feat(web): hero view transitions between timeline and asset viewer

Change-Id: I19e0c7385cc38adbc85177ae9706cff06a6a6964

fix(web): fix e2e test failures for view transitions

Change-Id: Ida64f2d509efce0a85a50b89fd4137276a6a6964
Change-Id: I19e0c7385cc38adbc85177ae9706cff06a6a6964

e2e/src/ui/specs/timeline/utils.ts

@@ -143,8 +143,9 @@ export const timelineUtils = {
     return page.locator('#asset-grid');
   },
   async waitForTimelineLoad(page: Page) {
-    await expect(timelineUtils.locator(page)).toBeInViewport();
+    await page.locator('#asset-grid[data-initialized]').waitFor();
     await expect.poll(() => thumbnailUtils.locator(page).count()).toBeGreaterThan(0);
+    await page.locator('#virtual-timeline:not(.invisible)').waitFor();
   },
   async getScrollTop(page: Page) {
     const queryTop = () =>
@@ -163,14 +164,17 @@ export const assetViewerUtils = {
     return page.locator('#immich-asset-viewer');
   },
   async waitForViewerLoad(page: Page, asset: TimelineAssetConfig) {
-    await page
-      .locator(
-        `img[draggable="false"][src="/api/assets/${asset.id}/thumbnail?size=preview&c=${asset.thumbhash}&edited=true"]`,
-      )
-      .or(
-        page.locator(`video[poster="/api/assets/${asset.id}/thumbnail?size=preview&c=${asset.thumbhash}&edited=true"]`),
-      )
-      .waitFor();
+    const imgLocator = page.locator(`[data-viewer-content] img[data-testid="preview"][src*="${asset.id}"]`);
+    const videoLocator = page.locator(`[data-viewer-content] video[poster*="${asset.id}"]`);
+    await imgLocator.or(videoLocator).waitFor();
+
+    if ((await videoLocator.count()) === 0) {
+      await expect
+        .poll(() => imgLocator.evaluate((img: HTMLImageElement) => img.complete && img.naturalWidth > 0))
+        .toBe(true);
+    }
+
+    await expect(page.locator('#immich-asset-viewer')).not.toHaveAttribute('data-navigating');
   },
   async expectActiveAssetToBe(page: Page, assetId: string) {
     const activeElement = () =>

package-lock.json

@@ -0,0 +1,15 @@
+{
+  "name": "immich-monorepo",
+  "version": "2.7.5",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "immich-monorepo",
+      "version": "2.7.5",
+      "engines": {
+        "pnpm": ">=10.0.0"
+      }
+    }
+  }
+}

web/src/app.css

@@ -75,6 +75,11 @@
     --immich-dark-bg: 10 10 10;
     --immich-dark-fg: 229 231 235;
     --immich-dark-gray: 33 33 33;
+
+    /* view transition variables */
+    --vt-duration-default: 250ms;
+    --vt-duration-hero: 280ms;
+    --vt-memory-easing: cubic-bezier(0.2, 0, 0, 1);
   }
 
   button:not(:disabled),
@@ -175,3 +180,173 @@
     @apply bg-subtle rounded-lg;
   }
 }
+
+@layer base {
+  ::view-transition {
+    background: var(--color-black);
+    animation-duration: var(--vt-duration-default);
+  }
+
+  ::view-transition-old(*),
+  ::view-transition-new(*) {
+    mix-blend-mode: normal;
+    animation-duration: inherit;
+  }
+
+  ::view-transition-old(*) {
+    animation-name: fadeOut;
+    animation-fill-mode: forwards;
+  }
+  ::view-transition-new(*) {
+    animation-name: fadeIn;
+    animation-fill-mode: forwards;
+  }
+
+  ::view-transition-old(root) {
+    animation: var(--vt-duration-default) 0s fadeOut forwards;
+  }
+  ::view-transition-new(root) {
+    animation: var(--vt-duration-default) 0s fadeIn forwards;
+  }
+
+  ::view-transition-image-pair(info) {
+    isolation: auto;
+  }
+  ::view-transition-old(info) {
+    animation: var(--vt-duration-default) 0s panelSlideOutRight forwards;
+  }
+  ::view-transition-new(info) {
+    animation: var(--vt-duration-default) 0s panelSlideInRight forwards;
+  }
+
+  html[dir='rtl']::view-transition-old(info) {
+    animation: var(--vt-duration-default) 0s panelSlideOutLeft forwards;
+  }
+  html[dir='rtl']::view-transition-new(info) {
+    animation: var(--vt-duration-default) 0s panelSlideInLeft forwards;
+  }
+
+  ::view-transition-group(exclude-previousbutton),
+  ::view-transition-group(exclude-nextbutton),
+  ::view-transition-group(exclude) {
+    animation: none;
+    z-index: 5;
+  }
+  ::view-transition-old(exclude-previousbutton),
+  ::view-transition-old(exclude-nextbutton),
+  ::view-transition-old(exclude) {
+    visibility: hidden;
+  }
+  ::view-transition-new(exclude-previousbutton),
+  ::view-transition-new(exclude-nextbutton),
+  ::view-transition-new(exclude) {
+    animation: none;
+    z-index: 5;
+  }
+
+  ::view-transition-group(hero) {
+    animation-duration: var(--vt-duration-hero);
+    animation-timing-function: var(--vt-memory-easing);
+  }
+  ::view-transition-old(hero) {
+    animation: none;
+    display: none;
+  }
+  ::view-transition-new(hero) {
+    animation: none;
+    align-content: center;
+  }
+
+  @keyframes panelSlideInRight {
+    from {
+      transform: translateX(100%);
+    }
+    to {
+      transform: translateX(0);
+    }
+  }
+
+  @keyframes panelSlideOutRight {
+    from {
+      transform: translateX(0);
+    }
+    to {
+      transform: translateX(100%);
+    }
+  }
+
+  @keyframes panelSlideInLeft {
+    from {
+      transform: translateX(-100%);
+    }
+    to {
+      transform: translateX(0);
+    }
+  }
+
+  @keyframes panelSlideOutLeft {
+    from {
+      transform: translateX(0);
+    }
+    to {
+      transform: translateX(-100%);
+    }
+  }
+
+  @keyframes fadeIn {
+    from {
+      opacity: 0;
+    }
+    50% {
+      opacity: 0.85;
+    }
+    to {
+      opacity: 1;
+    }
+  }
+  @keyframes fadeOut {
+    from {
+      opacity: 1;
+    }
+    50% {
+      opacity: 0.85;
+    }
+    to {
+      opacity: 0;
+    }
+  }
+
+  @media (prefers-reduced-motion: reduce) {
+    ::view-transition-group(hero) {
+      animation-name: none;
+    }
+
+    ::view-transition-old(hero) {
+      animation: none;
+      display: none;
+    }
+
+    ::view-transition-new(hero) {
+      animation: none;
+    }
+
+    html:active-view-transition-type(viewer) {
+      &::view-transition-old(hero) {
+        animation: none;
+        display: none;
+      }
+      &::view-transition-new(hero) {
+        animation: var(--vt-duration-default) 0s fadeIn forwards;
+      }
+    }
+
+    html:active-view-transition-type(timeline) {
+      &::view-transition-old(hero) {
+        animation: var(--vt-duration-default) 0s fadeOut forwards;
+      }
+      &::view-transition-new(hero) {
+        animation: var(--vt-duration-default) 0s fadeIn forwards;
+      }
+    }
+  }
+}

web/src/lib/components/AdaptiveImage.svelte

@@ -18,6 +18,8 @@
     sharedLink?: SharedLinkResponseDto;
     objectFit?: 'contain' | 'cover';
     container: Size;
+    imageClass?: string;
+    transitionName?: string;
     onUrlChange?: (url: string) => void;
     onImageReady?: () => void;
     onError?: () => void;
@@ -35,6 +37,8 @@
     sharedLink,
     objectFit = 'contain',
     container,
+    imageClass,
+    transitionName,
     onUrlChange,
     onImageReady,
     onError,
@@ -152,11 +156,12 @@
   {@render backdrop?.()}
 
