fix: back/forward navigation won't reset scroll in timeline

web/src/lib/components/timeline/Photostream.svelte

@@ -1,6 +1,5 @@
 <script lang="ts">
-  import { afterNavigate, beforeNavigate } from '$app/navigation';
-  import { page } from '$app/stores';
+  import { page } from '$app/state';
   import { resizeObserver, type OnResizeCallback } from '$lib/actions/resize-observer';
   import HotModuleReload from '$lib/elements/HotModuleReload.svelte';
   import type { PhotostreamManager } from '$lib/managers/photostream-manager/PhotostreamManager.svelte';
@@ -121,51 +120,41 @@
     return height;
   };
 
-  const assetIsVisible = (assetTop: number): boolean => {
-    if (!element) {
-      return false;
-    }
-
-    const { clientHeight, scrollTop } = element;
-    return assetTop >= scrollTop && assetTop < scrollTop + clientHeight;
-  };
-
-  export const scrollToAssetId = (assetId: string) => {
-    const monthGroup = timelineManager.getSegmentForAssetId(assetId);
+  export const scrollToAssetId = async (assetId: string) => {
+    const monthGroup = await timelineManager.findSegmentForAssetId(assetId);
     if (!monthGroup) {
       return false;
     }
+
     const height = getAssetHeight(assetId, monthGroup);
-
-    // If the asset is already visible, then don't scroll.
-    if (assetIsVisible(height)) {
-      return true;
-    }
-
     scrollTo(height);
     return true;
   };
 
-  const completeNav = () => {
-    const scrollTarget = $gridScrollTarget?.at;
-    let scrolled = false;
-    if (scrollTarget) {
-      scrolled = scrollToAssetId(scrollTarget);
+  export const completeAfterNavigate = async ({ scrollToAssetQueryParam }: { scrollToAssetQueryParam: boolean }) => {
+    if (timelineManager.viewportHeight === 0 || timelineManager.viewportWidth === 0) {
+      // this can happen if you do the following navigation order
+      // /photos?at=<id>, /photos/<id>, http://example.com, browser back, browser back
+      const rect = element?.getBoundingClientRect();
+      if (rect) {
+        timelineManager.viewportHeight = rect.height;
+        timelineManager.viewportWidth = rect.width;
+      }
     }
-    if (!scrolled) {
-      // if the asset is not found, scroll to the top
-      scrollTo(0);
+    if (scrollToAssetQueryParam) {
+      const scrollTarget = $gridScrollTarget?.at;
+      let scrolled = false;
+      if (scrollTarget) {
+        scrolled = await scrollToAssetId(scrollTarget);
+      }
+      if (!scrolled) {
+        // if the asset is not found, scroll to the top
+        scrollTo(0);
+      }
     }
     showSkeleton = false;
   };
 
-  beforeNavigate(() => (timelineManager.suspendTransitions = true));
-
-  afterNavigate((nav) => {
-    const { complete } = nav;
-    complete.then(completeNav, completeNav);
-  });
-
   const updateIsScrolling = () => (timelineManager.scrolling = true);
   // Yes, updateSlideWindow() is called by the onScroll event. However, if you also just scrolled
   // by explicitly invoking element.scrollX functions, there may be a delay with enough time to
@@ -191,11 +180,11 @@
     // this handler will run the navigation/scroll-to-asset handler when hmr is performed,
     // preventing skeleton from showing after hmr
     const finishHmr = () => {
-      const asset = $page.url.searchParams.get('at');
+      const asset = page.url.searchParams.get('at');
       if (asset) {
         $gridScrollTarget = { at: asset };
       }
-      void completeNav();
+      void completeAfterNavigate({ scrollToAssetQueryParam: true });
     };
     const assetGridUpdate = payload.updates.some((update) => update.path.endsWith('Photostream.svelte'));
     if (assetGridUpdate) {

