagName === 'TEXTAREA')) {
-        return
-      }
-
-      const findActive = (): { row: number; col: number } | null => {
-        const aid = navStateRef.current.activePhotoId
-        if (!aid) return null
-        for (let r = 0; r < photoRows.length; r++) {
-          const c = photoRows[r].cells.findIndex((cell) => cell.photo.id === aid)
-          if (c >= 0) return { row: r, col: c }
-        }
-        return null
-      }
-      const move = (dr: number, dc: number) => {
-        const current = findActive() ?? { row: 0, col: -1 }
-        let nextRow = current.row
-        let nextCol = current.col + dc
-
-        if (dc !== 0) {
-          // Wrap left/right across row boundaries.
-          while (nextCol < 0 && nextRow > 0) {
-            nextRow -= 1
-            nextCol = photoRows[nextRow].cells.length - 1
-          }
-          while (
-            nextRow < photoRows.length &&
-            nextCol >= photoRows[nextRow].cells.length
-          ) {
-            if (nextRow === photoRows.length - 1) {
-              nextCol = photoRows[nextRow].cells.length - 1
-              break
-            }
-            nextRow += 1
-            nextCol = 0
-          }
-          if (nextCol < 0) nextCol = 0
-        }
-
-        if (dr !== 0) {
-          nextRow += dr
-          if (nextRow < 0) nextRow = 0
-          if (nextRow >= photoRows.length) nextRow = photoRows.length - 1
-          // Clamp the column to the destination row's actual width so
-          // moving down into a half-full row lands on its last cell
-          // instead of nothing.
-          const rowLen = photoRows[nextRow].cells.length
-          if (nextCol >= rowLen) nextCol = rowLen - 1
-          if (nextCol < 0) nextCol = 0
-        }
-
-        const dest = photoRows[nextRow]?.cells[nextCol]
-        if (!dest) return
-        if (e.shiftKey) {
-          selectRange(dest.photo.id)
-        } else {
-          selectPhoto(dest.photo.id)
-        }
-        // Bring the destination row into view if it's off-screen, leaving
-        // a "peek" margin so the next row above/below stays partly visible
-        // — cues the user that there's more content in the scroll direction.
-        // In-viewport moves are a no-op, so same-row arrow presses don't
-        // jitter the scroll position.
-        const itemIdx = photoRowItemIndex[nextRow]
-        const scrollEl = parentRef.current
-        if (itemIdx !== undefined && scrollEl) {
-          // Sum item heights up to itemIdx to get this row's offset in the
-          // virtualizer's coordinate space. Cheap enough at O(items) and
-          // avoids reaching into virtualizer.measurementsCache internals.
-          let rowTop = 0
-          for (let i = 0; i < itemIdx; i++) rowTop += items[i].height
-          const rowHeight = items[itemIdx].height
-          const peek = Math.round(cellSize * 0.35)
-          const viewTop = scrollEl.scrollTop
-          const viewBottom = viewTop + scrollEl.clientHeight
-          if (rowTop - peek < viewTop) {
-            // Destination is above (or flush with) the viewport top. Leave
-            // `peek` pixels of the previous row visible above it.
-            scrollEl.scrollTo({ top: Math.max(0, rowTop - peek) })
-          } else if (rowTop + rowHeight + peek > viewBottom) {
-            // Destination is below the viewport bottom. Leave `peek` pixels
-            // of the next row visible below it.
-            scrollEl.scrollTo({
-              top: rowTop + rowHeight + peek - scrollEl.clientHeight,
-            })
-          }
-        }
-      }
-
-      switch (e.key) {
-        case 'ArrowUp':
-          e.preventDefault()
-          move(-1, 0)
-          break
-        case 'ArrowDown':
-          e.preventDefault()
-          move(1, 0)
-          break
-        case 'ArrowLeft':
-          e.preventDefault()
-          move(0, -1)
-          break
-        case 'ArrowRight':
-          e.preventDefault()
-          move(0, 1)
-          break
-        case 'a':
-          if (e.ctrlKey || e.metaKey) {
-            e.preventDefault()
-            photos.forEach((photo) => {
-              if (!selectedPhotos.includes(photo.id)) {
-                togglePhotoSelection(photo.id)
-              }
-            })
-          }
-          break
-        case 'Escape':
-          e.preventDefault()
-          clearSelection()
-          break
-      }
-    }
-
-    window.addEventListener('keydown', handleKeyDown)
-    return () => window.removeEventListener('keydown', handleKeyDown)
-  }, [
-    viewMode,
-    currentSection,
-    selectRange,
-    selectPhoto,
-    togglePhotoSelection,
-    clearSelection,
-  ])
 
   if (isLoading) {
     return (
@@ -759,7 +738,7 @@ export function Timeline() {
       )}
 
