feat: 文件清单与图片预览的 P2P 部分挪到浏览器端(WebRTC)，服务端仅缓存兜底

app/components/ImagePreview.vue

@@ -1,5 +1,6 @@
 <script setup lang="ts">
 import type { TorrentFileEntry } from '~/types/api'
+import { readFileBytesClient } from '~/utils/clientTorrent'
 
 const props = defineProps<{
   infoHash: string
@@ -16,6 +17,20 @@ const errorText = ref('')
 const src = ref('')
 let objectUrl = ''
 
+const MIME: Record<string, string> = {
+  jpg: 'image/jpeg',
+  jpeg: 'image/jpeg',
+  png: 'image/png',
+  gif: 'image/gif',
+  webp: 'image/webp',
+  bmp: 'image/bmp',
+  avif: 'image/avif'
+}
+function extOf(p: string): string {
+  const i = p.lastIndexOf('.')
+  return i >= 0 ? p.slice(i + 1).toLowerCase() : ''
+}
+
 const current = computed<TorrentFileEntry | undefined>(() => props.images[props.index])
 const requestUrl = computed(
   () =>
@@ -36,10 +51,18 @@ async function load() {
   src.value = ''
   errorText.value = ''
   status.value = 'loading'
+  try {
+    // 优先在用户浏览器里用 WebRTC 从 P2P 网络直接拉取图片字节（不经过 Vercel/Serverless）
+    const bytes = await readFileBytesClient(props.magnet, current.value?.path || '', 25000)
+    const mime = MIME[extOf(current.value?.path || '')] || 'application/octet-stream'
+    objectUrl = URL.createObjectURL(new Blob([bytes], { type: mime }))
+    src.value = objectUrl
+    status.value = 'ok'
+  } catch {
+    // 回退到服务端预览（自托管环境可用；Serverless 上也会失败，此时给出可读错误）
     try {
       const res = await fetch(requestUrl.value)
       if (!res.ok) {
-      // 服务端用 statusMessage 带上可读原因：没有做种节点 / 图片过大 / 文件不存在
         const text = await res.text()
         let message = text
         try {
@@ -58,6 +81,7 @@ async function load() {
       status.value = 'err'
     }
   }
+}
 
 function step(delta: number) {
   const next = props.index + delta

app/components/TorrentDetail.vue

@@ -1,5 +1,6 @@
 <script setup lang="ts">
 import type { TorrentFileEntry, TorrentView } from '~/types/api'
+import { resolveMetadataClient } from '~/utils/clientTorrent'
 
 const props = defineProps<{
   torrent: TorrentView
@@ -49,24 +50,36 @@ const sourceIcon: Record<string, string> = {
   database: '数据库'
 }
 
-async function doResolve() {
+function applyResolved(res: { files: TorrentFileEntry[]; size: number; name: string }) {
-  resolving.value = true
-  try {
-    const res = await $fetch<{ files: TorrentFileEntry[]; size: number; name: string }>(
-      `/api/torrent/${local.value.infoHash}/resolve`,
-      { method: 'POST', body: { magnet: local.value.magnet } }
-    )
   local.value.files = res.files
   local.value.size = res.size
   local.value.fileCount = res.files.length
   local.value.resolveError = null
   if (res.name) local.value.name = res.name
   emit('resolved', res)
+}
+
+async function doResolve() {
+  resolving.value = true
+  try {
+    // 服务端先尝试（缓存服务取清单，自托管还会走 P2P），成功即返回并落库
+    const res = await $fetch<{ files: TorrentFileEntry[]; size: number; name: string }>(
+      `/api/torrent/${local.value.infoHash}/resolve`,
+      { method: 'POST', body: { magnet: local.value.magnet } }
+    )
+    applyResolved(res)
     pushToast('ok', '文件清单已解析', `共 ${res.files.length} 个文件 / ${formatBytes(res.size)}`)
-  } catch (err) {
+  } catch {
-    const msg = errorMessage(err)
+    // 服务端无法走 P2P（如 Vercel/Serverless）→ 回退到浏览器端 WebRTC 直接解析
+    try {
+      const meta = await resolveMetadataClient(local.value.magnet, 30000)
+      applyResolved(meta)
+      pushToast('ok', '通过浏览器 P2P 解析文件清单', `共 ${meta.files.length} 个文件 / ${formatBytes(meta.size)}`)
+    } catch (err2) {
+      const msg = errorMessage(err2)
       local.value.resolveError = msg
       pushToast('err', '解析失败', msg)
+    }
   } finally {
     resolving.value = false
   }

