fix: update asset video previews for card and list (#8908)

## Summary
Render generated video previews in list items using a real video element (instead of an image element (this caused errors before)) and include a custom play button with dimming per [the designs](https://www.figma.com/design/LVilZgHGk5RwWOkVN6yCEK/Queue-Progress-Modal?node-id=3928-39270&m=dev).

## Changes
- **What**:
  - List item preview path now renders a `video` element when `isVideoPreview` is true.
  - Video list preview uses `preload="metadata"`, `muted`, `playsinline`, and `pointer-events-none` so row click behavior stays unchanged.
  - Kept the custom overlay/play affordance and increased overlay dimming from `bg-black/10` to `bg-black/15`.
  - Updated tests for `AssetsListItem`, `MediaVideoTop`, and `AssetsSidebarListView`.

## Review Focus
- Confirm list item click behavior still opens/selects asset (no inline playback interaction).
- Confirm video list previews now show actual video frame path instead of broken image fallback.

## Limitation
Backend does not currently provide a dedicated poster/thumbnail image for video outputs in the job preview payload. In the frontend today, we can either show a video icon placeholder, or load/render the full video itself to obtain a preview frame.

## Screenshots (if applicable)
<img width="427" height="499" alt="image" src="https://github.com/user-attachments/assets/3f974817-9d73-4fee-9fa5-2f1f68942c06" />
<img width="230" height="92" alt="image" src="https://github.com/user-attachments/assets/1fbfdd6a-72dd-47e2-96bf-8f7eb41c36f2" />

src/components/sidebar/tabs/AssetsSidebarListView.test.ts

@@ -2,8 +2,8 @@ import { mount } from '@vue/test-utils'
 import { defineComponent } from 'vue'
 import { describe, expect, it, vi } from 'vitest'
 
-import type { AssetItem } from '@/platform/assets/schemas/assetSchema'
 import type { OutputStackListItem } from '@/platform/assets/composables/useOutputStacks'
+import type { AssetItem } from '@/platform/assets/schemas/assetSchema'
 
 import AssetsSidebarListView from './AssetsSidebarListView.vue'
 
@@ -72,4 +72,21 @@ describe('AssetsSidebarListView', () => {
 
     expect(wrapper.text()).not.toContain('sideToolbar.generatedAssetsHeader')
   })
+
+  it('marks mp4 assets as video previews', () => {
+    const videoAsset = {
+      ...buildAsset('video-asset', 'clip.mp4'),
+      preview_url: '/api/view/clip.mp4',
+      user_metadata: {}
+    } satisfies AssetItem
+
+    const wrapper = mountListView([buildOutputItem(videoAsset)])
+
+    const listItems = wrapper.findAllComponents({ name: 'AssetsListItem' })
+    const assetListItem = listItems.at(-1)
+
+    expect(assetListItem).toBeDefined()
+    expect(assetListItem?.props('previewUrl')).toBe('/api/view/clip.mp4')
+    expect(assetListItem?.props('isVideoPreview')).toBe(true)
+  })
 })

src/components/sidebar/tabs/AssetsSidebarListView.vue

@@ -34,7 +34,7 @@
             :aria-label="
               t('assetBrowser.ariaLabel.assetCard', {
                 name: item.asset.name,
-                type: getMediaTypeFromFilename(item.asset.name)
+                type: getAssetMediaType(item.asset)
               })
             "
             :class="
@@ -45,9 +45,8 @@
             "
             :preview-url="item.asset.preview_url"
             :preview-alt="item.asset.name"
-            :icon-name="
+            :icon-name="iconForMediaType(getAssetMediaType(item.asset))"
-              iconForMediaType(getMediaTypeFromFilename(item.asset.name))
+            :is-video-preview="isVideoAsset(item.asset)"
-            "
             :primary-text="getAssetPrimaryText(item.asset)"
             :secondary-text="getAssetSecondaryText(item.asset)"
             :stack-count="getStackCount(item.asset)"
@@ -135,6 +134,14 @@ function getAssetPrimaryText(asset: AssetItem): string {
   return truncateFilename(asset.name)
 }
 
+function getAssetMediaType(asset: AssetItem) {
+  return getMediaTypeFromFilename(asset.name)
+}
+
+function isVideoAsset(asset: AssetItem): boolean {
+  return getAssetMediaType(asset) === 'video'
+}
+
 function getAssetSecondaryText(asset: AssetItem): string {
   const metadata = getOutputAssetMetadata(asset.user_metadata)
   if (typeof metadata?.executionTimeInSeconds === 'number') {

src/platform/assets/components/AssetsListItem.stories.ts

@@ -82,6 +82,7 @@ export const GeneratedVideo: Story = {
   args: {
     previewUrl: VIDEO_PREVIEW,
     previewAlt: 'clip-01.mp4',
+    isVideoPreview: true,
     primaryText: 'clip-01.mp4',
     secondaryText: '2m 12s'
   }