   <div
-    class="absolute inset-0 pointer-events-none"
+    class={['absolute inset-0 pointer-events-none', imageClass]}
     style:inset-inline-start={insetInlineStart}
     style:top
     style:width
     style:height
+    style:view-transition-name={transitionName ?? assetViewerManager.transitionName}
   >
     {#if show.alphaBackground}
       <AlphaBackground />

web/src/lib/components/asset-viewer/AssetViewer.svelte

@@ -13,6 +13,7 @@
   import { authManager } from '$lib/managers/auth-manager.svelte';
   import { editManager, EditToolType } from '$lib/managers/edit/edit-manager.svelte';
   import { eventManager } from '$lib/managers/event-manager.svelte';
+  import { viewTransitionManager } from '$lib/managers/ViewTransitionManager.svelte';
   import { getAssetActions } from '$lib/services/asset.service';
   import { ocrManager } from '$lib/stores/ocr.svelte';
   import { alwaysLoadOriginalVideo } from '$lib/stores/preferences.store';
@@ -37,7 +38,7 @@
   import { onDestroy, onMount, untrack } from 'svelte';
   import type { SwipeCustomEvent } from 'svelte-gestures';
   import { t } from 'svelte-i18n';
-  import { fly } from 'svelte/transition';
+  import { slide } from 'svelte/transition';
   import Thumbnail from '../assets/thumbnail/Thumbnail.svelte';
   import ActivityStatus from './ActivityStatus.svelte';
   import ActivityViewer from './ActivityViewer.svelte';
@@ -146,8 +147,45 @@
     }
   };
 
+  let detailPanelTransitionName = $state<string | undefined>();
+  let navigationBarTransitionName = $state<string | undefined>();
+  let previousButtonTransitionName = $state<string | undefined>();
+  let nextButtonTransitionName = $state<string | undefined>();
+
+  const activateViewTransitionNames = () => {
+    detailPanelTransitionName = 'info';
+    assetViewerManager.transitionName = 'hero';
+  };
+
   onMount(() => {
     syncAssetViewerOpenClass(true);
+
+    const unsubAssetViewerEvents = assetViewerManager.on({
+      ViewerOpenTransition: activateViewTransitionNames,
+      ViewerCloseTransition: activateViewTransitionNames,
+    });
+    const unsubViewTransitionEvents = viewTransitionManager.on({
+      PrepareOldSnapshot: (types) => {
+        if (types.includes('timeline')) {
+          navigationBarTransitionName = 'exclude';
+          previousButtonTransitionName = 'exclude-previousbutton';
+          nextButtonTransitionName = 'exclude-nextbutton';
+        }
+      },
+      PrepareNewSnapshot: (types) => {
+        const isViewer = types.includes('viewer');
+        navigationBarTransitionName = isViewer ? 'exclude' : undefined;
+        previousButtonTransitionName = isViewer ? 'exclude-previousbutton' : undefined;
+        nextButtonTransitionName = isViewer ? 'exclude-nextbutton' : undefined;
+      },
+      Finished: () => {
+        navigationBarTransitionName = undefined;
+        previousButtonTransitionName = undefined;
+        nextButtonTransitionName = undefined;
+        assetViewerManager.transitionName = undefined;
+        detailPanelTransitionName = undefined;
+      },
+    });
     const slideshowStateUnsubscribe = slideshowState.subscribe((value) => {
       if (value === SlideshowState.PlaySlideshow) {
         slideshowHistory.reset();
@@ -166,6 +204,8 @@
     });
 
     return () => {
+      unsubAssetViewerEvents();
+      unsubViewTransitionEvents();
       slideshowStateUnsubscribe();
       slideshowNavigationUnsubscribe();
     };
@@ -192,6 +232,7 @@
   };
 
   const tracker = new InvocationTracker();
+  let navigating = $state(false);
   const navigateAsset = (order?: 'previous' | 'next') => {
     if (!order) {
       if ($slideshowState === SlideshowState.PlaySlideshow) {
@@ -207,7 +248,8 @@
       return;
     }
 
-    void tracker.invoke(async () => {
+    navigating = true;
+    const navigation = tracker.invoke(async () => {
       const isShuffle =
         $slideshowState === SlideshowState.PlaySlideshow && $slideshowNavigation === SlideshowNavigation.Shuffle;
 
@@ -244,6 +286,7 @@
 
       await handleStopSlideshow();
     }, $t('error_while_navigating'));
+    void navigation.finally(() => (navigating = false));
   };
 
   /**
@@ -457,13 +500,17 @@
 
 <section
   id="immich-asset-viewer"
-  class="fixed start-0 top-0 grid size-full grid-cols-4 grid-rows-[64px_1fr] overflow-hidden bg-black"
+  class="fixed inset-s-0 top-0 z-10 grid size-full grid-cols-4 grid-rows-[64px_1fr] overflow-hidden bg-black"
+  data-navigating={navigating || undefined}
   use:focusTrap
   bind:this={assetViewerHtmlElement}
 >
   <!-- Top navigation bar -->
   {#if $slideshowState === SlideshowState.None && !assetViewerManager.isShowEditor}
-    <div class="col-span-4 col-start-1 row-span-1 row-start-1 transition-transform">
+    <div
+      class="col-span-4 col-start-1 row-span-1 row-start-1 transition-transform"
+      style:view-transition-name={navigationBarTransitionName}
+    >
       <AssetViewerNavBar
         {asset}
         {album}
@@ -496,7 +543,11 @@
   {/if}
 
   {#if $slideshowState === SlideshowState.None && showNavigation && !assetViewerManager.isShowEditor && !assetViewerManager.isFaceEditMode && previousAsset}
-    <div class="my-auto col-span-1 col-start-1 row-span-full row-start-1 justify-self-start">
+    <div
+      data-test-id="previous-asset"
+      class="my-auto col-span-1 col-start-1 row-span-full row-start-1 justify-self-start"
+      style:view-transition-name={previousButtonTransitionName}
+    >
       <PreviousAssetAction onPreviousAsset={() => navigateAsset('previous')} />
     </div>
   {/if}
@@ -569,19 +620,24 @@
   </div>
 
   {#if $slideshowState === SlideshowState.None && showNavigation && !assetViewerManager.isShowEditor && !assetViewerManager.isFaceEditMode && nextAsset}
-    <div class="my-auto col-span-1 col-start-4 row-span-full row-start-1 justify-self-end">
+    <div
+      data-test-id="next-asset"
+      class="my-auto col-span-1 col-start-4 row-span-full row-start-1 justify-self-end"
+      style:view-transition-name={nextButtonTransitionName}
+    >
       <NextAssetAction onNextAsset={() => navigateAsset('next')} />
     </div>
   {/if}
 