       <div
-        ref={parentRef}
+        ref={scrollContainerRef}
         className="h-full overflow-auto bg-bg"
         // Extra bottom padding so the last row clears the floating
         // KeyboardHints pill (which sits at bottom-4, ~40px tall).
@@ -772,23 +751,6 @@ export function Timeline() {
             position: 'relative',
           }}
         >
-          {/* Width sentinel — a 1px-tall normal-flow div that takes the
-           *  full width of the inner virtualizer wrapper, which is the
-           *  exact width rows render at. clientWidth on this is what we
-           *  base the column count on, sidestepping any padding /
-           *  scrollbar mismatch the parentRef-based measurement is
-           *  vulnerable to. ResizeObserver doesn't reliably fire on
-           *  zero-area absolute elements, so 1px tall + relative flow. */}
-          <div
-            ref={widthSentinelRef}
-            aria-hidden="true"
-            style={{
-              width: '100%',
-              height: 1,
-              marginBottom: -1,
-              pointerEvents: 'none',
-            }}
-          />
           {virtualizer.getVirtualItems().map((virtualItem) => {
             const item = items[virtualItem.index]
             if (!item) return null

frontend/src/components/ui/calendar.tsx

@@ -16,48 +16,41 @@ function Calendar({
   return (
     <DayPicker
       showOutsideDays={showOutsideDays}
-      className={cn('p-3', className)}
+      className={cn('p-1.5', className)}
       classNames={{
-        months: 'flex flex-col sm:flex-row gap-4',
-        month: 'flex flex-col gap-3',
-        // Row layout: prev-nav · dropdowns (Month / Year) · next-nav.
-        // Works for both button and dropdown caption layouts.
-        caption: 'flex items-center justify-between px-1 pt-1',
-        caption_label: 'text-sm font-medium text-text',
-        // Dropdown caption — react-day-picker v8 renders each dropdown
-        // as an invisible <select> layered over a visible caption_label
-        // span. We position the <select> absolutely + transparent so
-        // the label is what's actually drawn, while clicks still open
-        // the native picker. The top-level CaptionLabel ("January 2026"
-        // in full) sits inside a .vhidden wrapper — absolutely clipped
-        // so it stays screen-reader only.
-        caption_dropdowns: 'flex items-center justify-center gap-2',
-        dropdown_month: 'relative inline-flex items-center rounded-md px-1 text-sm font-medium text-text hover:bg-surface-2',
-        dropdown_year: 'relative inline-flex items-center rounded-md px-1 text-sm font-medium text-text hover:bg-surface-2',
+        months: 'flex flex-col sm:flex-row gap-2',
+        month: 'flex flex-col gap-1.5',
+        caption: 'flex items-center justify-between px-0.5 pt-0.5',
+        caption_label: 'text-xs font-medium text-text',
+        caption_dropdowns: 'flex items-center justify-center gap-1.5',
+        dropdown_month:
+          'relative inline-flex items-center rounded px-0.5 text-xs font-medium text-text hover:bg-surface-2',
+        dropdown_year:
+          'relative inline-flex items-center rounded px-0.5 text-xs font-medium text-text hover:bg-surface-2',
         dropdown:
           'absolute inset-0 z-10 cursor-pointer appearance-none bg-transparent opacity-0',
-        dropdown_icon: 'ml-1 h-3 w-3 opacity-60',
+        dropdown_icon: 'ml-0.5 h-3 w-3 opacity-60',
         vhidden:
           '!absolute !-m-px !h-px !w-px !overflow-hidden !whitespace-nowrap !border-0 !p-0 ![clip:rect(0,0,0,0)]',
-        nav: 'flex items-center gap-1',
+        nav: 'flex items-center gap-0.5',
         nav_button: cn(
           buttonVariants({ variant: 'ghost' }),
-          'h-6 w-6 p-0 text-text-muted hover:text-text'
+          'h-5 w-5 p-0 text-text-muted hover:text-text',
         ),
         nav_button_previous: '',
         nav_button_next: '',
         table: 'w-full border-collapse',
         head_row: 'flex',
         head_cell:
-          'text-text-muted rounded-md w-7 font-normal text-[0.7rem]',
-        row: 'flex w-full mt-1',
+          'text-text-muted rounded w-6 font-normal text-[9px] uppercase tracking-wide',
+        row: 'flex w-full mt-0.5',
         cell: cn(
-          'relative p-0 text-center text-sm focus-within:relative focus-within:z-20',
-          '[&:has([aria-selected])]:bg-surface-2 [&:has([aria-selected].day-outside)]:bg-surface-2/50'
+          'relative p-0 text-center text-xs focus-within:relative focus-within:z-20',
+          '[&:has([aria-selected])]:bg-surface-2 [&:has([aria-selected].day-outside)]:bg-surface-2/50',
         ),
         day: cn(
           buttonVariants({ variant: 'ghost' }),
-          'h-7 w-7 p-0 font-normal aria-selected:opacity-100'
+          'h-6 w-6 p-0 text-xs font-normal aria-selected:opacity-100',
         ),
         day_range_end: 'day-range-end',
         day_selected:

frontend/src/components/ui/sonner.tsx

@@ -10,16 +10,20 @@ const Toaster = ({ ...props }: ToasterProps) => (
   <Sonner
     position="bottom-left"
     theme="dark"
+    // Compact toasts: tight padding, smaller gap, single-line title+desc
+    // so they don't hog the corner of the screen.
+    gap={6}
     toastOptions={{
       classNames: {
         toast:
-          'group toast bg-surface/90 border border-border backdrop-blur-md text-text shadow-lg',
-        title: 'text-text text-sm font-semibold',
-        description: 'text-text-muted text-xs',
+          'group toast !gap-1.5 !p-2 !min-h-0 bg-surface/90 border border-border backdrop-blur-md text-text shadow',
+        title: 'text-text text-xs font-medium leading-tight',
+        description: 'text-text-muted text-[11px] leading-tight',
         actionButton:
-          'bg-primary text-bg hover:bg-primary/90 rounded-md px-2 py-1 text-xs font-medium',
+          '!h-6 bg-primary text-bg hover:bg-primary/90 rounded-md px-1.5 text-[11px] font-medium',
         cancelButton:
-          'bg-surface-2 text-text-muted hover:bg-surface-offset rounded-md px-2 py-1 text-xs',
+          '!h-6 bg-surface-2 text-text-muted hover:bg-surface-offset rounded-md px-1.5 text-[11px]',
+        icon: '!size-3.5 !mr-1',
         success: 'border-l-2 border-l-pick',
         error: 'border-l-2 border-l-reject',
         info: 'border-l-2 border-l-primary',

frontend/src/hooks/useBulkPhotoMutations.ts

@@ -4,6 +4,7 @@ import { toast } from '../components/ToastContainer'
 import { formatApiError } from '../lib/apiError'
 import { LIBRARY_STATS_QUERY_KEY } from './useLibraryStatsQuery'
 import type { Photo } from '../types/photo'
+import type { MemoriesResponse, MemoryPhoto } from '../services/api'
 
 /**
  * Centralised bulk-mutation hook used by both the RightSidebar multi-
@@ -48,6 +49,22 @@ export function useBulkPhotoMutations() {
       const single = queryClient.getQueryData<Photo>(['photo', id])
       if (single) snap.set(id, { ...single })
     }
+    // Fall back to memories cache for photos only surfaced via
+    // "On this day" — otherwise a rollback on error can't restore them.
+    const mem = queryClient.getQueryData<MemoriesResponse>(['memories'])
+    if (mem) {
+      for (const g of mem.memories) {
+        for (const p of g.photos) {
+          if (want.has(p.id) && !snap.has(p.id)) {
+            snap.set(p.id, {
+              rating: p.rating,
+              color_label: p.color_label,
+              is_discarded: p.is_discarded,
+            } as Partial<Photo>)
+          }
+        }
+      }
+    }
     return snap
   }
 
