diff --git a/src/platform/assets/composables/useOutputStacks.test.ts b/src/platform/assets/composables/useOutputStacks.test.ts
new file mode 100644
index 000000000..d770b3c75
--- /dev/null
+++ b/src/platform/assets/composables/useOutputStacks.test.ts
@@ -0,0 +1,200 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+import { ref } from 'vue'
+
+import type { AssetItem } from '@/platform/assets/schemas/assetSchema'
+import { useOutputStacks } from '@/platform/assets/composables/useOutputStacks'
+
+const mocks = vi.hoisted(() => ({
+  resolveOutputAssetItems: vi.fn()
+}))
+
+vi.mock('@/platform/assets/utils/outputAssetUtil', () => ({
+  resolveOutputAssetItems: mocks.resolveOutputAssetItems
+}))
+
+type Deferred<T> = {
+  promise: Promise<T>
+  resolve: (value: T) => void
+  reject: (reason?: unknown) => void
+}
+
+function createDeferred<T>(): Deferred<T> {
+  let resolve!: (value: T) => void
+  let reject!: (reason?: unknown) => void
+  const promise = new Promise<T>((resolveFn, rejectFn) => {
+    resolve = resolveFn
+    reject = rejectFn
+  })
+  return { promise, resolve, reject }
+}
+
+function createAsset(overrides: Partial<AssetItem> = {}): AssetItem {
+  return {
+    id: 'asset-1',
+    name: 'parent.png',
+    tags: [],
+    created_at: '2025-01-01T00:00:00.000Z',
+    user_metadata: {
+      promptId: 'prompt-1',
+      nodeId: 'node-1',
+      subfolder: 'outputs'
+    },
+    ...overrides
+  }
+}
+
+describe('useOutputStacks', () => {
+  beforeEach(() => {
+    vi.resetAllMocks()
+  })
+
+  it('expands stacks and exposes children as selectable assets', async () => {
+    const parent = createAsset({ id: 'parent', name: 'parent.png' })
+    const childA = createAsset({
+      id: 'child-a',
+      name: 'child-a.png',
+      user_metadata: undefined
+    })
+    const childB = createAsset({
+      id: 'child-b',
+      name: 'child-b.png',
+      user_metadata: undefined
+    })
+
+    vi.mocked(mocks.resolveOutputAssetItems).mockResolvedValue([childA, childB])
+
+    const { assetItems, isStackExpanded, selectableAssets, toggleStack } =
+      useOutputStacks({ assets: ref([parent]) })
+
+    await toggleStack(parent)
+
+    expect(mocks.resolveOutputAssetItems).toHaveBeenCalledWith(
+      expect.objectContaining({ promptId: 'prompt-1' }),
+      {
+        createdAt: parent.created_at,
+        excludeOutputKey: parent.name
+      }
+    )
+    expect(isStackExpanded(parent)).toBe(true)
+    expect(assetItems.value.map((item) => item.asset.id)).toEqual([
+      parent.id,
+      childA.id,
+      childB.id
+    ])
+    expect(assetItems.value[1]).toMatchObject({
+      asset: childA,
+      isChild: true
+    })
+    expect(assetItems.value[2]).toMatchObject({
+      asset: childB,
+      isChild: true
+    })
+    expect(selectableAssets.value).toEqual([parent, childA, childB])
+  })
+
+  it('collapses an expanded stack when toggled again', async () => {
+    const parent = createAsset({ id: 'parent', name: 'parent.png' })
+    const child = createAsset({
+      id: 'child',
+      name: 'child.png',
+      user_metadata: undefined
+    })
+
+    vi.mocked(mocks.resolveOutputAssetItems).mockResolvedValue([child])
+
+    const { assetItems, isStackExpanded, toggleStack } = useOutputStacks({
+      assets: ref([parent])
+    })
+
+    await toggleStack(parent)
+    await toggleStack(parent)
+
+    expect(isStackExpanded(parent)).toBe(false)
+    expect(assetItems.value.map((item) => item.asset.id)).toEqual([parent.id])
+  })
+
+  it('ignores assets without stack metadata', async () => {
+    const asset = createAsset({
+      id: 'no-meta',
+      name: 'no-meta.png',
+      user_metadata: undefined
+    })
+
+    const { assetItems, isStackExpanded, toggleStack } = useOutputStacks({
+      assets: ref([asset])
+    })
+
+    await toggleStack(asset)
+
+    expect(mocks.resolveOutputAssetItems).not.toHaveBeenCalled()
+    expect(isStackExpanded(asset)).toBe(false)
+    expect(assetItems.value).toHaveLength(1)
+    expect(assetItems.value[0].asset).toMatchObject(asset)
+  })
+
+  it('does not expand when no children are resolved', async () => {
+    const parent = createAsset({ id: 'parent', name: 'parent.png' })
+
+    vi.mocked(mocks.resolveOutputAssetItems).mockResolvedValue([])
+
+    const { assetItems, isStackExpanded, toggleStack } = useOutputStacks({
+      assets: ref([parent])
+    })
+
+    await toggleStack(parent)
+
+    expect(isStackExpanded(parent)).toBe(false)
+    expect(assetItems.value.map((item) => item.asset.id)).toEqual([parent.id])
+  })
+
+  it('does not expand when resolving children throws', async () => {
+    const parent = createAsset({ id: 'parent', name: 'parent.png' })
+    const errorSpy = vi.spyOn(console, 'error').mockImplementation(() => {})
+
+    vi.mocked(mocks.resolveOutputAssetItems).mockRejectedValue(
+      new Error('resolve failed')
+    )
+
+    const { assetItems, isStackExpanded, toggleStack } = useOutputStacks({