   {#if showDetailPanel || assetViewerManager.isShowEditor}
     <div
-      transition:fly={{ duration: 150 }}
+      transition:slide={{ axis: 'x', duration: 150 }}
       id="detail-panel"
       class={[
         'row-start-1 row-span-4 overflow-y-auto transition-all dark:border-l dark:border-s-immich-dark-gray bg-light',
         showDetailPanel ? 'w-90' : 'w-100',
       ]}
+      style:view-transition-name={detailPanelTransitionName}
       translate="yes"
     >
       {#if showDetailPanel}
@@ -630,7 +686,7 @@
 
   {#if isShared && album && assetViewerManager.isShowActivityPanel && authManager.authenticated}
     <div
-      transition:fly={{ duration: 150 }}
+      transition:slide={{ axis: 'x', duration: 150 }}
       id="activity-panel"
       class="row-start-1 row-span-5 w-90 md:w-115 overflow-y-auto transition-all dark:border-l dark:border-s-immich-dark-gray"
       translate="yes"

web/src/lib/components/asset-viewer/ImagePanoramaViewer.svelte

@@ -4,7 +4,6 @@
   import { AssetMediaSize, viewAsset, type AssetResponseDto } from '@immich/sdk';
   import { LoadingSpinner } from '@immich/ui';
   import { t } from 'svelte-i18n';
-  import { fade } from 'svelte/transition';
 
   type Props = {
     asset: AssetResponseDto;
@@ -20,7 +19,7 @@
   };
 </script>
 
-<div transition:fade={{ duration: 150 }} class="flex h-full select-none place-content-center place-items-center">
+<div class="flex h-dvh w-dvw select-none place-content-center place-items-center">
   {#await Promise.all([loadAssetData(assetId), import('./PhotoSphereViewerAdapter.svelte')])}
     <LoadingSpinner />
   {:then [data, { default: PhotoSphereViewer }]}

web/src/lib/components/asset-viewer/PhotoSphereViewerAdapter.svelte

@@ -211,6 +211,7 @@
       zoomSpeed: 0.5,
       fisheye: false,
     });
+    viewer.addEventListener('ready', () => assetViewerManager.emit('ViewerOpenTransitionReady'), { once: true });
     const resolutionPlugin = viewer.getPlugin<ResolutionPlugin>(ResolutionPlugin);
     const zoomHandler = ({ zoomLevel }: events.ZoomUpdatedEvent) => {
       // zoomLevel is 0-100
@@ -255,7 +256,12 @@
 <AssetViewerEvents {onZoom} />
 
 <svelte:document use:shortcuts={[{ shortcut: { key: 'z' }, onShortcut: onZoom, preventDefault: true }]} />
-<div class="h-full w-full mb-0" bind:this={container}></div>
+<div
+  id="sphere"
+  class="h-dvh w-dvw mb-0"
+  bind:this={container}
+  style:view-transition-name={assetViewerManager.transitionName}
+></div>
 
 <style>
   /* Reset the default tooltip styling */

web/src/lib/components/asset-viewer/PhotoViewer.svelte

@@ -28,12 +28,11 @@
     cursor: AssetCursor;
     element?: HTMLDivElement;
     sharedLink?: SharedLinkResponseDto;
-    onReady?: () => void;
     onError?: () => void;
     onSwipe?: (event: SwipeCustomEvent) => void;
   };
 
-  let { cursor, element = $bindable(), sharedLink, onReady, onError, onSwipe }: Props = $props();
+  let { cursor, element = $bindable(), sharedLink, onError, onSwipe }: Props = $props();
 
   const { slideshowState, slideshowLook } = slideshowStore;
   const asset = $derived(cursor.current);
@@ -231,11 +230,11 @@
     {onUrlChange}
     onImageReady={() => {
       visibleImageReady = true;
-      onReady?.();
+      assetViewerManager.emit('ViewerOpenTransitionReady');
     }}
     onError={() => {
       onError?.();
-      onReady?.();
+      assetViewerManager.emit('ViewerOpenTransitionReady');
     }}
     bind:imgRef={assetViewerManager.imgRef}
     bind:ref={adaptiveImage}

web/src/lib/components/asset-viewer/VideoNativeViewer.svelte

@@ -146,7 +146,9 @@
         controls
         disablePictureInPicture
         class="h-full object-contain"
+        style:view-transition-name={assetViewerManager.transitionName}
         {...useSwipe(onSwipe)}
+        onloadedmetadata={() => assetViewerManager.emit('ViewerOpenTransitionReady')}
         oncanplay={(e) => handleCanPlay(e.currentTarget)}
         onended={onVideoEnded}
         onvolumechange={(e) => ($videoViewerMuted = e.currentTarget.muted)}

web/src/lib/components/asset-viewer/VideoPanoramaViewer.svelte

@@ -3,7 +3,6 @@
   import type { AssetResponseDto } from '@immich/sdk';
   import { LoadingSpinner } from '@immich/ui';
   import { t } from 'svelte-i18n';
-  import { fade } from 'svelte/transition';
 
   interface Props {
     asset: AssetResponseDto;
@@ -19,7 +18,7 @@
   ]);
 </script>
 
-<div transition:fade={{ duration: 150 }} class="flex h-full select-none place-content-center place-items-center">
+<div class="flex h-full select-none place-content-center place-items-center">
   {#await modules}
     <LoadingSpinner />
   {:then [PhotoSphereViewer, adapter, videoPlugin]}

web/src/lib/components/asset-viewer/editor/transform-tool/CropArea.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+  import { assetViewerManager } from '$lib/managers/asset-viewer-manager.svelte';
   import { ResizeBoundary, transformManager } from '$lib/managers/edit/transform-manager.svelte';
   import { getAssetMediaUrl } from '$lib/utils';
   import { getAltText } from '$lib/utils/thumbnail-util';
@@ -74,6 +75,8 @@
       alt={$getAltText(toTimelineAsset(asset))}
       class="h-full select-none transition-transform motion-reduce:transition-none"
       style:transform={imageTransform}
+      onload={() => assetViewerManager.emit('ViewerOpenTransitionReady')}
+      onerror={() => assetViewerManager.emit('ViewerOpenTransitionReady')}
     />
     <div
       class={[

web/src/lib/components/layouts/UserPageLayout.svelte

@@ -7,6 +7,8 @@
   import NavigationBar from '$lib/components/shared-components/navigation-bar/NavigationBar.svelte';
   import UserSidebar from '$lib/components/shared-components/side-bar/UserSidebar.svelte';
   import type { HeaderButtonActionItem } from '$lib/types';
+  import { page } from '$app/state';
+  import { isAssetViewerRoute } from '$lib/utils/navigation';
   import { openFileUploadDialog } from '$lib/utils/file-uploader';
   import { Button, ContextMenuButton, HStack, isMenuItemType, type MenuItemType } from '@immich/ui';
   import type { Snippet } from 'svelte';
@@ -48,7 +50,7 @@
 
 <header>
   {#if !hideNavbar}
-    <NavigationBar onUploadClick={() => openFileUploadDialog()} />
+    <NavigationBar hidden={isAssetViewerRoute(page)} onUploadClick={() => openFileUploadDialog()} />
   {/if}
 </header>
 <div
@@ -64,7 +66,7 @@
     <UserSidebar />
   {/if}
 