@@ -62,6 +79,27 @@ export function useBulkPhotoMutations() {
       const cur = queryClient.getQueryData<Photo>(['photo', id])
       if (cur) queryClient.setQueryData<Photo>(['photo', id], { ...cur, ...patch })
     }
+    // Memories cache has a nested {memories:[{photos:[...]}]} shape —
+    // only the fields MemoryPhoto carries (rating/color_label/is_discarded)
+    // can be patched in-place, which covers every culling shortcut.
+    const memPatch: Partial<MemoryPhoto> = {}
+    if (patch.rating !== undefined) memPatch.rating = patch.rating
+    if (patch.color_label !== undefined) memPatch.color_label = patch.color_label
+    if (patch.is_discarded !== undefined) memPatch.is_discarded = patch.is_discarded
+    if (Object.keys(memPatch).length === 0) return
+    queryClient.setQueryData<MemoriesResponse>(['memories'], (prev) =>
+      prev
+        ? {
+            ...prev,
+            memories: prev.memories.map((g) => ({
+              ...g,
+              photos: g.photos.map((p) =>
+                want.has(p.id) ? { ...p, ...memPatch } : p,
+              ),
+            })),
+          }
+        : prev,
+    )
   }
 
   const restoreFromSnapshot = (snap: Map<string, Partial<Photo>>) => {
@@ -81,6 +119,27 @@ export function useBulkPhotoMutations() {
         queryClient.setQueryData<Photo>(['photo', id], { ...cur, ...orig })
       }
     }
+    queryClient.setQueryData<MemoriesResponse>(['memories'], (prev) =>
+      prev
+        ? {
+            ...prev,
+            memories: prev.memories.map((g) => ({
+              ...g,
+              photos: g.photos.map((p) => {
+                const orig = snap.get(p.id)
+                if (!orig) return p
+                const out: MemoryPhoto = { ...p }
+                if (orig.rating !== undefined) out.rating = orig.rating
+                if (orig.color_label !== undefined)
+                  out.color_label = orig.color_label ?? null
+                if (orig.is_discarded !== undefined)
+                  out.is_discarded = orig.is_discarded
+                return out
+              }),
+            })),
+          }
+        : prev,
+    )
   }
 