app/utils/clientTorrent.ts

@@ -0,0 +1,115 @@
+// 浏览器端 WebTorrent（WebRTC）：把 P2P 流量放到用户自己的设备，
+// 绕开 Vercel / Cloudflare 等 Serverless 不支持 UDP/DHT 的限制。
+// 服务端仍保留非 P2P 的缓存服务兜底；这里是真正的 P2P 取数据路径。
+
+// 浏览器只支持 WebRTC 节点，需要走 wss:// 的 tracker 才能发现对端
+const WS_TRACKERS = [
+  'wss://tracker.openwebtorrent.com',
+  'wss://tracker.btorrent.xyz',
+  'wss://tracker.webtorrent.dev'
+]
+
+function normPath(p: string): string {
+  return p.replace(/\\/g, '/').replace(/^\.\//, '')
+}
+
+function withWsTrackers(magnet: string): string {
+  const existing = new Set<string>()
+  for (const m of magnet.matchAll(/[?&]tr=([^&]+)/g)) {
+    try {
+      existing.add(decodeURIComponent(m[1]))
+    } catch {
+      /* ignore */
+    }
+  }
+  const add = WS_TRACKERS.filter((t) => !existing.has(t))
+  if (!add.length) return magnet
+  const sep = magnet.includes('?') ? '&' : '?'
+  return magnet + sep + add.map((t) => `tr=${encodeURIComponent(t)}`).join('&')
+}
+
+let wtPromise: Promise<any> | null = null
+function loadWebTorrent(): Promise<any> {
+  if (!wtPromise) {
+    // 仅在浏览器运行时按需加载，Vite 会将其单独拆包；服务端不会执行到此处
+    wtPromise = import('webtorrent').then((m) => (m as any).default || m)
+  }
+  return wtPromise
+}
+
+function waitForMetadata(torrent: any, timeoutMs: number): Promise<void> {
+  return new Promise((resolve, reject) => {
+    if (torrent.metadata || torrent.ready) return resolve()
+    const timer = setTimeout(
+      () => reject(new Error('浏览器 P2P 获取元数据超时，可能该种子没有 WebRTC 节点')),
+      timeoutMs
+    )
+    const done = () => {
+      clearTimeout(timer)
+      resolve()
+    }
+    torrent.on('metadata', done)
+    torrent.on('ready', done)
+    torrent.on('error', (e: Error) => {
+      clearTimeout(timer)
+      reject(e)
+    })
+  })
+}
+
+export async function resolveMetadataClient(
+  magnet: string,
+  timeoutMs = 30000
+): Promise<{ name: string; files: { path: string; length: number }[]; size: number }> {
+  const WebTorrent = await loadWebTorrent()
+  const client = new WebTorrent()
+  try {
+    const torrent = client.add(withWsTrackers(magnet))
+    await waitForMetadata(torrent, timeoutMs)
+    const files = (torrent.files || []).map((f: any) => ({
+      path: normPath(String(f.path || f.name || '')),
+      length: Number(f.length) || 0
+    }))
+    if (!files.length) throw new Error('已连上节点，但对方没有返回任何文件信息')
+    return { name: String(torrent.name || ''), files, size: files.reduce((s, f) => s + f.length, 0) }
+  } finally {
+    try {
+      client.destroy()
+    } catch {
+      /* ignore */
+    }
+  }
+}
+
+export async function readFileBytesClient(
+  magnet: string,
+  filePath: string,
+  timeoutMs = 25000
+): Promise<ArrayBuffer> {
+  const WebTorrent = await loadWebTorrent()
+  const client = new WebTorrent()
+  try {
+    const torrent = client.add(withWsTrackers(magnet))
+    await waitForMetadata(torrent, timeoutMs)
+    const target = (torrent.files || []).find(
+      (f: any) => normPath(String(f.path || f.name || '')) === normPath(filePath)
+    )
+    if (!target) throw new Error('这个种子里没有该文件，文件清单可能已过期')
+    return await target.arrayBuffer()
+  } finally {
+    try {
+      client.destroy()
+    } catch {
+      /* ignore */
+    }
+  }
+}
+
+export async function isClientWebTorrentAvailable(): Promise<boolean> {
+  try {
+    await loadWebTorrent()
+    return true
+  } catch {
+    return false
+  }
+}

nuxt.config.ts

@@ -1,3 +1,5 @@
+import nodePolyfills from 'vite-plugin-node-polyfills'
+
 export default defineNuxtConfig({
   compatibilityDate: '2025-07-15',
   devtools: { enabled: false },
@@ -27,6 +29,12 @@ export default defineNuxtConfig({
     }
   },
   vite: {
+    plugins: [
+      nodePolyfills({
+        globals: { Buffer: true, global: true, process: true },
+        protocolImports: true
+      })
+    ],
     server: {
       fs: { strict: false }
     }

package.json

@@ -20,6 +20,7 @@
   },
   "devDependencies": {
     "@types/node": "^22.13.0",
-    "typescript": "^5.7.3"
+    "typescript": "^5.7.3",
+    "vite-plugin-node-polyfills": "^0.23.0"
   }
 }