-  <main class="relative">
+  <main class="relative w-full">
     <div class="{scrollbarClass} absolute {hasTitleClass} w-full overflow-y-auto p-2" use:useActions={use}>
       {@render children?.()}
     </div>

web/src/lib/components/shared-components/navigation-bar/NavigationBar.svelte

@@ -10,6 +10,7 @@
   import SkipLink from '$lib/elements/SkipLink.svelte';
   import { authManager } from '$lib/managers/auth-manager.svelte';
   import { featureFlagsManager } from '$lib/managers/feature-flags-manager.svelte';
+  import { viewTransitionManager } from '$lib/managers/ViewTransitionManager.svelte';
   import { Route } from '$lib/route';
   import { getGlobalActions } from '$lib/services/app.service';
   import { mediaQueryManager } from '$lib/stores/media-query-manager.svelte';
@@ -27,21 +28,35 @@
     onUploadClick?: () => void;
     // TODO: remove once this is only used in <AppShellHeader>
     noBorder?: boolean;
+    hidden?: boolean;
   };
 
-  let { onUploadClick, noBorder = false }: Props = $props();
+  let { onUploadClick, noBorder = false, hidden = false }: Props = $props();
 
+  let viewTransitionName = $state<string | undefined>();
   let shouldShowAccountInfoPanel = $state(false);
   let shouldShowNotificationPanel = $state(false);
   let innerWidth: number = $state(0);
   const hasUnreadNotifications = $derived(notificationManager.notifications.length > 0);
 
-  onMount(async () => {
-    try {
-      await notificationManager.refresh();
-    } catch (error) {
+  onMount(() => {
+    notificationManager.refresh().catch((error) => {
       console.error('Failed to load notifications on mount', error);
-    }
+    });
+
+    return viewTransitionManager.on({
+      PrepareOldSnapshot: (types) => {
+        if (types.includes('viewer')) {
+          viewTransitionName = 'exclude';
+        }
+      },
+      PrepareNewSnapshot: (types) => {
+        viewTransitionName = types.includes('timeline') ? 'exclude' : undefined;
+      },
+      Finished: () => {
+        viewTransitionName = undefined;
+      },
+    });
   });
 
   const { Cast } = $derived(getGlobalActions($t));
@@ -49,7 +64,11 @@
 
 <svelte:window bind:innerWidth />
 
-<nav id="dashboard-navbar" class="max-md:h-(--navbar-height-md) h-(--navbar-height) w-dvw text-sm">
+<nav
+  id="dashboard-navbar"
+  class={['max-md:h-(--navbar-height-md) h-(--navbar-height) w-dvw text-sm', hidden && 'invisible']}
+  style:view-transition-name={viewTransitionName}
+>
   <SkipLink text={$t('skip_to_content')} />
   <div
     class="grid h-full grid-cols-[--spacing(32)_auto] items-center py-2 sidebar:grid-cols-[--spacing(64)_auto] {noBorder

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

@@ -2,7 +2,6 @@
   import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
   import { filterIsInOrNearViewport } from '$lib/managers/timeline-manager/utils.svelte';
   import type { ViewerAsset } from '$lib/managers/timeline-manager/viewer-asset.svelte';
-  import type { VirtualScrollManager } from '$lib/managers/VirtualScrollManager/VirtualScrollManager.svelte';
   import { uploadAssetsStore } from '$lib/stores/upload';
   import type { CommonPosition } from '$lib/utils/layout-utils';
   import type { Snippet } from 'svelte';
@@ -12,10 +11,11 @@
   let { isUploading } = uploadAssetsStore;
 
   type Props = {
+    heroTransitionAssetId?: string | null;
+    suspendTransitions?: boolean;
     viewerAssets: ViewerAsset[];
     width: number;
     height: number;
-    manager: VirtualScrollManager;
     thumbnail: Snippet<
       [
         {
@@ -27,9 +27,17 @@
     customThumbnailLayout?: Snippet<[asset: TimelineAsset]>;
   };
 
-  const { viewerAssets, width, height, manager, thumbnail, customThumbnailLayout }: Props = $props();
+  const {
+    heroTransitionAssetId,
+    suspendTransitions = false,
+    viewerAssets,
+    width,
+    height,
+    thumbnail,
+    customThumbnailLayout,
+  }: Props = $props();
 
-  const transitionDuration = $derived(manager.suspendTransitions && !$isUploading ? 0 : 150);
+  const transitionDuration = $derived(suspendTransitions && !$isUploading ? 0 : 150);
   const scaleDuration = $derived(transitionDuration === 0 ? 0 : transitionDuration + 100);
 </script>
 
@@ -38,11 +46,13 @@
   {#each filterIsInOrNearViewport(viewerAssets) as viewerAsset (viewerAsset.id)}
     {@const position = viewerAsset.position!}
     {@const asset = viewerAsset.asset!}
+    {@const transitionName = heroTransitionAssetId === asset.id ? 'hero' : undefined}
 
     <!-- note: don't remove data-asset-id - its used by web e2e tests -->
     <div
       data-asset-id={asset.id}
       class="absolute"
+      style:view-transition-name={transitionName}
       style:top={position.top + 'px'}
       style:inset-inline-start={position.left + 'px'}
       style:width={position.width + 'px'}

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

@@ -1,19 +1,23 @@
 <script lang="ts">
+  import { focusAsset } from '$lib/components/timeline/actions/focus-actions';
   import AssetLayout from '$lib/components/timeline/AssetLayout.svelte';
+  import { assetViewerManager } from '$lib/managers/asset-viewer-manager.svelte';
   import type { AssetMultiSelectManager } from '$lib/managers/asset-multi-select-manager.svelte';
+  import { eventManager } from '$lib/managers/event-manager.svelte';
   import { TimelineDay } from '$lib/managers/timeline-manager/timeline-day.svelte';
   import type { TimelineMonth } from '$lib/managers/timeline-manager/timeline-month.svelte';
   import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
   import { assetsSnapshot, filterIsInOrNearViewport } from '$lib/managers/timeline-manager/utils.svelte';
-  import type { VirtualScrollManager } from '$lib/managers/VirtualScrollManager/VirtualScrollManager.svelte';
+  import { viewTransitionManager } from '$lib/managers/ViewTransitionManager.svelte';
   import { uploadAssetsStore } from '$lib/stores/upload';
   import type { CommonPosition } from '$lib/utils/layout-utils';
   import { fromTimelinePlainDate, getDateLocaleString } from '$lib/utils/timeline-util';
   import { Icon } from '@immich/ui';
   import { mdiCheckCircle, mdiCircleOutline } from '@mdi/js';
-  import type { Snippet } from 'svelte';
+  import { onMount, tick, type Snippet } from 'svelte';
 
   type Props = {
+    toViewerHeroAssetId?: string | null;
     thumbnail: Snippet<
       [
         {
@@ -28,16 +32,16 @@
     singleSelect: boolean;
     assetInteraction: AssetMultiSelectManager;
     timelineMonth: TimelineMonth;
-    manager: VirtualScrollManager;
     onTimelineDaySelect: (timelineDay: TimelineDay, assets: TimelineAsset[]) => void;
   };
+
   let {
+    toViewerHeroAssetId,
     thumbnail: thumbnailWithGroup,
     customThumbnailLayout,
     singleSelect,
     assetInteraction,
     timelineMonth,
-    manager,
     onTimelineDaySelect,
   }: Props = $props();
 
