Push up operations to VirtualScrollManager

push top level functions from timelinemanager into extensions
Relocate/rename internal timeline functions to follow TimelineExtensions pattern
2025-12-11 01:10:23 +03:00 · 2025-11-02 19:50:55 +00:00 · 2025-11-02 19:44:41 +00:00 · 2025-11-02 19:44:41 +00:00 · 2025-11-02 16:59:57 +00:00
34 changed files with 1587 additions and 1485 deletions
--- a/web/src/lib/components/timeline/Scrubber.svelte
+++ b/web/src/lib/components/timeline/Scrubber.svelte
@@ -91,7 +91,7 @@
    scrubberWidth = usingMobileDevice ? MOBILE_WIDTH : DESKTOP_WIDTH;
  });

-  const toScrollFromMonthPercentage = (
+  const toScrollFromMonthGroupPercentage = (
    scrubberMonth: ViewportTopMonth,
    scrubberMonthPercent: number,
    scrubOverallPercent: number,
@@ -124,7 +124,7 @@
    }
  };
  const scrollY = $derived(
-    toScrollFromMonthPercentage(viewportTopMonth, viewportTopMonthScrollPercent, timelineScrollPercent),
+    toScrollFromMonthGroupPercentage(viewportTopMonth, viewportTopMonthScrollPercent, timelineScrollPercent),
  );
  const timelineFullHeight = $derived(timelineManager.scrubberTimelineHeight);
  const relativeTopOffset = $derived(toScrollY(timelineTopOffset / timelineFullHeight));
@@ -280,12 +280,12 @@
      const boundingClientRect = bestElement.boundingClientRect;
      const sy = boundingClientRect.y;
      const relativeY = y - sy;
-      const monthPercentY = relativeY / boundingClientRect.height;
+      const monthGroupPercentY = relativeY / boundingClientRect.height;
      return {
        isOnPaddingTop: false,
        isOnPaddingBottom: false,
        segment,
-        monthPercentY,
+        monthGroupPercentY,
      };
    }

@@ -308,7 +308,7 @@
      isOnPaddingTop,
      isOnPaddingBottom,
      segment: undefined,
-      monthPercentY: 0,
+      monthGroupPercentY: 0,
    };
  };

@@ -327,7 +327,7 @@
    const upper = rect?.height - (PADDING_TOP + PADDING_BOTTOM);
    hoverY = clamp(clientY - rect?.top - PADDING_TOP, lower, upper);
    const x = rect!.left + rect!.width / 2;
-    const { segment, monthPercentY, isOnPaddingTop, isOnPaddingBottom } = getActive(x, clientY);
+    const { segment, monthGroupPercentY, isOnPaddingTop, isOnPaddingBottom } = getActive(x, clientY);
    activeSegment = segment;
    isHoverOnPaddingTop = isOnPaddingTop;
    isHoverOnPaddingBottom = isOnPaddingBottom;
@@ -335,7 +335,7 @@
    const scrubData = {
      scrubberMonth: segmentDate,
      overallScrollPercent: toTimelineY(hoverY),
-      scrubberMonthScrollPercent: monthPercentY,
+      scrubberMonthScrollPercent: monthGroupPercentY,
    };
    if (wasDragging === false && isDragging) {
      void startScrub?.(scrubData);
--- a/web/src/lib/components/timeline/Timeline.svelte
+++ b/web/src/lib/components/timeline/Timeline.svelte
@@ -2,17 +2,17 @@
  import { afterNavigate, beforeNavigate } from '$app/navigation';
  import { page } from '$app/state';
  import { resizeObserver, type OnResizeCallback } from '$lib/actions/resize-observer';
-  import TimelineKeyboardActions from '$lib/components/timeline/actions/TimelineKeyboardActions.svelte';
  import Scrubber from '$lib/components/timeline/Scrubber.svelte';
  import TimelineAssetViewer from '$lib/components/timeline/TimelineAssetViewer.svelte';
+  import TimelineKeyboardActions from '$lib/components/timeline/actions/TimelineKeyboardActions.svelte';
  import { AssetAction } from '$lib/constants';
  import HotModuleReload from '$lib/elements/HotModuleReload.svelte';
  import Portal from '$lib/elements/Portal.svelte';
  import Skeleton from '$lib/elements/Skeleton.svelte';
-  import { isIntersecting } from '$lib/managers/timeline-manager/internal/intersection-support.svelte';
-  import { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
+  import { isIntersecting } from '$lib/managers/VirtualScrollManager/ScrollSegment.svelte';
+  import type { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
  import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
-  import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
+  import type { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
  import type { TimelineAsset, TimelineManagerOptions, ViewportTopMonth } from '$lib/managers/timeline-manager/types';
  import { assetsSnapshot } from '$lib/managers/timeline-manager/utils.svelte';
  import type { AssetInteraction } from '$lib/stores/asset-interaction.svelte';
@@ -20,7 +20,7 @@
  import { isSelectingAllAssets } from '$lib/stores/assets-store.svelte';
  import { mobileDevice } from '$lib/stores/mobile-device.svelte';
  import { isAssetViewerRoute } from '$lib/utils/navigation';
-  import { getTimes, type ScrubberListener } from '$lib/utils/timeline-util';
+  import { getSegmentIdentifier, getTimes, type ScrubberListener } from '$lib/utils/timeline-util';
  import { type AlbumResponseDto, type PersonResponseDto } from '@immich/sdk';
  import { DateTime } from 'luxon';
  import { onDestroy, onMount, type Snippet } from 'svelte';
@@ -62,7 +62,7 @@
      onClick: (
        timelineManager: TimelineManager,
        assets: TimelineAsset[],
-        dayTitle: string,
+        groupTitle: string,
        asset: TimelineAsset,
      ) => void,
    ) => void;
@@ -109,7 +109,7 @@
  let timelineScrollPercent: number = $state(0);
  let scrubberWidth = $state(0);

-  const isEmpty = $derived(timelineManager.isInitialized && timelineManager.months.length === 0);
+  const isEmpty = $derived(timelineManager.isInitialized && timelineManager.segments.length === 0);
  const maxMd = $derived(mobileDevice.maxMd);
  const usingMobileDevice = $derived(mobileDevice.pointerCoarse);

@@ -130,10 +130,8 @@
    timelineManager.scrollableElement = scrollableElement;
  });

-  const getAssetPosition = (assetId: string, month: TimelineMonth) => month.findAssetAbsolutePosition(assetId);
-
  const scrollToAssetPosition = (assetId: string, month: TimelineMonth) => {
-    const position = getAssetPosition(assetId, month);
+    const position = month.findAssetAbsolutePosition(assetId);

    if (!position) {
      return;
@@ -141,7 +139,7 @@

    // Need to update window positions/intersections because <Portal> may have
    // gone from invisible to visible.
-    timelineManager.updateSlidingWindow();
+    timelineManager.updateVisibleWindow();

    const assetTop = position.top;
    const assetBottom = position.top + position.height;
@@ -176,7 +174,7 @@
  };

  const scrollAndLoadAsset = async (assetId: string) => {
-    const month = await timelineManager.findMonthForAsset(assetId);
+    const month = await timelineManager.search.getMonthForAsset(assetId);
    if (!month) {
      return false;
    }
@@ -185,7 +183,7 @@
  };

  const scrollToAsset = (asset: TimelineAsset) => {
-    const month = timelineManager.getMonthByAssetId(asset.id);
+    const month = timelineManager.search.findMonthForAsset(asset.id)?.month;
    if (!month) {
      return false;
    }
@@ -296,7 +294,7 @@
        scrubberMonthScrollPercent,
      );
    } else {
-      const month = timelineManager.months.find(
+      const month = timelineManager.segments.find(
        ({ yearMonth: { year, month } }) => year === scrubberMonth.year && month === scrubberMonth.month,
      );
      if (!month) {
@@ -325,7 +323,7 @@
      let top = scrollableElement.scrollTop;
      let maxScrollPercent = timelineManager.maxScrollPercent;

-      const monthsLength = timelineManager.months.length;
+      const monthsLength = timelineManager.segments.length;
      for (let i = -1; i < monthsLength + 1; i++) {
        let month: ViewportTopMonth;
        let monthHeight = 0;
@@ -338,8 +336,8 @@
          month = 'lead-out';
          monthHeight = timelineManager.bottomSectionHeight;
        } else {
-          month = timelineManager.months[i].yearMonth;
-          monthHeight = timelineManager.months[i].height;
+          month = timelineManager.segments[i].yearMonth;
+          monthHeight = timelineManager.segments[i].height;
        }

        let next = top - monthHeight * maxScrollPercent;
@@ -352,7 +350,7 @@

          // compensate for lost precision/rounding errors advance to the next bucket, if present
          if (viewportTopMonthScrollPercent > 0.9999 && i + 1 < monthsLength - 1) {
-            viewportTopMonth = timelineManager.months[i + 1].yearMonth;
+            viewportTopMonth = timelineManager.segments[i + 1].yearMonth;
            viewportTopMonthScrollPercent = 0;
          }
          break;
@@ -442,21 +440,21 @@
    assetInteraction.clearAssetSelectionCandidates();

    if (assetInteraction.assetSelectionStart && rangeSelection) {
-      let startBucket = timelineManager.getMonthByAssetId(assetInteraction.assetSelectionStart.id);
-      let endBucket = timelineManager.getMonthByAssetId(asset.id);
+      let startBucket = await timelineManager.search.getMonthForAsset(assetInteraction.assetSelectionStart.id);
+      let endBucket = await timelineManager.search.getMonthForAsset(asset.id);

-      if (startBucket === null || endBucket === null) {
+      if (!startBucket || !endBucket) {
        return;
      }

      // Select/deselect assets in range (start,end)
      let started = false;
-      for (const month of timelineManager.months) {
+      for (const month of timelineManager.segments) {
        if (month === endBucket) {
          break;
        }
        if (started) {
-          await timelineManager.loadMonth(month.yearMonth);
+          await timelineManager.loadSegment(getSegmentIdentifier(month.yearMonth));
          for (const asset of month.assetsIterator()) {
            if (deselect) {
              assetInteraction.removeAssetFromMultiselectGroup(asset.id);
@@ -472,7 +470,7 @@

      // Update date group selection in range [start,end]
      started = false;
-      for (const month of timelineManager.months) {
+      for (const month of timelineManager.segments) {
        if (month === startBucket) {
          started = true;
        }
@@ -506,7 +504,7 @@
      return;
    }

-    const assets = assetsSnapshot(await timelineManager.retrieveRange(startAsset, endAsset));
+    const assets = assetsSnapshot(await timelineManager.search.retrieveRange(startAsset, endAsset));
    assetInteraction.setAssetSelectionCandidates(assets);
  };

@@ -531,7 +529,7 @@
  $effect(() => {
    if ($showAssetViewer) {
      const { localDateTime } = getTimes($viewingAsset.fileCreatedAt, DateTime.local().offset / 60);
-      void timelineManager.loadMonth({ year: localDateTime.year, month: localDateTime.month });
+      void timelineManager.loadSegment(getSegmentIdentifier({ year: localDateTime.year, month: localDateTime.month }));
    }
  });
 </script>
@@ -562,7 +560,7 @@
  {onEscape}
 />

-{#if timelineManager.months.length > 0}
+{#if timelineManager.segments.length > 0}
  <Scrubber
    {timelineManager}
    height={timelineManager.viewportHeight}
@@ -600,7 +598,7 @@
  bind:clientHeight={timelineManager.viewportHeight}
  bind:clientWidth={timelineManager.viewportWidth}
  bind:this={scrollableElement}
-  onscroll={() => (handleTimelineScroll(), timelineManager.updateSlidingWindow(), updateIsScrolling())}
+  onscroll={() => (handleTimelineScroll(), timelineManager.updateVisibleWindow(), updateIsScrolling())}
 >
  <section
    bind:this={timelineElement}
@@ -622,11 +620,11 @@
      {/if}
    </section>

-    {#each timelineManager.months as month (month.viewId)}
+    {#each timelineManager.segments as month (month.identifier.id)}
      {@const display = month.intersecting}
      {@const absoluteHeight = month.top}

-      {#if !month.isLoaded}
+      {#if !month.loaded}
        <div
          style:height={month.height + 'px'}
          style:position="absolute"
--- a/web/src/lib/components/timeline/TimelineAssetViewer.svelte
+++ b/web/src/lib/components/timeline/TimelineAssetViewer.svelte
@@ -40,10 +40,10 @@

  const handlePrevious = async () => {
    const release = await mutex.acquire();
-    const laterAsset = await timelineManager.getLaterAsset($viewingAsset);
+    const laterAsset = await timelineManager.search.getLaterAsset($viewingAsset);

    if (laterAsset) {
-      const preloadAsset = await timelineManager.getLaterAsset(laterAsset);
+      const preloadAsset = await timelineManager.search.getLaterAsset(laterAsset);
      const asset = await getAssetInfo({ ...authManager.params, id: laterAsset.id });
      assetViewingStore.setAsset(asset, preloadAsset ? [preloadAsset] : []);
      await navigate({ targetRoute: 'current', assetId: laterAsset.id });
@@ -55,10 +55,10 @@

  const handleNext = async () => {
    const release = await mutex.acquire();
-    const earlierAsset = await timelineManager.getEarlierAsset($viewingAsset);
+    const earlierAsset = await timelineManager.search.getEarlierAsset($viewingAsset);

    if (earlierAsset) {
-      const preloadAsset = await timelineManager.getEarlierAsset(earlierAsset);
+      const preloadAsset = await timelineManager.search.getEarlierAsset(earlierAsset);
      const asset = await getAssetInfo({ ...authManager.params, id: earlierAsset.id });
      assetViewingStore.setAsset(asset, preloadAsset ? [preloadAsset] : []);
      await navigate({ targetRoute: 'current', assetId: earlierAsset.id });
@@ -69,7 +69,7 @@
  };

  const handleRandom = async () => {
-    const randomAsset = await timelineManager.getRandomAsset();
+    const randomAsset = await timelineManager.search.getRandomAsset();

    if (randomAsset) {
      const asset = await getAssetInfo({ ...authManager.params, id: randomAsset.id });
--- a/web/src/lib/components/timeline/TimelineDateGroup.svelte
+++ b/web/src/lib/components/timeline/TimelineDateGroup.svelte
@@ -1,8 +1,8 @@
 <script lang="ts">
  import Thumbnail from '$lib/components/assets/thumbnail/thumbnail.svelte';
-  import { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
-  import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
-  import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
+  import type { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
+  import type { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
+  import type { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
  import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
  import { assetSnapshot, assetsSnapshot } from '$lib/managers/timeline-manager/utils.svelte';
  import type { AssetInteraction } from '$lib/stores/asset-interaction.svelte';
@@ -38,7 +38,7 @@
      onClick: (
        timelineManager: TimelineManager,
        assets: TimelineAsset[],
-        dayTitle: string,
+        groupTitle: string,
        asset: TimelineAsset,
      ) => void,
    ) => void;
@@ -49,7 +49,7 @@
    singleSelect,
    withStacked,
    showArchiveIcon,
-    month = $bindable(),
+    month: monthGroup = $bindable(),
    assetInteraction,
    timelineManager,
    customLayout,
@@ -61,18 +61,20 @@
  }: Props = $props();

  let isMouseOverGroup = $state(false);
-  let hoveredDay = $state();
+  let hoveredDayGroup = $state();

-  const transitionDuration = $derived.by(() => (month.timelineManager.suspendTransitions && !$isUploading ? 0 : 150));
+  const transitionDuration = $derived.by(() =>
+    monthGroup.scrollManager.suspendTransitions && !$isUploading ? 0 : 150,
+  );
  const scaleDuration = $derived(transitionDuration === 0 ? 0 : transitionDuration + 100);
  const _onClick = (
    timelineManager: TimelineManager,
    assets: TimelineAsset[],
-    dayTitle: string,
+    groupTitle: string,
    asset: TimelineAsset,
  ) => {
    if (isSelectionMode || assetInteraction.selectionActive) {
-      assetSelectHandler(timelineManager, asset, assets, dayTitle);
+      assetSelectHandler(timelineManager, asset, assets, groupTitle);
      return;
    }
    void navigate({ targetRoute: 'current', assetId: asset.id });
@@ -83,19 +85,21 @@
  const assetSelectHandler = (
    timelineManager: TimelineManager,
    asset: TimelineAsset,
-    assetsInDay: TimelineAsset[],
-    dayTitle: string,
+    assetsInDayGroup: TimelineAsset[],
+    groupTitle: string,
  ) => {
    onSelectAssets(asset);

    // Check if all assets are selected in a group to toggle the group selection's icon
-    let selectedAssetsInDayCount = assetsInDay.filter((asset) => assetInteraction.hasSelectedAsset(asset.id)).length;
+    let selectedAssetsInGroupCount = assetsInDayGroup.filter((asset) =>
+      assetInteraction.hasSelectedAsset(asset.id),
+    ).length;

    // if all assets are selected in a group, add the group to selected group
-    if (selectedAssetsInDayCount == assetsInDay.length) {
-      assetInteraction.addGroupToMultiselectGroup(dayTitle);
+    if (selectedAssetsInGroupCount == assetsInDayGroup.length) {
+      assetInteraction.addGroupToMultiselectGroup(groupTitle);
    } else {
-      assetInteraction.removeGroupFromMultiselectGroup(dayTitle);
+      assetInteraction.removeGroupFromMultiselectGroup(groupTitle);
    }

    if (timelineManager.assetCount == assetInteraction.selectedAssets.length) {
@@ -105,9 +109,9 @@
    }
  };

-  const assetMouseEventHandler = (dayTitle: string, asset: TimelineAsset | null) => {
+  const assetMouseEventHandler = (groupTitle: string, asset: TimelineAsset | null) => {
    // Show multi select icon on hover on date group
-    hoveredDay = dayTitle;
+    hoveredDayGroup = groupTitle;

    if (assetInteraction.selectionActive) {
      onSelectAssetCandidates(asset);
@@ -118,7 +122,7 @@
    return intersectable.filter((int) => int.intersecting);
  }

-  const getDayFullDate = (day: TimelineDay): string => {
+  const getDayGroupFullDate = (day: TimelineDay): string => {
    const { month, year } = day.month.yearMonth;
    const date = fromTimelinePlainDate({
      year,
@@ -129,14 +133,14 @@
  };
 </script>

-{#each filterIntersecting(month.days) as day, groupIndex (day.day)}
+{#each filterIntersecting(monthGroup.days) as day, groupIndex (day.day)}
  {@const absoluteWidth = day.left}

  <!-- svelte-ignore a11y_no_static_element_interactions -->
  <section
    class={[
-      { 'transition-all': !month.timelineManager.suspendTransitions },
-      !month.timelineManager.suspendTransitions && `delay-${transitionDuration}`,
+      { 'transition-all': !monthGroup.scrollManager.suspendTransitions },
+      !monthGroup.scrollManager.suspendTransitions && `delay-${transitionDuration}`,
    ]}
    data-group
    style:position="absolute"
@@ -158,7 +162,7 @@
      {#if !singleSelect}
        <div
          class="hover:cursor-pointer transition-all duration-200 ease-out overflow-hidden w-0"
-          class:w-8={(hoveredDay === day.dayTitle && isMouseOverGroup) ||
+          class:w-8={(hoveredDayGroup === day.dayTitle && isMouseOverGroup) ||
            assetInteraction.selectedGroup.has(day.dayTitle)}
          onclick={() => handleSelectGroup(day.dayTitle, assetsSnapshot(day.getAssets()))}
          onkeydown={() => handleSelectGroup(day.dayTitle, assetsSnapshot(day.getAssets()))}
@@ -171,7 +175,7 @@
        </div>
      {/if}

-      <span class="w-full truncate first-letter:capitalize" title={getDayFullDate(day)}>
+      <span class="w-full truncate first-letter:capitalize" title={getDayGroupFullDate(day)}>
        {day.dayTitle}
      </span>
    </div>
@@ -208,10 +212,9 @@
            }}
            onSelect={(asset) => assetSelectHandler(timelineManager, asset, day.getAssets(), day.dayTitle)}
            onMouseEvent={() => assetMouseEventHandler(day.dayTitle, assetSnapshot(asset))}
-            selected={assetInteraction.hasSelectedAsset(asset.id) ||
-              day.month.timelineManager.albumAssets.has(asset.id)}
+            selected={assetInteraction.hasSelectedAsset(asset.id) || day.month.scrollManager.albumAssets.has(asset.id)}
            selectionCandidate={assetInteraction.hasSelectionCandidate(asset.id)}
-            disabled={day.month.timelineManager.albumAssets.has(asset.id)}
+            disabled={day.month.scrollManager.albumAssets.has(asset.id)}
            thumbnailWidth={position.width}
            thumbnailHeight={position.height}
          />
--- a/web/src/lib/components/timeline/actions/TimelineKeyboardActions.svelte
+++ b/web/src/lib/components/timeline/actions/TimelineKeyboardActions.svelte
@@ -122,7 +122,7 @@
  };

  const isTrashEnabled = $derived($featureFlags.loaded && $featureFlags.trash);
-  const isEmpty = $derived(timelineManager.isInitialized && timelineManager.months.length === 0);
+  const isEmpty = $derived(timelineManager.isInitialized && timelineManager.segments.length === 0);
  const idsSelectedAssets = $derived(assetInteraction.selectedAssets.map(({ id }) => id));
  let isShortcutModalOpen = false;

