[feat] Add model metadata fetching with loading skeleton and gated repo support (#9415)

## Summary
- Fetch file sizes via HEAD requests (HuggingFace) and Civitai API with
caching and request deduplication
- Show skeleton loader while metadata is loading
- Display "Accept terms" link for gated HuggingFace models instead of
download button

## Changes
- **`missingModelsUtils.ts`**: Add `fetchModelMetadata` with Civitai API
support, HuggingFace gated repo detection, in-memory cache, and inflight
request deduplication
- **`MissingModelsContent.vue`**: Add Skeleton loading state, gated
model "Accept terms" link, extract `showSkeleton` helper
- **`missingModelsUtils.test.ts`**: Tests for HEAD/Civitai fetching,
gated repo detection, caching, and deduplication
- **`main.json`**: Add `acceptTerms` i18n key

## Related Issues
https://github.com/Comfy-Org/ComfyUI_frontend/issues/9410
https://github.com/Comfy-Org/ComfyUI_frontend/issues/9412


┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9415-feat-Add-model-metadata-fetching-with-loading-skeleton-and-gated-repo-support-31a6d73d36508127859efa0b3847505e)
by [Unito](https://www.unito.io)

src/components/dialog/content/MissingModelsContent.vue

@@ -29,14 +29,24 @@
             </span>
           </div>
           <div class="flex shrink-0 items-center gap-2">
+            <Skeleton v-if="showSkeleton(model)" class="ml-1.5 h-4 w-12" />
             <span
-              v-if="model.isDownloadable && fileSizes.get(model.url)"
-              class="text-xs text-muted-foreground"
+              v-else-if="model.isDownloadable && fileSizes.get(model.url)"
+              class="pl-1.5 text-xs text-muted-foreground"
             >
               {{ formatSize(fileSizes.get(model.url)) }}
             </span>
+            <a
+              v-else-if="gatedModelUrls.has(model.url)"
+              :href="gatedModelUrls.get(model.url)"
+              target="_blank"
+              rel="noopener noreferrer"
+              class="text-xs text-primary hover:underline"
+            >
+              {{ $t('missingModelsDialog.acceptTerms') }}
+            </a>
             <Button
-              v-if="model.isDownloadable"
+              v-else-if="model.isDownloadable"
               variant="textonly"
               size="icon"
               :title="model.url"
@@ -100,15 +110,17 @@
 </template>
 
 <script setup lang="ts">
-import { computed, onMounted, reactive } from 'vue'
+import { computed, onMounted, reactive, ref } from 'vue'
 
 import Button from '@/components/ui/button/Button.vue'
+import Skeleton from '@/components/ui/skeleton/Skeleton.vue'
 import { useCopyToClipboard } from '@/composables/useCopyToClipboard'
 import { formatSize } from '@/utils/formatUtil'
 
 import type { ModelWithUrl } from './missingModelsUtils'
 import {
   downloadModel,
+  fetchModelMetadata,
   getBadgeLabel,
   hasValidDirectory,
   isModelDownloadable
@@ -142,6 +154,7 @@ const hasCustomModels = computed(() =>
   processedModels.value.some((m) => !m.isDownloadable)
 )
 
+const loading = ref(true)
 const fileSizes = reactive(new Map<string, number>())
 
 const totalDownloadSize = computed(() =>
@@ -150,6 +163,17 @@ const totalDownloadSize = computed(() =>
     .reduce((total, model) => total + (fileSizes.get(model.url) ?? 0), 0)
 )
 
+const gatedModelUrls = reactive(new Map<string, string>())
+
+function showSkeleton(model: ProcessedModel): boolean {
+  return (
+    model.isDownloadable &&
+    loading.value &&
+    !fileSizes.has(model.url) &&
+    !gatedModelUrls.has(model.url)
+  )
+}
+
 onMounted(async () => {
   const downloadableUrls = processedModels.value
     .filter((m) => m.isDownloadable)
@@ -157,16 +181,12 @@ onMounted(async () => {
 
   await Promise.allSettled(
     downloadableUrls.map(async (url) => {
-      try {
-        const response = await fetch(url, { method: 'HEAD' })
-        if (!response.ok) return
-        const size = response.headers.get('content-length')
-        if (size) fileSizes.set(url, parseInt(size, 10))
-      } catch {
-        // Silently skip size fetch failures
-      }
+      const metadata = await fetchModelMetadata(url)
+      if (metadata.fileSize !== null) fileSizes.set(url, metadata.fileSize)
+      if (metadata.gatedRepoUrl) gatedModelUrls.set(url, metadata.gatedRepoUrl)
     })
   )
+  loading.value = false
 })
 
 const { copyToClipboard } = useCopyToClipboard()