@@ -55,6 +59,32 @@
     });
     return getDateLocaleString(date);
   };
+
+  let toTimelineHeroAssetId = $state<string | null>(null);
+  let heroTransitionAssetId = $derived(toTimelineHeroAssetId ?? toViewerHeroAssetId ?? null);
+
+  const handleViewerCloseTransition = ({ id }: { id: string }) => {
+    const asset = timelineMonth.findAssetById({ id });
+    if (!asset) {
+      return;
+    }
+    void viewTransitionManager.startTransition({
+      types: ['timeline'],
+      performUpdate: async () => {
+        assetViewerManager.emit('ViewerCloseTransitionReady');
+        const event = await eventManager.untilNext('TimelineLoaded');
+        toTimelineHeroAssetId = event.id;
+        await tick();
+      },
+      onFinished: () => {
+        toTimelineHeroAssetId = null;
+        focusAsset(asset.id);
+      },
+    });
+  };
+  if (viewTransitionManager.isSupported()) {
+    onMount(() => assetViewerManager.on({ ViewerCloseTransition: handleViewerCloseTransition }));
+  }
 </script>
 
 {#each filterIsInOrNearViewport(timelineMonth.timelineDays) as timelineDay, groupIndex (timelineDay.day)}
@@ -99,7 +129,8 @@
     </div>
 
     <AssetLayout
-      {manager}
+      {heroTransitionAssetId}
+      suspendTransitions={timelineMonth.timelineManager.suspendTransitions}
       viewerAssets={timelineDay.viewerAssets}
       height={timelineDay.height}
       width={timelineDay.width}

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

@@ -11,6 +11,7 @@
   import { fade, fly } from 'svelte/transition';
 
   interface Props {
+    invisible: boolean;
     /** Offset from the top of the timeline (e.g., for headers) */
     timelineTopOffset?: number;
     /** Offset from the bottom of the timeline (e.g., for footers) */
@@ -39,6 +40,7 @@
   }
 
   let {
+    invisible = false,
     timelineTopOffset = 0,
     timelineBottomOffset = 0,
     height = 0,
@@ -509,6 +511,7 @@
   aria-valuemin={toScrollY(0)}
   data-id="scrubber"
   class="absolute end-0 z-1 select-none hover:cursor-row-resize"
+  class:invisible
   style:padding-top={PADDING_TOP + 'px'}
   style:padding-bottom={PADDING_BOTTOM + 'px'}
   style:width

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

@@ -13,6 +13,8 @@
   import Skeleton from '$lib/elements/Skeleton.svelte';
   import type { AssetMultiSelectManager } from '$lib/managers/asset-multi-select-manager.svelte';
   import { assetViewerManager } from '$lib/managers/asset-viewer-manager.svelte';
+  import { eventManager } from '$lib/managers/event-manager.svelte';
+  import { startViewerTransition } from '$lib/utils/transition-utils';
   import type { TimelineDay } from '$lib/managers/timeline-manager/timeline-day.svelte';
   import { isIntersecting } from '$lib/managers/timeline-manager/internal/intersection-support.svelte';
   import type { TimelineMonth } from '$lib/managers/timeline-manager/timeline-month.svelte';
@@ -99,6 +101,7 @@
   // Overall scroll percentage through the entire timeline (0-1)
   let timelineScrollPercent: number = $state(0);
   let scrubberWidth = $state(0);
+  let toViewerHeroAssetId = $state<string | null>(null);
 
   const isEmpty = $derived(timelineManager.isInitialized && timelineManager.months.length === 0);
   const maxMd = $derived(mediaQueryManager.maxMd);
@@ -207,7 +210,7 @@
         timelineManager.viewportWidth = rect.width;
       }
     }
-    const scrollTarget = assetViewerManager.gridScrollTarget?.at;
+    const scrollTarget = getScrollTarget();
     let scrolled = false;
     if (scrollTarget) {
       scrolled = await scrollAndLoadAsset(scrollTarget);
@@ -219,7 +222,7 @@
       await tick();
       focusAsset(scrollTarget);
     }
-    invisible = false;
+    invisible = isAssetViewerRoute(page) ? true : false;
   };
 
   // note: only modified once in afterNavigate()
@@ -237,10 +240,13 @@
     hasNavigatedToOrFromAssetViewer = isNavigatingToAssetViewer !== isNavigatingFromAssetViewer;
   });
 
+  const getScrollTarget = () => {
+    return assetViewerManager.gridScrollTarget?.at ?? page.params.assetId ?? null;
+  };
   // afterNavigate is only called after navigation to a new URL, {complete} will resolve
   // after successful navigation.
   afterNavigate(({ complete }) => {
-    void complete.finally(() => {
+    void complete.finally(async () => {
       const isAssetViewerPage = isAssetViewerRoute(page);
 
       // Set initial load state only once - if initialLoadWasAssetViewer is null, then
@@ -251,6 +257,12 @@
       }
 
       void scrollAfterNavigate();
+      if (!isAssetViewerPage) {
+        const scrollTarget = getScrollTarget();
+        await tick();
+
+        eventManager.emit('TimelineLoaded', { id: scrollTarget });
+      }
     });
   });
 
@@ -258,7 +270,7 @@
   // note: don't throttle, debounch, or otherwise do this function async - it causes flicker
 
   onMount(() => {
-    if (!enableRouting) {
+    if (!enableRouting && !isAssetViewerRoute(page)) {
       invisible = false;
     }
   });
@@ -545,7 +557,7 @@
     assetInteraction.selectAll = timelineManager.assetCount === assetInteraction.assets.length;
   };
 
-  const _onClick = (
+  const defaultThumbnailClick = (
     timelineManager: TimelineManager,
     assets: TimelineAsset[],
     groupTitle: string,
@@ -557,6 +569,25 @@
     }
     void navigate({ targetRoute: 'current', assetId: asset.id });
   };
+
+  const handleThumbnailClick = (asset: TimelineAsset, timelineDay: TimelineDay) => {
+    if (typeof onThumbnailClick === 'function' || isSelectionMode || assetInteraction.selectionActive) {
+      if (typeof onThumbnailClick === 'function') {
+        onThumbnailClick(asset, timelineManager, timelineDay, defaultThumbnailClick);
+      } else {
+        defaultThumbnailClick(timelineManager, timelineDay.getAssets(), timelineDay.groupTitle, asset);
+      }
+      return;
+    }
+
+    const openViewer = () => void navigate({ targetRoute: 'current', assetId: asset.id });
+    startViewerTransition(
+      asset.id,
+      openViewer,
+      (id) => (toViewerHeroAssetId = id),
+      () => (toViewerHeroAssetId = null),
+    );
+  };
 </script>
 