--- a/web/src/lib/components/timeline/actions/focus-actions.ts
+++ b/web/src/lib/components/timeline/actions/focus-actions.ts
@@ -31,7 +31,7 @@ export const setFocusToAsset = (scrollToAsset: (asset: TimelineAsset) => boolean

 export const setFocusTo = async (
  scrollToAsset: (asset: TimelineAsset) => boolean,
-  store: TimelineManager,
+  timelineManager: TimelineManager,
  direction: 'earlier' | 'later',
  interval: 'day' | 'month' | 'year' | 'asset',
 ) => {
@@ -53,8 +53,8 @@ export const setFocusTo = async (

  const asset =
    direction === 'earlier'
-      ? await store.getEarlierAsset({ id }, interval)
-      : await store.getLaterAsset({ id }, interval);
+      ? await timelineManager.search.getEarlierAsset({ id }, interval)
+      : await timelineManager.search.getLaterAsset({ id }, interval);

  if (!invocation.isStillValid()) {
    return;
--- a/web/src/lib/managers/VirtualScrollManager/ScrollSegment.svelte.ts
+++ b/web/src/lib/managers/VirtualScrollManager/ScrollSegment.svelte.ts
@@ -1 +1,243 @@
-export class ScrollSegment {}
+import type { TimelineAsset, UpdateGeometryOptions } from '$lib/managers/timeline-manager/types';
+import type { ViewerAsset } from '$lib/managers/timeline-manager/viewer-asset.svelte';
+import type {
+  AssetOperation,
+  VirtualScrollManager,
+  VisibleWindow,
+} from '$lib/managers/VirtualScrollManager/VirtualScrollManager.svelte';
+import { CancellableTask, TaskStatus } from '$lib/utils/cancellable-task';
+import { handleError } from '$lib/utils/handle-error';
+import { TUNABLES } from '$lib/utils/tunables';
+import { t } from 'svelte-i18n';
+import { get } from 'svelte/store';
+const {
+  TIMELINE: { INTERSECTION_EXPAND_TOP, INTERSECTION_EXPAND_BOTTOM },
+} = TUNABLES;
+
+export type SegmentIdentifier = {
+  get id(): string;
+  matches(segment: ScrollSegment): boolean;
+};
+export abstract class ScrollSegment {
+  #intersecting = $state(false);
+  #actuallyIntersecting = $state(false);
+  #isLoaded = $state(false);
+  #height = $state(0);
+  #top = $state(0);
+  #assets = $derived.by(() => this.viewerAssets.map((viewerAsset) => viewerAsset.asset));
+
+  initialCount = $state(0);
+  percent = $state(0);
+  isHeightActual = $state(false);
+  assetsCount = $derived.by(() => (this.loaded ? this.viewerAssets.length : this.initialCount));
+  loader = new CancellableTask(
+    () => (this.loaded = true),
+    () => (this.loaded = false),
+    () => this.handleLoadError,
+  );
+
+  abstract get scrollManager(): VirtualScrollManager;
+
+  abstract get identifier(): SegmentIdentifier;
+
+  abstract get viewerAssets(): ViewerAsset[];
+
+  abstract findAssetAbsolutePosition(assetId: string): { top: number; height: number } | undefined;
+
+  protected abstract fetch(signal: AbortSignal): Promise<unknown>;
+
+  get loaded() {
+    return this.#isLoaded;
+  }
+
+  protected set loaded(newValue: boolean) {
+    this.#isLoaded = newValue;
+  }
+
+  get intersecting() {
+    return this.#intersecting;
+  }
+
+  set intersecting(newValue: boolean) {
+    const old = this.#intersecting;
+    if (old === newValue) {
+      return;
+    }
+    this.#intersecting = newValue;
+    if (newValue) {
+      void this.load(true);
+    } else {
+      this.cancel();
+    }
+  }
+
+  get actuallyIntersecting() {
+    return this.#actuallyIntersecting;
+  }
+
+  get assets(): TimelineAsset[] {
+    return this.#assets;
+  }
+
+  get height() {
+    return this.#height;
+  }
+
+  set height(height: number) {
+    if (this.#height === height) {
+      return;
+    }
+    const scrollManager = this.scrollManager;
+    const index = scrollManager.segments.indexOf(this);
+    const heightDelta = height - this.#height;
+    this.#height = height;
+    const prevSegment = scrollManager.segments[index - 1];
+    if (prevSegment) {
+      const newTop = prevSegment.#top + prevSegment.#height;
+      if (this.#top !== newTop) {
+        this.#top = newTop;
+      }
+    }
+    if (heightDelta === 0) {
+      return;
+    }
+    for (let cursor = index + 1; cursor < scrollManager.segments.length; cursor++) {
+      const segment = this.scrollManager.segments[cursor];
+      const newTop = segment.#top + heightDelta;
+      if (segment.#top !== newTop) {
+        segment.#top = newTop;
+      }
+    }
+    if (!scrollManager.viewportTopSegmentIntersection) {
+      return;
+    }
+
+    const { segment, viewportTopSegmentRatio, segmentBottomViewportRatio } =
+      scrollManager.viewportTopSegmentIntersection;
+
+    const currentIndex = segment ? scrollManager.segments.indexOf(segment) : -1;
+    if (!segment || currentIndex <= 0 || index > currentIndex) {
+      return;
+    }
+    if (index < currentIndex || segmentBottomViewportRatio < 1) {
+      scrollManager.scrollBy(heightDelta);
+    } else if (index === currentIndex) {
+      const scrollTo = this.top + heightDelta * viewportTopSegmentRatio;
+      scrollManager.scrollTo(scrollTo);
+    }
+  }
+
+  get top(): number {
+    return this.#top + this.scrollManager.topSectionHeight;
+  }
+
+  async load(cancelable: boolean): Promise<TaskStatus> {
+    const result = await this.loader?.execute(async (signal: AbortSignal) => {
+      await this.fetch(signal);
+    }, cancelable);
+    if (result === TaskStatus.LOADED) {
+      this.updateGeometry({ invalidateHeight: false });
+      this.calculateAndUpdateIntersection(this.scrollManager.visibleWindow);
+    }
+    return result;
+  }
+
+  protected handleLoadError(error: unknown) {
+    const _$t = get(t);
+    handleError(error, _$t('errors.failed_to_load_assets'));
+  }
+
+  cancel() {
+    this.loader?.cancel();
+  }
+
+  updateIntersection({ intersecting, actuallyIntersecting }: { intersecting: boolean; actuallyIntersecting: boolean }) {
+    this.intersecting = intersecting;
+    this.#actuallyIntersecting = actuallyIntersecting;
+  }
+
+  updateGeometry(options: UpdateGeometryOptions) {
+    const { invalidateHeight = true, noDefer = false } = options;
+    if (invalidateHeight) {
+      this.isHeightActual = false;
+    }
+    if (!this.loaded) {
+      const viewportWidth = this.scrollManager.viewportWidth;
+      if (!this.isHeightActual) {
+        const unwrappedWidth = (3 / 2) * this.assetsCount * this.scrollManager.rowHeight * (7 / 10);
+        const rows = Math.ceil(unwrappedWidth / viewportWidth);
+        const height = 51 + Math.max(1, rows) * this.scrollManager.rowHeight;
+        this.height = height;
+      }
+      return;
+    }
+    this.layout(noDefer);
+  }
+
+  layout(_: boolean) {}
+
+  protected calculateSegmentIntersecting(visibleWindow: VisibleWindow, expandTop: number, expandBottom: number) {
+    const segmentTop = this.top;
+    const segmentBottom = segmentTop + this.height;
+    const topWindow = visibleWindow.top - expandTop;
+    const bottomWindow = visibleWindow.bottom + expandBottom;
+
+    return isIntersecting(segmentTop, segmentBottom, topWindow, bottomWindow);
+  }
+
+  calculateAndUpdateIntersection(visibleWindow: VisibleWindow) {
+    const actuallyIntersecting = this.calculateSegmentIntersecting(visibleWindow, 0, 0);
+    let preIntersecting = false;
+    if (!actuallyIntersecting) {
+      preIntersecting = this.calculateSegmentIntersecting(
+        visibleWindow,
+        INTERSECTION_EXPAND_TOP,
+        INTERSECTION_EXPAND_BOTTOM,
+      );
+    }
+    this.updateIntersection({ intersecting: actuallyIntersecting || preIntersecting, actuallyIntersecting });
+  }
+
+  runAssetOperation(ids: Set<string>, operation: AssetOperation) {
+    // eslint-disable-next-line svelte/prefer-svelte-reactivity
+    const unprocessedIds = new Set<string>(ids);
+    // eslint-disable-next-line svelte/prefer-svelte-reactivity
+    const processedIds = new Set<string>();
+    const moveAssets: TimelineAsset[] = [];
+    let changedGeometry = false;
+    for (const assetId of unprocessedIds) {
+      const index = this.viewerAssets.findIndex((viewAsset) => viewAsset.id == assetId);
+      if (index === -1) {
+        continue;
+      }
+
+      const asset = this.viewerAssets[index].asset!;
+      const opResult = operation(asset);
+      let remove = false;
+      if (opResult) {
+        remove = (opResult as { remove: boolean }).remove ?? false;
+      }
+
+      unprocessedIds.delete(assetId);
+      processedIds.add(assetId);
+      if (remove || this.scrollManager.isExcluded(asset)) {
+        this.viewerAssets.splice(index, 1);
+        changedGeometry = true;
+      }
+    }
+    return { moveAssets, processedIds, unprocessedIds, changedGeometry };
+  }
+}
+
+/**
+ * General function to check if a segment region intersects with a window region.
+ * @param regionTop - Top position of the region to check
+ * @param regionBottom - Bottom position of the region to check
+ * @param windowTop - Top position of the window
+ * @param windowBottom - Bottom position of the window
+ * @returns true if the region intersects with the window
+ */
+export const isIntersecting = (regionTop: number, regionBottom: number, windowTop: number, windowBottom: number) =>
+  (regionTop >= windowTop && regionTop < windowBottom) ||
+  (regionBottom >= windowTop && regionBottom < windowBottom) ||
+  (regionTop < windowTop && regionBottom >= windowBottom);
--- a/web/src/lib/managers/VirtualScrollManager/VirtualScrollManager.svelte.ts
+++ b/web/src/lib/managers/VirtualScrollManager/VirtualScrollManager.svelte.ts
@@ -1,20 +1,60 @@
-import { debounce } from 'lodash-es';
+import type { TimelineAsset, Viewport } from '$lib/managers/timeline-manager/types';
+import { setDifferenceInPlace } from '$lib/managers/timeline-manager/utils.svelte';
+import type { ScrollSegment, SegmentIdentifier } from '$lib/managers/VirtualScrollManager/ScrollSegment.svelte';
+import { updateObject } from '$lib/managers/VirtualScrollManager/utils.svelte';
+
+import { clamp, debounce } from 'lodash-es';
+
+export type VisibleWindow = {
+  top: number;
+  bottom: number;
+};
+export type AssetOperation = (asset: TimelineAsset) => unknown;

 type LayoutOptions = {
  headerHeight: number;
  rowHeight: number;
  gap: number;
 };
+type ViewportTopSegmentIntersection = {
+  segment: ScrollSegment | null;
+  // Where viewport top intersects segment (0 = segment top, 1 = segment bottom)
+  viewportTopSegmentRatio: number;
+  // Where first segment bottom is in viewport (0 = viewport top, 1 = viewport bottom)
+  segmentBottomViewportRatio: number;
+};
+
 export abstract class VirtualScrollManager {
  topSectionHeight = $state(0);
-  bodySectionHeight = $state(0);
+  bodySectionHeight = $derived.by(() => {
+    let height = 0;
+    for (const segment of this.segments) {
+      height += segment.height;
+    }
+    return height;
+  });
  bottomSectionHeight = $state(0);
  totalViewerHeight = $derived.by(() => this.topSectionHeight + this.bodySectionHeight + this.bottomSectionHeight);
-
-  visibleWindow = $derived.by(() => ({
+  isInitialized = $state(false);
+  streamViewerHeight = $derived.by(() => {
+    let height = this.topSectionHeight;
+    for (const segment of this.segments) {
+      height += segment.height;
+    }
+    return height;
+  });
+  assetCount = $derived.by(() => {
+    let count = 0;
+    for (const segment of this.segments) {
+      count += segment.assetsCount;
+    }
+    return count;
+  });
+  visibleWindow: VisibleWindow = $derived.by(() => ({
    top: this.#scrollTop,
    bottom: this.#scrollTop + this.viewportHeight,
  }));
+  viewportTopSegmentIntersection: ViewportTopSegmentIntersection | undefined;

  #viewportHeight = $state(0);
  #viewportWidth = $state(0);
@@ -24,14 +64,15 @@ export abstract class VirtualScrollManager {
  #gap = $state(12);
  #scrolling = $state(false);
  #suspendTransitions = $state(false);
-  #resetScrolling = debounce(() => (this.#scrolling = false), 1000);
-  #resetSuspendTransitions = debounce(() => (this.suspendTransitions = false), 1000);
+  #resumeTransitionsAfterDelay = debounce(() => (this.suspendTransitions = false), 1000);
+  #resumeScrollingStatusAfterDelay = debounce(() => (this.#scrolling = false), 1000);
  #justifiedLayoutOptions = $derived({
    spacing: 2,
    heightTolerance: 0.5,
    rowHeight: this.#rowHeight,
    rowWidth: Math.floor(this.viewportWidth),
  });
+  #updatingIntersections = false;

  constructor() {
    this.setLayoutOptions();
@@ -45,6 +86,8 @@ export abstract class VirtualScrollManager {
    return this.#justifiedLayoutOptions;
  }

+  abstract get segments(): ScrollSegment[];
+
  get maxScrollPercent() {
    const totalHeight = this.totalViewerHeight;
    return (totalHeight - this.viewportHeight) / totalHeight;
@@ -94,7 +137,7 @@ export abstract class VirtualScrollManager {
    this.#scrolling = value;
    if (value) {
      this.suspendTransitions = true;
-      this.#resetScrolling();
+      this.#resumeScrollingStatusAfterDelay();
    }
  }

@@ -105,7 +148,7 @@ export abstract class VirtualScrollManager {
  set suspendTransitions(value: boolean) {
    this.#suspendTransitions = value;
    if (value) {
-      this.#resetSuspendTransitions();
+      this.#resumeTransitionsAfterDelay();
    }
  }

@@ -114,10 +157,11 @@ export abstract class VirtualScrollManager {
  }

  set viewportWidth(value: number) {
-    const changed = value !== this.#viewportWidth;
+    const oldViewport = this.viewportSnapshot;
    this.#viewportWidth = value;
    this.suspendTransitions = true;
-    void this.updateViewportGeometry(changed);
+    const newViewport = this.viewportSnapshot;
+    void this.onUpdateViewport(oldViewport, newViewport);
  }

  get viewportWidth() {
@@ -125,22 +169,78 @@ export abstract class VirtualScrollManager {
  }

  set viewportHeight(value: number) {
+    const oldViewport = this.viewportSnapshot;
    this.#viewportHeight = value;
    this.#suspendTransitions = true;
-    void this.updateViewportGeometry(false);
+    const newViewport = this.viewportSnapshot;
+    void this.onUpdateViewport(oldViewport, newViewport);
  }

  get viewportHeight() {
    return this.#viewportHeight;
  }

-  get hasEmptyViewport() {
-    return this.viewportWidth === 0 || this.viewportHeight === 0;
+  get viewportSnapshot(): Viewport {
+    return {
+      width: $state.snapshot(this.#viewportWidth),
+      height: $state.snapshot(this.#viewportHeight),
+    };
  }

-  protected updateIntersections(): void {}
+  scrollTo(_: number) {}

-  protected updateViewportGeometry(_: boolean) {}
+  scrollBy(_: number) {}
+
+  #calculateSegmentBottomViewportRatio(segment: ScrollSegment | null) {
+    if (!segment) {
+      return 0;
+    }
+    const windowHeight = this.visibleWindow.bottom - this.visibleWindow.top;
+    const bottomOfSegment = segment.top + segment.height;
+    const bottomOfSegmentInViewport = bottomOfSegment - this.visibleWindow.top;
+    return clamp(bottomOfSegmentInViewport / windowHeight, 0, 1);
+  }
+
+  #calculateViewportTopRatioInMonth(month: ScrollSegment | null) {
+    if (!month) {
+      return 0;
+    }
+    return clamp((this.visibleWindow.top - month.top) / month.height, 0, 1);
+  }
+
+  protected updateIntersections() {
+    if (this.#updatingIntersections || !this.isInitialized || this.visibleWindow.bottom === this.visibleWindow.top) {
+      return;
+    }
+
+    this.#updatingIntersections = true;
+    let topSegment: ScrollSegment | null = null;
+    for (const segment of this.segments) {
+      segment.calculateAndUpdateIntersection(this.visibleWindow);
+      if (segment.actuallyIntersecting && topSegment === null) {
+        topSegment = segment;
+      }
+    }
+
+    const viewportTopSegmentRatio = this.#calculateViewportTopRatioInMonth(topSegment);
+    const segmentBottomViewportRatio = this.#calculateSegmentBottomViewportRatio(topSegment);
+
+    this.viewportTopSegmentIntersection = {
+      segment: topSegment,
+      viewportTopSegmentRatio,
+      segmentBottomViewportRatio,
+    };
+
+    this.#updatingIntersections = false;
+  }
+
+  protected onUpdateViewport(oldViewport: Viewport, newViewport: Viewport) {
+    if (!this.isInitialized || isEmptyViewport(newViewport)) {
+      return;
+    }
+    const changedWidth = oldViewport.width !== newViewport.width || isEmptyViewport(oldViewport);
+    this.refreshLayout({ invalidateHeight: changedWidth });
+  }

  setLayoutOptions({ headerHeight = 48, rowHeight = 235, gap = 12 }: Partial<LayoutOptions> = {}) {
    let changed = false;
@@ -152,7 +252,7 @@ export abstract class VirtualScrollManager {
    }
  }

-  updateSlidingWindow() {
+  updateVisibleWindow() {
    const scrollTop = this.scrollTop;
    if (this.#scrollTop !== scrollTop) {
      this.#scrollTop = scrollTop;
@@ -160,9 +260,132 @@ export abstract class VirtualScrollManager {
    }
  }

-  refreshLayout() {
+  protected refreshLayout({ invalidateHeight = true }: { invalidateHeight?: boolean } = {}) {
+    for (const segment of this.segments) {
+      segment.updateGeometry({ invalidateHeight });
+    }
    this.updateIntersections();
  }