web/src/lib/components/timeline/PhotostreamWithScrubber.svelte

@@ -43,7 +43,7 @@
     enableRouting,
     timelineManager = $bindable(),
 
-    showSkeleton = $bindable(true),
+    showSkeleton = true,
     isShowDeleteConfirmation = $bindable(false),
     segment,
     skeleton,
@@ -160,7 +160,10 @@
     handleScrollTop?.(scrollToTop);
   };
   let baseTimelineViewer: Photostream | undefined = $state();
-  export const scrollToAsset = (asset: TimelineAsset) => baseTimelineViewer?.scrollToAssetId(asset.id) ?? false;
+  export const scrollToAsset = async (asset: TimelineAsset) =>
+    (await baseTimelineViewer?.scrollToAssetId(asset.id)) ?? false;
+  export const completeAfterNavigate = (args: { scrollToAssetQueryParam: boolean }) =>
+    baseTimelineViewer?.completeAfterNavigate(args);
 </script>
 
 <Photostream

web/src/lib/components/timeline/Timeline.svelte

@@ -1,4 +1,6 @@
 <script lang="ts">
+  import { afterNavigate, beforeNavigate } from '$app/navigation';
+  import { page } from '$app/state';
   import Thumbnail from '$lib/components/assets/thumbnail/thumbnail.svelte';
   import MonthSegment from '$lib/components/timeline/MonthSegment.svelte';
   import PhotostreamWithScrubber from '$lib/components/timeline/PhotostreamWithScrubber.svelte';
@@ -14,6 +16,7 @@
   import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
   import type { AssetInteraction } from '$lib/stores/asset-interaction.svelte';
   import { assetViewingStore } from '$lib/stores/asset-viewing.store';
+  import { isAssetViewerRoute, navigate } from '$lib/utils/navigation';
   import { getSegmentIdentifier, getTimes } from '$lib/utils/timeline-util';
   import { type AlbumResponseDto, type PersonResponseDto } from '@immich/sdk';
   import { DateTime } from 'luxon';
@@ -71,11 +74,51 @@
     customThumbnailLayout,
   }: Props = $props();
 
-  let { isViewing: showAssetViewer, asset: viewingAsset } = assetViewingStore;
+  let { isViewing: showAssetViewer, asset: viewingAsset, gridScrollTarget } = assetViewingStore;
 
   let viewer: PhotostreamWithScrubber | undefined = $state();
   let showSkeleton: boolean = $state(true);
 
+  // tri-state boolean
+  let initialLoadWasAssetViewer: boolean | null = null;
+  let hasNavigatedToOrFromAssetViewer: boolean = false;
+  let timelineScrollPositionInitialized = false;
+
+  beforeNavigate(({ from, to }) => {
+    timelineManager.suspendTransitions = true;
+    hasNavigatedToOrFromAssetViewer = isAssetViewerRoute(to) || isAssetViewerRoute(from);
+  });
+
+  const completeAfterNavigate = () => {
+    const assetViewerPage = !!(page.route.id?.endsWith('/[[assetId=id]]') && page.params.assetId);
+    let isInitial = false;
+    // Set initial load state only once
+    if (initialLoadWasAssetViewer === null) {
+      initialLoadWasAssetViewer = assetViewerPage && !hasNavigatedToOrFromAssetViewer;
+      isInitial = true;
+    }
+
+    let scrollToAssetQueryParam = false;
+    if (
+      !timelineScrollPositionInitialized &&
+      ((isInitial && !assetViewerPage) || // Direct timeline load
+        (!isInitial && hasNavigatedToOrFromAssetViewer)) // Navigated from asset viewer
+    ) {
+      scrollToAssetQueryParam = true;
+      timelineScrollPositionInitialized = true;
+    }
+
+    return viewer?.completeAfterNavigate({ scrollToAssetQueryParam });
+  };
+  afterNavigate(({ complete }) => void complete.then(completeAfterNavigate, completeAfterNavigate));
+
+  const onViewerClose = async (asset: { id: string }) => {
+    assetViewingStore.showAssetViewer(false);
+    showSkeleton = true;
+    $gridScrollTarget = { at: asset.id };
+    await navigate({ targetRoute: 'current', assetId: null, assetGridRouteSearchParams: $gridScrollTarget });
+  };
+
   $effect(() => {
     if ($showAssetViewer) {
       const { localDateTime } = getTimes($viewingAsset.fileCreatedAt, DateTime.local().offset / 60);
@@ -85,7 +128,7 @@
 </script>
 