src/components/dialog/content/missingModelsUtils.test.ts

@@ -0,0 +1,142 @@
+import { describe, expect, it, vi, beforeEach } from 'vitest'
+
+import { fetchModelMetadata } from './missingModelsUtils'
+
+const fetchMock = vi.fn()
+vi.stubGlobal('fetch', fetchMock)
+
+vi.mock('@/platform/distribution/types', () => ({ isDesktop: false }))
+vi.mock('@/stores/electronDownloadStore', () => ({}))
+
+let testId = 0
+
+describe('fetchModelMetadata', () => {
+  beforeEach(() => {
+    fetchMock.mockReset()
+    testId++
+  })
+
+  it('fetches file size via HEAD for non-Civitai URLs', async () => {
+    fetchMock.mockResolvedValueOnce({
+      ok: true,
+      headers: new Headers({ 'content-length': '1048576' })
+    })
+
+    const url = `https://huggingface.co/org/model/resolve/main/head-${testId}.safetensors`
+    const metadata = await fetchModelMetadata(url)
+    expect(metadata.fileSize).toBe(1048576)
+    expect(metadata.gatedRepoUrl).toBeNull()
+    expect(fetchMock).toHaveBeenCalledWith(url, { method: 'HEAD' })
+  })
+
+  it('uses Civitai API for Civitai model URLs', async () => {
+    const url = `https://civitai.com/api/download/models/${testId}`
+    fetchMock.mockResolvedValueOnce({
+      ok: true,
+      json: async () => ({
+        files: [{ sizeKB: 1024, downloadUrl: url }]
+      })
+    })
+
+    const metadata = await fetchModelMetadata(url)
+    expect(metadata.fileSize).toBe(1024 * 1024)
+    expect(metadata.gatedRepoUrl).toBeNull()
+    expect(fetchMock).toHaveBeenCalledWith(
+      `https://civitai.com/api/v1/model-versions/${testId}`
+    )
+  })
+
+  it('returns null fileSize when Civitai API fails', async () => {
+    fetchMock.mockResolvedValueOnce({ ok: false })
+
+    const metadata = await fetchModelMetadata(
+      `https://civitai.com/api/download/models/${testId}`
+    )
+    expect(metadata.fileSize).toBeNull()
+    expect(metadata.gatedRepoUrl).toBeNull()
+    expect(fetchMock).toHaveBeenCalledTimes(1)
+  })
+
+  it('returns gatedRepoUrl for gated HuggingFace HEAD requests (403)', async () => {
+    fetchMock.mockResolvedValueOnce({ ok: false, status: 403 })
+
+    const metadata = await fetchModelMetadata(
+      `https://huggingface.co/bfl/FLUX.1/resolve/main/gated-${testId}.safetensors`
+    )
+    expect(metadata.gatedRepoUrl).toBe('https://huggingface.co/bfl/FLUX.1')
+    expect(metadata.fileSize).toBeNull()
+  })
+
+  it('does not treat HuggingFace 404/500 as gated', async () => {
+    fetchMock.mockResolvedValueOnce({ ok: false, status: 404 })
+
+    const metadata = await fetchModelMetadata(
+      `https://huggingface.co/org/model/resolve/main/notfound-${testId}.safetensors`
+    )
+    expect(metadata.gatedRepoUrl).toBeNull()
+    expect(metadata.fileSize).toBeNull()
+  })
+
+  it('returns null for unrecognized Civitai URL patterns', async () => {
+    const url = `https://civitai.com/api/v1/models/${testId}`
+    const metadata = await fetchModelMetadata(url)
+    expect(metadata.fileSize).toBeNull()
+    expect(metadata.gatedRepoUrl).toBeNull()
+    expect(fetchMock).not.toHaveBeenCalled()
+  })
+
+  it('returns cached metadata on second call', async () => {
+    const url = `https://huggingface.co/org/model/resolve/main/cached-${testId}.safetensors`
+
+    fetchMock.mockResolvedValueOnce({
+      ok: true,
+      headers: new Headers({ 'content-length': '500' })
+    })
+
+    const first = await fetchModelMetadata(url)
+    const second = await fetchModelMetadata(url)
+
+    expect(first.fileSize).toBe(500)
+    expect(second.fileSize).toBe(500)
+    expect(fetchMock).toHaveBeenCalledTimes(1)
+  })
+
+  it('does not cache incomplete results so retries are possible', async () => {
+    const url = `https://example.com/retry-${testId}.safetensors`
+
+    fetchMock
+      .mockResolvedValueOnce({
+        ok: true,
+        headers: new Headers({})
+      })
+      .mockResolvedValueOnce({
+        ok: true,
+        headers: new Headers({ 'content-length': '1024' })
+      })
+
+    const first = await fetchModelMetadata(url)
+    const second = await fetchModelMetadata(url)
+
+    expect(first.fileSize).toBeNull()
+    expect(second.fileSize).toBe(1024)
+    expect(fetchMock).toHaveBeenCalledTimes(2)
+  })
+
+  it('deduplicates concurrent requests for the same URL', async () => {
+    const url = `https://huggingface.co/org/model/resolve/main/dedup-${testId}.safetensors`
+
+    fetchMock.mockResolvedValueOnce({
+      ok: true,
+      headers: new Headers({ 'content-length': '2048' })
+    })
+
+    const [first, second] = await Promise.all([
+      fetchModelMetadata(url),
+      fetchModelMetadata(url)
+    ])
+
+    expect(first.fileSize).toBe(2048)
+    expect(second.fileSize).toBe(2048)
+    expect(fetchMock).toHaveBeenCalledTimes(1)
+  })
+})