-  destroy(): void {}
+  destroy() {
+    this.isInitialized = false;
+  }
+
+  async loadSegment(identifier: SegmentIdentifier, options?: { cancelable: boolean }): Promise<void> {
+    const { cancelable = true } = options ?? {};
+    const segment = this.segments.find((segment) => identifier.matches(segment));
+    if (!segment || segment.loader?.executed) {
+      return;
+    }
+
+    await segment.load(cancelable);
+  }
+
+  upsertAssets(assets: TimelineAsset[]) {
+    const notExcluded = assets.filter((asset) => !this.isExcluded(asset));
+    const notUpdated = this.#updateAssets(notExcluded);
+    this.addAssetsToSegments(notUpdated);
+  }
+
+  removeAssets(ids: string[]) {
+    this.#runAssetOperation(ids, () => ({ remove: true }));
+  }
+
+  /**
+   * Executes the given operation against every passed in asset id.
+   *
+   * @returns An object with the changed ids, unprocessed ids, and if this resulted
+   * in changes of the timeline geometry.
+   */
+  updateAssetOperation(ids: string[], operation: AssetOperation) {
+    return this.#runAssetOperation(ids, operation);
+  }
+
+  isExcluded(_: TimelineAsset) {
+    return false;
+  }
+
+  protected addAssetsToSegments(assets: TimelineAsset[]) {
+    if (assets.length === 0) {
+      return;
+    }
+    const context = this.createUpsertContext();
+    const monthCount = this.segments.length;
+    for (const asset of assets) {
+      this.upsertAssetIntoSegment(asset, context);
+    }
+    if (this.segments.length !== monthCount) {
+      this.postCreateSegments();
+    }
+    this.postUpsert(context);
+    this.updateIntersections();
+  }
+
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  protected upsertAssetIntoSegment(asset: TimelineAsset, context: unknown): void {}
+  protected createUpsertContext(): unknown {
+    return undefined;
+  }
+  protected postUpsert(_: unknown): void {}
+  protected postCreateSegments(): void {}
+
+  /**
+     * Looks up the specified asset from the TimelineAsset using its id, and then updates the
+     * existing object to match the rest of the TimelineAsset parameter.
+  
+     * @returns list of assets that were updated (not found)
+     */
+  #updateAssets(updatedAssets: TimelineAsset[]) {
+    // eslint-disable-next-line svelte/prefer-svelte-reactivity
+    const lookup = new Map<string, TimelineAsset>();
+    const ids = [];
+    for (const asset of updatedAssets) {
+      ids.push(asset.id);
+      lookup.set(asset.id, asset);
+    }
+    const { unprocessedIds } = this.#runAssetOperation(ids, (asset) => updateObject(asset, lookup.get(asset.id)));
+    const result: TimelineAsset[] = [];
+    for (const id of unprocessedIds) {
+      result.push(lookup.get(id)!);
+    }
+    return result;
+  }
+
+  #runAssetOperation(ids: string[], operation: AssetOperation) {
+    // eslint-disable-next-line svelte/prefer-svelte-reactivity
+    const changedMonths = new Set<ScrollSegment>();
+    // eslint-disable-next-line svelte/prefer-svelte-reactivity
+    const idsToProcess = new Set(ids);
+    // eslint-disable-next-line svelte/prefer-svelte-reactivity
+    const idsProcessed = new Set<string>();
+    const combinedMoveAssets: TimelineAsset[] = [];
+    for (const month of this.segments) {
+      if (idsToProcess.size > 0) {
+        const { moveAssets, processedIds, changedGeometry } = month.runAssetOperation(idsToProcess, operation);
+        if (moveAssets.length > 0) {
+          combinedMoveAssets.push(...moveAssets);
+        }
+        setDifferenceInPlace(idsToProcess, processedIds);
+        for (const id of processedIds) {
+          idsProcessed.add(id);
+        }
+        if (changedGeometry) {
+          changedMonths.add(month);
+        }
+      }
+    }
+    if (combinedMoveAssets.length > 0) {
+      this.addAssetsToSegments(combinedMoveAssets);
+    }
+    const changedGeometry = changedMonths.size > 0;
+    for (const month of changedMonths) {
+      month.updateGeometry({ invalidateHeight: true });
+    }
+    if (changedGeometry) {
+      this.updateIntersections();
+    }
+    return { unprocessedIds: idsToProcess, processedIds: idsProcessed, changedGeometry };
+  }
 }
+
+export const isEmptyViewport = (viewport: Viewport) => viewport.width === 0 || viewport.height === 0;
--- a/web/src/lib/managers/VirtualScrollManager/utils.svelte.ts
+++ b/web/src/lib/managers/VirtualScrollManager/utils.svelte.ts
@@ -0,0 +1,52 @@
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export function updateObject(target: any, source: any): boolean {
+  if (!target) {
+    return false;
+  }
+  let updated = false;
+  for (const key in source) {
+    if (!Object.prototype.hasOwnProperty.call(source, key)) {
+      continue;
+    }
+    if (key === '__proto__' || key === 'constructor') {
+      continue;
+    }
+    const isDate = target[key] instanceof Date;
+    if (typeof target[key] === 'object' && !isDate) {
+      updated = updated || updateObject(target[key], source[key]);
+    } else {
+      if (target[key] !== source[key]) {
+        target[key] = source[key];
+        updated = true;
+      }
+    }
+  }
+  return updated;
+}
+
+export function setDifference<T>(setA: Set<T>, setB: Set<T>): Set<T> {
+  // Check if native Set.prototype.difference is available (ES2025)
+
+  const setWithDifference = setA as unknown as Set<T> & { difference?: (other: Set<T>) => Set<T> };
+  if (setWithDifference.difference && typeof setWithDifference.difference === 'function') {
+    return setWithDifference.difference(setB);
+  }
+  // eslint-disable-next-line svelte/prefer-svelte-reactivity
+  const result = new Set<T>();
+  for (const value of setA) {
+    if (!setB.has(value)) {
+      result.add(value);
+    }
+  }
+  return result;
+}
+
+/**
+ * Removes all elements of setB from setA in-place (mutates setA).
+ */
+export function setDifferenceInPlace<T>(setA: Set<T>, setB: Set<T>): Set<T> {
+  for (const value of setB) {
+    setA.delete(value);
+  }
+  return setA;
+}
--- a/web/src/lib/managers/timeline-manager/TimelineDay.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/TimelineDay.svelte.ts
@@ -1,7 +1,7 @@
-import { onCreateDay } from '$lib/managers/timeline-manager/internal/TestHooks.svelte';
-import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
+import type { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
+import { onCreateTimelineDay } from '$lib/managers/timeline-manager/TimelineTestHooks.svelte';
 import type { AssetOperation, Direction, TimelineAsset } from '$lib/managers/timeline-manager/types';
-import { ViewerAsset } from '$lib/managers/timeline-manager/viewer-asset.svelte';
+import type { ViewerAsset } from '$lib/managers/timeline-manager/viewer-asset.svelte';
 import type { CommonLayoutOptions } from '$lib/utils/layout-utils';
 import { getJustifiedLayoutFromAssets } from '$lib/utils/layout-utils';
 import { plainDateTimeCompare } from '$lib/utils/timeline-util';
@@ -11,6 +11,7 @@ export class TimelineDay {
  readonly month: TimelineMonth;
  readonly index: number;
  readonly dayTitle: string;
+  readonly dayTitleFull: string;
  readonly day: number;
  viewerAssets: ViewerAsset[] = $state([]);

@@ -24,13 +25,14 @@ export class TimelineDay {
  #col = $state(0);
  #deferredLayout = false;

-  constructor(month: TimelineMonth, index: number, day: number, dayTitle: string) {
+  constructor(month: TimelineMonth, index: number, day: number, groupTitle: string, groupTitleFull: string) {
    this.index = index;
    this.month = month;
    this.day = day;
-    this.dayTitle = dayTitle;
+    this.dayTitle = groupTitle;
+    this.dayTitleFull = groupTitleFull;
    if (import.meta.env.DEV) {
-      onCreateDay(this);
+      onCreateTimelineDay(this);
    }
  }

@@ -103,15 +105,6 @@ export class TimelineDay {
  }

  runAssetOperation(ids: Set<string>, operation: AssetOperation) {
-    if (ids.size === 0) {
-      return {
-        moveAssets: [] as TimelineAsset[],
-        // eslint-disable-next-line svelte/prefer-svelte-reactivity
-        processedIds: new Set<string>(),
-        unprocessedIds: ids,
-        changedGeometry: false,
-      };
-    }
    // eslint-disable-next-line svelte/prefer-svelte-reactivity
    const unprocessedIds = new Set<string>(ids);
    // eslint-disable-next-line svelte/prefer-svelte-reactivity
@@ -142,7 +135,7 @@ export class TimelineDay {
      }
      unprocessedIds.delete(assetId);
      processedIds.add(assetId);
-      if (remove || this.month.timelineManager.isExcluded(asset)) {
+      if (remove || this.month.scrollManager.isExcluded(asset)) {
        this.viewerAssets.splice(index, 1);
        changedGeometry = true;
      }
@@ -165,7 +158,7 @@ export class TimelineDay {
    }
  }

-  get absoluteTop() {
+  get topAbsolute() {
    return this.month.top + this.#top;
  }
 }
--- a/web/src/lib/managers/timeline-manager/TimelineInsertionCache.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/TimelineInsertionCache.svelte.ts
@@ -1,7 +1,8 @@
-import { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
-import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
+import type { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
+import type { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
 import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
-import { setDifference, type TimelineDate } from '$lib/utils/timeline-util';
+import { setDifference } from '$lib/managers/timeline-manager/utils.svelte';
+import { type TimelineDate } from '$lib/utils/timeline-util';
 import { AssetOrder } from '@immich/sdk';

 export class GroupInsertionCache {
@@ -18,14 +19,14 @@ export class GroupInsertionCache {
    return this.#lookupCache[year]?.[month]?.[day];
  }

-  setDay(day: TimelineDay, { year, month, day: dayNumber }: TimelineDate) {
+  setDay(day: TimelineDay, { year, month, day: dayNum }: TimelineDate) {
    if (!this.#lookupCache[year]) {
      this.#lookupCache[year] = {};
    }
    if (!this.#lookupCache[year][month]) {
      this.#lookupCache[year][month] = {};
    }
-    this.#lookupCache[year][month][dayNumber] = day;
+    this.#lookupCache[year][month][dayNum] = day;
  }

  get existingDays() {
--- a/web/src/lib/managers/timeline-manager/TimelineManager.svelte.spec.ts
+++ b/web/src/lib/managers/timeline-manager/TimelineManager.svelte.spec.ts
@@ -1,13 +1,12 @@
 import { sdkMock } from '$lib/__mocks__/sdk.mock';
-import { getMonthByDate } from '$lib/managers/timeline-manager/internal/search-support.svelte';
-import { setTestHooks } from '$lib/managers/timeline-manager/internal/TestHooks.svelte';
-import { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
+import type { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
 import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
-import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
+import type { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
+import { setTestHooks } from '$lib/managers/timeline-manager/TimelineTestHooks.svelte';
 import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
 import { AbortError } from '$lib/utils';
-import { fromISODateTimeUTCToObject } from '$lib/utils/timeline-util';
-import { AssetVisibility, type AssetResponseDto, type TimeBucketAssetResponseDto } from '@immich/sdk';
+import { fromISODateTimeUTCToObject, getSegmentIdentifier } from '$lib/utils/timeline-util';
+import { type AssetResponseDto, type TimeBucketAssetResponseDto } from '@immich/sdk';
 import { timelineAssetFactory, toResponseDto } from '@test-data/factories/asset-factory';
 import { tick } from 'svelte';
 import type { MockInstance } from 'vitest';
@@ -20,6 +19,10 @@ async function getAssets(timelineManager: TimelineManager) {
  return assets;
 }

+function getMonthForAssetId(timelineManager: TimelineManager, id: string) {
+  return timelineManager.search.findMonthForAsset(id)?.month;
+}
+
 function deriveLocalDateTimeFromFileCreatedAt(arg: TimelineAsset): TimelineAsset {
  return {
    ...arg,
@@ -78,7 +81,7 @@ describe('TimelineManager', () => {
    });

    it('calculates month height', () => {
-      const plainMonths = timelineManager.months.map((month) => ({
+      const plainMonths = timelineManager.segments.map((month) => ({
        year: month.yearMonth.year,
        month: month.yearMonth.month,
        height: month.height,
@@ -98,7 +101,7 @@ describe('TimelineManager', () => {
    });
  });

-  describe('loadMonth', () => {
+  describe('loadSegment', () => {
    let timelineManager: TimelineManager;
    const bucketAssets: Record<string, TimelineAsset[]> = {
      '2024-01-03T00:00:00.000Z': timelineAssetFactory.buildList(1).map((asset) =>
@@ -134,48 +137,48 @@ describe('TimelineManager', () => {
    });

    it('loads a month', async () => {
-      expect(getMonthByDate(timelineManager, { year: 2024, month: 1 })?.getAssets().length).toEqual(0);
-      await timelineManager.loadMonth({ year: 2024, month: 1 });
+      expect(timelineManager.search.findMonthByDate({ year: 2024, month: 1 })?.assets.length).toEqual(0);
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 1 }));
      expect(sdkMock.getTimeBucket).toBeCalledTimes(1);
-      expect(getMonthByDate(timelineManager, { year: 2024, month: 1 })?.getAssets().length).toEqual(3);
+      expect(timelineManager.search.findMonthByDate({ year: 2024, month: 1 })?.assets.length).toEqual(3);
    });

    it('ignores invalid months', async () => {
-      await timelineManager.loadMonth({ year: 2023, month: 1 });
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2023, month: 1 }));
      expect(sdkMock.getTimeBucket).toBeCalledTimes(0);
    });

    it('cancels month loading', async () => {
-      const month = getMonthByDate(timelineManager, { year: 2024, month: 1 })!;
-      void timelineManager.loadMonth({ year: 2024, month: 1 });
+      const month = timelineManager.search.findMonthByDate({ year: 2024, month: 1 })!;
+      void timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 1 }));
      const abortSpy = vi.spyOn(month!.loader!.cancelToken!, 'abort');
      month?.cancel();
      expect(abortSpy).toBeCalledTimes(1);
-      await timelineManager.loadMonth({ year: 2024, month: 1 });
-      expect(getMonthByDate(timelineManager, { year: 2024, month: 1 })?.getAssets().length).toEqual(3);
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 1 }));
+      expect(timelineManager.search.findMonthByDate({ year: 2024, month: 1 })?.assets.length).toEqual(3);
    });

    it('prevents loading months multiple times', async () => {
      await Promise.all([
-        timelineManager.loadMonth({ year: 2024, month: 1 }),
-        timelineManager.loadMonth({ year: 2024, month: 1 }),
+        timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 1 })),
+        timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 1 })),
      ]);
      expect(sdkMock.getTimeBucket).toBeCalledTimes(1);

-      await timelineManager.loadMonth({ year: 2024, month: 1 });
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 1 }));
      expect(sdkMock.getTimeBucket).toBeCalledTimes(1);
    });

    it('allows loading a canceled month', async () => {
-      const month = getMonthByDate(timelineManager, { year: 2024, month: 1 })!;
-      const loadPromise = timelineManager.loadMonth({ year: 2024, month: 1 });
+      const month = timelineManager.search.findMonthByDate({ year: 2024, month: 1 })!;
+      const loadPromise = timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 1 }));

      month.cancel();
      await loadPromise;
-      expect(month?.getAssets().length).toEqual(0);
+      expect(month?.assets.length).toEqual(0);

-      await timelineManager.loadMonth({ year: 2024, month: 1 });
-      expect(month!.getAssets().length).toEqual(3);
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 1 }));
+      expect(month!.assets.length).toEqual(3);
    });
  });

@@ -190,7 +193,7 @@ describe('TimelineManager', () => {
    });

    it('is empty initially', () => {
-      expect(timelineManager.months.length).toEqual(0);
+      expect(timelineManager.segments.length).toEqual(0);
      expect(timelineManager.assetCount).toEqual(0);
    });

@@ -202,12 +205,12 @@ describe('TimelineManager', () => {
      );
      timelineManager.upsertAssets([asset]);

-      expect(timelineManager.months.length).toEqual(1);
+      expect(timelineManager.segments.length).toEqual(1);
      expect(timelineManager.assetCount).toEqual(1);
-      expect(timelineManager.months[0].getAssets().length).toEqual(1);
-      expect(timelineManager.months[0].yearMonth.year).toEqual(2024);
-      expect(timelineManager.months[0].yearMonth.month).toEqual(1);
-      expect(timelineManager.months[0].getFirstAsset().id).toEqual(asset.id);
+      expect(timelineManager.segments[0].assets.length).toEqual(1);
+      expect(timelineManager.segments[0].yearMonth.year).toEqual(2024);
+      expect(timelineManager.segments[0].yearMonth.month).toEqual(1);
+      expect(timelineManager.segments[0].getFirstAsset().id).toEqual(asset.id);
    });

    it('adds assets to existing month', () => {
@@ -219,11 +222,11 @@ describe('TimelineManager', () => {
      timelineManager.upsertAssets([assetOne]);
      timelineManager.upsertAssets([assetTwo]);

-      expect(timelineManager.months.length).toEqual(1);
+      expect(timelineManager.segments.length).toEqual(1);
      expect(timelineManager.assetCount).toEqual(2);
-      expect(timelineManager.months[0].getAssets().length).toEqual(2);
-      expect(timelineManager.months[0].yearMonth.year).toEqual(2024);
-      expect(timelineManager.months[0].yearMonth.month).toEqual(1);
+      expect(timelineManager.segments[0].assets.length).toEqual(2);
+      expect(timelineManager.segments[0].yearMonth.year).toEqual(2024);
+      expect(timelineManager.segments[0].yearMonth.month).toEqual(1);
    });

    it('orders assets in months by descending date', () => {
@@ -244,12 +247,12 @@ describe('TimelineManager', () => {
      );
      timelineManager.upsertAssets([assetOne, assetTwo, assetThree]);

-      const month = getMonthByDate(timelineManager, { year: 2024, month: 1 });
+      const month = timelineManager.search.findMonthByDate({ year: 2024, month: 1 });
      expect(month).not.toBeNull();
-      expect(month?.getAssets().length).toEqual(3);
-      expect(month?.getAssets()[0].id).toEqual(assetOne.id);
-      expect(month?.getAssets()[1].id).toEqual(assetThree.id);
-      expect(month?.getAssets()[2].id).toEqual(assetTwo.id);
+      expect(month?.assets.length).toEqual(3);
+      expect(month?.assets[0].id).toEqual(assetOne.id);
+      expect(month?.assets[1].id).toEqual(assetThree.id);
+      expect(month?.assets[2].id).toEqual(assetTwo.id);
    });

    it('orders months by descending date', () => {
@@ -270,15 +273,15 @@ describe('TimelineManager', () => {
      );
      timelineManager.upsertAssets([assetOne, assetTwo, assetThree]);

-      expect(timelineManager.months.length).toEqual(3);
-      expect(timelineManager.months[0].yearMonth.year).toEqual(2024);
-      expect(timelineManager.months[0].yearMonth.month).toEqual(4);
+      expect(timelineManager.segments.length).toEqual(3);
+      expect(timelineManager.segments[0].yearMonth.year).toEqual(2024);
+      expect(timelineManager.segments[0].yearMonth.month).toEqual(4);

-      expect(timelineManager.months[1].yearMonth.year).toEqual(2024);
-      expect(timelineManager.months[1].yearMonth.month).toEqual(1);
+      expect(timelineManager.segments[1].yearMonth.year).toEqual(2024);
+      expect(timelineManager.segments[1].yearMonth.month).toEqual(1);

-      expect(timelineManager.months[2].yearMonth.year).toEqual(2023);
-      expect(timelineManager.months[2].yearMonth.month).toEqual(1);
+      expect(timelineManager.segments[2].yearMonth.year).toEqual(2023);
+      expect(timelineManager.segments[2].yearMonth.month).toEqual(1);
    });

    it('updates existing asset', () => {
@@ -322,19 +325,19 @@ describe('TimelineManager', () => {
      sortDaysFn: MockInstance;
    };

-    const days = new Map<TimelineDay, DayMocks>();
+    const dayGroups = new Map<TimelineDay, DayMocks>();
    const months = new Map<TimelineMonth, MonthMocks>();

    beforeEach(async () => {
      timelineManager = new TimelineManager();
      setTestHooks({
-        onCreateDay: (day: TimelineDay) => {
-          days.set(day, {
+        onCreateTimelineDay: (day: TimelineDay) => {
+          dayGroups.set(day, {
            layoutFn: vi.spyOn(day, 'layout'),
            sortAssetsFn: vi.spyOn(day, 'sortAssets'),
          });
        },
-        onCreateMonth: (month: TimelineMonth) => {
+        onCreateTimelineMonth: (month: TimelineMonth) => {
          months.set(month, {
            sortDaysFn: vi.spyOn(month, 'sortDays'),
          });
@@ -394,7 +397,7 @@ describe('TimelineManager', () => {
      timelineManager.updateAssetOperation([month1day2asset1.id], (asset) => {
        asset.localDateTime.day = asset.localDateTime.day + 1;
      });
-      for (const [day, mocks] of days) {
+      for (const [day, mocks] of dayGroups) {
        if (day.day === 15 && day.month.yearMonth.month === 1) {
          // source - should be layout once
          expect.soft(mocks.layoutFn).toBeCalledTimes(1);
@@ -435,11 +438,11 @@ describe('TimelineManager', () => {

      timelineManager.upsertAssets([asset]);
      expect(timelineManager.assetCount).toEqual(1);
-      expect(timelineManager.months[0].getFirstAsset().isFavorite).toEqual(false);
+      expect(timelineManager.segments[0].getFirstAsset().isFavorite).toEqual(false);

      timelineManager.upsertAssets([updatedAsset]);
      expect(timelineManager.assetCount).toEqual(1);
-      expect(timelineManager.months[0].getFirstAsset().isFavorite).toEqual(true);
+      expect(timelineManager.segments[0].getFirstAsset().isFavorite).toEqual(true);
    });

    it('asset moves months when asset date changes', () => {
@@ -454,79 +457,16 @@ describe('TimelineManager', () => {
      });

      timelineManager.upsertAssets([asset]);
-      expect(timelineManager.months.length).toEqual(1);
-      expect(getMonthByDate(timelineManager, { year: 2024, month: 1 })).not.toBeUndefined();
-      expect(getMonthByDate(timelineManager, { year: 2024, month: 1 })?.getAssets().length).toEqual(1);
+      expect(timelineManager.segments.length).toEqual(1);
+      expect(timelineManager.search.findMonthByDate({ year: 2024, month: 1 })).not.toBeUndefined();
+      expect(timelineManager.search.findMonthByDate({ year: 2024, month: 1 })?.assets.length).toEqual(1);

      timelineManager.upsertAssets([updatedAsset]);
-      expect(timelineManager.months.length).toEqual(2);
-      expect(getMonthByDate(timelineManager, { year: 2024, month: 1 })).not.toBeUndefined();
-      expect(getMonthByDate(timelineManager, { year: 2024, month: 1 })?.getAssets().length).toEqual(0);
-      expect(getMonthByDate(timelineManager, { year: 2024, month: 3 })).not.toBeUndefined();
-      expect(getMonthByDate(timelineManager, { year: 2024, month: 3 })?.getAssets().length).toEqual(1);
-    });
-
-    it('asset is removed during upsert when TimelineManager if visibility changes', async () => {
-      await timelineManager.updateOptions({
-        visibility: AssetVisibility.Archive,
-      });
-      const fixture = deriveLocalDateTimeFromFileCreatedAt(
-        timelineAssetFactory.build({
-          visibility: AssetVisibility.Archive,
-        }),
-      );
-
-      timelineManager.upsertAssets([fixture]);
-      expect(timelineManager.assetCount).toEqual(1);
-
-      const updated = Object.freeze({ ...fixture, visibility: AssetVisibility.Timeline });
-      timelineManager.upsertAssets([updated]);
-      expect(timelineManager.assetCount).toEqual(0);
-
-      timelineManager.upsertAssets([{ ...fixture, visibility: AssetVisibility.Archive }]);
-      expect(timelineManager.assetCount).toEqual(1);
-    });
-
-    it('asset is removed during upsert when TimelineManager if isFavorite changes', async () => {
-      await timelineManager.updateOptions({
-        isFavorite: true,
-      });
-      const fixture = deriveLocalDateTimeFromFileCreatedAt(
-        timelineAssetFactory.build({
-          isFavorite: true,
-        }),
-      );
-
-      timelineManager.upsertAssets([fixture]);
-      expect(timelineManager.assetCount).toEqual(1);
-
-      const updated = Object.freeze({ ...fixture, isFavorite: false });
-      timelineManager.upsertAssets([updated]);
-      expect(timelineManager.assetCount).toEqual(0);
-
-      timelineManager.upsertAssets([{ ...fixture, isFavorite: true }]);
-      expect(timelineManager.assetCount).toEqual(1);
-    });
-
-    it('asset is removed during upsert when TimelineManager if isTrashed changes', async () => {
-      await timelineManager.updateOptions({
-        isTrashed: true,
-      });
-      const fixture = deriveLocalDateTimeFromFileCreatedAt(
-        timelineAssetFactory.build({
-          isTrashed: true,
-        }),
-      );
-
-      timelineManager.upsertAssets([fixture]);
-      expect(timelineManager.assetCount).toEqual(1);
-
-      const updated = Object.freeze({ ...fixture, isTrashed: false });
-      timelineManager.upsertAssets([updated]);
-      expect(timelineManager.assetCount).toEqual(0);
-
-      timelineManager.upsertAssets([{ ...fixture, isTrashed: true }]);
-      expect(timelineManager.assetCount).toEqual(1);
+      expect(timelineManager.segments.length).toEqual(2);
+      expect(timelineManager.search.findMonthByDate({ year: 2024, month: 1 })).not.toBeUndefined();
+      expect(timelineManager.search.findMonthByDate({ year: 2024, month: 1 })?.assets.length).toEqual(0);
+      expect(timelineManager.search.findMonthByDate({ year: 2024, month: 3 })).not.toBeUndefined();
+      expect(timelineManager.search.findMonthByDate({ year: 2024, month: 3 })?.assets.length).toEqual(1);
    });
  });