   const bulkRating = useMutation({

frontend/src/hooks/useGridKeyNav.ts

@@ -0,0 +1,161 @@
+import { useEffect, useRef } from 'react'
+import { usePhotoStore } from '../store/photoStore'
+
+/** A single row of the visual grid. Only the photo id is required —
+ *  callers (Timeline, MemoriesView) can keep richer cell shapes but we
+ *  only care about id for navigation. */
+export interface GridNavRow {
+  cells: { id: string }[]
+}
+
+interface UseGridKeyNavArgs {
+  /** The flat, in-order grid rows the user sees. Navigation wraps at
+   *  row ends and clamps to the destination row's width on vertical
+   *  moves so half-full trailing rows don't land on empty cells. */
+  rows: GridNavRow[]
+  /** Gate the listener. Typically `viewMode === 'grid'` AND the view
+   *  is mounted. When false, the window keydown listener is detached. */
+  enabled: boolean
+  /** Called after a successful arrow-nav move so the caller can scroll
+   *  the destination row into view. No-op moves (same row, within
+   *  viewport) still call it — the callback decides whether to scroll. */
+  scrollRowIntoView?: (rowIdx: number) => void
+}
+
+/**
+ * Shared arrow/Ctrl+A/Escape grid keyboard handler. Centralises the
+ * navigation logic Timeline and MemoriesView both need so they stay in
+ * lockstep — any future grid view can opt in by supplying its own
+ * `rows` and (optionally) a scroll callback.
+ *
+ * Scroll math stays with the caller because each grid measures row
+ * geometry differently (TanStack virtualizer for Timeline; native DOM
+ * offsets for the non-virtualised MemoriesView).
+ */
+export function useGridKeyNav({
+  rows,
+  enabled,
+  scrollRowIntoView,
+}: UseGridKeyNavArgs) {
+  // Read inputs through a ref so the listener binds once per `enabled`
+  // toggle — without this the handler would re-attach on every render,
+  // churning the window event map.
+  const stateRef = useRef({ rows, scrollRowIntoView })
+  stateRef.current = { rows, scrollRowIntoView }
+
+  useEffect(() => {
+    if (!enabled) return
+
+    const handleKeyDown = (e: KeyboardEvent) => {
+      const { rows, scrollRowIntoView } = stateRef.current
+      if (rows.length === 0) return
+
+      const target = e.target as HTMLElement | null
+      if (
+        target &&
+        (target.tagName === 'INPUT' || target.tagName === 'TEXTAREA')
+      ) {
+        return
+      }
+
+      const store = usePhotoStore.getState()
+
+      const findActive = (): { row: number; col: number } | null => {
+        const aid = store.activePhotoId
+        if (!aid) return null
+        for (let r = 0; r < rows.length; r++) {
+          const c = rows[r].cells.findIndex((cell) => cell.id === aid)
+          if (c >= 0) return { row: r, col: c }
+        }
+        return null
+      }
+
+      const move = (dr: number, dc: number) => {
+        const current = findActive() ?? { row: 0, col: -1 }
+        let nextRow = current.row
+        let nextCol = current.col + dc
+
+        if (dc !== 0) {
+          // Wrap left/right across row boundaries.
+          while (nextCol < 0 && nextRow > 0) {
+            nextRow -= 1
+            nextCol = rows[nextRow].cells.length - 1
+          }
+          while (
+            nextRow < rows.length &&
+            nextCol >= rows[nextRow].cells.length
+          ) {
+            if (nextRow === rows.length - 1) {
+              nextCol = rows[nextRow].cells.length - 1
+              break
+            }
+            nextRow += 1
+            nextCol = 0
+          }
+          if (nextCol < 0) nextCol = 0
+        }
+
+        if (dr !== 0) {
+          nextRow += dr
+          if (nextRow < 0) nextRow = 0
+          if (nextRow >= rows.length) nextRow = rows.length - 1
+          // Clamp the column to the destination row's actual width so
+          // moving down into a half-full row lands on its last cell
+          // instead of nothing.
+          const rowLen = rows[nextRow].cells.length
+          if (nextCol >= rowLen) nextCol = rowLen - 1
+          if (nextCol < 0) nextCol = 0
+        }
+
+        const dest = rows[nextRow]?.cells[nextCol]
+        if (!dest) return
+
+        // Read fresh actions each call so the hook stays zero-dep.
+        const { selectRange, selectPhoto } = usePhotoStore.getState()
+        if (e.shiftKey) selectRange(dest.id)
+        else selectPhoto(dest.id)
+
+        scrollRowIntoView?.(nextRow)
+      }
+
+      switch (e.key) {
+        case 'ArrowUp':
+          e.preventDefault()
+          move(-1, 0)
+          break
+        case 'ArrowDown':
+          e.preventDefault()
+          move(1, 0)
+          break
+        case 'ArrowLeft':
+          e.preventDefault()
+          move(0, -1)
+          break
+        case 'ArrowRight':
+          e.preventDefault()
+          move(0, 1)
+          break
+        case 'a':
+          if (e.ctrlKey || e.metaKey) {
+            e.preventDefault()
+            const { selectedPhotos, togglePhotoSelection } =
+              usePhotoStore.getState()
+            const selected = new Set(selectedPhotos)
+            for (const row of rows) {
+              for (const cell of row.cells) {
+                if (!selected.has(cell.id)) togglePhotoSelection(cell.id)
+              }
+            }
+          }
+          break
+        case 'Escape':
+          e.preventDefault()
+          usePhotoStore.getState().clearSelection()
+          break
+      }
+    }
+
+    window.addEventListener('keydown', handleKeyDown)
+    return () => window.removeEventListener('keydown', handleKeyDown)
+  }, [enabled])
+}

frontend/src/hooks/useKeyboardShortcuts.ts

@@ -10,6 +10,7 @@ import { LIBRARY_STATS_QUERY_KEY } from './useLibraryStatsQuery'
 import { useBulkPhotoMutations } from './useBulkPhotoMutations'
 import { formatApiError } from '../lib/apiError'
 import type { Photo } from '../types/photo'
+import type { MemoriesResponse, MemoryPhoto } from '../services/api'
 
 interface KeyboardShortcutsProps {
   onToggleLeftSidebar: () => void
@@ -76,6 +77,21 @@ export function useKeyboardShortcuts(props: KeyboardShortcutsProps) {
         ? prev.map((p) => (set.has(p.id) ? { ...p, is_discarded: discarded } : p))
         : prev
     )
+    // Memories view has its own cache shape ({memories: [{photos: [...]}]})
+    // — patch it too so the grayscale flip shows up in "On this day".
+    queryClient.setQueryData<MemoriesResponse>(['memories'], (prev) =>
+      prev
+        ? {
+            ...prev,
+            memories: prev.memories.map((g) => ({
+              ...g,
+              photos: g.photos.map((p) =>
+                set.has(p.id) ? { ...p, is_discarded: discarded } : p,
+              ),
+            })),
+          }
+        : prev,
+    )
   }
 