 <TimelineKeyboardActions
-  scrollToAsset={(asset) => viewer?.scrollToAsset(asset) ?? false}
+  scrollToAsset={async (asset) => (await viewer?.scrollToAsset(asset)) ?? Promise.resolve(false)}
   {timelineManager}
   {assetInteraction}
   bind:isShowDeleteConfirmation
@@ -165,6 +208,6 @@
 
 <Portal target="body">
   {#if $showAssetViewer}
-    <TimelineAssetViewer bind:showSkeleton {timelineManager} {removeAction} {withStacked} {isShared} {album} {person} />
+    <TimelineAssetViewer {timelineManager} {removeAction} {withStacked} {isShared} {album} {person} {onViewerClose} />
   {/if}
 </Portal>

web/src/lib/components/timeline/TimelineAssetViewer.svelte

@@ -9,15 +9,16 @@
   import { toTimelineAsset } from '$lib/utils/timeline-util';
   import { getAssetInfo, type AlbumResponseDto, type PersonResponseDto } from '@immich/sdk';
 
-  let { asset: viewingAsset, gridScrollTarget, mutex, preloadAssets } = assetViewingStore;
+  let { asset: viewingAsset, mutex, preloadAssets } = assetViewingStore;
 
   interface Props {
     timelineManager: TimelineManager;
-    showSkeleton: boolean;
+
     withStacked?: boolean;
     isShared?: boolean;
     album?: AlbumResponseDto | null;
     person?: PersonResponseDto | null;
+    onViewerClose?: (asset: { id: string }) => Promise<void>;
 
     removeAction?:
       | AssetAction.UNARCHIVE
@@ -30,12 +31,12 @@
 
   let {
     timelineManager,
-    showSkeleton = $bindable(false),
     removeAction,
     withStacked = false,
     isShared = false,
     album = null,
     person = null,
+    onViewerClose = () => Promise.resolve(void 0),
   }: Props = $props();
 
   const handlePrevious = async () => {
@@ -79,13 +80,6 @@
     }
   };
 
-  const handleClose = async (asset: { id: string }) => {
-    assetViewingStore.showAssetViewer(false);
-    showSkeleton = true;
-    $gridScrollTarget = { at: asset.id };
-    await navigate({ targetRoute: 'current', assetId: null, assetGridRouteSearchParams: $gridScrollTarget });
-  };
-
   const handlePreAction = async (action: Action) => {
     switch (action.type) {
       case removeAction:
@@ -97,7 +91,7 @@
       case AssetAction.SET_VISIBILITY_TIMELINE: {
         // find the next asset to show or close the viewer
         // eslint-disable-next-line @typescript-eslint/no-unused-expressions
-        (await handleNext()) || (await handlePrevious()) || (await handleClose(action.asset));
+        (await handleNext()) || (await handlePrevious()) || (await onViewerClose?.(action.asset));
 