 <svelte:document onkeydown={onKeyDown} onkeyup={onKeyUp} />
@@ -587,6 +618,7 @@
 {#if timelineManager.months.length > 0}
   <Scrubber
     {timelineManager}
+    {invisible}
     height={timelineManager.viewportHeight}
     timelineTopOffset={timelineManager.topSectionHeight}
     timelineBottomOffset={timelineManager.bottomSectionHeight}
@@ -618,6 +650,7 @@
   id="asset-grid"
   class={['scrollbar-hidden h-full overflow-y-auto outline-none', { 'm-0': isEmpty }, { 'ms-0': !isEmpty }]}
   style:margin-inline-end={(usingMobileDevice ? 0 : scrubberWidth) + 'px'}
+  data-initialized={timelineManager.isInitialized || undefined}
   tabindex="-1"
   bind:clientHeight={timelineManager.viewportHeight}
   bind:clientWidth={timelineManager.viewportWidth}
@@ -666,11 +699,11 @@
           style:width="100%"
         >
           <Month
+            {toViewerHeroAssetId}
             {assetInteraction}
             {customThumbnailLayout}
             {singleSelect}
             {timelineMonth}
-            manager={timelineManager}
             onTimelineDaySelect={handleGroupSelect}
           >
             {#snippet thumbnail({ asset, position, timelineDay, groupIndex })}
@@ -684,13 +717,7 @@
                 {asset}
                 {albumUsers}
                 {groupIndex}
-                onClick={(asset) => {
-                  if (typeof onThumbnailClick === 'function') {
-                    onThumbnailClick(asset, timelineManager, timelineDay, _onClick);
-                  } else {
-                    _onClick(timelineManager, timelineDay.getAssets(), timelineDay.groupTitle, asset);
-                  }
-                }}
+                onClick={(asset) => handleThumbnailClick(asset, timelineDay)}
                 onSelect={() => {
                   if (isSelectionMode || assetInteraction.selectionActive) {
                     assetSelectHandler(timelineManager, asset, timelineDay.getAssets(), timelineDay.groupTitle);

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

@@ -5,6 +5,7 @@
   import { assetViewerManager } from '$lib/managers/asset-viewer-manager.svelte';
   import { assetCacheManager } from '$lib/managers/AssetCacheManager.svelte';
   import { authManager } from '$lib/managers/auth-manager.svelte';
+  import { viewTransitionManager } from '$lib/managers/ViewTransitionManager.svelte';
   import { TimelineManager } from '$lib/managers/timeline-manager/timeline-manager.svelte';
   import type { TimelineAsset } from '$lib/managers/timeline-manager/types';
   import { websocketEvents } from '$lib/stores/websocket';
@@ -97,6 +98,12 @@
   };
 
   const handleClose = async (asset: { id: string }) => {
+    if (viewTransitionManager.isSupported()) {
+      const transitionReady = assetViewerManager.untilNext('ViewerCloseTransitionReady');
+      assetViewerManager.emit('ViewerCloseTransition', { id: asset.id });
+      await transitionReady;
+    }
+
     invisible = true;
     assetViewerManager.gridScrollTarget = { at: asset.id };
     await navigate({

