diff --git a/sdk/index.ts b/sdk/index.ts
index b576300..90df692 100644
--- a/sdk/index.ts
+++ b/sdk/index.ts
@@ -86,19 +86,17 @@ interface MatchCandidate extends SongInfo {
  * @param params.name 歌名
  * @param params.singer 歌手
  * @param params.excludeSource 指定平台时，聚合结果会跳过该平台
+ * @param params.only 只搜该平台（与 excludeSource 互斥，优先生效）
  * @param params.limit 单平台结果条数
  */
 export const searchMusic = async (
-  { name, singer, source: excludeSource, limit = 25 }: { name: string; singer?: string; source?: string; limit?: number },
+  { name, singer, source: excludeSource, only, limit = 25 }: { name: string; singer?: string; source?: string; only?: string; limit?: number },
 ): Promise<Array<SearchResult | null>> => {
   const musicName = trimStr(name)
   const tasks: Array<Promise<SearchResult | null>> = []
   for (const source of SUPPORTED_SOURCES) {
-    if (
-      source.id === excludeSource ||
-      !source.module.musicSearch
-    )
-      continue
+    if (!source.module.musicSearch) continue
+    if (only ? source.id !== only : source.id === excludeSource) continue
     tasks.push(
       source.module.musicSearch
         .search(`${musicName} ${singer || ''}`.trim(), 1, limit)
@@ -120,11 +118,12 @@ const pickMatching = <T>(items: T[], predicate: (item: T) => boolean): { matched
 
 /**
  * 跨平台精确匹配歌曲（按歌手、歌名、专辑、时长综合排序）
+ * @param params.only 只在该平台内匹配（跨平台兜底取流用）
  */
 export const findMusic = async (
-  { name, singer, albumName, interval, source: s }: { name: string; singer?: string; albumName?: string; interval?: string; source?: string },
+  { name, singer, albumName, interval, source: s, only }: { name: string; singer?: string; albumName?: string; interval?: string; source?: string; only?: string },
 ): Promise<MatchCandidate[]> => {
-  const lists = await searchMusic({ name, singer, source: s, limit: 25 })
+  const lists = await searchMusic({ name, singer, source: s, only, limit: 25 })
 
   const fMusicName = filterStr(name).toLowerCase()
   const fSinger = filterStr(sortSingle(singer)).toLowerCase()
diff --git a/src/openapi/components.ts b/src/openapi/components.ts
index 6eb8bb3..e1b590f 100644
--- a/src/openapi/components.ts
+++ b/src/openapi/components.ts
@@ -67,8 +67,9 @@ export const COMPONENT_SCHEMAS = {
   MusicUrlResult: {
     type: 'object',
     properties: {
-      type: { type: 'string', example: '320k' },
+      type: { type: 'string', example: '320k', description: '实际命中的音质（降级链可能低于请求音质）' },
       url: { type: 'string', description: '播放地址' },
+      via: { type: 'string', example: 'kw', description: '实际命中通道：script=外部音源脚本 / 平台 id / kw=酷我兜底；直接命中时不返回该字段' },
     },
     additionalProperties: true,
   },
diff --git a/src/routes.ts b/src/routes.ts
index 757f0b6..50fc829 100644
--- a/src/routes.ts
+++ b/src/routes.ts
@@ -4,6 +4,7 @@
 // 抛出 ApiError → 由全局 setErrorHandler 转为对应 HTTP 状态码
 
 import { notFound, upstream } from './http/api-error.ts'
+import { getMusicInfo } from '../sdk/kg/musicInfo.ts'
 
 const QUALITIES = ['128k', '320k', 'flac', 'flac24bit']
 