         // delete after find the next one
         timelineManager.removeAssets([action.asset.id]);
@@ -172,6 +166,6 @@
     onPrevious={handlePrevious}
     onNext={handleNext}
     onRandom={handleRandom}
-    onClose={handleClose}
+    onClose={onViewerClose}
   />
 {/await}

web/src/lib/components/timeline/actions/TimelineKeyboardActions.svelte

@@ -7,8 +7,10 @@
     type RelativeResult,
   } from '$lib/components/shared-components/change-date.svelte';
   import {
-    setFocusToAsset as setFocusAssetInit,
-    setFocusTo as setFocusToInit,
+    setFocusToAsset as setFocusAssetUtil,
+    setFocusTo as setFocusToUtil,
+    type FocusDirection,
+    type FocusInterval,
   } from '$lib/components/timeline/actions/focus-actions';
   import { AppRoute } from '$lib/constants';
   import { TimelineManager } from '$lib/managers/timeline-manager/timeline-manager.svelte';
@@ -32,7 +34,7 @@
     assetInteraction: AssetInteraction;
     isShowDeleteConfirmation: boolean;
     onEscape?: () => void;
-    scrollToAsset: (asset: TimelineAsset) => boolean;
+    scrollToAsset: (asset: TimelineAsset) => Promise<boolean>;
   }
 
   let {
@@ -147,8 +149,10 @@
     }
   });
 
-  const setFocusTo = setFocusToInit.bind(undefined, scrollToAsset, timelineManager);
-  const setFocusAsset = setFocusAssetInit.bind(undefined, scrollToAsset);
+  const setFocusTo = (direction: FocusDirection, interval: FocusInterval) =>
+    setFocusToUtil(scrollToAsset, timelineManager, direction, interval);
+
+  const setFocusAsset = (asset: TimelineAsset) => setFocusAssetUtil(scrollToAsset, asset);
 
   let shortcutList = $derived(
     (() => {
@@ -212,7 +216,7 @@
           (DateTime.fromISO(dateString.date) as DateTime<true>).toObject(),
         );
         if (asset) {
-          setFocusAsset(asset);
+          void setFocusAsset(asset);
         }
       }
     }}

web/src/lib/components/timeline/actions/focus-actions.ts

@@ -21,19 +21,26 @@ export const focusPreviousAsset = () =>
 
 const queryHTMLElement = (query: string) => document.querySelector(query) as HTMLElement;
 
-export const setFocusToAsset = (scrollToAsset: (asset: TimelineAsset) => boolean, asset: TimelineAsset) => {
-  const scrolled = scrollToAsset(asset);
+export const setFocusToAsset = async (
+  scrollToAsset: (asset: TimelineAsset) => Promise<boolean>,
+  asset: TimelineAsset,
+) => {
+  const scrolled = await scrollToAsset(asset);
   if (scrolled) {
     const element = queryHTMLElement(`[data-thumbnail-focus-container][data-asset="${asset.id}"]`);
     element?.focus();
   }
 };
 
+export type FocusDirection = 'earlier' | 'later';
+
+export type FocusInterval = 'day' | 'month' | 'year' | 'asset';
+
 export const setFocusTo = async (
-  scrollToAsset: (asset: TimelineAsset) => boolean,
+  scrollToAsset: (asset: TimelineAsset) => Promise<boolean>,
   store: TimelineManager,
-  direction: 'earlier' | 'later',
-  interval: 'day' | 'month' | 'year' | 'asset',
+  direction: FocusDirection,
+  interval: FocusInterval,
 ) => {
   if (tracker.isActive()) {
     // there are unfinished running invocations, so return early
@@ -65,7 +72,10 @@ export const setFocusTo = async (
     return;
   }
 
-  const scrolled = scrollToAsset(asset);
+  const scrolled = await scrollToAsset(asset);
+  if (!invocation.isStillValid()) {
+    return;
+  }
   if (scrolled) {
     await tick();
     if (!invocation.isStillValid()) {

web/src/lib/managers/photostream-manager/PhotostreamManager.svelte.ts

@@ -269,13 +269,14 @@ export abstract class PhotostreamManager {
     return this.months.find((segment) => identifier.matches(segment));
   }
 