src/platform/assets/components/AssetsListItem.test.ts

@@ -0,0 +1,38 @@
+import { mount } from '@vue/test-utils'
+import { describe, expect, it } from 'vitest'
+
+import AssetsListItem from './AssetsListItem.vue'
+
+describe('AssetsListItem', () => {
+  it('renders video element with play overlay for video previews', () => {
+    const wrapper = mount(AssetsListItem, {
+      props: {
+        previewUrl: 'https://example.com/preview.mp4',
+        previewAlt: 'clip.mp4',
+        isVideoPreview: true
+      }
+    })
+
+    const video = wrapper.find('video')
+    expect(video.exists()).toBe(true)
+    expect(video.attributes('src')).toBe('https://example.com/preview.mp4')
+    expect(video.attributes('preload')).toBe('metadata')
+    expect(wrapper.find('img').exists()).toBe(false)
+    expect(wrapper.find('.bg-black\\/15').exists()).toBe(true)
+    expect(wrapper.find('.icon-\\[lucide--play\\]').exists()).toBe(true)
+  })
+
+  it('does not show play overlay for non-video previews', () => {
+    const wrapper = mount(AssetsListItem, {
+      props: {
+        previewUrl: 'https://example.com/preview.jpg',
+        previewAlt: 'image.png',
+        isVideoPreview: false
+      }
+    })
+
+    expect(wrapper.find('img').exists()).toBe(true)
+    expect(wrapper.find('video').exists()).toBe(false)
+    expect(wrapper.find('.icon-\\[lucide--play\\]').exists()).toBe(false)
+  })
+})

src/platform/assets/components/AssetsListItem.vue

@@ -35,12 +35,24 @@
         :icon-class="iconClass"
         :icon-aria-label="iconAriaLabel"
       >
-        <img
+        <div v-if="previewUrl" class="relative size-full">
-          v-if="previewUrl"
+          <template v-if="isVideoPreview">
-          :src="previewUrl"
+            <video
-          :alt="previewAlt"
+              :src="previewUrl"
-          class="size-full object-cover"
+              preload="metadata"
-        />
+              muted
+              playsinline
+              class="pointer-events-none size-full object-cover"
+            />
+            <VideoPlayOverlay size="sm" />
+          </template>
+          <img
+            v-else
+            :src="previewUrl"
+            :alt="previewAlt"
+            class="size-full object-cover"
+          />
+        </div>
         <div v-else class="flex size-full items-center justify-center">
           <i
             aria-hidden="true"
@@ -119,6 +131,8 @@ import { useProgressBarBackground } from '@/composables/useProgressBarBackground
 import Button from '@/components/ui/button/Button.vue'
 import { cn } from '@/utils/tailwindUtil'
 
+import VideoPlayOverlay from './VideoPlayOverlay.vue'
+
 const emit = defineEmits<{
   'stack-toggle': []
 }>()
@@ -130,6 +144,7 @@ const {
   iconAriaLabel,
   iconClass,
   iconWrapperClass,
+  isVideoPreview = false,
   primaryText,
   secondaryText,
   stackCount,
@@ -144,6 +159,7 @@ const {
   iconAriaLabel?: string
   iconClass?: string
   iconWrapperClass?: string
+  isVideoPreview?: boolean
   primaryText?: string
   secondaryText?: string
   stackCount?: number

src/platform/assets/components/MediaVideoTop.test.ts

@@ -0,0 +1,102 @@
+import { mount } from '@vue/test-utils'
+import { describe, expect, it, vi } from 'vitest'
+
+import type { AssetMeta } from '../schemas/mediaAssetSchema'
+import MediaVideoTop from './MediaVideoTop.vue'
+
+function createVideoAsset(
+  src: string,
+  mimeType: AssetMeta['mime_type'] = 'video/mp4'
+): AssetMeta {
+  return {
+    id: 'video-1',
+    name: 'clip.mp4',
+    asset_hash: null,
+    mime_type: mimeType,
+    tags: [],
+    kind: 'video',
+    src
+  }
+}
+
+describe('MediaVideoTop', () => {
+  it('renders playable video with darkened paused overlay and play icon', () => {
+    const wrapper = mount(MediaVideoTop, {
+      props: {
+        asset: createVideoAsset('https://example.com/thumb.jpg')
+      }
+    })
+
+    const video = wrapper.find('video')
+    const videoElement = video.element as HTMLVideoElement
+    expect(video.exists()).toBe(true)
+    expect(videoElement.controls).toBe(false)
+    expect(wrapper.find('source').attributes('src')).toBe(
+      'https://example.com/thumb.jpg'
+    )
+    expect(wrapper.find('source').attributes('type')).toBe('video/mp4')
+    expect(wrapper.find('.bg-black\\/15').exists()).toBe(true)
+    expect(wrapper.find('.icon-\\[lucide--play\\]').exists()).toBe(true)
+  })
+
+  it('does not render source element when src is empty', () => {
+    const wrapper = mount(MediaVideoTop, {
+      props: {
+        asset: createVideoAsset('')
+      }
+    })
+
+    expect(wrapper.find('video').exists()).toBe(true)
+    expect(wrapper.find('source').exists()).toBe(false)
+  })
+
+  it('emits playback events and hides paused overlay while playing', async () => {
+    const wrapper = mount(MediaVideoTop, {
+      props: {
+        asset: createVideoAsset('https://example.com/thumb.jpg')
+      }
+    })
+
+    const video = wrapper.find('video')
+    const videoElement = video.element as HTMLVideoElement
+    expect(video.exists()).toBe(true)
+
+    await video.trigger('play')
+    expect(wrapper.emitted('videoPlayingStateChanged')?.at(-1)).toEqual([true])
+    expect(wrapper.find('.bg-black\\/15').exists()).toBe(false)
+
+    await wrapper.trigger('mouseenter')
+    expect(videoElement.controls).toBe(true)
+
+    await wrapper.trigger('mouseleave')
+    expect(videoElement.controls).toBe(false)
+
+    await video.trigger('pause')
+    expect(wrapper.emitted('videoPlayingStateChanged')?.at(-1)).toEqual([false])
+    expect(wrapper.find('.bg-black\\/15').exists()).toBe(true)
+    expect(videoElement.controls).toBe(false)
+  })
+
+  it('starts playback from click when controls are hidden', async () => {
+    const wrapper = mount(MediaVideoTop, {
+      props: {
+        asset: createVideoAsset('https://example.com/thumb.jpg')
+      }
+    })
+
+    const video = wrapper.find('video')
+    const videoElement = video.element as HTMLVideoElement
+    const playSpy = vi
+      .spyOn(videoElement, 'play')
+      .mockImplementation(() => Promise.resolve())
+
+    Object.defineProperty(videoElement, 'paused', {
+      value: true,
+      configurable: true
+    })
+
+    await video.trigger('click')
+
+    expect(playSpy).toHaveBeenCalledTimes(1)
+  })
+})