web/src/lib/managers/ViewTransitionManager.svelte.spec.ts

@@ -0,0 +1,327 @@
+import { ViewTransitionManager } from '$lib/managers/ViewTransitionManager.svelte';
+
+function mockViewTransition({
+  updateCallbackDone = Promise.resolve(),
+  finished = Promise.resolve(),
+  ready = Promise.resolve(),
+  skipTransition = vi.fn(),
+}: {
+  updateCallbackDone?: Promise<void>;
+  finished?: Promise<void>;
+  ready?: Promise<void>;
+  skipTransition?: ReturnType<typeof vi.fn>;
+} = {}) {
+  // eslint-disable-next-line tscompat/tscompat
+  document.startViewTransition = vi.fn().mockImplementation((arg: unknown) => {
+    const updateFn = typeof arg === 'function' ? arg : (arg as { update: () => Promise<void> }).update;
+    void updateFn();
+    return { updateCallbackDone, finished, ready, skipTransition };
+  });
+}
+
+describe('ViewTransitionManager', () => {
+  let manager: ViewTransitionManager;
+
+  beforeEach(() => {
+    manager = new ViewTransitionManager();
+  });
+
+  afterEach(() => {
+    delete (document as Partial<typeof document> & { startViewTransition?: unknown }).startViewTransition;
+  });
+
+  describe('when View Transition API is not supported', () => {
+    it('should still call performUpdate', async () => {
+      const performUpdate = vi.fn().mockResolvedValue(undefined);
+
+      await manager.startTransition({ performUpdate });
+
+      expect(performUpdate).toHaveBeenCalledOnce();
+    });
+
+    it('should call onFinished after performUpdate', async () => {
+      const callOrder: string[] = [];
+      const performUpdate = vi.fn().mockImplementation(() => {
+        callOrder.push('performUpdate');
+      });
+      const onFinished = vi.fn().mockImplementation(() => {
+        callOrder.push('onFinished');
+      });
+
+      await manager.startTransition({ performUpdate, onFinished });
+
+      expect(onFinished).toHaveBeenCalledOnce();
+      expect(callOrder).toEqual(['performUpdate', 'onFinished']);
+    });
+
+    it('should not call prepareOldSnapshot or prepareNewSnapshot', async () => {
+      const prepareOldSnapshot = vi.fn();
+      const prepareNewSnapshot = vi.fn();
+      const performUpdate = vi.fn().mockResolvedValue(undefined);
+
+      await manager.startTransition({ performUpdate, prepareOldSnapshot, prepareNewSnapshot });
+
+      expect(prepareOldSnapshot).not.toHaveBeenCalled();
+      expect(prepareNewSnapshot).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('when a transition is already active', () => {
+    it('should skip the first transition and run the second', async () => {
+      let resolveFirstUpdate!: () => void;
+      const firstUpdateCallbackDone = new Promise<void>((resolve) => {
+        resolveFirstUpdate = resolve;
+      });
+      const firstFinished = new Promise<void>(() => {});
+      const firstSkipTransition = vi.fn();
+
+      let callCount = 0;
+      // eslint-disable-next-line tscompat/tscompat
+      document.startViewTransition = vi.fn().mockImplementation((arg: unknown) => {
+        callCount++;
+        const updateFn = typeof arg === 'function' ? arg : (arg as { update: () => Promise<void> }).update;
+        void updateFn();
+        if (callCount === 1) {
+          return {
+            updateCallbackDone: firstUpdateCallbackDone,
+            finished: firstFinished,
+            ready: Promise.resolve(),
+            skipTransition: firstSkipTransition,
+          };
+        }
+        return {
+          updateCallbackDone: Promise.resolve(),
+          finished: Promise.resolve(),
+          ready: Promise.resolve(),
+          skipTransition: vi.fn(),
+        };
+      });
+
+      const secondPerformUpdate = vi.fn().mockResolvedValue(undefined);
+
+      const firstPromise = manager.startTransition({
+        performUpdate: async () => {},
+      });
+
+      await new Promise<void>((r) => queueMicrotask(r));
+
+      // While first is active, start a second — should skip the first and proceed
+      await manager.startTransition({ performUpdate: secondPerformUpdate });
+      expect(firstSkipTransition).toHaveBeenCalledOnce();
+      expect(secondPerformUpdate).toHaveBeenCalledOnce();
+
+      resolveFirstUpdate();
+      await firstPromise;
+    });
+  });
+
+  describe('skipTransitions', () => {
+    it('should return false when no transition is active', () => {
+      expect(manager.skipTransitions()).toBe(false);
+    });
+
+    it('should call skipTransition on the active transition and return true', async () => {
+      let resolveFinished!: () => void;
+      const finished = new Promise<void>((resolve) => {
+        resolveFinished = resolve;
+      });
+      let resolveUpdate!: () => void;
+      const updateCallbackDone = new Promise<void>((resolve) => {
+        resolveUpdate = resolve;
+      });
+      const skipTransition = vi.fn();
+
+      mockViewTransition({ updateCallbackDone, finished, skipTransition });
+
+      const promise = manager.startTransition({ performUpdate: async () => {} });
+      await new Promise<void>((r) => queueMicrotask(r));
+
+      const skipped = manager.skipTransitions();
+      expect(skipped).toBe(true);
+      expect(skipTransition).toHaveBeenCalledOnce();
+
+      resolveUpdate();
+      resolveFinished();
+      await promise;
+    });
+
+    it('should allow a new transition after skipping', async () => {
+      let resolveFinished!: () => void;
+      const finished = new Promise<void>((resolve) => {
+        resolveFinished = resolve;
+      });
+      let resolveUpdate!: () => void;
+      const updateCallbackDone = new Promise<void>((resolve) => {
+        resolveUpdate = resolve;
+      });
+
+      mockViewTransition({ updateCallbackDone, finished });
+
+      const promise = manager.startTransition({ performUpdate: async () => {} });
+      await new Promise<void>((r) => queueMicrotask(r));
+
+      manager.skipTransitions();
+      resolveUpdate();
+      resolveFinished();
+      await promise;
+
+      const secondUpdate = vi.fn().mockResolvedValue(undefined);
+      mockViewTransition({ updateCallbackDone: Promise.resolve(), finished: Promise.resolve() });
+
+      await manager.startTransition({ performUpdate: secondUpdate });
+      expect(secondUpdate).toHaveBeenCalledOnce();
+    });
+  });
+
+  describe('error handling', () => {
+    it('should propagate error from performUpdate when API is not supported', async () => {
+      const error = new Error('update failed');
+      const performUpdate = vi.fn().mockRejectedValue(error);
+
+      await expect(manager.startTransition({ performUpdate })).rejects.toThrow('update failed');
+    });
+
+    it('should clean up activeViewTransition when performUpdate throws (API supported)', async () => {
+      const error = new Error('update failed');
+      let resolveFinished!: () => void;
+      const finished = new Promise<void>((resolve) => {
+        resolveFinished = resolve;
+      });
+
+      // eslint-disable-next-line tscompat/tscompat
+      document.startViewTransition = vi.fn().mockImplementation((arg: unknown) => {
+        const updateFn = typeof arg === 'function' ? arg : (arg as { update: () => Promise<void> }).update;
+        const updateCallbackDone = updateFn();
+        return { updateCallbackDone, finished, ready: Promise.resolve(), skipTransition: vi.fn() };
+      });
+
+      await expect(manager.startTransition({ performUpdate: () => Promise.reject(error) })).rejects.toThrow(
+        'update failed',
+      );
+
+      resolveFinished();
+      await new Promise<void>((r) => queueMicrotask(r));
+
+      const secondUpdate = vi.fn().mockResolvedValue(undefined);
+      mockViewTransition();
+
+      await manager.startTransition({ performUpdate: secondUpdate });
+      expect(secondUpdate).toHaveBeenCalledOnce();
+    });
+  });
+
+  describe('fallback path', () => {
+    it('should fall back to function argument when object argument throws', async () => {
+      const performUpdate = vi.fn().mockResolvedValue(undefined);
+      const prepareNewSnapshot = vi.fn();
+      const finished = Promise.resolve();
+      const updateCallbackDone = Promise.resolve();
+
+      let callCount = 0;
+      // eslint-disable-next-line tscompat/tscompat
+      document.startViewTransition = vi.fn().mockImplementation((arg: unknown) => {
+        callCount++;
+        if (callCount === 1 && typeof arg !== 'function') {
+          throw new TypeError('object form not supported');
+        }
+        const updateFn = typeof arg === 'function' ? arg : (arg as { update: () => Promise<void> }).update;
+        void updateFn();
+        return { updateCallbackDone, finished, ready: Promise.resolve(), skipTransition: vi.fn() };
+      });
+
+      await manager.startTransition({ performUpdate, prepareNewSnapshot, types: ['test'] });
+
+      expect(performUpdate).toHaveBeenCalledOnce();
+      expect(prepareNewSnapshot).toHaveBeenCalledOnce();
+      // eslint-disable-next-line tscompat/tscompat
+      expect(document.startViewTransition).toHaveBeenCalledTimes(2);
+    });
+  });
+
+  describe('abort signal', () => {
+    it('should pass an AbortSignal to performUpdate', async () => {
+      const performUpdate = vi.fn().mockResolvedValue(undefined);
+
+      mockViewTransition();
+
+      await manager.startTransition({ performUpdate });
+
+      expect(performUpdate).toHaveBeenCalledWith(expect.any(AbortSignal));
+    });
+
+    it('should abort the signal when transition.ready rejects', async () => {
+      let capturedSignal: AbortSignal | undefined;
+      let resolveUpdate!: () => void;
+      const updateCallbackDone = new Promise<void>((resolve) => {
+        resolveUpdate = resolve;
+      });
+
+      const readyError = new Error('Transition was aborted because of timeout in DOM update');
+
+      mockViewTransition({
+        updateCallbackDone,
+        finished: Promise.reject(readyError),
+        ready: Promise.reject(readyError),
+      });
+
+      const performUpdate = vi.fn().mockImplementation((signal: AbortSignal) => {
+        capturedSignal = signal;
+        return new Promise<void>((resolve) => {
+          signal.addEventListener('abort', () => resolve(), { once: true });
+        });
+      });
+
+      const promise = manager.startTransition({ performUpdate });
+
+      await new Promise<void>((r) => queueMicrotask(r));
+      await new Promise<void>((r) => queueMicrotask(r));
+
+      expect(capturedSignal?.aborted).toBe(true);
+
+      resolveUpdate();
+      await promise;
+    });
+
+    it('should not abort the signal when transition completes normally', async () => {
+      let capturedSignal: AbortSignal | undefined;
+
+      mockViewTransition();
+
+      await manager.startTransition({
+        performUpdate: (signal) => {
+          capturedSignal = signal;
+          return Promise.resolve();
+        },
+      });
+
+      expect(capturedSignal?.aborted).toBe(false);
+    });
+
+    it('should pass a non-aborted signal in the unsupported fallback path', async () => {
+      let capturedSignal: AbortSignal | undefined;
+
+      await manager.startTransition({
+        performUpdate: (signal) => {
+          capturedSignal = signal;
+          return Promise.resolve();
+        },
+      });
+
+      expect(capturedSignal).toBeInstanceOf(AbortSignal);
+      expect(capturedSignal?.aborted).toBe(false);
+    });
+  });
+
+  describe('isSupported', () => {
+    it('should return false when startViewTransition is not in document', () => {
+      expect(manager.isSupported()).toBe(false);
+    });
+
+    it('should return true when startViewTransition is in document', () => {
+      // eslint-disable-next-line tscompat/tscompat
+      document.startViewTransition = vi.fn();
+
+      expect(manager.isSupported()).toBe(true);
+    });
+  });
+});