src/components/dialog/content/missingModelsUtils.ts

@@ -1,3 +1,4 @@
+import { downloadUrlToHfRepoUrl, isCivitaiModelUrl } from '@/utils/formatUtil'
 import { isDesktop } from '@/platform/distribution/types'
 import { useElectronDownloadStore } from '@/stores/electronDownloadStore'
 
@@ -81,3 +82,99 @@ export function downloadModel(
     })
   }
 }
+
+interface ModelMetadata {
+  fileSize: number | null
+  gatedRepoUrl: string | null
+}
+
+interface CivitaiModelFile {
+  sizeKB: number
+  downloadUrl: string
+}
+
+interface CivitaiModelVersionResponse {
+  files: CivitaiModelFile[]
+}
+
+const metadataCache = new Map<string, ModelMetadata>()
+const inflight = new Map<string, Promise<ModelMetadata>>()
+
+async function fetchCivitaiMetadata(url: string): Promise<ModelMetadata> {
+  try {
+    const pathname = new URL(url).pathname
+    const versionIdMatch =
+      pathname.match(/^\/api\/download\/models\/(\d+)$/) ??
+      pathname.match(/^\/api\/v1\/models-versions\/(\d+)$/)
+
+    if (!versionIdMatch) return { fileSize: null, gatedRepoUrl: null }
+
+    const [, modelVersionId] = versionIdMatch
+    const apiUrl = `https://civitai.com/api/v1/model-versions/${modelVersionId}`
+    const res = await fetch(apiUrl)
+    if (!res.ok) return { fileSize: null, gatedRepoUrl: null }
+
+    const data: CivitaiModelVersionResponse = await res.json()
+    const matchingFile = data.files?.find(
+      (file) => file.downloadUrl && file.downloadUrl.startsWith(url)
+    )
+    const fileSize = matchingFile?.sizeKB ? matchingFile.sizeKB * 1024 : null
+    return { fileSize, gatedRepoUrl: null }
+  } catch {
+    return { fileSize: null, gatedRepoUrl: null }
+  }
+}
+
+const GATED_STATUS_CODES = new Set([401, 403, 451])
+
+async function fetchHeadMetadata(url: string): Promise<ModelMetadata> {
+  try {
+    const response = await fetch(url, { method: 'HEAD' })
+    if (!response.ok) {
+      if (
+        url.includes('huggingface.co') &&
+        GATED_STATUS_CODES.has(response.status)
+      ) {
+        return { fileSize: null, gatedRepoUrl: downloadUrlToHfRepoUrl(url) }
+      }
+      return { fileSize: null, gatedRepoUrl: null }
+    }
+    const size = response.headers.get('content-length')
+    return {
+      fileSize: size ? parseInt(size, 10) : null,
+      gatedRepoUrl: null
+    }
+  } catch {
+    return { fileSize: null, gatedRepoUrl: null }
+  }
+}
+
+function isComplete(metadata: ModelMetadata): boolean {
+  return metadata.fileSize !== null || metadata.gatedRepoUrl !== null
+}
+
+export async function fetchModelMetadata(url: string): Promise<ModelMetadata> {
+  const cached = metadataCache.get(url)
+  if (cached !== undefined) return cached
+
+  const existing = inflight.get(url)
+  if (existing) return existing
+
+  const promise = (async () => {
+    const metadata = isCivitaiModelUrl(url)
+      ? await fetchCivitaiMetadata(url)
+      : await fetchHeadMetadata(url)
+
+    if (isComplete(metadata)) {
+      metadataCache.set(url, metadata)
+    }
+    return metadata
+  })()
+
+  inflight.set(url, promise)
+  try {
+    return await promise
+  } finally {
+    inflight.delete(url)
+  }
+}

src/locales/en/main.json

@@ -1788,7 +1788,8 @@
     "gotIt": "Ok, got it",
     "footerDescription": "Download and place these models in the correct folder.\nNodes with missing models are highlighted red on the canvas.",
     "customModelsWarning": "Some of these are custom models that we don't recognize.",
-    "customModelsInstruction": "You'll need to find and download them manually. Search for them online (try Civitai or HuggingFace) or contact the original workflow provider."
+    "customModelsInstruction": "You'll need to find and download them manually. Search for them online (try Civitai or HuggingFace) or contact the original workflow provider.",
+    "acceptTerms": "Accept terms"
   },
   "versionMismatchWarning": {
     "title": "Version Compatibility Warning",