+      assets: ref([parent])
+    })
+
+    await toggleStack(parent)
+
+    expect(isStackExpanded(parent)).toBe(false)
+    expect(assetItems.value.map((item) => item.asset.id)).toEqual([parent.id])
+
+    errorSpy.mockRestore()
+  })
+
+  it('guards against duplicate loads while a stack is resolving', async () => {
+    const parent = createAsset({ id: 'parent', name: 'parent.png' })
+    const child = createAsset({
+      id: 'child',
+      name: 'child.png',
+      user_metadata: undefined
+    })
+    const deferred = createDeferred<AssetItem[]>()
+
+    vi.mocked(mocks.resolveOutputAssetItems).mockReturnValue(deferred.promise)
+
+    const { assetItems, toggleStack } = useOutputStacks({
+      assets: ref([parent])
+    })
+
+    const firstToggle = toggleStack(parent)
+    const secondToggle = toggleStack(parent)
+
+    expect(mocks.resolveOutputAssetItems).toHaveBeenCalledTimes(1)
+
+    deferred.resolve([child])
+
+    await firstToggle
+    await secondToggle
+
+    expect(assetItems.value.map((item) => item.asset.id)).toEqual([
+      parent.id,
+      child.id
+    ])
+  })
+})
diff --git a/src/platform/assets/composables/useOutputStacks.ts b/src/platform/assets/composables/useOutputStacks.ts
new file mode 100644
index 000000000..5c53c23e4
--- /dev/null
+++ b/src/platform/assets/composables/useOutputStacks.ts
@@ -0,0 +1,127 @@
+import { computed, ref } from 'vue'
+import type { Ref } from 'vue'
+
+import { getOutputAssetMetadata } from '@/platform/assets/schemas/assetMetadataSchema'
+import type { AssetItem } from '@/platform/assets/schemas/assetSchema'
+import { resolveOutputAssetItems } from '@/platform/assets/utils/outputAssetUtil'
+
+type OutputStackListItem = {
+  key: string
+  asset: AssetItem
+  isChild?: boolean
+}
+
+type UseOutputStacksOptions = {
+  assets: Ref<AssetItem[]>
+}
+
+export function useOutputStacks({ assets }: UseOutputStacksOptions) {
+  const expandedStackPromptIds = ref<Set<string>>(new Set())
+  const stackChildrenByPromptId = ref<Record<string, AssetItem[]>>({})
+  const loadingStackPromptIds = ref<Set<string>>(new Set())
+
+  const assetItems = computed<OutputStackListItem[]>(() => {
+    const items: OutputStackListItem[] = []
+
+    for (const asset of assets.value) {
+      const promptId = getStackPromptId(asset)
+      items.push({
+        key: `asset-${asset.id}`,
+        asset
+      })
+
+      if (!promptId || !expandedStackPromptIds.value.has(promptId)) {
+        continue
+      }
+
+      const children = stackChildrenByPromptId.value[promptId] ?? []
+      for (const child of children) {
+        items.push({
+          key: `asset-${child.id}`,
+          asset: child,
+          isChild: true
+        })
+      }
+    }
+
+    return items
+  })
+
+  const selectableAssets = computed(() =>
+    assetItems.value.map((item) => item.asset)
+  )
+
+  function getStackPromptId(asset: AssetItem): string | null {
+    const metadata = getOutputAssetMetadata(asset.user_metadata)
+    return metadata?.promptId ?? null
+  }
+
+  function isStackExpanded(asset: AssetItem): boolean {
+    const promptId = getStackPromptId(asset)
+    if (!promptId) return false
+    return expandedStackPromptIds.value.has(promptId)
+  }
+
+  async function toggleStack(asset: AssetItem) {
+    const promptId = getStackPromptId(asset)
+    if (!promptId) return
+
+    if (expandedStackPromptIds.value.has(promptId)) {
+      const next = new Set(expandedStackPromptIds.value)
+      next.delete(promptId)
+      expandedStackPromptIds.value = next
+      return
+    }
+
+    if (!stackChildrenByPromptId.value[promptId]?.length) {
+      if (loadingStackPromptIds.value.has(promptId)) {
+        return
+      }
+      const nextLoading = new Set(loadingStackPromptIds.value)
+      nextLoading.add(promptId)
+      loadingStackPromptIds.value = nextLoading
+
+      const children = await resolveStackChildren(asset)
+
+      const afterLoading = new Set(loadingStackPromptIds.value)
+      afterLoading.delete(promptId)
+      loadingStackPromptIds.value = afterLoading
+
+      if (!children.length) {
+        return
+      }
+
+      stackChildrenByPromptId.value = {
+        ...stackChildrenByPromptId.value,
+        [promptId]: children
+      }
+    }
+
+    const nextExpanded = new Set(expandedStackPromptIds.value)
+    nextExpanded.add(promptId)
+    expandedStackPromptIds.value = nextExpanded
+  }
+
+  async function resolveStackChildren(asset: AssetItem): Promise<AssetItem[]> {
+    const metadata = getOutputAssetMetadata(asset.user_metadata)
+    if (!metadata) {
+      return []
+    }
+    try {
+      return await resolveOutputAssetItems(metadata, {
+        createdAt: asset.created_at,
+        excludeOutputKey: asset.name
+      })
+    } catch (error) {
+      console.error('Failed to resolve stack children:', error)
+      return []
+    }
+  }
+
+  return {
+    assetItems,
+    selectableAssets,
+    isStackExpanded,
+    toggleStack
+  }
+}