web/src/lib/managers/ViewTransitionManager.svelte.ts

@@ -0,0 +1,102 @@
+import { tick } from 'svelte';
+import { BaseEventManager } from '$lib/utils/base-event-manager.svelte';
+
+type TransitionEvents = {
+  PrepareOldSnapshot: [string[]];
+  PrepareNewSnapshot: [string[]];
+  Finished: [string[]];
+};
+
+interface TransitionRequest {
+  types?: string[];
+  prepareOldSnapshot?: () => void;
+  performUpdate: (signal: AbortSignal) => Promise<void>;
+  prepareNewSnapshot?: () => void;
+  onFinished?: () => void;
+}
+
+export class ViewTransitionManager extends BaseEventManager<TransitionEvents> {
+  #activeViewTransition: ViewTransition | null = null;
+  #activeOnFinished: (() => void) | undefined = undefined;
+
+  isSupported() {
+    return 'startViewTransition' in document;
+  }
+
+  skipTransitions() {
+    const skipped = !!this.#activeViewTransition;
+    this.#activeViewTransition?.skipTransition();
+    this.#activeViewTransition = null;
+    const onFinished = this.#activeOnFinished;
+    this.#activeOnFinished = undefined;
+    onFinished?.();
+    return skipped;
+  }
+
+  async startTransition({
+    types,
+    prepareOldSnapshot,
+    performUpdate,
+    prepareNewSnapshot,
+    onFinished,
+  }: TransitionRequest) {
+    if (this.#activeViewTransition) {
+      this.skipTransitions();
+    }
+
+    const resolvedTypes = types ?? [];
+
+    if (!this.isSupported()) {
+      await performUpdate(AbortSignal.timeout(10_000));
+      onFinished?.();
+      return;
+    }
+
+    this.emit('PrepareOldSnapshot', resolvedTypes);
+    prepareOldSnapshot?.();
+    await tick();
+
+    const abortController = new AbortController();
+    const update = async () => {
+      await performUpdate(abortController.signal);
+      this.emit('PrepareNewSnapshot', resolvedTypes);
+      prepareNewSnapshot?.();
+      await tick();
+    };
+
+    let transition: ViewTransition;
+    try {
+      // eslint-disable-next-line tscompat/tscompat
+      transition = document.startViewTransition({ update, types });
+    } catch {
+      // Fallback: browsers supporting VT Level 1 but not Level 2 (object form with types) will throw
+      // eslint-disable-next-line tscompat/tscompat
+      transition = document.startViewTransition(update);
+    }
+
+    this.#activeViewTransition = transition;
+    this.#activeOnFinished = onFinished;
+
+    // eslint-disable-next-line tscompat/tscompat
+    void transition.ready.catch((error: unknown) => {
+      abortController.abort(error);
+    });
+
+    // eslint-disable-next-line tscompat/tscompat
+    void transition.finished
+      .catch(() => {})
+      .finally(() => {
+        if (this.#activeViewTransition === transition) {
+          this.#activeViewTransition = null;
+          this.#activeOnFinished = undefined;
+          this.emit('Finished', resolvedTypes);
+          onFinished?.();
+        }
+      });
+
+    // eslint-disable-next-line tscompat/tscompat
+    await transition.updateCallbackDone;
+  }
+}
+
+export const viewTransitionManager = new ViewTransitionManager();

web/src/lib/managers/asset-viewer-manager.svelte.ts

@@ -24,12 +24,17 @@ export type Events = {
   ZoomChange: [ZoomImageWheelState];
   Copy: [];
   FaceEditModeChange: [boolean];
+  ViewerOpenTransitionReady: [];
+  ViewerOpenTransition: [];
+  ViewerCloseTransition: [{ id: string }];
+  ViewerCloseTransitionReady: [];
 };
 
 class AssetViewerManager extends BaseEventManager<Events> {
   #zoomState = $state(createDefaultZoomState());
   #animationFrameId: number | null = null;
 
+  transitionName = $state<string | undefined>();
   imgRef = $state<HTMLImageElement | undefined>();
   imageLoaderStatus = $state<ImageLoaderStatus | undefined>();
   #isImageLoading = $derived.by(() => {

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

@@ -89,6 +89,8 @@ export type Events = {
   ReleaseEvent: [ReleaseEvent];
 
   WebsocketConnect: [];
+
+  TimelineLoaded: [{ id: string | null }];
 };
 
 export const eventManager = new BaseEventManager<Events>();

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

@@ -19,7 +19,7 @@ class LanguageManager {
 
     this.rtl = item.rtl ?? false;
 
-    document.body.setAttribute('dir', item.rtl ? 'rtl' : 'ltr');
+    document.documentElement.setAttribute('dir', item.rtl ? 'rtl' : 'ltr');
 
     eventManager.emit('LanguageChange', item);
   }

web/src/lib/utils/base-event-manager.svelte.ts

@@ -43,6 +43,50 @@ export class BaseEventManager<Events extends EventsBase> {
     };
   }
 
+  private once<T extends keyof Events>(event: T, callback: EventCallback<Events, T>) {
+    const unsubscribe = this.#onEvent(event, (...args: Events[T]) => {
+      unsubscribe();
+      return callback(...args);
+    });
+    return unsubscribe;
+  }
+
+  untilNext<T extends keyof Events>(
+    event: T,
+    { timeoutMs = 10_000, signal }: { timeoutMs?: number; signal?: AbortSignal } = {},
+  ): Promise<Events[T] extends [] ? void : Events[T][0]> {
+    type Result = Events[T] extends [] ? void : Events[T][0];
+    return new Promise<Result>((resolve, reject) => {
+      let settled = false;
+      const settle = () => {
+        if (settled) {
+          return false;
+        }
+        settled = true;
+        unsubscribe();
+        clearTimeout(timer);
+        signal?.removeEventListener('abort', onAbort);
+        return true;
+      };
+      const unsubscribe = this.once(event, (...args: Events[T]) => {
+        if (settle()) {
+          resolve(args[0] as Result);
+        }
+      });
+      const timer = setTimeout(() => {
+        if (settle()) {
+          reject(new Error(`untilNext('${String(event)}') timed out after ${timeoutMs}ms`));
+        }
+      }, timeoutMs);
+      const onAbort = () => {
+        if (settle()) {
+          resolve(undefined as Result);
+        }
+      };
+      signal?.addEventListener('abort', onAbort, { once: true });
+    });
+  }
+
   emit<T extends keyof Events>(event: T, ...params: Events[T]) {
     const listeners = this.getListeners(event);
     for (const listener of listeners) {

web/src/lib/utils/transition-utils.ts

@@ -0,0 +1,25 @@
+import { tick } from 'svelte';
+import { viewTransitionManager } from '$lib/managers/ViewTransitionManager.svelte';
+import { assetViewerManager } from '$lib/managers/asset-viewer-manager.svelte';
+
+export function startViewerTransition(
+  heroAssetId: string,
+  openViewer: () => void,
+  activateHeroAsset: (assetId: string) => void,
+  deactivateHeroAsset: () => void,
+) {
+  void viewTransitionManager.startTransition({
+    types: ['viewer'],
+    prepareOldSnapshot: () => {
+      activateHeroAsset(heroAssetId);
+    },
+    performUpdate: async (signal) => {
+      deactivateHeroAsset();
+      const ready = assetViewerManager.untilNext('ViewerOpenTransitionReady', { signal });
+      openViewer();
+      await ready;
+      assetViewerManager.emit('ViewerOpenTransition');
+      await tick();
+    },
+  });
+}

web/src/routes/(user)/+layout.svelte

@@ -22,7 +22,7 @@
   });
 </script>
 
-<div class:display-none={assetViewerManager.isViewing}>
+<div class:invisible={assetViewerManager.isViewing}>
   {@render children?.()}
 </div>
 <UploadCover />
@@ -31,7 +31,4 @@
   :root {
     overscroll-behavior: none;
   }
-  .display-none {
-    display: none;
-  }
 </style>