@@ -551,8 +491,8 @@ describe('TimelineManager', () => {
      timelineManager.removeAssets(['', 'invalid', '4c7d9acc']);

      expect(timelineManager.assetCount).toEqual(2);
-      expect(timelineManager.months.length).toEqual(1);
-      expect(timelineManager.months[0].getAssets().length).toEqual(2);
+      expect(timelineManager.segments.length).toEqual(1);
+      expect(timelineManager.segments[0].assets.length).toEqual(2);
    });

    it('removes asset from month', () => {
@@ -565,8 +505,8 @@ describe('TimelineManager', () => {
      timelineManager.removeAssets([assetOne.id]);

      expect(timelineManager.assetCount).toEqual(1);
-      expect(timelineManager.months.length).toEqual(1);
-      expect(timelineManager.months[0].getAssets().length).toEqual(1);
+      expect(timelineManager.segments.length).toEqual(1);
+      expect(timelineManager.segments[0].assets.length).toEqual(1);
    });

    it('does not remove month when empty', () => {
@@ -579,7 +519,7 @@ describe('TimelineManager', () => {
      timelineManager.removeAssets(assets.map((asset) => asset.id));

      expect(timelineManager.assetCount).toEqual(0);
-      expect(timelineManager.months.length).toEqual(1);
+      expect(timelineManager.segments.length).toEqual(1);
    });
  });

@@ -650,63 +590,63 @@ describe('TimelineManager', () => {
    });

    it('returns null for invalid assetId', async () => {
-      expect(() => timelineManager.getLaterAsset({ id: 'invalid' } as AssetResponseDto)).not.toThrow();
-      expect(await timelineManager.getLaterAsset({ id: 'invalid' } as AssetResponseDto)).toBeUndefined();
+      expect(() => timelineManager.search.getLaterAsset({ id: 'invalid' } as AssetResponseDto)).not.toThrow();
+      expect(await timelineManager.search.getLaterAsset({ id: 'invalid' } as AssetResponseDto)).toBeUndefined();
    });

    it('returns previous assetId', async () => {
-      await timelineManager.loadMonth({ year: 2024, month: 1 });
-      const month = getMonthByDate(timelineManager, { year: 2024, month: 1 });
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 1 }));
+      const month = timelineManager.search.findMonthByDate({ year: 2024, month: 1 });

-      const a = month!.getAssets()[0];
-      const b = month!.getAssets()[1];
-      const previous = await timelineManager.getLaterAsset(b);
+      const a = month!.assets[0];
+      const b = month!.assets[1];
+      const previous = await timelineManager.search.getLaterAsset(b);
      expect(previous).toEqual(a);
    });

    it('returns previous assetId spanning multiple months', async () => {
-      await timelineManager.loadMonth({ year: 2024, month: 2 });
-      await timelineManager.loadMonth({ year: 2024, month: 3 });
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 2 }));
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 3 }));

-      const month = getMonthByDate(timelineManager, { year: 2024, month: 2 });
-      const previousMonth = getMonthByDate(timelineManager, { year: 2024, month: 3 });
-      const a = month!.getAssets()[0];
-      const b = previousMonth!.getAssets()[0];
-      const previous = await timelineManager.getLaterAsset(a);
+      const month = timelineManager.search.findMonthByDate({ year: 2024, month: 2 });
+      const previousMonth = timelineManager.search.findMonthByDate({ year: 2024, month: 3 });
+      const a = month!.assets[0];
+      const b = previousMonth!.assets[0];
+      const previous = await timelineManager.search.getLaterAsset(a);
      expect(previous).toEqual(b);
    });

    it('loads previous month', async () => {
-      await timelineManager.loadMonth({ year: 2024, month: 2 });
-      const month = getMonthByDate(timelineManager, { year: 2024, month: 2 });
-      const previousMonth = getMonthByDate(timelineManager, { year: 2024, month: 3 });
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 2 }));
+      const month = timelineManager.search.findMonthByDate({ year: 2024, month: 2 });
+      const previousMonth = timelineManager.search.findMonthByDate({ year: 2024, month: 3 });
      const a = month!.getFirstAsset();
      const b = previousMonth!.getFirstAsset();
-      const loadMonthSpy = vi.spyOn(month!.loader!, 'execute');
+      const loadmonthSpy = vi.spyOn(month!.loader!, 'execute');
      const previousMonthSpy = vi.spyOn(previousMonth!.loader!, 'execute');
-      const previous = await timelineManager.getLaterAsset(a);
+      const previous = await timelineManager.search.getLaterAsset(a);
      expect(previous).toEqual(b);
-      expect(loadMonthSpy).toBeCalledTimes(0);
+      expect(loadmonthSpy).toBeCalledTimes(0);
      expect(previousMonthSpy).toBeCalledTimes(0);
    });

    it('skips removed assets', async () => {
-      await timelineManager.loadMonth({ year: 2024, month: 1 });
-      await timelineManager.loadMonth({ year: 2024, month: 2 });
-      await timelineManager.loadMonth({ year: 2024, month: 3 });
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 1 }));
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 2 }));
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 3 }));

      const [assetOne, assetTwo, assetThree] = await getAssets(timelineManager);
      timelineManager.removeAssets([assetTwo.id]);
-      expect(await timelineManager.getLaterAsset(assetThree)).toEqual(assetOne);
+      expect(await timelineManager.search.getLaterAsset(assetThree)).toEqual(assetOne);
    });

    it('returns null when no more assets', async () => {
-      await timelineManager.loadMonth({ year: 2024, month: 3 });
-      expect(await timelineManager.getLaterAsset(timelineManager.months[0].getFirstAsset())).toBeUndefined();
+      await timelineManager.loadSegment(getSegmentIdentifier({ year: 2024, month: 3 }));
+      expect(await timelineManager.search.getLaterAsset(timelineManager.segments[0].getFirstAsset())).toBeUndefined();
    });
  });

-  describe('getMonthIndexByAssetId', () => {
+  describe('getmonthIndexByAssetId', () => {
    let timelineManager: TimelineManager;

    beforeEach(async () => {
@@ -717,8 +657,8 @@ describe('TimelineManager', () => {
    });

    it('returns null for invalid months', () => {
-      expect(getMonthByDate(timelineManager, { year: -1, month: -1 })).toBeUndefined();
-      expect(getMonthByDate(timelineManager, { year: 2024, month: 3 })).toBeUndefined();
+      expect(timelineManager.search.findMonthByDate({ year: -1, month: -1 })).toBeUndefined();
+      expect(timelineManager.search.findMonthByDate({ year: 2024, month: 3 })).toBeUndefined();
    });

    it('returns the month index', () => {
@@ -734,10 +674,10 @@ describe('TimelineManager', () => {
      );
      timelineManager.upsertAssets([assetOne, assetTwo]);

-      expect(timelineManager.getMonthByAssetId(assetTwo.id)?.yearMonth.year).toEqual(2024);
-      expect(timelineManager.getMonthByAssetId(assetTwo.id)?.yearMonth.month).toEqual(2);
-      expect(timelineManager.getMonthByAssetId(assetOne.id)?.yearMonth.year).toEqual(2024);
-      expect(timelineManager.getMonthByAssetId(assetOne.id)?.yearMonth.month).toEqual(1);
+      expect(getMonthForAssetId(timelineManager, assetTwo.id)?.yearMonth.year).toEqual(2024);
+      expect(getMonthForAssetId(timelineManager, assetTwo.id)?.yearMonth.month).toEqual(2);
+      expect(getMonthForAssetId(timelineManager, assetOne.id)?.yearMonth.year).toEqual(2024);
+      expect(getMonthForAssetId(timelineManager, assetOne.id)?.yearMonth.month).toEqual(1);
    });

    it('ignores removed months', () => {
@@ -754,8 +694,8 @@ describe('TimelineManager', () => {
      timelineManager.upsertAssets([assetOne, assetTwo]);

      timelineManager.removeAssets([assetTwo.id]);
-      expect(timelineManager.getMonthByAssetId(assetOne.id)?.yearMonth.year).toEqual(2024);
-      expect(timelineManager.getMonthByAssetId(assetOne.id)?.yearMonth.month).toEqual(1);
+      expect(getMonthForAssetId(timelineManager, assetOne.id)?.yearMonth.year).toEqual(2024);
+      expect(getMonthForAssetId(timelineManager, assetOne.id)?.yearMonth.month).toEqual(1);
    });
  });

@@ -804,7 +744,7 @@ describe('TimelineManager', () => {
      expect(assetCount).toBe(14);
      const discoveredAssets: Set<string> = new Set();
      for (let idx = 0; idx < assetCount; idx++) {
-        const asset = await timelineManager.getRandomAsset(idx);
+        const asset = await timelineManager.search.getRandomAsset(idx);
        expect(asset).toBeDefined();
        const id = asset!.id;
        expect(discoveredAssets.has(id)).toBeFalsy();
--- a/web/src/lib/managers/timeline-manager/TimelineManager.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/TimelineManager.svelte.ts
@@ -1,99 +1,60 @@
 import { VirtualScrollManager } from '$lib/managers/VirtualScrollManager/VirtualScrollManager.svelte';
 import { authManager } from '$lib/managers/auth-manager.svelte';
-import { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
+import type { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
+import { GroupInsertionCache } from '$lib/managers/timeline-manager/TimelineInsertionCache.svelte';
 import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
-import { GroupInsertionCache } from '$lib/managers/timeline-manager/group-insertion-cache.svelte';
-import { updateIntersectionMonth } from '$lib/managers/timeline-manager/internal/intersection-support.svelte';
-import { updateGeometry } from '$lib/managers/timeline-manager/internal/layout-support.svelte';
-import { loadFromTimeBuckets } from '$lib/managers/timeline-manager/internal/load-support.svelte';
-import {
-  findClosestGroupForDate,
-  findMonthForAsset as findMonthForAssetUtil,
-  findMonthForDate,
-  getAssetWithOffset,
-  getMonthByDate,
-  retrieveRange as retrieveRangeUtil,
-} from '$lib/managers/timeline-manager/internal/search-support.svelte';
-import { isMismatched, updateObject } from '$lib/managers/timeline-manager/internal/utils.svelte';
-import { WebsocketSupport } from '$lib/managers/timeline-manager/internal/websocket-support.svelte';
+import { TimelineSearchExtension } from '$lib/managers/timeline-manager/TimelineSearchExtension.svelte';
+import { TimelineWebsocketExtension } from '$lib/managers/timeline-manager/TimelineWebsocketExtension';
 import type {
-  AssetDescriptor,
-  AssetOperation,
  Direction,
  ScrubberMonth,
  TimelineAsset,
  TimelineManagerOptions,
  Viewport,
 } from '$lib/managers/timeline-manager/types';
+import { isMismatched } from '$lib/managers/timeline-manager/utils.svelte';
 import { CancellableTask } from '$lib/utils/cancellable-task';
-import {
-  setDifferenceInPlace,
-  toTimelineAsset,
-  type TimelineDateTime,
-  type TimelineYearMonth,
-} from '$lib/utils/timeline-util';
-import { AssetOrder, getAssetInfo, getTimeBuckets } from '@immich/sdk';
-import { clamp, isEqual } from 'lodash-es';
+import { getSegmentIdentifier } from '$lib/utils/timeline-util';
+import { AssetOrder, getTimeBuckets } from '@immich/sdk';
+import { isEqual } from 'lodash-es';
 import { SvelteDate, SvelteSet } from 'svelte/reactivity';

-type ViewportTopMonthIntersection = {
-  month: TimelineMonth | undefined;
-  // Where viewport top intersects month (0 = month top, 1 = month bottom)
-  viewportTopRatioInMonth: number;
-  // Where month bottom is in viewport (0 = viewport top, 1 = viewport bottom)
-  monthBottomViewportRatio: number;
-};
 export class TimelineManager extends VirtualScrollManager {
  override bottomSectionHeight = $state(60);
-
-  override bodySectionHeight = $derived.by(() => {
-    let height = 0;
-    for (const month of this.months) {
-      height += month.height;
-    }
-    return height;
-  });
-
-  assetCount = $derived.by(() => {
-    let count = 0;
-    for (const month of this.months) {
-      count += month.assetsCount;
-    }
-    return count;
-  });
-
-  isInitialized = $state(false);
-  months: TimelineMonth[] = $state([]);
-  albumAssets: Set<string> = new SvelteSet();
-  scrubberMonths: ScrubberMonth[] = $state([]);
-  scrubberTimelineHeight: number = $state(0);
-  viewportTopMonthIntersection: ViewportTopMonthIntersection | undefined;
-  limitedScroll = $derived(this.maxScrollPercent < 0.5);
-  initTask = new CancellableTask(
+  readonly search = new TimelineSearchExtension(this);
+  readonly websocket = new TimelineWebsocketExtension(this);
+  readonly albumAssets: Set<string> = new SvelteSet();
+  readonly limitedScroll = $derived(this.maxScrollPercent < 0.5);
+  readonly initTask = new CancellableTask(
    () => {
      this.isInitialized = true;
      if (this.#options.albumId || this.#options.personId) {
        return;
      }
-      this.connect();
+      this.websocket.connect();
    },
    () => {
-      this.disconnect();
+      this.websocket.disconnect();
      this.isInitialized = false;
    },
    () => void 0,
  );

-  static #INIT_OPTIONS = {};
-  #websocketSupport: WebsocketSupport | undefined;
-  #options: TimelineManagerOptions = TimelineManager.#INIT_OPTIONS;
-  #updatingIntersections = false;
+  segments: TimelineMonth[] = $state([]);
+  scrubberMonths: ScrubberMonth[] = $state([]);
+  scrubberTimelineHeight: number = $state(0);
+
+  #options: TimelineManagerOptions = {};
  #scrollableElement: HTMLElement | undefined = $state();

  constructor() {
    super();
  }

+  get options() {
+    return this.#options;
+  }
+
  override get scrollTop(): number {
    return this.#scrollableElement?.scrollTop ?? 0;
  }
@@ -102,158 +63,38 @@ export class TimelineManager extends VirtualScrollManager {
    this.#scrollableElement = element;
  }

-  scrollTo(top: number) {
+  override scrollTo(top: number) {
    this.#scrollableElement?.scrollTo({ top });
-    this.updateSlidingWindow();
+    this.updateVisibleWindow();
  }

-  scrollBy(y: number) {
+  override scrollBy(y: number) {
    this.#scrollableElement?.scrollBy(0, y);
-    this.updateSlidingWindow();
+    this.updateVisibleWindow();
  }

-  async *assetsIterator(options?: {
-    startMonth?: TimelineMonth;
-    startDay?: TimelineDay;
-    startAsset?: TimelineAsset;
-    direction?: Direction;
-  }) {
-    const direction = options?.direction ?? 'earlier';
-    let { startDay, startAsset } = options ?? {};
-    for (const month of this.monthIterator({ direction, startMonth: options?.startMonth })) {
-      await this.loadMonth(month.yearMonth, { cancelable: false });
-      yield* month.assetsIterator({ startDay, startAsset, direction });
-      startDay = startAsset = undefined;
+  protected override refreshLayout({ invalidateHeight = true }: { invalidateHeight?: boolean } = {}) {
+    super.refreshLayout({ invalidateHeight });
+    if (invalidateHeight) {
+      this.#createScrubberMonths();
    }
  }

-  *monthIterator(options?: { direction?: Direction; startMonth?: TimelineMonth }) {
-    const isEarlier = options?.direction === 'earlier';
-    let startIndex = options?.startMonth
-      ? this.months.indexOf(options.startMonth)
-      : isEarlier
-        ? 0
-        : this.months.length - 1;
-
-    while (startIndex >= 0 && startIndex < this.months.length) {
-      yield this.months[startIndex];
-      startIndex += isEarlier ? 1 : -1;
-    }
-  }
-
-  connect() {
-    if (this.#websocketSupport) {
-      throw new Error('TimelineManager already connected');
-    }
-    this.#websocketSupport = new WebsocketSupport(this);
-    this.#websocketSupport.connectWebsocketEvents();
-  }
-
-  disconnect() {
-    if (!this.#websocketSupport) {
-      return;
-    }
-    this.#websocketSupport.disconnectWebsocketEvents();
-    this.#websocketSupport = undefined;
-  }
-
-  #calculateMonthBottomViewportRatio(month: TimelineMonth | undefined) {
-    if (!month) {
-      return 0;
-    }
-    const windowHeight = this.visibleWindow.bottom - this.visibleWindow.top;
-    const bottomOfMonth = month.top + month.height;
-    const bottomOfMonthInViewport = bottomOfMonth - this.visibleWindow.top;
-    return clamp(bottomOfMonthInViewport / windowHeight, 0, 1);
-  }
-
-  #calculateVewportTopRatioInMonth(month: TimelineMonth | undefined) {
-    if (!month) {
-      return 0;
-    }
-    return clamp((this.visibleWindow.top - month.top) / month.height, 0, 1);
-  }
-
-  override updateIntersections() {
-    if (this.#updatingIntersections || !this.isInitialized || this.visibleWindow.bottom === this.visibleWindow.top) {
-      return;
-    }
-    this.#updatingIntersections = true;
-
-    for (const month of this.months) {
-      updateIntersectionMonth(this, month);
-    }
-
-    const month = this.months.find((month) => month.actuallyIntersecting);
-    const viewportTopRatioInMonth = this.#calculateVewportTopRatioInMonth(month);
-    const monthBottomViewportRatio = this.#calculateMonthBottomViewportRatio(month);
-
-    this.viewportTopMonthIntersection = {
-      month,
-      monthBottomViewportRatio,
-      viewportTopRatioInMonth,
-    };
-
-    this.#updatingIntersections = false;
-  }
-
-  clearDeferredLayout(month: TimelineMonth) {
-    const hasDeferred = month.days.some((group) => group.deferredLayout);
-    if (hasDeferred) {
-      updateGeometry(this, month, { invalidateHeight: true, noDefer: true });
-      for (const group of month.days) {
-        group.deferredLayout = false;
-      }
-    }
-  }
-
-  async #initializeMonths() {
-    const timebuckets = await getTimeBuckets({
-      ...authManager.params,
-      ...this.#options,
-    });
-
-    this.months = timebuckets.map((timeBucket) => {
-      const date = new SvelteDate(timeBucket.timeBucket);
-      return new TimelineMonth(
-        this,
-        { year: date.getUTCFullYear(), month: date.getUTCMonth() + 1 },
-        timeBucket.count,
-        false,
-        this.#options.order,
-      );
-    });
-    this.albumAssets.clear();
-    this.updateViewportGeometry(false);
+  public override destroy() {
+    this.websocket.disconnect();
+    super.destroy();
  }

  async updateOptions(options: TimelineManagerOptions) {
    if (options.deferInit) {
      return;
    }
-    if (this.#options !== TimelineManager.#INIT_OPTIONS && isEqual(this.#options, options)) {
+    if (isEqual(this.#options, options)) {
      return;
    }
    await this.initTask.reset();
    await this.#init(options);
-    this.updateViewportGeometry(false);
-    this.#createScrubberMonths();
-  }
-
-  async #init(options: TimelineManagerOptions) {
-    this.isInitialized = false;
-    this.months = [];
-    this.albumAssets.clear();
-    await this.initTask.execute(async () => {
-      this.#options = options;
-      await this.#initializeMonths();
-    }, true);
-  }
-
-  public override destroy() {
-    this.disconnect();
-    this.isInitialized = false;
-    super.destroy();
+    this.refreshLayout();
  }

  async updateViewport(viewport: Viewport) {
@@ -269,296 +110,55 @@ export class TimelineManager extends VirtualScrollManager {
      await (this.initTask.loading ? this.initTask.waitUntilCompletion() : this.#init(this.#options));
    }