-  getSegmentForAssetId(assetId: string) {
+  findSegmentForAssetId(assetId: string): Promise<PhotostreamSegment | undefined> {
     for (const month of this.months) {
       const asset = month.assets.find((asset) => asset.id === assetId);
       if (asset) {
-        return month;
+        return Promise.resolve(month);
       }
     }
+    return Promise.resolve(void 0);
   }
 
   refreshLayout() {

web/src/lib/managers/timeline-manager/timeline-manager.svelte.spec.ts

@@ -1,5 +1,8 @@
 import { sdkMock } from '$lib/__mocks__/sdk.mock';
-import { getMonthGroupByDate } from '$lib/managers/timeline-manager/internal/search-support.svelte';
+import {
+  findMonthGroupForAsset,
+  getMonthGroupByDate,
+} from '$lib/managers/timeline-manager/internal/search-support.svelte';
 import { AbortError } from '$lib/utils';
 import { fromISODateTimeUTCToObject, getSegmentIdentifier } from '$lib/utils/timeline-util';
 import { type AssetResponseDto, type TimeBucketAssetResponseDto } from '@immich/sdk';
@@ -556,10 +559,10 @@ describe('TimelineManager', () => {
       );
       timelineManager.addAssets([assetOne, assetTwo]);
 
-      expect(timelineManager.getMonthGroupByAssetId(assetTwo.id)?.yearMonth.year).toEqual(2024);
-      expect(timelineManager.getMonthGroupByAssetId(assetTwo.id)?.yearMonth.month).toEqual(2);
-      expect(timelineManager.getMonthGroupByAssetId(assetOne.id)?.yearMonth.year).toEqual(2024);
-      expect(timelineManager.getMonthGroupByAssetId(assetOne.id)?.yearMonth.month).toEqual(1);
+      expect(findMonthGroupForAsset(timelineManager, assetTwo.id)?.monthGroup.yearMonth.year).toEqual(2024);
+      expect(findMonthGroupForAsset(timelineManager, assetTwo.id)?.monthGroup.yearMonth.month).toEqual(2);
+      expect(findMonthGroupForAsset(timelineManager, assetOne.id)?.monthGroup.yearMonth.year).toEqual(2024);
+      expect(findMonthGroupForAsset(timelineManager, assetOne.id)?.monthGroup.yearMonth.month).toEqual(1);
     });
 
     it('ignores removed months', () => {
@@ -576,8 +579,8 @@ describe('TimelineManager', () => {
       timelineManager.addAssets([assetOne, assetTwo]);
 
       timelineManager.removeAssets([assetTwo.id]);
-      expect(timelineManager.getMonthGroupByAssetId(assetOne.id)?.yearMonth.year).toEqual(2024);
-      expect(timelineManager.getMonthGroupByAssetId(assetOne.id)?.yearMonth.month).toEqual(1);
+      expect(findMonthGroupForAsset(timelineManager, assetOne.id)?.monthGroup.yearMonth.year).toEqual(2024);
+      expect(findMonthGroupForAsset(timelineManager, assetOne.id)?.monthGroup.yearMonth.month).toEqual(1);
     });
   });
 });

web/src/lib/managers/timeline-manager/timeline-manager.svelte.ts

@@ -187,7 +187,7 @@ export class TimelineManager extends PhotostreamManager {
     addAssetsToMonthGroups(this, [...notUpdated], { order: this.#options.order ?? AssetOrder.Desc });
   }
 
-  async findMonthGroupForAsset(id: string) {
+  async findSegmentForAssetId(id: string) {
     if (!this.isInitialized) {
       await this.initTask.waitUntilCompletion();
     }
@@ -218,11 +218,6 @@ export class TimelineManager extends PhotostreamManager {
     return getMonthGroupByDate(this, yearMonth);
   }
 
-  getMonthGroupByAssetId(assetId: string) {
-    const monthGroupInfo = findMonthGroupForAssetUtil(this, assetId);
-    return monthGroupInfo?.monthGroup;
-  }
-
   async getRandomMonthGroup() {
     const random = Math.floor(Math.random() * this.months.length);
     const month = this.months[random];