   /** Look up a photo's CURRENT cached state (is_discarded etc) without
@@ -88,9 +104,35 @@ export function useKeyboardShortcuts(props: KeyboardShortcutsProps) {
       const p = list.find((x) => x.id === id)
       if (p) return p
     }
+    // Fall through to memories cache (On this day) and then per-photo.
+    const mem = queryClient.getQueryData<MemoriesResponse>(['memories'])
+    if (mem) {
+      for (const g of mem.memories) {
+        const m = g.photos.find((p: MemoryPhoto) => p.id === id)
+        if (m) return memoryToPhotoPartial(m)
+      }
+    }
     return queryClient.getQueryData<Photo>(['photo', id])
   }
 
+  const memoryToPhotoPartial = (m: MemoryPhoto): Photo =>
+    ({
+      id: m.id,
+      filepath: m.filename,
+      filename: m.filename,
+      media_type: m.media_type,
+      width: m.width,
+      height: m.height,
+      taken_at: m.taken_at,
+      rating: m.rating,
+      color_label: m.color_label,
+      is_discarded: m.is_discarded,
+      is_duplicate: false,
+      file_hash: '',
+      folder_id: null,
+      added_at: null,
+    } as Photo)
+
   // Discard / restore mutation — the only path that doesn't auto-
   // invalidate ['photos']. Invalidating would refetch with the active
   // filter (which excludes discarded photos in every section except

frontend/src/services/api.ts

@@ -600,6 +600,8 @@ export interface MemoryPhoto {
   width: number | null
   height: number | null
   rating: number
+  color_label: string | null
+  is_discarded: boolean
 }
 
 export interface MemoryGroup {

frontend/src/store/photoStore.ts

@@ -25,6 +25,17 @@ interface PhotoStore {
    *  on the photo they came from instead of whatever neighbour they
    *  arrow-navigated to inside the preview. */
   previewOriginPhotoId: string | null
+  /** yyyy-mm-dd ISO date of the photo currently under the top of the
+   *  timeline viewport. Timeline/MemoriesView publish this as the user
+   *  scrolls; the DateRangePicker in the left sidebar reads it to keep
+   *  its displayed month in sync with what the user's actually looking
+   *  at, so picking a range around the current position is one click. */
+  visibleAnchorDate: string | null
+  /** One-shot jump request: when a photo id is written here, the
+   *  Timeline scrolls it into the viewport's centre and then clears
+   *  the slot. Used by the sidebar calendar to jump to photos taken
+   *  on a clicked date. */
+  jumpTargetId: string | null
 
   setPhotos: (photos: Photo[]) => void
   selectPhoto: (id: string) => void
@@ -55,6 +66,11 @@ interface PhotoStore {
    *  to the next surviving neighbour so the grid still has a target
    *  for arrow keys after the removal. */
   removePhotosFromTimeline: (ids: string[]) => void
+  setVisibleAnchorDate: (iso: string | null) => void
+  /** Focus `id` and request the Timeline to scroll to it. Selection +
+   *  anchor move with it so arrow-nav continues from there. */
+  jumpToPhoto: (id: string) => void
+  clearJumpTarget: () => void
 }
 
 export const usePhotoStore = create<PhotoStore>((set) => ({
@@ -65,9 +81,26 @@ export const usePhotoStore = create<PhotoStore>((set) => ({
   viewMode: 'grid',
   visiblePhotoIds: [],
   previewOriginPhotoId: null,
+  visibleAnchorDate: null,
+  jumpTargetId: null,
 
   setPhotos: (photos) => set({ photos }),
 
+  // Guarded set — only write when the value actually changes, so
+  // Timeline's scroll listener can fire freely without re-rendering
+  // every subscriber on every pixel.
+  setVisibleAnchorDate: (iso) =>
+    set((s) => (s.visibleAnchorDate === iso ? s : { visibleAnchorDate: iso })),
+
+  jumpToPhoto: (id) =>
+    set({
+      activePhotoId: id,
+      rangeStartId: id,
+      selectedPhotos: [id],
+      jumpTargetId: id,
+    }),
+  clearJumpTarget: () => set({ jumpTargetId: null }),
+
   selectPhoto: (id) => set({
     selectedPhotos: [id],
     activePhotoId: id,