-    const changedWidth = viewport.width !== this.viewportWidth;
+    const oldViewport: Viewport = {
+      width: this.viewportWidth,
+      height: this.viewportHeight,
+    };
+
    this.viewportHeight = viewport.height;
    this.viewportWidth = viewport.width;
-    this.updateViewportGeometry(changedWidth);
+    this.onUpdateViewport(oldViewport, viewport);
  }

-  protected override updateViewportGeometry(changedWidth: boolean) {
-    if (!this.isInitialized || this.hasEmptyViewport) {
-      return;
-    }
-    for (const month of this.months) {
-      updateGeometry(this, month, { invalidateHeight: changedWidth });
-    }
-    this.updateIntersections();
-    if (changedWidth) {
-      this.#createScrubberMonths();
-    }
-  }
-
-  #createScrubberMonths() {
-    this.scrubberMonths = this.months.map((month) => ({
-      assetCount: month.assetsCount,
-      year: month.yearMonth.year,
-      month: month.yearMonth.month,
-      title: month.monthTitle,
-      height: month.height,
-    }));
-    this.scrubberTimelineHeight = this.totalViewerHeight;
-  }
-
-  async loadMonth(yearMonth: TimelineYearMonth, options?: { cancelable: boolean }): Promise<void> {
-    let cancelable = true;
-    if (options) {
-      cancelable = options.cancelable;
-    }
-    const month = getMonthByDate(this, yearMonth);
-    if (!month) {
-      return;
-    }
-
-    if (month.loader?.executed) {
-      return;
-    }
-
-    const executionStatus = await month.loader?.execute(async (signal: AbortSignal) => {
-      await loadFromTimeBuckets(this, month, this.#options, signal);
-    }, cancelable);
-    if (executionStatus === 'LOADED') {
-      updateGeometry(this, month, { invalidateHeight: false });
-      this.updateIntersections();
-    }
-  }
-
-  upsertAssets(assets: TimelineAsset[]) {
-    const notUpdated = this.#updateAssets(assets);
-    const notExcluded = notUpdated.filter((asset) => !this.isExcluded(asset));
-    this.addAssetsToSegments(notExcluded);
-  }
-
-  async findMonthForAsset(id: string) {
-    if (!this.isInitialized) {
-      await this.initTask.waitUntilCompletion();
-    }
-
-    let { month } = findMonthForAssetUtil(this, id) ?? {};
-    if (month) {
-      return month;
-    }
-
-    const response = await getAssetInfo({ ...authManager.params, id }).catch(() => null);
-    if (!response) {
-      return;
-    }
-
-    const asset = toTimelineAsset(response);
-    if (!asset || this.isExcluded(asset)) {
-      return;
-    }
-
-    month = await this.#loadMonthAtTime(asset.localDateTime, { cancelable: false });
-    if (month?.findAssetById({ id })) {
-      return month;
-    }
-  }
-
-  async #loadMonthAtTime(yearMonth: TimelineYearMonth, options?: { cancelable: boolean }) {
-    await this.loadMonth(yearMonth, options);
-    return getMonthByDate(this, yearMonth);
-  }
-
-  getMonthByAssetId(assetId: string) {
-    const monthInfo = findMonthForAssetUtil(this, assetId);
-    return monthInfo?.month;
-  }
-
-  // note: the `index` input is expected to be in the range [0, assetCount). This
-  // value can be passed to make the method deterministic, which is mainly useful
-  // for testing.
-  async getRandomAsset(index?: number): Promise<TimelineAsset | undefined> {
-    const randomAssetIndex = index ?? Math.floor(Math.random() * this.assetCount);
-
-    let accumulatedCount = 0;
-
-    let randomMonth: TimelineMonth | undefined = undefined;
-    for (const month of this.months) {
-      if (randomAssetIndex < accumulatedCount + month.assetsCount) {
-        randomMonth = month;
-        break;
-      }
-
-      accumulatedCount += month.assetsCount;
-    }
-    if (!randomMonth) {
-      return;
-    }
-    await this.loadMonth(randomMonth.yearMonth, { cancelable: false });
-
-    let randomDay: TimelineDay | undefined = undefined;
-    for (const day of randomMonth.days) {
-      if (randomAssetIndex < accumulatedCount + day.viewerAssets.length) {
-        randomDay = day;
-        break;
-      }
-
-      accumulatedCount += day.viewerAssets.length;
-    }
-    if (!randomDay) {
-      return;
-    }
-
-    return randomDay.viewerAssets[randomAssetIndex - accumulatedCount].asset;
-  }
-
-  /**
-   * Executes the given operation against every passed in asset id.
-   *
-   * @returns An object with the changed ids, unprocessed ids, and if this resulted
-   * in changes of the timeline geometry.
-   */
-  updateAssetOperation(ids: string[], operation: AssetOperation) {
-    return this.#runAssetOperation(ids, operation);
-  }
-
-  /**
-   * Looks up the specified asset from the TimelineAsset using its id, and then updates the
-   * existing object to match the rest of the TimelineAsset parameter.
-
-   * @returns list of assets that were updated (not found)
-   */
-  #updateAssets(updatedAssets: TimelineAsset[]) {
-    // eslint-disable-next-line svelte/prefer-svelte-reactivity
-    const lookup = new Map<string, TimelineAsset>();
-    const ids = [];
-    for (const asset of updatedAssets) {
-      ids.push(asset.id);
-      lookup.set(asset.id, asset);
-    }
-    const { unprocessedIds } = this.#runAssetOperation(ids, (asset) => updateObject(asset, lookup.get(asset.id)));
-    const result: TimelineAsset[] = [];
-    for (const id of unprocessedIds) {
-      result.push(lookup.get(id)!);
-    }
-    return result;
-  }
-
-  removeAssets(ids: string[]) {
-    this.#runAssetOperation(ids, () => ({ remove: true }));
-  }
-
-  protected createUpsertContext(): GroupInsertionCache {
+  protected override createUpsertContext(): GroupInsertionCache {
    return new GroupInsertionCache();
  }

-  protected upsertAssetIntoSegment(asset: TimelineAsset, context: GroupInsertionCache): void {
-    let month = getMonthByDate(this, asset.localDateTime);
+  protected override upsertAssetIntoSegment(asset: TimelineAsset, context: GroupInsertionCache): void {
+    let month = this.search.findMonthByDate(asset.localDateTime);

    if (!month) {
      month = new TimelineMonth(this, asset.localDateTime, 1, true, this.#options.order);
-      this.months.push(month);
+      this.segments.push(month);
    }

    month.addTimelineAsset(asset, context);
  }

-  protected addAssetsToSegments(assets: TimelineAsset[]) {
-    if (assets.length === 0) {
-      return;
-    }
-    const context = this.createUpsertContext();
-    const monthCount = this.months.length;
-    for (const asset of assets) {
-      this.upsertAssetIntoSegment(asset, context);
-    }
-    if (this.months.length !== monthCount) {
-      this.postCreateSegments();
-    }
-    this.postUpsert(context);
-    this.updateIntersections();
+  protected override postCreateSegments(): void {
+    this.segments.sort((a, b) => {
+      return a.yearMonth.year === b.yearMonth.year
+        ? b.yearMonth.month - a.yearMonth.month
+        : b.yearMonth.year - a.yearMonth.year;
+    });
  }

-  #runAssetOperation(ids: string[], operation: AssetOperation) {
-    if (ids.length === 0) {
-      // eslint-disable-next-line svelte/prefer-svelte-reactivity
-      return { processedIds: new Set<string>(), unprocessedIds: new Set<string>(), changedGeometry: false };
+  protected override postUpsert(context: GroupInsertionCache): void {
+    for (const group of context.existingDays) {
+      group.sortAssets(this.#options.order);
    }

-    // eslint-disable-next-line svelte/prefer-svelte-reactivity
-    const changedMonths = new Set<TimelineMonth>();
-    // eslint-disable-next-line svelte/prefer-svelte-reactivity
-    const idsToProcess = new Set(ids);
-    // eslint-disable-next-line svelte/prefer-svelte-reactivity
-    const idsProcessed = new Set<string>();
-    const combinedMoveAssets: TimelineAsset[] = [];
-    for (const month of this.months) {
-      if (idsToProcess.size > 0) {
-        const { moveAssets, processedIds, changedGeometry } = month.runAssetOperation(idsToProcess, operation);
-        if (moveAssets.length > 0) {
-          combinedMoveAssets.push(...moveAssets);
-        }
-        setDifferenceInPlace(idsToProcess, processedIds);
-        for (const id of processedIds) {
-          idsProcessed.add(id);
-        }
-        if (changedGeometry) {
-          changedMonths.add(month);
-        }
-      }
+    for (const month of context.monthsWithNewDays) {
+      month.sortDays();
    }
-    if (combinedMoveAssets.length > 0) {
-      this.addAssetsToSegments(combinedMoveAssets);
-    }
-    const changedGeometry = changedMonths.size > 0;
-    for (const month of changedMonths) {
-      updateGeometry(this, month, { invalidateHeight: true });
-    }
-    if (changedGeometry) {
-      this.updateIntersections();
-    }
-    return { unprocessedIds: idsToProcess, processedIds: idsProcessed, changedGeometry };
-  }

-  override refreshLayout() {
-    for (const month of this.months) {
-      updateGeometry(this, month, { invalidateHeight: true });
-    }
-    this.updateIntersections();
-  }
-
-  getFirstAsset(): TimelineAsset | undefined {
-    return this.months[0]?.getFirstAsset();
-  }
-
-  async getLaterAsset(
-    assetDescriptor: AssetDescriptor,
-    interval: 'asset' | 'day' | 'month' | 'year' = 'asset',
-  ): Promise<TimelineAsset | undefined> {
-    return await getAssetWithOffset(this, assetDescriptor, interval, 'later');
-  }
-
-  async getEarlierAsset(
-    assetDescriptor: AssetDescriptor,
-    interval: 'asset' | 'day' | 'month' | 'year' = 'asset',
-  ): Promise<TimelineAsset | undefined> {
-    return await getAssetWithOffset(this, assetDescriptor, interval, 'earlier');
-  }
-
-  async getClosestAssetToDate(dateTime: TimelineDateTime) {
-    let month = findMonthForDate(this, dateTime);
-    if (!month) {
-      // if exact match not found, find closest
-      month = findClosestGroupForDate(this.months, dateTime);
-      if (!month) {
-        return;
-      }
-    }
-    await this.loadMonth(dateTime, { cancelable: false });
-    const asset = month.findClosest(dateTime);
-    if (asset) {
-      return asset;
-    }
-    for await (const asset of this.assetsIterator({ startMonth: month })) {
-      return asset;
+    for (const month of context.updatedMonths) {
+      month.sortDays();
+      month.updateGeometry({ invalidateHeight: true });
    }
  }

-  async retrieveRange(start: AssetDescriptor, end: AssetDescriptor) {
-    return retrieveRangeUtil(this, start, end);
-  }
-
-  isExcluded(asset: TimelineAsset) {
+  override isExcluded(asset: TimelineAsset) {
    return (
      isMismatched(this.#options.visibility, asset.visibility) ||
      isMismatched(this.#options.isFavorite, asset.isFavorite) ||
@@ -570,26 +170,75 @@ export class TimelineManager extends VirtualScrollManager {
    return this.#options.order ?? AssetOrder.Desc;
  }

-  protected postCreateSegments(): void {
-    this.months.sort((a, b) => {
-      return a.yearMonth.year === b.yearMonth.year
-        ? b.yearMonth.month - a.yearMonth.month
-        : b.yearMonth.year - a.yearMonth.year;
-    });
+  getFirstAsset(): TimelineAsset | undefined {
+    return this.segments[0]?.getFirstAsset();
  }

-  protected postUpsert(context: GroupInsertionCache): void {
-    for (const group of context.existingDays) {
-      group.sortAssets(this.#options.order);
+  async *assetsIterator(options?: {
+    startMonth?: TimelineMonth;
+    startDay?: TimelineDay;
+    startAsset?: TimelineAsset;
+    direction?: Direction;
+  }) {
+    const direction = options?.direction ?? 'earlier';
+    let { startDay, startAsset } = options ?? {};
+    for (const month of this.monthIterator({ direction, startMonth: options?.startMonth })) {
+      await this.loadSegment(getSegmentIdentifier(month.yearMonth), { cancelable: false });
+      yield* month.assetsIterator({ startDay, startAsset, direction });
+      startDay = startAsset = undefined;
    }
+  }

-    for (const month of context.monthsWithNewDays) {
-      month.sortDays();
-    }
+  *monthIterator(options?: { direction?: Direction; startMonth?: TimelineMonth }) {
+    const isEarlier = options?.direction === 'earlier';
+    let startIndex = options?.startMonth
+      ? this.segments.indexOf(options.startMonth)
+      : isEarlier
+        ? 0
+        : this.segments.length - 1;

-    for (const month of context.updatedMonths) {
-      month.sortDays();
-      updateGeometry(this, month, { invalidateHeight: true });
+    while (startIndex >= 0 && startIndex < this.segments.length) {
+      yield this.segments[startIndex];
+      startIndex += isEarlier ? 1 : -1;
    }
  }
+
+  async #init(options: TimelineManagerOptions) {
+    this.isInitialized = false;
+    this.segments = [];
+    this.albumAssets.clear();
+    await this.initTask.execute(async () => {
+      this.#options = options;
+      const timebuckets = await getTimeBuckets({
+        ...authManager.params,
+        ...this.#options,
+      });
+
+      for (const timeBucket of timebuckets) {
+        const date = new SvelteDate(timeBucket.timeBucket);
+        this.segments.push(
+          new TimelineMonth(
+            this,
+            { year: date.getUTCFullYear(), month: date.getUTCMonth() + 1 },
+            timeBucket.count,
+            false,
+            this.#options.order,
+          ),
+        );
+      }
+      this.albumAssets.clear();
+    }, true);
+    this.refreshLayout();
+  }
+
+  #createScrubberMonths() {
+    this.scrubberMonths = this.segments.map((month) => ({
+      assetCount: month.assetsCount,
+      year: month.yearMonth.year,
+      month: month.yearMonth.month,
+      title: month.monthTitle,
+      height: month.height,
+    }));
+    this.scrubberTimelineHeight = this.totalViewerHeight;
+  }
 }
--- a/web/src/lib/managers/timeline-manager/TimelineMonth.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/TimelineMonth.svelte.ts
@@ -1,49 +1,37 @@
-import { GroupInsertionCache } from '$lib/managers/timeline-manager/group-insertion-cache.svelte';
-import { onCreateMonth } from '$lib/managers/timeline-manager/internal/TestHooks.svelte';
+import { authManager } from '$lib/managers/auth-manager.svelte';
 import { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
-import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
-import type { AssetDescriptor, AssetOperation, Direction, TimelineAsset } from '$lib/managers/timeline-manager/types';
+import { GroupInsertionCache } from '$lib/managers/timeline-manager/TimelineInsertionCache.svelte';
+import type { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
+import { onCreateTimelineMonth } from '$lib/managers/timeline-manager/TimelineTestHooks.svelte';
+import type { AssetDescriptor, Direction, TimelineAsset } from '$lib/managers/timeline-manager/types';
 import { ViewerAsset } from '$lib/managers/timeline-manager/viewer-asset.svelte';
-import { ScrollSegment } from '$lib/managers/VirtualScrollManager/ScrollSegment.svelte';
-import { CancellableTask } from '$lib/utils/cancellable-task';
-import { handleError } from '$lib/utils/handle-error';
+import { ScrollSegment, type SegmentIdentifier } from '$lib/managers/VirtualScrollManager/ScrollSegment.svelte';
+import { setDifferenceInPlace } from '$lib/managers/VirtualScrollManager/utils.svelte';
+import type { AssetOperation } from '$lib/managers/VirtualScrollManager/VirtualScrollManager.svelte';
 import {
-  formatDayTitle,
-  formatMonthTitle,
+  formatGroupTitle,
+  formatGroupTitleFull,
+  formatMonthGroupTitle,
  fromTimelinePlainDate,
  fromTimelinePlainDateTime,
  fromTimelinePlainYearMonth,
+  getSegmentIdentifier,
  getTimes,
-  setDifferenceInPlace,
+  toISOYearMonthUTC,
  type TimelineDateTime,
  type TimelineYearMonth,
 } from '$lib/utils/timeline-util';
-import { AssetOrder, type TimeBucketAssetResponseDto } from '@immich/sdk';
-import { t } from 'svelte-i18n';
-import { get } from 'svelte/store';
+import { AssetOrder, getTimeBucket, type TimeBucketAssetResponseDto } from '@immich/sdk';

 export class TimelineMonth extends ScrollSegment {
-  #intersecting: boolean = $state(false);
-  actuallyIntersecting: boolean = $state(false);
-  isLoaded: boolean = $state(false);
  days: TimelineDay[] = $state([]);
-  readonly timelineManager: TimelineManager;

-  #height: number = $state(0);
-  #top: number = $state(0);
-
-  #initialCount: number = 0;
  #sortOrder: AssetOrder = AssetOrder.Desc;
-  percent: number = $state(0);
-
-  assetsCount: number = $derived(
-    this.isLoaded ? this.days.reduce((accumulator, g) => accumulator + g.viewerAssets.length, 0) : this.#initialCount,
-  );
-  loader: CancellableTask | undefined;
-  isHeightActual: boolean = $state(false);
+  #yearMonth: TimelineYearMonth;
+  #identifier: SegmentIdentifier;
+  #timelineManager: TimelineManager;

  readonly monthTitle: string;
-  readonly yearMonth: TimelineYearMonth;

  constructor(
    timelineManager: TimelineManager,
@@ -53,46 +41,162 @@ export class TimelineMonth extends ScrollSegment {
    order: AssetOrder = AssetOrder.Desc,
  ) {
    super();
-    this.timelineManager = timelineManager;
-    this.#initialCount = initialCount;
+    this.initialCount = initialCount;
+    this.#yearMonth = yearMonth;
+    this.#identifier = getSegmentIdentifier(yearMonth);
+    this.#timelineManager = timelineManager;
    this.#sortOrder = order;
-
-    this.yearMonth = yearMonth;
-    this.monthTitle = formatMonthTitle(fromTimelinePlainYearMonth(yearMonth));
-
-    this.loader = new CancellableTask(
-      () => {
-        this.isLoaded = true;
-      },
-      () => {
-        this.days = [];
-        this.isLoaded = false;
-      },
-      this.#handleLoadError,
-    );
-    if (loaded) {
-      this.isLoaded = true;
-    }
+    this.monthTitle = formatMonthGroupTitle(fromTimelinePlainYearMonth(yearMonth));
+    this.loaded = loaded;
    if (import.meta.env.DEV) {
-      onCreateMonth(this);
+      onCreateTimelineMonth(this);
    }
  }

-  set intersecting(newValue: boolean) {
-    const old = this.#intersecting;
-    if (old === newValue) {
+  get identifier() {
+    return this.#identifier;
+  }
+
+  get scrollManager(): TimelineManager {
+    return this.#timelineManager;
+  }
+
+  get viewerAssets() {
+    const assets: ViewerAsset[] = [];
+    for (const day of this.days) {
+      assets.push(...day.viewerAssets);
+    }
+    return assets;
+  }
+
+  override findAssetAbsolutePosition(assetId: string) {
+    this.#clearDeferredLayout();
+    for (const day of this.days) {
+      const viewerAsset = day.viewerAssets.find((viewAsset) => viewAsset.id === assetId);
+      if (viewerAsset) {
+        if (!viewerAsset.position) {
+          console.warn('No position for asset');
+          return;
+        }
+        return {
+          top: this.top + day.top + viewerAsset.position.top + this.#timelineManager.headerHeight,
+          height: viewerAsset.position.height,
+        };
+      }
+    }
+  }
+
+  protected async fetch(signal: AbortSignal): Promise<unknown> {
+    if (this.getFirstAsset()) {
      return;
    }
-    this.#intersecting = newValue;
-    if (newValue) {
-      void this.timelineManager.loadMonth(this.yearMonth);
-    } else {
-      this.cancel();
+    const timelineManager = this.#timelineManager;
+    const options = timelineManager.options;
+    const timeBucket = toISOYearMonthUTC(this.yearMonth);
+    const bucketResponse = await getTimeBucket(
+      {
+        ...authManager.params,
+        ...options,
+        timeBucket,
+      },
+      { signal },
+    );
+
+    if (!bucketResponse) {
+      return;
+    }
+
+    if (options.timelineAlbumId) {
+      const albumAssets = await getTimeBucket(
+        {
+          ...authManager.params,
+          albumId: options.timelineAlbumId,
+          timeBucket,
+        },
+        { signal },
+      );
+      for (const id of albumAssets.id) {
+        timelineManager.albumAssets.add(id);
+      }
+    }
+
+    const unprocessedAssets = this.addAssets(bucketResponse, true);
+    if (unprocessedAssets.length > 0) {
+      console.error(
+        `Warning: getTimeBucket API returning assets not in requested month: ${this.yearMonth.month}, ${JSON.stringify(
+          unprocessedAssets.map((unprocessed) => ({
+            id: unprocessed.id,
+            localDateTime: unprocessed.localDateTime,
+          })),
+        )}`,
+      );
    }
  }