@@ -128,39 +129,81 @@ export const musicRoutes = async(fastify: any) => {
 
   const urlHandler = async(request) => {
     const { source, id } = request.params
-    const { quality, albumId } = request.query
+    const { quality, albumId, name, singer, interval } = request.query
     const m = getSource(musicSdk, source, 'getMusicUrl')
-    // 音源模式下服务端把取流重定向到外部音源脚本；未挂载时走 SDK 官方直连接口
-    const impl = fastify.sourceApi?.[source] ?? m
     const songInfo = { songmid: id, hash: id, copyrightId: id, albumId: albumId || '', _types: {} }
-    let result
-    try {
-      result = unwrap(impl.getMusicUrl(songInfo, quality))
-    } catch (err: any) {
-      throw upstream(err.message)
-    }
-    return result.then(res => {
-      if (!res?.url) throw upstream('获取播放地址失败')
+
+    // 取流链：外部音源脚本（SOURCE_ENABLED 启用时）→ SDK 官方直连 → 酷我兜底（跨平台匹配）
+    const finish = (res: any, via: string) => {
+      if (!res?.url) throw new Error('获取播放地址失败')
       // qs 解密流等代理地址返回相对路径，按请求的协议与 host 补全（兼容本机/局域网播放器）
       const url = String(res.url).startsWith('/')
         ? `${request.protocol}://${request.headers.host}${res.url}`
         : res.url
-      return { type: quality, url }
-    }).catch(err => {
-      throw err.status ? err : upstream(err.message)
-    })
+      // type 用实际音质（kw 等通道可能降级）；via 标记兜底链中真正命中的通道
+      return { type: res.type || quality, url, ...(via !== source ? { via } : {}) }
+    }
+
+    const attempts: Array<{ via: string, run: () => Promise<any> }> = []
+    if (fastify.sourceApi?.[source]) {
+      attempts.push({ via: 'script', run: () => unwrap(fastify.sourceApi[source].getMusicUrl(songInfo, quality)) })
+    }
+    attempts.push({ via: source, run: () => unwrap(m.getMusicUrl(songInfo, quality)) })
+
+    const errors: string[] = []
+    for (const attempt of attempts) {
+      try {
+        return finish(await attempt.run(), attempt.via)
+      } catch (err: any) {
+        errors.push(`${attempt.via}: ${err?.message || err}`)
+      }
+    }
+
+    // 酷我兜底：匿名可拿真无损的通道，按歌名/歌手/时长匹配同一首歌后取流
+    if (source !== 'kw') {
+      try {
+        let meta: { name?: string, singer?: string, interval?: string } | null = name ? { name, singer, interval } : null
+        if (!meta && source === 'kg') {
+          // kg 的 id 是 hash，可反查出歌名/歌手/时长
+          const info = await getMusicInfo(id)
+          if (info?.name) meta = { name: String(info.name), singer: info.singer ? String(info.singer) : undefined, interval: info.interval ? String(info.interval) : undefined }
+        }
+        if (meta?.name) {
+          const [best] = await musicSdk.findMusic({ ...meta, only: 'kw' })
+          if (best) {
+            const res = await unwrap(musicSdk.kw.getMusicUrl({ songmid: best.songmid, hash: best.songmid, _types: {} }, quality))
+            return finish(res, 'kw')
+          }
+          errors.push('kw 兜底: 未匹配到同名歌曲')
+        } else {
+          errors.push('kw 兜底: 缺少歌名信息（传 name/singer/interval 查询参数可启用）')
+        }
+      } catch (err: any) {
+        errors.push(`kw 兜底: ${err?.message || err}`)
+      }
+    }
+    throw upstream(`取流失败（${errors.join('；')}）`)
   }
 
   fastify.get('/url/:source/:id', {
     schema: {
       summary: '获取播放地址',
-      description: 'id 为平台歌曲 id：kw/tx/wy 用 songmid，kg 用 hash。',
+      description: 'id 为平台歌曲 id：kw/tx/wy 用 songmid，kg 用 hash，qs 用 track id。' +
+        '取流按「外部音源脚本（SOURCE_ENABLED 启用时）→ SDK 官方直连 → 酷我兜底」顺序尝试，' +
+        '酷我兜底按歌名/歌手/时长匹配同一首歌（匿名可用无损），kg 可由 hash 反查歌曲信息，' +
+        '其它平台需要兜底时传 name/singer/interval。响应中的 via 字段标记实际命中通道（仅兜底时出现）。',
       tags: ['歌曲资源'],
       params: params({
         source: pSource('url'),
         id: pId,
       }),
-      querystring: qs({ quality: pQuality, albumId: { type: 'string', description: '专辑 id' } }),
+      querystring: qs({
+        quality: pQuality,
+        albumId: { type: 'string', description: '专辑 id' },
+        name: { type: 'string', description: '歌名（酷我兜底匹配用）' },
+        singer: { type: 'string', description: '歌手名（酷我兜底匹配用）' },
+        interval: { type: 'string', description: '时长 mm:ss（酷我兜底匹配用）', example: '04:17' },
+      }),
       response: responses('MusicUrlResult'),
     },
   }, urlHandler)
diff --git a/test/smoke-test.ts b/test/smoke-test.ts
index 1b3a11e..8982ee3 100644
--- a/test/smoke-test.ts
+++ b/test/smoke-test.ts
@@ -152,6 +152,7 @@ await test('URL kw 128k 免费歌', async() => {
   const r = await get('/url/kw/151826618?quality=128k')
   if (r.code != 0) throw new Error(r.msg)
   if (!r.data?.url) throw new Error('无 url')
+  if (r.data.via !== undefined) throw new Error(`直接命中不应有 via 字段，实际 ${r.data.via}`)
   return r.data.url.slice(0, 60)
 })
 
@@ -193,6 +194,24 @@ await test('URL qs 试听 128k', async() => {
   return r.data.url.slice(0, 60)
 })
 
+// 取流链兜底：平台直连失败后按 name/singer 匹配酷我（via=kw 标记实际命中通道）
+await test('URL wy 坏 id → 酷我兜底（via=kw）', async() => {
+  const r = await get('/url/wy/not-exist-id?quality=128k&name=晴天&singer=周杰伦&interval=04:29')
+  if (r.code != 0) throw new Error(r.msg)
+  if (r.data?.via !== 'kw') throw new Error(`期望 via=kw，实际 ${JSON.stringify(r.data)}`)
+  if (!r.data?.url) throw new Error('无 url')
+  return r.data.url.slice(0, 60)
+})
+
+// 坏 id 且未传歌名：kg hash 反查也失败时，应返回聚合各阶段错误的 502 而非裸错误
+await test('URL kg 坏 hash 无歌名 → 502 聚合错误', async() => {
+  const r = await getRaw('/url/kg/00000000000000000000000000000000?quality=128k')
+  if (r.status !== 502) throw new Error(`期望 502，实际 ${r.status}`)
+  const msg = JSON.parse(r.body).msg
+  if (!msg.includes('取流失败')) throw new Error(`错误信息应为取流失败聚合，实际 ${msg}`)
+  return msg
+})
+
 // 歌词
 await test('歌词 kw', async() => {
   const r = await get('/lyric/kw/28423286')