src/platform/assets/components/MediaVideoTop.vue

@@ -5,20 +5,24 @@
     @mouseleave="isHovered = false"
   >
     <video
+      ref="videoElement"
       :controls="shouldShowControls"
       preload="metadata"
       muted
       loop
       playsinline
-      :poster="asset.preview_url"
       class="relative size-full object-contain transition-transform duration-300 group-hover:scale-105 group-data-[selected=true]:scale-105"
-      @click.stop
+      @click.stop="onVideoClick"
       @play="onVideoPlay"
       @pause="onVideoPause"
-      @ended="onVideoEnded"
     >
-      <source :src="asset.src || ''" />
+      <source
+        v-if="asset.src"
+        :src="asset.src"
+        :type="asset.mime_type ?? undefined"
+      />
     </video>
+    <VideoPlayOverlay :visible="!isPlaying" size="md" />
   </div>
 </template>
 
@@ -27,6 +31,8 @@ import { computed, onMounted, ref, watch } from 'vue'
 
 import type { AssetMeta } from '../schemas/mediaAssetSchema'
 
+import VideoPlayOverlay from './VideoPlayOverlay.vue'
+
 const { asset } = defineProps<{
   asset: AssetMeta
 }>()
@@ -36,11 +42,12 @@ const emit = defineEmits<{
   videoControlsChanged: [showControls: boolean]
 }>()
 
+const videoElement = ref<HTMLVideoElement | null>(null)
 const isHovered = ref(false)
 const isPlaying = ref(false)
 
-// Always show controls when not playing, hide/show based on hover when playing
+// Show native controls only while actively playing and hovered.
-const shouldShowControls = computed(() => !isPlaying.value || isHovered.value)
+const shouldShowControls = computed(() => isPlaying.value && isHovered.value)
 
 watch(shouldShowControls, (controlsVisible) => {
   emit('videoControlsChanged', controlsVisible)
@@ -60,8 +67,17 @@ const onVideoPause = () => {
   emit('videoPlayingStateChanged', false)
 }
 
-const onVideoEnded = () => {
+const onVideoClick = async () => {
-  isPlaying.value = false
+  if (shouldShowControls.value) return
-  emit('videoPlayingStateChanged', false)
+
+  const video = videoElement.value
+  if (!video) return
+
+  if (video.paused || video.ended) {
+    await video.play().catch(() => {})
+    return
+  }
+
+  video.pause()
 }
 </script>

src/platform/assets/components/VideoPlayOverlay.vue

@@ -0,0 +1,31 @@
+<template>
+  <template v-if="visible">
+    <div :class="cn('pointer-events-none absolute inset-0', overlayClass)" />
+    <div
+      class="pointer-events-none absolute inset-0 flex items-center justify-center"
+    >
+      <i
+        aria-hidden="true"
+        :class="cn('icon-[lucide--play] text-white', iconSizeClass)"
+      />
+    </div>
+  </template>
+</template>
+
+<script setup lang="ts">
+import { computed } from 'vue'
+
+import { cn } from '@/utils/tailwindUtil'
+
+const {
+  visible = true,
+  size = 'md',
+  overlayClass = 'bg-black/15'
+} = defineProps<{
+  visible?: boolean
+  size?: 'sm' | 'md'
+  overlayClass?: string
+}>()
+
+const iconSizeClass = computed(() => (size === 'sm' ? 'size-3' : 'size-6'))
+</script>