-  get intersecting() {
-    return this.#intersecting;
+  override layout(noDefer: boolean) {
+    let cumulativeHeight = 0;
+    let cumulativeWidth = 0;
+    let currentRowHeight = 0;
+
+    let dayGroupRow = 0;
+    let dayGroupCol = 0;
+
+    const options = this.scrollManager.justifiedLayoutOptions;
+    for (const dayGroup of this.days) {
+      dayGroup.layout(options, noDefer);
+
+      // Calculate space needed for this item (including gap if not first in row)
+      const spaceNeeded = dayGroup.width + (dayGroupCol > 0 ? this.scrollManager.gap : 0);
+      const fitsInCurrentRow = cumulativeWidth + spaceNeeded <= this.scrollManager.viewportWidth;
+
+      if (fitsInCurrentRow) {
+        dayGroup.row = dayGroupRow;
+        dayGroup.col = dayGroupCol++;
+        dayGroup.left = cumulativeWidth;
+        dayGroup.top = cumulativeHeight;
+
+        cumulativeWidth += dayGroup.width + this.scrollManager.gap;
+      } else {
+        // Move to next row
+        cumulativeHeight += currentRowHeight;
+        cumulativeWidth = 0;
+        dayGroupRow++;
+        dayGroupCol = 0;
+
+        // Position at start of new row
+        dayGroup.row = dayGroupRow;
+        dayGroup.col = dayGroupCol;
+        dayGroup.left = 0;
+        dayGroup.top = cumulativeHeight;
+
+        dayGroupCol++;
+        cumulativeWidth += dayGroup.width + this.scrollManager.gap;
+      }
+      currentRowHeight = dayGroup.height + this.scrollManager.headerHeight;
+    }
+
+    // Add the height of the final row
+    cumulativeHeight += currentRowHeight;
+
+    this.height = cumulativeHeight;
+    this.isHeightActual = true;
+  }
+
+  override updateIntersection({
+    intersecting,
+    actuallyIntersecting,
+  }: {
+    intersecting: boolean;
+    actuallyIntersecting: boolean;
+  }) {
+    super.updateIntersection({ intersecting, actuallyIntersecting });
+    if (intersecting) {
+      this.#clearDeferredLayout();
+    }
+  }
+
+  get yearMonth() {
+    return this.#yearMonth;
  }

  get lastDay() {
@@ -103,29 +207,7 @@ export class TimelineMonth extends ScrollSegment {
    return this.days[0]?.getFirstAsset();
  }

-  getAssets() {
-    // eslint-disable-next-line unicorn/no-array-reduce
-    return this.days.reduce((accumulator: TimelineAsset[], g: TimelineDay) => accumulator.concat(g.getAssets()), []);
-  }
-
-  sortDays() {
-    if (this.#sortOrder === AssetOrder.Asc) {
-      return this.days.sort((a, b) => a.day - b.day);
-    }
-
-    return this.days.sort((a, b) => b.day - a.day);
-  }
-
-  runAssetOperation(ids: Set<string>, operation: AssetOperation) {
-    if (ids.size === 0) {
-      return {
-        moveAssets: [] as TimelineAsset[],
-        // eslint-disable-next-line svelte/prefer-svelte-reactivity
-        processedIds: new Set<string>(),
-        unprocessedIds: ids,
-        changedGeometry: false,
-      };
-    }
+  override runAssetOperation(ids: Set<string>, operation: AssetOperation) {
    const { days } = this;
    let combinedChangedGeometry = false;
    // eslint-disable-next-line svelte/prefer-svelte-reactivity
@@ -138,6 +220,7 @@ export class TimelineMonth extends ScrollSegment {
      if (idsToProcess.size > 0) {
        const group = days[index];
        const { moveAssets, processedIds, changedGeometry } = group.runAssetOperation(ids, operation);
+
        if (moveAssets.length > 0) {
          combinedMoveAssets.push(...moveAssets);
        }
@@ -215,6 +298,14 @@ export class TimelineMonth extends ScrollSegment {
    return addContext.unprocessedAssets;
  }

+  sortDays() {
+    if (this.#sortOrder === AssetOrder.Asc) {
+      return this.days.sort((a, b) => a.day - b.day);
+    }
+
+    return this.days.sort((a, b) => b.day - a.day);
+  }
+
  addTimelineAsset(timelineAsset: TimelineAsset, addContext: GroupInsertionCache) {
    const { localDateTime } = timelineAsset;

@@ -228,8 +319,9 @@ export class TimelineMonth extends ScrollSegment {
    if (day) {
      addContext.setDay(day, localDateTime);
    } else {
-      const dayTitle = formatDayTitle(fromTimelinePlainDate(localDateTime));
-      day = new TimelineDay(this, this.days.length, localDateTime.day, dayTitle);
+      const groupTitle = formatGroupTitle(fromTimelinePlainDate(localDateTime));
+      const groupTitleFull = formatGroupTitleFull(fromTimelinePlainDate(localDateTime));
+      day = new TimelineDay(this, this.days.length, localDateTime.day, groupTitle, groupTitleFull);
      this.days.push(day);
      addContext.setDay(day, localDateTime);
      addContext.newDays.add(day);
@@ -240,94 +332,6 @@ export class TimelineMonth extends ScrollSegment {
    addContext.changedDays.add(day);
  }

-  get viewId() {
-    const { year, month } = this.yearMonth;
-    return year + '-' + month;
-  }
-
-  set height(height: number) {
-    if (this.#height === height) {
-      return;
-    }
-    const timelineManager = this.timelineManager;
-    const index = timelineManager.months.indexOf(this);
-    const heightDelta = height - this.#height;
-    this.#height = height;
-    const prevMonth = timelineManager.months[index - 1];
-    if (prevMonth) {
-      const newTop = prevMonth.#top + prevMonth.#height;
-      if (this.#top !== newTop) {
-        this.#top = newTop;
-      }
-    }
-    if (heightDelta === 0) {
-      return;
-    }
-    for (let cursor = index + 1; cursor < timelineManager.months.length; cursor++) {
-      const month = this.timelineManager.months[cursor];
-      const newTop = month.#top + heightDelta;
-      if (month.#top !== newTop) {
-        month.#top = newTop;
-      }
-    }
-    if (!timelineManager.viewportTopMonthIntersection) {
-      return;
-    }
-    const { month, monthBottomViewportRatio, viewportTopRatioInMonth } = timelineManager.viewportTopMonthIntersection;
-    const currentIndex = month ? timelineManager.months.indexOf(month) : -1;
-    if (!month || currentIndex <= 0 || index > currentIndex) {
-      return;
-    }
-    if (index < currentIndex || monthBottomViewportRatio < 1) {
-      timelineManager.scrollBy(heightDelta);
-    } else if (index === currentIndex) {
-      const scrollTo = this.top + height * viewportTopRatioInMonth;
-      timelineManager.scrollTo(scrollTo);
-    }
-  }
-
-  get height() {
-    return this.#height;
-  }
-
-  get top(): number {
-    return this.#top + this.timelineManager.topSectionHeight;
-  }
-
-  #handleLoadError(error: unknown) {
-    const _$t = get(t);
-    handleError(error, _$t('errors.failed_to_load_assets'));
-  }
-
-  findDayForAsset(asset: TimelineAsset) {
-    for (const group of this.days) {
-      if (group.viewerAssets.some((viewerAsset) => viewerAsset.id === asset.id)) {
-        return group;
-      }
-    }
-  }
-
-  findDayByDay(day: number) {
-    return this.days.find((group) => group.day === day);
-  }
-
-  findAssetAbsolutePosition(assetId: string) {
-    this.timelineManager.clearDeferredLayout(this);
-    for (const group of this.days) {
-      const viewerAsset = group.viewerAssets.find((viewAsset) => viewAsset.id === assetId);
-      if (viewerAsset) {
-        if (!viewerAsset.position) {
-          console.warn('No position for asset');
-          return;
-        }
-        return {
-          top: this.top + group.top + viewerAsset.position.top + this.timelineManager.headerHeight,
-          height: viewerAsset.position.height,
-        };
-      }
-    }
-  }
-
  *assetsIterator(options?: { startDay?: TimelineDay; startAsset?: TimelineAsset; direction?: Direction }) {
    const direction = options?.direction ?? 'earlier';
    let { startAsset } = options ?? {};
@@ -342,6 +346,18 @@ export class TimelineMonth extends ScrollSegment {
    }
  }

+  findDayForAsset(asset: TimelineAsset) {
+    for (const group of this.days) {
+      if (group.viewerAssets.some((viewerAsset) => viewerAsset.id === asset.id)) {
+        return group;
+      }
+    }
+  }
+
+  findDayByDay(day: number) {
+    return this.days.find((group) => group.day === day);
+  }
+
  findAssetById(assetDescriptor: AssetDescriptor) {
    for (const asset of this.assetsIterator()) {
      if (asset.id === assetDescriptor.id) {
@@ -365,7 +381,13 @@ export class TimelineMonth extends ScrollSegment {
    return closest;
  }

-  cancel() {
-    this.loader?.cancel();
+  #clearDeferredLayout() {
+    const hasDeferred = this.days.some((group) => group.deferredLayout);
+    if (hasDeferred) {
+      this.updateGeometry({ invalidateHeight: true, noDefer: true });
+      for (const group of this.days) {
+        group.deferredLayout = false;
+      }
+    }
  }
 }
--- a/web/src/lib/managers/timeline-manager/TimelineSearchExtension.svelte.spec.ts
+++ b/web/src/lib/managers/timeline-manager/TimelineSearchExtension.svelte.spec.ts
@@ -0,0 +1,75 @@
+import type { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
+import { findClosestMonthToDate } from '$lib/utils/timeline-util';
+import { describe, expect, it } from 'vitest';
+
+function createMockMonthGroup(year: number, month: number): TimelineMonth {
+  return {
+    yearMonth: { year, month },
+  } as TimelineMonth;
+}
+
+describe('findClosestMonthToDate', () => {
+  it('should return undefined for empty months array', () => {
+    const result = findClosestMonthToDate([], { year: 2024, month: 1 });
+    expect(result).toBeUndefined();
+  });
+
+  it('should return the only month when there is only one month', () => {
+    const months = [createMockMonthGroup(2024, 6)];
+    const result = findClosestMonthToDate(months, { year: 2025, month: 1 });
+    expect(result?.yearMonth).toEqual({ year: 2024, month: 6 });
+  });
+
+  it('should return exact match when available', () => {
+    const months = [createMockMonthGroup(2024, 1), createMockMonthGroup(2024, 6), createMockMonthGroup(2024, 12)];
+    const result = findClosestMonthToDate(months, { year: 2024, month: 6 });
+    expect(result?.yearMonth).toEqual({ year: 2024, month: 6 });
+  });
+
+  it('should find closest month when target is between two months', () => {
+    const months = [createMockMonthGroup(2024, 1), createMockMonthGroup(2024, 6), createMockMonthGroup(2024, 12)];
+    const result = findClosestMonthToDate(months, { year: 2024, month: 4 });
+    expect(result?.yearMonth).toEqual({ year: 2024, month: 6 });
+  });
+
+  it('should handle year boundaries correctly (2023-12 vs 2024-01)', () => {
+    const months = [createMockMonthGroup(2023, 12), createMockMonthGroup(2024, 2)];
+    const result = findClosestMonthToDate(months, { year: 2024, month: 1 });
+    // 2024-01 is 1 month from 2023-12 and 1 month from 2024-02
+    // Should return first encountered with min distance (2023-12)
+    expect(result?.yearMonth).toEqual({ year: 2023, month: 12 });
+  });
+
+  it('should correctly calculate distance across years', () => {
+    const months = [createMockMonthGroup(2022, 6), createMockMonthGroup(2024, 6)];
+    const result = findClosestMonthToDate(months, { year: 2023, month: 6 });
+    // Both are exactly 12 months away, should return first encountered
+    expect(result?.yearMonth).toEqual({ year: 2022, month: 6 });
+  });
+
+  it('should handle target before all months', () => {
+    const months = [createMockMonthGroup(2024, 6), createMockMonthGroup(2024, 12)];
+    const result = findClosestMonthToDate(months, { year: 2024, month: 1 });
+    expect(result?.yearMonth).toEqual({ year: 2024, month: 6 });
+  });
+
+  it('should handle target after all months', () => {
+    const months = [createMockMonthGroup(2024, 1), createMockMonthGroup(2024, 6)];
+    const result = findClosestMonthToDate(months, { year: 2025, month: 1 });
+    expect(result?.yearMonth).toEqual({ year: 2024, month: 6 });
+  });
+
+  it('should handle multiple years correctly', () => {
+    const months = [createMockMonthGroup(2020, 1), createMockMonthGroup(2022, 1), createMockMonthGroup(2024, 1)];
+    const result = findClosestMonthToDate(months, { year: 2023, month: 1 });
+    // 2023-01 is 12 months from 2022-01 and 12 months from 2024-01
+    expect(result?.yearMonth).toEqual({ year: 2022, month: 1 });
+  });
+
+  it('should prefer closer month when one is clearly closer', () => {
+    const months = [createMockMonthGroup(2024, 1), createMockMonthGroup(2024, 10)];
+    const result = findClosestMonthToDate(months, { year: 2024, month: 11 });
+    // 2024-11 is 1 month from 2024-10 and 10 months from 2024-01
+    expect(result?.yearMonth).toEqual({ year: 2024, month: 10 });
+  });
+});
--- a/web/src/lib/managers/timeline-manager/TimelineSearchExtension.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/TimelineSearchExtension.svelte.ts
@@ -0,0 +1,252 @@
+import { authManager } from '$lib/managers/auth-manager.svelte';
+import type { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
+import type { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
+import type { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
+import type { AssetDescriptor, Direction, TimelineAsset } from '$lib/managers/timeline-manager/types';
+import {
+  findClosestMonthToDate,
+  getSegmentIdentifier,
+  plainDateTimeCompare,
+  toTimelineAsset,
+  type TimelineDateTime,
+  type TimelineYearMonth,
+} from '$lib/utils/timeline-util';
+import { AssetOrder, getAssetInfo } from '@immich/sdk';
+
+export class TimelineSearchExtension {
+  #timelineManager: TimelineManager;
+  constructor(timelineManager: TimelineManager) {
+    this.#timelineManager = timelineManager;
+  }
+
+  async getLaterAsset(
+    assetDescriptor: AssetDescriptor,
+    interval: 'asset' | 'day' | 'month' | 'year' = 'asset',
+  ): Promise<TimelineAsset | undefined> {
+    return await this.#getAssetWithOffset(assetDescriptor, interval, 'later');
+  }
+
+  async getEarlierAsset(
+    assetDescriptor: AssetDescriptor,
+    interval: 'asset' | 'day' | 'month' | 'year' = 'asset',
+  ): Promise<TimelineAsset | undefined> {
+    return await this.#getAssetWithOffset(assetDescriptor, interval, 'earlier');
+  }
+
+  async getMonthForAsset(id: string) {
+    if (!this.#timelineManager.isInitialized) {
+      await this.#timelineManager.initTask.waitUntilCompletion();
+    }
+
+    let { month } = this.findMonthForAsset(id) ?? {};
+    if (month) {
+      return month;
+    }
+
+    const response = await getAssetInfo({ ...authManager.params, id }).catch(() => null);
+    if (!response) {
+      return;
+    }
+
+    const asset = toTimelineAsset(response);
+    if (!asset || this.#timelineManager.isExcluded(asset)) {
+      return;
+    }
+
+    month = await this.#loadMonthAtTime(asset.localDateTime, { cancelable: false });
+    if (month?.findAssetById({ id })) {
+      return month;
+    }
+  }
+
+  async #loadMonthAtTime(yearMonth: TimelineYearMonth, options?: { cancelable: boolean }) {
+    await this.#timelineManager.loadSegment(getSegmentIdentifier(yearMonth), options);
+    return this.findMonthByDate(yearMonth);
+  }
+
+  async #getAssetWithOffset(
+    assetDescriptor: AssetDescriptor,
+    interval: 'asset' | 'day' | 'month' | 'year' = 'asset',
+    direction: Direction,
+  ): Promise<TimelineAsset | undefined> {
+    const { asset, month } = this.findMonthForAsset(assetDescriptor.id) ?? {};
+    if (!month || !asset) {
+      return;
+    }
+
+    switch (interval) {
+      case 'asset': {
+        return this.#getAssetByAssetOffset(asset, month, direction);
+      }
+      case 'day': {
+        return this.#getAssetByDayOffset(asset, month, direction);
+      }
+      case 'month': {
+        return this.#getAssetByMonthOffset(month, direction);
+      }
+      case 'year': {
+        return this.#getAssetByYearOffset(month, direction);
+      }
+    }
+  }
+
+  findMonthForAsset(id: string) {
+    for (const month of this.#timelineManager.segments) {
+      const asset = month.findAssetById({ id });
+      if (asset) {
+        return { month, asset };
+      }
+    }
+  }
+
+  findMonthByDate(targetYearMonth: TimelineYearMonth): TimelineMonth | undefined {
+    return this.#timelineManager.segments.find(
+      (month) => month.yearMonth.year === targetYearMonth.year && month.yearMonth.month === targetYearMonth.month,
+    );
+  }
+
+  // note: the `index` input is expected to be in the range [0, assetCount). This
+  // value can be passed to make the method deterministic, which is mainly useful
+  // for testing.
+  async getRandomAsset(index?: number): Promise<TimelineAsset | undefined> {
+    const randomAssetIndex = index ?? Math.floor(Math.random() * this.#timelineManager.assetCount);
+
+    let accumulatedCount = 0;
+
+    let randomMonth: TimelineMonth | undefined = undefined;
+    for (const month of this.#timelineManager.segments) {
+      if (randomAssetIndex < accumulatedCount + month.assetsCount) {
+        randomMonth = month;
+        break;
+      }
+
+      accumulatedCount += month.assetsCount;
+    }
+    if (!randomMonth) {
+      return;
+    }
+    await this.#timelineManager.loadSegment(getSegmentIdentifier(randomMonth.yearMonth), { cancelable: false });
+
+    let randomDay: TimelineDay | undefined = undefined;
+    for (const day of randomMonth.days) {
+      if (randomAssetIndex < accumulatedCount + day.viewerAssets.length) {
+        randomDay = day;
+        break;
+      }
+
+      accumulatedCount += day.viewerAssets.length;
+    }
+    if (!randomDay) {
+      return;
+    }
+
+    return randomDay.viewerAssets[randomAssetIndex - accumulatedCount].asset;
+  }
+
+  async #getAssetByAssetOffset(asset: TimelineAsset, month: TimelineMonth, direction: Direction) {
+    const day = month.findDayForAsset(asset);
+    for await (const targetAsset of this.#timelineManager.assetsIterator({
+      startMonth: month,
+      startDay: day,
+      startAsset: asset,
+      direction,
+    })) {
+      if (asset.id !== targetAsset.id) {
+        return targetAsset;
+      }
+    }
+  }
+
+  async #getAssetByDayOffset(asset: TimelineAsset, month: TimelineMonth, direction: Direction) {
+    const day = month.findDayForAsset(asset);
+    for await (const targetAsset of this.#timelineManager.assetsIterator({
+      startMonth: month,
+      startDay: day,
+      startAsset: asset,
+      direction,
+    })) {
+      if (targetAsset.localDateTime.day !== asset.localDateTime.day) {
+        return targetAsset;
+      }
+    }
+  }
+
+  async #getAssetByMonthOffset(month: TimelineMonth, direction: Direction) {
+    for (const targetMonth of this.#timelineManager.monthIterator({ startMonth: month, direction })) {
+      if (targetMonth.yearMonth.month !== month.yearMonth.month) {
+        const { value, done } = await this.#timelineManager
+          .assetsIterator({ startMonth: targetMonth, direction })
+          .next();
+        return done ? undefined : value;
+      }
+    }
+  }
+
+  async #getAssetByYearOffset(month: TimelineMonth, direction: Direction) {
+    for (const targetMonth of this.#timelineManager.monthIterator({ startMonth: month, direction })) {
+      if (targetMonth.yearMonth.year !== month.yearMonth.year) {
+        const { value, done } = await this.#timelineManager
+          .assetsIterator({ startMonth: targetMonth, direction })
+          .next();
+        return done ? undefined : value;
+      }
+    }
+  }
+
+  async retrieveRange(start: AssetDescriptor, end: AssetDescriptor) {
+    let { asset: startAsset, month: startMonth } = this.findMonthForAsset(start.id) ?? {};
+    if (!startMonth || !startAsset) {
+      return [];
+    }
+    let { asset: endAsset, month: endMonth } = this.findMonthForAsset(end.id) ?? {};
+    if (!endMonth || !endAsset) {
+      return [];
+    }
+    const assetOrder: AssetOrder = this.#timelineManager.getAssetOrder();
+    if (plainDateTimeCompare(assetOrder === AssetOrder.Desc, startAsset.localDateTime, endAsset.localDateTime) < 0) {
+      [startAsset, endAsset] = [endAsset, startAsset];
+      [startMonth, endMonth] = [endMonth, startMonth];
+    }
+
+    const range: TimelineAsset[] = [];
+    const startDay = startMonth.findDayForAsset(startAsset);
+    for await (const targetAsset of this.#timelineManager.assetsIterator({
+      startMonth,
+      startDay,
+      startAsset,
+    })) {
+      range.push(targetAsset);
+      if (targetAsset.id === endAsset.id) {
+        break;
+      }
+    }
+    return range;
+  }
+
+  findMonthForDate(targetYearMonth: TimelineYearMonth) {
+    for (const month of this.#timelineManager.segments) {
+      const { year, month: monthNum } = month.yearMonth;
+      if (monthNum === targetYearMonth.month && year === targetYearMonth.year) {
+        return month;
+      }
+    }
+  }
+
+  async getClosestAssetToDate(dateTime: TimelineDateTime) {
+    let month = this.findMonthForDate(dateTime);
+    if (!month) {
+      month = findClosestMonthToDate(this.#timelineManager.segments, dateTime);
+      if (!month) {
+        return;
+      }
+    }
+    await this.#timelineManager.loadSegment(getSegmentIdentifier(dateTime), { cancelable: false });
+    const asset = month.findClosest(dateTime);
+    if (asset) {
+      return asset;
+    }
+    for await (const asset of this.#timelineManager.assetsIterator({ startMonth: month })) {
+      return asset;
+    }
+  }
+}
--- a/web/src/lib/managers/timeline-manager/TimelineTestHooks.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/TimelineTestHooks.svelte.ts
@@ -0,0 +1,16 @@
+import type { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
+import type { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
+
+export type TestHooks = {
+  onCreateTimelineMonth(month: TimelineMonth): unknown;
+  onCreateTimelineDay(day: TimelineDay): unknown;
+};
+
+let testHooks: TestHooks | undefined = undefined;
+
+export const setTestHooks = (hooks: TestHooks) => {
+  testHooks = hooks;
+};
+
+export const onCreateTimelineMonth = (month: TimelineMonth) => testHooks?.onCreateTimelineMonth(month);
+export const onCreateTimelineDay = (day: TimelineDay) => testHooks?.onCreateTimelineDay(day);
--- a/web/src/lib/managers/timeline-manager/internal/websocket-support.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/internal/websocket-support.svelte.ts
@@ -1,16 +1,13 @@
-import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
+import type { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
 import type { PendingChange, TimelineAsset } from '$lib/managers/timeline-manager/types';
 import { websocketEvents } from '$lib/stores/websocket';
 import { toTimelineAsset } from '$lib/utils/timeline-util';
 import { throttle } from 'lodash-es';
 import type { Unsubscriber } from 'svelte/store';

-export class WebsocketSupport {
-  #pendingChanges: PendingChange[] = [];
-  #unsubscribers: Unsubscriber[] = [];
-  #timelineManager: TimelineManager;
-
-  #processPendingChanges = throttle(() => {
+export class TimelineWebsocketExtension {
+  readonly #timelineManager: TimelineManager;
+  readonly #processPendingChanges = throttle(() => {
    const { add, update, remove } = this.#getPendingChangeBatches();
    if (add.length > 0) {
      this.#timelineManager.upsertAssets(add);
@@ -24,11 +21,26 @@ export class WebsocketSupport {
    this.#pendingChanges = [];
  }, 2500);

+  #pendingChanges: PendingChange[] = [];
+  #unsubscribers: Unsubscriber[] = [];
+  #connected = false;
+
  constructor(timeineManager: TimelineManager) {
    this.#timelineManager = timeineManager;
  }

-  connectWebsocketEvents() {
+  connect() {
+    if (this.#connected) {
+      throw new Error('TimelineManager already connected');
+    }
+    this.#connectWebsocketEvents();
+  }
+
+  disconnect() {
+    this.#disconnectWebsocketEvents();
+  }
+
+  #connectWebsocketEvents() {
    this.#unsubscribers.push(
      websocketEvents.on('on_upload_success', (asset) =>
        this.#addPendingChanges({ type: 'add', values: [toTimelineAsset(asset)] }),
@@ -41,7 +53,7 @@ export class WebsocketSupport {
    );
  }

-  disconnectWebsocketEvents() {
+  #disconnectWebsocketEvents() {
    for (const unsubscribe of this.#unsubscribers) {
      unsubscribe();
    }
--- a/web/src/lib/managers/timeline-manager/internal/TestHooks.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/internal/TestHooks.svelte.ts
@@ -1,16 +0,0 @@
-import { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
-import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
-
-let testHooks: TestHooks | undefined = undefined;
-
-export type TestHooks = {
-  onCreateMonth(month: TimelineMonth): unknown;
-  onCreateDay(day: TimelineDay): unknown;
-};
-
-export const setTestHooks = (hooks: TestHooks) => {
-  testHooks = hooks;
-};
-
-export const onCreateMonth = (month: TimelineMonth) => testHooks?.onCreateMonth(month);
-export const onCreateDay = (day: TimelineDay) => testHooks?.onCreateDay(day);
--- a/web/src/lib/managers/timeline-manager/internal/intersection-support.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/internal/intersection-support.svelte.ts
@@ -1,73 +0,0 @@
-import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
-import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
-import { TUNABLES } from '$lib/utils/tunables';
-
-const {
-  TIMELINE: { INTERSECTION_EXPAND_TOP, INTERSECTION_EXPAND_BOTTOM },
-} = TUNABLES;
-
-export function updateIntersectionMonth(timelineManager: TimelineManager, month: TimelineMonth) {
-  const actuallyIntersecting = calculateMonthIntersecting(timelineManager, month, 0, 0);
-  let preIntersecting = false;
-  if (!actuallyIntersecting) {
-    preIntersecting = calculateMonthIntersecting(
-      timelineManager,
-      month,
-      INTERSECTION_EXPAND_TOP,
-      INTERSECTION_EXPAND_BOTTOM,
-    );
-  }
-  month.intersecting = actuallyIntersecting || preIntersecting;
-  month.actuallyIntersecting = actuallyIntersecting;
-  if (preIntersecting || actuallyIntersecting) {
-    timelineManager.clearDeferredLayout(month);
-  }
-}
-
-/**
- * General function to check if a rectangular region intersects with a window.
- * @param regionTop - Top position of the region to check
- * @param regionBottom - Bottom position of the region to check
- * @param windowTop - Top position of the window
- * @param windowBottom - Bottom position of the window
- * @returns true if the region intersects with the window
- */
-export function isIntersecting(regionTop: number, regionBottom: number, windowTop: number, windowBottom: number) {
-  return (
-    (regionTop >= windowTop && regionTop < windowBottom) ||
-    (regionBottom >= windowTop && regionBottom < windowBottom) ||
-    (regionTop < windowTop && regionBottom >= windowBottom)
-  );
-}
-
-export function calculateMonthIntersecting(
-  timelineManager: TimelineManager,
-  month: TimelineMonth,
-  expandTop: number,
-  expandBottom: number,
-) {
-  const monthTop = month.top;
-  const monthBottom = monthTop + month.height;
-  const topWindow = timelineManager.visibleWindow.top - expandTop;
-  const bottomWindow = timelineManager.visibleWindow.bottom + expandBottom;
-
-  return isIntersecting(monthTop, monthBottom, topWindow, bottomWindow);
-}
-
-/**
- * Calculate intersection for viewer assets with additional parameters like header height
- */
-export function calculateViewerAssetIntersecting(
-  timelineManager: TimelineManager,
-  positionTop: number,
-  positionHeight: number,
-  expandTop: number = INTERSECTION_EXPAND_TOP,
-  expandBottom: number = INTERSECTION_EXPAND_BOTTOM,
-) {
-  const topWindow = timelineManager.visibleWindow.top - timelineManager.headerHeight - expandTop;
-  const bottomWindow = timelineManager.visibleWindow.bottom + timelineManager.headerHeight + expandBottom;
-
-  const positionBottom = positionTop + positionHeight;
-
-  return isIntersecting(positionTop, positionBottom, topWindow, bottomWindow);
-}
--- a/web/src/lib/managers/timeline-manager/internal/layout-support.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/internal/layout-support.svelte.ts
@@ -1,70 +0,0 @@
-import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
-import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
-import type { UpdateGeometryOptions } from '$lib/managers/timeline-manager/types';
-
-export function updateGeometry(timelineManager: TimelineManager, month: TimelineMonth, options: UpdateGeometryOptions) {
-  const { invalidateHeight, noDefer = false } = options;
-  if (invalidateHeight) {
-    month.isHeightActual = false;
-  }
-  if (!month.isLoaded) {
-    const viewportWidth = timelineManager.viewportWidth;
-    if (!month.isHeightActual) {
-      const unwrappedWidth = (3 / 2) * month.assetsCount * timelineManager.rowHeight * (7 / 10);
-      const rows = Math.ceil(unwrappedWidth / viewportWidth);
-      const height = 51 + Math.max(1, rows) * timelineManager.rowHeight;
-      month.height = height;
-    }
-    return;
-  }
-  layoutMonth(timelineManager, month, noDefer);
-}
-
-export function layoutMonth(timelineManager: TimelineManager, month: TimelineMonth, noDefer: boolean = false) {
-  let cumulativeHeight = 0;
-  let cumulativeWidth = 0;
-  let currentRowHeight = 0;
-
-  let dayRow = 0;
-  let dayCol = 0;
-
-  const options = timelineManager.justifiedLayoutOptions;
-  for (const day of month.days) {
-    day.layout(options, noDefer);
-
-    // Calculate space needed for this item (including gap if not first in row)
-    const spaceNeeded = day.width + (dayCol > 0 ? timelineManager.gap : 0);
-    const fitsInCurrentRow = cumulativeWidth + spaceNeeded <= timelineManager.viewportWidth;
-
-    if (fitsInCurrentRow) {
-      day.row = dayRow;
-      day.col = dayCol++;
-      day.left = cumulativeWidth;
-      day.top = cumulativeHeight;
-
-      cumulativeWidth += day.width + timelineManager.gap;
-    } else {
-      // Move to next row
-      cumulativeHeight += currentRowHeight;
-      cumulativeWidth = 0;
-      dayRow++;
-      dayCol = 0;
-
-      // Position at start of new row
-      day.row = dayRow;
-      day.col = dayCol;
-      day.left = 0;
-      day.top = cumulativeHeight;
-
-      dayCol++;
-      cumulativeWidth += day.width + timelineManager.gap;
-    }
-    currentRowHeight = day.height + timelineManager.headerHeight;
-  }
-
-  // Add the height of the final row
-  cumulativeHeight += currentRowHeight;
-
-  month.height = cumulativeHeight;
-  month.isHeightActual = true;
-}
--- a/web/src/lib/managers/timeline-manager/internal/load-support.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/internal/load-support.svelte.ts
@@ -1,57 +0,0 @@
-import { authManager } from '$lib/managers/auth-manager.svelte';
-import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
-import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
-import type { TimelineManagerOptions } from '$lib/managers/timeline-manager/types';
-import { toISOYearMonthUTC } from '$lib/utils/timeline-util';
-import { getTimeBucket } from '@immich/sdk';
-
-export async function loadFromTimeBuckets(
-  timelineManager: TimelineManager,
-  month: TimelineMonth,
-  options: TimelineManagerOptions,
-  signal: AbortSignal,
-): Promise<void> {
-  if (month.getFirstAsset()) {
-    return;
-  }
-
-  const timeBucket = toISOYearMonthUTC(month.yearMonth);
-  const bucketResponse = await getTimeBucket(
-    {
-      ...authManager.params,
-      ...options,
-      timeBucket,
-    },
-    { signal },
-  );
-
-  if (!bucketResponse) {
-    return;
-  }
-
-  if (options.timelineAlbumId) {
-    const albumAssets = await getTimeBucket(
-      {
-        ...authManager.params,
-        albumId: options.timelineAlbumId,
-        timeBucket,
-      },
-      { signal },
-    );
-    for (const id of albumAssets.id) {
-      timelineManager.albumAssets.add(id);
-    }
-  }
-
-  const unprocessedAssets = month.addAssets(bucketResponse, true);
-  if (unprocessedAssets.length > 0) {
-    console.error(
-      `Warning: getTimeBucket API returning assets not in requested month: ${month.yearMonth.month}, ${JSON.stringify(
-        unprocessedAssets.map((unprocessed) => ({
-          id: unprocessed.id,
-          localDateTime: unprocessed.localDateTime,
-        })),
-      )}`,
-    );
-  }
-}
--- a/web/src/lib/managers/timeline-manager/internal/search-support.svelte.spec.ts
+++ b/web/src/lib/managers/timeline-manager/internal/search-support.svelte.spec.ts
@@ -1,75 +0,0 @@
-import { findClosestGroupForDate } from '$lib/managers/timeline-manager/internal/search-support.svelte';
-import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
-import { describe, expect, it } from 'vitest';
-
-function createMockMonth(year: number, month: number): TimelineMonth {
-  return {
-    yearMonth: { year, month },
-  } as TimelineMonth;
-}
-
-describe('findClosestGroupForDate', () => {
-  it('should return undefined for empty months array', () => {
-    const result = findClosestGroupForDate([], { year: 2024, month: 1 });
-    expect(result).toBeUndefined();
-  });
-
-  it('should return the only month when there is only one month', () => {
-    const months = [createMockMonth(2024, 6)];
-    const result = findClosestGroupForDate(months, { year: 2025, month: 1 });
-    expect(result?.yearMonth).toEqual({ year: 2024, month: 6 });
-  });
-
-  it('should return exact match when available', () => {
-    const months = [createMockMonth(2024, 1), createMockMonth(2024, 6), createMockMonth(2024, 12)];
-    const result = findClosestGroupForDate(months, { year: 2024, month: 6 });
-    expect(result?.yearMonth).toEqual({ year: 2024, month: 6 });
-  });
-
-  it('should find closest month when target is between two months', () => {
-    const months = [createMockMonth(2024, 1), createMockMonth(2024, 6), createMockMonth(2024, 12)];
-    const result = findClosestGroupForDate(months, { year: 2024, month: 4 });
-    expect(result?.yearMonth).toEqual({ year: 2024, month: 6 });
-  });
-
-  it('should handle year boundaries correctly (2023-12 vs 2024-01)', () => {
-    const months = [createMockMonth(2023, 12), createMockMonth(2024, 2)];
-    const result = findClosestGroupForDate(months, { year: 2024, month: 1 });
-    // 2024-01 is 1 month from 2023-12 and 1 month from 2024-02
-    // Should return first encountered with min distance (2023-12)
-    expect(result?.yearMonth).toEqual({ year: 2023, month: 12 });
-  });
-
-  it('should correctly calculate distance across years', () => {
-    const months = [createMockMonth(2022, 6), createMockMonth(2024, 6)];
-    const result = findClosestGroupForDate(months, { year: 2023, month: 6 });
-    // Both are exactly 12 months away, should return first encountered
-    expect(result?.yearMonth).toEqual({ year: 2022, month: 6 });
-  });
-
-  it('should handle target before all months', () => {
-    const months = [createMockMonth(2024, 6), createMockMonth(2024, 12)];
-    const result = findClosestGroupForDate(months, { year: 2024, month: 1 });
-    expect(result?.yearMonth).toEqual({ year: 2024, month: 6 });
-  });
-
-  it('should handle target after all months', () => {
-    const months = [createMockMonth(2024, 1), createMockMonth(2024, 6)];
-    const result = findClosestGroupForDate(months, { year: 2025, month: 1 });
-    expect(result?.yearMonth).toEqual({ year: 2024, month: 6 });
-  });
-
-  it('should handle multiple years correctly', () => {
-    const months = [createMockMonth(2020, 1), createMockMonth(2022, 1), createMockMonth(2024, 1)];
-    const result = findClosestGroupForDate(months, { year: 2023, month: 1 });
-    // 2023-01 is 12 months from 2022-01 and 12 months from 2024-01
-    expect(result?.yearMonth).toEqual({ year: 2022, month: 1 });
-  });
-
-  it('should prefer closer month when one is clearly closer', () => {
-    const months = [createMockMonth(2024, 1), createMockMonth(2024, 10)];
-    const result = findClosestGroupForDate(months, { year: 2024, month: 11 });
-    // 2024-11 is 1 month from 2024-10 and 10 months from 2024-01
-    expect(result?.yearMonth).toEqual({ year: 2024, month: 10 });
-  });
-});
--- a/web/src/lib/managers/timeline-manager/internal/search-support.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/internal/search-support.svelte.ts
@@ -1,165 +0,0 @@
-import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
-import { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
-import type { AssetDescriptor, Direction, TimelineAsset } from '$lib/managers/timeline-manager/types';
-import { plainDateTimeCompare, type TimelineYearMonth } from '$lib/utils/timeline-util';
-import { AssetOrder } from '@immich/sdk';
-import { DateTime } from 'luxon';
-
-export async function getAssetWithOffset(
-  timelineManager: TimelineManager,
-  assetDescriptor: AssetDescriptor,
-  interval: 'asset' | 'day' | 'month' | 'year' = 'asset',
-  direction: Direction,
-): Promise<TimelineAsset | undefined> {
-  const { asset, month } = findMonthForAsset(timelineManager, assetDescriptor.id) ?? {};
-  if (!month || !asset) {
-    return;
-  }
-
-  switch (interval) {
-    case 'asset': {
-      return getAssetByAssetOffset(timelineManager, asset, month, direction);
-    }
-    case 'day': {
-      return getAssetByDayOffset(timelineManager, asset, month, direction);
-    }
-    case 'month': {
-      return getAssetByMonthOffset(timelineManager, month, direction);
-    }
-    case 'year': {
-      return getAssetByYearOffset(timelineManager, month, direction);
-    }
-  }
-}
-
-export function findMonthForAsset(timelineManager: TimelineManager, id: string) {
-  for (const month of timelineManager.months) {
-    const asset = month.findAssetById({ id });
-    if (asset) {
-      return { month, asset };
-    }
-  }
-}
-
-export function getMonthByDate(
-  timelineManager: TimelineManager,
-  targetYearMonth: TimelineYearMonth,
-): TimelineMonth | undefined {
-  return timelineManager.months.find(
-    (month) => month.yearMonth.year === targetYearMonth.year && month.yearMonth.month === targetYearMonth.month,
-  );
-}
-
-async function getAssetByAssetOffset(
-  timelineManager: TimelineManager,
-  asset: TimelineAsset,
-  month: TimelineMonth,
-  direction: Direction,
-) {
-  const day = month.findDayForAsset(asset);
-  for await (const targetAsset of timelineManager.assetsIterator({
-    startMonth: month,
-    startDay: day,
-    startAsset: asset,
-    direction,
-  })) {
-    if (asset.id !== targetAsset.id) {
-      return targetAsset;
-    }
-  }
-}
-
-async function getAssetByDayOffset(
-  timelineManager: TimelineManager,
-  asset: TimelineAsset,
-  month: TimelineMonth,
-  direction: Direction,
-) {
-  const day = month.findDayForAsset(asset);
-  for await (const targetAsset of timelineManager.assetsIterator({
-    startMonth: month,
-    startDay: day,
-    startAsset: asset,
-    direction,
-  })) {
-    if (targetAsset.localDateTime.day !== asset.localDateTime.day) {
-      return targetAsset;
-    }
-  }
-}
-
-async function getAssetByMonthOffset(timelineManager: TimelineManager, month: TimelineMonth, direction: Direction) {
-  for (const targetMonth of timelineManager.monthIterator({ startMonth: month, direction })) {
-    if (targetMonth.yearMonth.month !== month.yearMonth.month) {
-      const { value, done } = await timelineManager.assetsIterator({ startMonth: targetMonth, direction }).next();
-      return done ? undefined : value;
-    }
-  }
-}
-
-async function getAssetByYearOffset(timelineManager: TimelineManager, month: TimelineMonth, direction: Direction) {
-  for (const targetMonth of timelineManager.monthIterator({ startMonth: month, direction })) {
-    if (targetMonth.yearMonth.year !== month.yearMonth.year) {
-      const { value, done } = await timelineManager.assetsIterator({ startMonth: targetMonth, direction }).next();
-      return done ? undefined : value;
-    }
-  }
-}
-
-export async function retrieveRange(timelineManager: TimelineManager, start: AssetDescriptor, end: AssetDescriptor) {
-  let { asset: startAsset, month: startMonth } = findMonthForAsset(timelineManager, start.id) ?? {};
-  if (!startMonth || !startAsset) {
-    return [];
-  }
-  let { asset: endAsset, month: endMonth } = findMonthForAsset(timelineManager, end.id) ?? {};
-  if (!endMonth || !endAsset) {
-    return [];
-  }
-  const assetOrder: AssetOrder = timelineManager.getAssetOrder();
-  if (plainDateTimeCompare(assetOrder === AssetOrder.Desc, startAsset.localDateTime, endAsset.localDateTime) < 0) {
-    [startAsset, endAsset] = [endAsset, startAsset];
-    [startMonth, endMonth] = [endMonth, startMonth];
-  }
-
-  const range: TimelineAsset[] = [];
-  const startDay = startMonth.findDayForAsset(startAsset);
-  for await (const targetAsset of timelineManager.assetsIterator({
-    startMonth,
-    startDay,
-    startAsset,
-  })) {
-    range.push(targetAsset);
-    if (targetAsset.id === endAsset.id) {
-      break;
-    }
-  }
-  return range;
-}
-
-export function findMonthForDate(timelineManager: TimelineManager, targetYearMonth: TimelineYearMonth) {
-  for (const month of timelineManager.months) {
-    const { year, month: monthNum } = month.yearMonth;
-    if (monthNum === targetYearMonth.month && year === targetYearMonth.year) {
-      return month;
-    }
-  }
-}
-
-export function findClosestGroupForDate(months: TimelineMonth[], targetYearMonth: TimelineYearMonth) {
-  const targetDate = DateTime.fromObject({ year: targetYearMonth.year, month: targetYearMonth.month });
-
-  let closestMonth: TimelineMonth | undefined;
-  let minDifference = Number.MAX_SAFE_INTEGER;
-
-  for (const month of months) {
-    const monthDate = DateTime.fromObject({ year: month.yearMonth.year, month: month.yearMonth.month });
-    const totalDiff = Math.abs(monthDate.diff(targetDate, 'months').months);
-
-    if (totalDiff < minDifference) {
-      minDifference = totalDiff;
-      closestMonth = month;
-    }
-  }
-
-  return closestMonth;
-}
--- a/web/src/lib/managers/timeline-manager/internal/utils.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/internal/utils.svelte.ts
@@ -1,28 +0,0 @@
-// eslint-disable-next-line @typescript-eslint/no-explicit-any
-export function updateObject(target: any, source: any): boolean {
-  if (!target) {
-    return false;
-  }
-  let updated = false;
-  for (const key in source) {
-    if (!Object.prototype.hasOwnProperty.call(source, key)) {
-      continue;
-    }
-    if (key === '__proto__' || key === 'constructor') {
-      continue;
-    }
-    const isDate = target[key] instanceof Date;
-    if (typeof target[key] === 'object' && !isDate) {
-      updated = updated || updateObject(target[key], source[key]);
-    } else {
-      if (target[key] !== source[key]) {
-        target[key] = source[key];
-        updated = true;
-      }
-    }
-  }
-  return updated;
-}
-export function isMismatched<T>(option: T | undefined, value: T): boolean {
-  return option === undefined ? false : option !== value;
-}
--- a/web/src/lib/managers/timeline-manager/utils.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/utils.svelte.ts
@@ -1,4 +1,59 @@
-import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
+import type { TimelineAsset } from './types';

 export const assetSnapshot = (asset: TimelineAsset): TimelineAsset => $state.snapshot(asset);
 export const assetsSnapshot = (assets: TimelineAsset[]) => assets.map((asset) => $state.snapshot(asset));
+
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export function updateObject(target: any, source: any): boolean {
+  if (!target) {
+    return false;
+  }
+  let updated = false;
+  for (const key in source) {
+    if (!Object.prototype.hasOwnProperty.call(source, key)) {
+      continue;
+    }
+    if (key === '__proto__' || key === 'constructor') {
+      continue;
+    }
+    const isDate = target[key] instanceof Date;
+    if (typeof target[key] === 'object' && !isDate) {
+      updated = updated || updateObject(target[key], source[key]);
+    } else {
+      if (target[key] !== source[key]) {
+        target[key] = source[key];
+        updated = true;
+      }
+    }
+  }
+  return updated;
+}
+export function isMismatched<T>(option: T | undefined, value: T): boolean {
+  return option === undefined ? false : option !== value;
+}
+
+export function setDifference<T>(setA: Set<T>, setB: Set<T>): Set<T> {
+  // Check if native Set.prototype.difference is available (ES2025)
+  const setWithDifference = setA as unknown as Set<T> & { difference?: (other: Set<T>) => Set<T> };
+  if (setWithDifference.difference && typeof setWithDifference.difference === 'function') {
+    return setWithDifference.difference(setB);
+  }
+  // eslint-disable-next-line svelte/prefer-svelte-reactivity
+  const result = new Set<T>();
+  for (const value of setA) {
+    if (!setB.has(value)) {
+      result.add(value);
+    }
+  }
+  return result;
+}
+
+/**
+ * Removes all elements of setB from setA in-place (mutates setA).
+ */
+export function setDifferenceInPlace<T>(setA: Set<T>, setB: Set<T>): Set<T> {
+  for (const value of setB) {
+    setA.delete(value);
+  }
+  return setA;
+}
--- a/web/src/lib/managers/timeline-manager/viewer-asset.svelte.ts
+++ b/web/src/lib/managers/timeline-manager/viewer-asset.svelte.ts
@@ -1,7 +1,14 @@
-import { calculateViewerAssetIntersecting } from '$lib/managers/timeline-manager/internal/intersection-support.svelte';
-import { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
+import type { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
 import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
+import { isIntersecting } from '$lib/managers/VirtualScrollManager/ScrollSegment.svelte';
+import type { VirtualScrollManager } from '$lib/managers/VirtualScrollManager/VirtualScrollManager.svelte';
+
 import type { CommonPosition } from '$lib/utils/layout-utils';
+import { TUNABLES } from '$lib/utils/tunables';
+
+const {
+  TIMELINE: { INTERSECTION_EXPAND_TOP, INTERSECTION_EXPAND_BOTTOM },
+} = TUNABLES;

 export class ViewerAsset {
  readonly #day: TimelineDay;
@@ -11,10 +18,10 @@ export class ViewerAsset {
      return false;
    }

-    const store = this.#day.month.timelineManager;
-    const positionTop = this.#day.absoluteTop + this.position.top;
+    const scrollManager = this.#day.month.scrollManager;
+    const positionTop = this.#day.topAbsolute + this.position.top;

-    return calculateViewerAssetIntersecting(store, positionTop, this.position.height);
+    return calculateViewerAssetIntersecting(scrollManager, positionTop, this.position.height);
  });

  position: CommonPosition | undefined = $state.raw();
@@ -26,3 +33,19 @@ export class ViewerAsset {
    this.asset = asset;
  }
 }
+
+/**
+ * Calculate intersection for viewer assets with additional parameters like header height
+ */
+function calculateViewerAssetIntersecting(
+  scrollManager: VirtualScrollManager,
+  positionTop: number,
+  positionHeight: number,
+  expandTop: number = INTERSECTION_EXPAND_TOP,
+  expandBottom: number = INTERSECTION_EXPAND_BOTTOM,
+) {
+  const topWindow = scrollManager.visibleWindow.top - scrollManager.headerHeight - expandTop;
+  const bottomWindow = scrollManager.visibleWindow.bottom + scrollManager.headerHeight + expandBottom;
+  const positionBottom = positionTop + positionHeight;
+  return isIntersecting(positionTop, positionBottom, topWindow, bottomWindow);
+}
--- a/web/src/lib/modals/NavigateToDateModal.svelte
+++ b/web/src/lib/modals/NavigateToDateModal.svelte
@@ -1,6 +1,6 @@
 <script lang="ts">
  import DateInput from '$lib/elements/DateInput.svelte';
-  import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
+  import type { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
  import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
  import { getPreferredTimeZone, getTimezones, toDatetime, type ZoneOption } from '$lib/modals/timezone-utils';
  import { Button, HStack, Modal, ModalBody, ModalFooter, VStack } from '@immich/ui';
@@ -28,7 +28,7 @@

    // Get the local date/time components from the selected string using neutral timezone
    const dateTime = toDatetime(selectedDate, selectedOption) as DateTime<true>;
-    const asset = await timelineManager.getClosestAssetToDate(dateTime.toObject());
+    const asset = await timelineManager.search.getClosestAssetToDate(dateTime.toObject());
    onClose(asset);
  };

--- a/web/src/lib/utils/asset-utils.ts
+++ b/web/src/lib/utils/asset-utils.ts
@@ -3,7 +3,7 @@ import ToastAction from '$lib/components/ToastAction.svelte';
 import { AppRoute } from '$lib/constants';
 import { authManager } from '$lib/managers/auth-manager.svelte';
 import { downloadManager } from '$lib/managers/download-manager.svelte';
-import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
+import type { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
 import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
 import { assetsSnapshot } from '$lib/managers/timeline-manager/utils.svelte';
 import type { AssetInteraction } from '$lib/stores/asset-interaction.svelte';
@@ -14,6 +14,7 @@ import { getByteUnitString } from '$lib/utils/byte-units';
 import { getFormatter } from '$lib/utils/i18n';
 import { navigate } from '$lib/utils/navigation';
 import { asQueryString } from '$lib/utils/shared-links';
+import { getSegmentIdentifier } from '$lib/utils/timeline-util';
 import {
  addAssetsToAlbum as addAssets,
  addAssetsToAlbums as addToAlbums,
@@ -490,16 +491,16 @@ export const selectAllAssets = async (timelineManager: TimelineManager, assetInt
  isSelectingAllAssets.set(true);

  try {
-    for (const month of timelineManager.months) {
-      await timelineManager.loadMonth(month.yearMonth);
+    for (const monthGroup of timelineManager.segments) {
+      await timelineManager.loadSegment(getSegmentIdentifier(monthGroup.yearMonth));

      if (!get(isSelectingAllAssets)) {
        assetInteraction.clearMultiselect();
        break; // Cancelled
      }
-      assetInteraction.selectAssets(assetsSnapshot([...month.assetsIterator()]));
+      assetInteraction.selectAssets(assetsSnapshot([...monthGroup.assetsIterator()]));

-      for (const dateGroup of month.days) {
+      for (const dateGroup of monthGroup.days) {
        assetInteraction.addGroupToMultiselectGroup(dateGroup.dayTitle);
      }
    }
--- a/web/src/lib/utils/cancellable-task.ts
+++ b/web/src/lib/utils/cancellable-task.ts
@@ -1,3 +1,10 @@
+export enum TaskStatus {
+  DONE,
+  WAITED,
+  CANCELED,
+  LOADED,
+  ERRORED,
+}
 export class CancellableTask {
  cancelToken: AbortController | null = null;
  cancellable: boolean = true;
@@ -32,18 +39,18 @@ export class CancellableTask {

  async waitUntilCompletion() {
    if (this.executed) {
-      return 'DONE';
+      return TaskStatus.DONE;
    }
    // if there is a cancel token, task is currently executing, so wait on the promise. If it
    // isn't, then  the task is in new state, it hasn't been loaded, nor has it been executed.
    // in either case, we wait on the promise.
    await this.complete;
-    return 'WAITED';
+    return TaskStatus.WAITED;
  }

  async execute<F extends (abortSignal: AbortSignal) => Promise<void>>(f: F, cancellable: boolean) {
    if (this.executed) {
-      return 'DONE';
+      return TaskStatus.DONE;
    }

    // if promise is pending, wait on previous request instead.
@@ -54,7 +61,7 @@ export class CancellableTask {
        this.cancellable = cancellable;
      }
      await this.complete;
-      return 'WAITED';
+      return TaskStatus.WAITED;
    }
    this.cancellable = cancellable;
    const cancelToken = (this.cancelToken = new AbortController());
@@ -62,18 +69,18 @@ export class CancellableTask {
    try {
      await f(cancelToken.signal);
      if (cancelToken.signal.aborted) {
-        return 'CANCELED';
+        return TaskStatus.CANCELED;
      }
      this.#transitionToExecuted();
-      return 'LOADED';
+      return TaskStatus.LOADED;
    } catch (error) {
      // eslint-disable-next-line  @typescript-eslint/no-explicit-any
      if ((error as any).name === 'AbortError') {
        // abort error is not treated as an error, but as a cancellation.
-        return 'CANCELED';
+        return TaskStatus.CANCELED;
      }
      this.#transitionToErrored(error);
-      return 'ERRORED';
+      return TaskStatus.ERRORED;
    } finally {
      this.cancelToken = null;
    }
--- a/web/src/lib/utils/timeline-util.spec.ts
+++ b/web/src/lib/utils/timeline-util.spec.ts
@@ -1,9 +1,9 @@
 import { locale } from '$lib/stores/preferences.store';
 import { parseUtcDate } from '$lib/utils/date-time';
-import { formatDayTitle, toISOYearMonthUTC } from '$lib/utils/timeline-util';
+import { formatGroupTitle, toISOYearMonthUTC } from '$lib/utils/timeline-util';
 import { DateTime } from 'luxon';

-describe('formatDayTitle', () => {
+describe('formatGroupTitle', () => {
  beforeAll(() => {
    vi.useFakeTimers();
    process.env.TZ = 'UTC';
@@ -18,63 +18,63 @@ describe('formatDayTitle', () => {
  it('formats today', () => {
    const date = parseUtcDate('2024-07-27T01:00:00Z');
    locale.set('en');
-    expect(formatDayTitle(date)).toBe('today');
+    expect(formatGroupTitle(date)).toBe('today');
    locale.set('es');
-    expect(formatDayTitle(date)).toBe('hoy');
+    expect(formatGroupTitle(date)).toBe('hoy');
  });

  it('formats yesterday', () => {
    const date = parseUtcDate('2024-07-26T23:59:59Z');
    locale.set('en');
-    expect(formatDayTitle(date)).toBe('yesterday');
+    expect(formatGroupTitle(date)).toBe('yesterday');
    locale.set('fr');
-    expect(formatDayTitle(date)).toBe('hier');
+    expect(formatGroupTitle(date)).toBe('hier');
  });

  it('formats last week', () => {
    const date = parseUtcDate('2024-07-21T00:00:00Z');
    locale.set('en');
-    expect(formatDayTitle(date)).toBe('Sunday');
+    expect(formatGroupTitle(date)).toBe('Sunday');
    locale.set('ar-SA');
-    expect(formatDayTitle(date)).toBe('الأحد');
+    expect(formatGroupTitle(date)).toBe('الأحد');
  });

  it('formats date 7 days ago', () => {
    const date = parseUtcDate('2024-07-20T00:00:00Z');
    locale.set('en');
-    expect(formatDayTitle(date)).toBe('Sat, Jul 20');
+    expect(formatGroupTitle(date)).toBe('Sat, Jul 20');
    locale.set('de');
-    expect(formatDayTitle(date)).toBe('Sa., 20. Juli');
+    expect(formatGroupTitle(date)).toBe('Sa., 20. Juli');
  });

  it('formats date this year', () => {
    const date = parseUtcDate('2020-01-01T00:00:00Z');
    locale.set('en');
-    expect(formatDayTitle(date)).toBe('Wed, Jan 1, 2020');
+    expect(formatGroupTitle(date)).toBe('Wed, Jan 1, 2020');
    locale.set('ja');
-    expect(formatDayTitle(date)).toBe('2020年1月1日(水)');
+    expect(formatGroupTitle(date)).toBe('2020年1月1日(水)');
  });

  it('formats future date', () => {
    const tomorrow = parseUtcDate('2024-07-28T00:00:00Z');
    locale.set('en');
-    expect(formatDayTitle(tomorrow)).toBe('Sun, Jul 28');
+    expect(formatGroupTitle(tomorrow)).toBe('Sun, Jul 28');

    const nextMonth = parseUtcDate('2024-08-28T00:00:00Z');
    locale.set('en');
-    expect(formatDayTitle(nextMonth)).toBe('Wed, Aug 28');
+    expect(formatGroupTitle(nextMonth)).toBe('Wed, Aug 28');

    const nextYear = parseUtcDate('2025-01-10T12:00:00Z');
    locale.set('en');
-    expect(formatDayTitle(nextYear)).toBe('Fri, Jan 10, 2025');
+    expect(formatGroupTitle(nextYear)).toBe('Fri, Jan 10, 2025');
  });

  it('returns "Invalid DateTime" when date is invalid', () => {
    const date = DateTime.invalid('test');
    locale.set('en');
-    expect(formatDayTitle(date)).toBe('Invalid DateTime');
+    expect(formatGroupTitle(date)).toBe('Invalid DateTime');
    locale.set('es');
-    expect(formatDayTitle(date)).toBe('Invalid DateTime');
+    expect(formatGroupTitle(date)).toBe('Invalid DateTime');
  });
 });

--- a/web/src/lib/utils/timeline-util.ts
+++ b/web/src/lib/utils/timeline-util.ts
@@ -1,4 +1,6 @@
+import type { TimelineMonth } from '$lib/managers/timeline-manager/TimelineMonth.svelte';
 import type { TimelineAsset, ViewportTopMonth } from '$lib/managers/timeline-manager/types';
+import type { ScrollSegment, SegmentIdentifier } from '$lib/managers/VirtualScrollManager/ScrollSegment.svelte';
 import { locale } from '$lib/stores/preferences.store';
 import { getAssetRatio } from '$lib/utils/asset-utils';
 import { AssetTypeEnum, type AssetResponseDto } from '@immich/sdk';
@@ -99,7 +101,7 @@ export const toISOYearMonthUTC = ({ year, month }: TimelineYearMonth): string =>
  return `${yearFull}-${monthFull}-01T00:00:00.000Z`;
 };

-export function formatMonthTitle(_date: DateTime): string {
+export function formatMonthGroupTitle(_date: DateTime): string {
  if (!_date.isValid) {
    return _date.toString();
  }
@@ -113,7 +115,7 @@ export function formatMonthTitle(_date: DateTime): string {
  );
 }

-export function formatDayTitle(_date: DateTime): string {
+export function formatGroupTitle(_date: DateTime): string {
  if (!_date.isValid) {
    return _date.toString();
  }
@@ -221,27 +223,47 @@ export const plainDateTimeCompare = (ascending: boolean, a: TimelineDateTime, b:
  return aDateTime.millisecond - bDateTime.millisecond;
 };

-export function setDifference<T>(setA: Set<T>, setB: Set<T>): Set<T> {
-  // Check if native Set.prototype.difference is available (ES2025)
-  const setWithDifference = setA as unknown as Set<T> & { difference?: (other: Set<T>) => Set<T> };
-  if (setWithDifference.difference && typeof setWithDifference.difference === 'function') {
-    return setWithDifference.difference(setB);
+export const formatGroupTitleFull = (_date: DateTime): string => {
+  if (!_date.isValid) {
+    return _date.toString();
  }
-  const result = new Set<T>();
-  for (const value of setA) {
-    if (!setB.has(value)) {
-      result.add(value);
-    }
-  }
-  return result;
-}
+  const date = _date as DateTime<true>;
+  return getDateLocaleString(date);
+};

 /**
- * Removes all elements of setB from setA in-place (mutates setA).
+ * Creates a segment identifier for a given year/month or date/time.
+ * This is used to uniquely identify and match timeline segments (MonthGroups).
 */
-export function setDifferenceInPlace<T>(setA: Set<T>, setB: Set<T>): Set<T> {
-  for (const value of setB) {
-    setA.delete(value);
+export const getSegmentIdentifier = (yearMonth: TimelineYearMonth | TimelineDateTime): SegmentIdentifier => ({
+  get id() {
+    return yearMonth.year + '-' + yearMonth.month;
+  },
+  matches: (segment: ScrollSegment) => {
+    const monthSegment = segment as TimelineMonth;
+    return (
+      monthSegment.yearMonth &&
+      monthSegment.yearMonth.year === yearMonth.year &&
+      monthSegment.yearMonth.month === yearMonth.month
+    );
+  },
+});
+
+export const findClosestMonthToDate = (months: TimelineMonth[], targetYearMonth: TimelineYearMonth) => {
+  const targetDate = DateTime.fromObject({ year: targetYearMonth.year, month: targetYearMonth.month });
+
+  let closestMonth: TimelineMonth | undefined;
+  let minDifference = Number.MAX_SAFE_INTEGER;
+
+  for (const month of months) {
+    const monthDate = DateTime.fromObject({ year: month.yearMonth.year, month: month.yearMonth.month });
+    const totalDiff = Math.abs(monthDate.diff(targetDate, 'months').months);
+
+    if (totalDiff < minDifference) {
+      minDifference = totalDiff;
+      closestMonth = month;
+    }
  }
-  return setA;
-}
+
+  return closestMonth;
+};
--- a/web/src/routes/(user)/albums/[albumId=id]/[[photos=photos]]/[[assetId=id]]/+page.svelte
+++ b/web/src/routes/(user)/albums/[albumId=id]/[[photos=photos]]/[[assetId=id]]/+page.svelte
@@ -140,8 +140,8 @@
  const handleStartSlideshow = async () => {
    const asset =
      $slideshowNavigation === SlideshowNavigation.Shuffle
-        ? await timelineManager.getRandomAsset()
-        : timelineManager.months[0]?.days[0]?.viewerAssets[0]?.asset;
+        ? await timelineManager.search.getRandomAsset()
+        : timelineManager.getFirstAsset();
    if (asset) {
      handlePromiseError(setAssetId(asset.id).then(() => ($slideshowState = SlideshowState.PlaySlideshow)));
    }
--- a/web/src/routes/(user)/utilities/geolocation/+page.svelte
+++ b/web/src/routes/(user)/utilities/geolocation/+page.svelte
@@ -5,7 +5,7 @@
  import Timeline from '$lib/components/timeline/Timeline.svelte';
  import { AssetAction } from '$lib/constants';
  import { authManager } from '$lib/managers/auth-manager.svelte';
-  import { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
+  import type { TimelineDay } from '$lib/managers/timeline-manager/TimelineDay.svelte';
  import { TimelineManager } from '$lib/managers/timeline-manager/TimelineManager.svelte';
  import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
  import GeolocationUpdateConfirmModal from '$lib/modals/GeolocationUpdateConfirmModal.svelte';
@@ -117,7 +117,7 @@
    onClick: (
      timelineManager: TimelineManager,
      assets: TimelineAsset[],
-      dayTitle: string,
+      groupTitle: string,
      asset: TimelineAsset,
    ) => void,
  ) => {
Author	SHA1	Message	Date
midzelis	12a59f8c68	Push up operations to VirtualScrollManager	2025-11-02 19:50:55 +00:00
midzelis	de84e46f62	push top level functions from timelinemanager into extensions	2025-11-02 19:44:41 +00:00
midzelis	6d3dda7e2e	Relocate/rename internal timeline functions to follow TimelineExtensions pattern	2025-11-02 19:44:41 +00:00
midzelis	4ca76b24e9	refactor: extract scrollsegment keeper	2025-11-02 16:59:57 +00:00