fix(api): add getPlaylistDetail provider method for QQ playlist detail

The /playlist/:id/detail route was hardcoded to call the NetEase API
path /playlist/detail on whatever provider was selected. For QQ this
hit a non-existent path, so clicking into any QQ playlist showed
"歌单不存在或加载失败".

Replace the platform-specific hack in the route handler with a proper
getPlaylistDetail method on MusicProvider. Implement it for NetEase
(porting the existing /playlist/detail logic) and QQ (calling
/getSongListDetail and reading from response.cdlist[0]).

Pre-existing bug exposed by the QQ source tab.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/music/netease.ts

@@ -3,6 +3,7 @@ import type {
   MusicProvider,
   Song,
   Playlist,
+  PlaylistDetail,
   LyricLine,
   SearchResult,
   QrCodeResult,
@@ -319,6 +320,21 @@ export class NeteaseProvider implements MusicProvider {
     }));
   }
 
+  async getPlaylistDetail(playlistId: string): Promise<PlaylistDetail | null> {
+    const res = await this.api.get("/playlist/detail", {
+      params: { id: playlistId, ...this.cookieParams },
+    });
+    const p = res.data?.playlist;
+    if (!p) return null;
+    return {
+      id: String(p.id),
+      name: p.name ?? "",
+      description: p.description ?? "",
+      coverUrl: p.coverImgUrl ?? "",
+      songCount: p.trackCount ?? 0,
+    };
+  }
+
   async getUserPlaylists(): Promise<Playlist[]> {
     // First get user ID from login status
     const statusRes = await this.api.get("/login/status", {

src/music/provider.ts

@@ -20,6 +20,14 @@ export interface Playlist {
   platform: "netease" | "qq" | "bilibili" | "youtube";
 }
 
+export interface PlaylistDetail {
+  id: string;
+  name: string;
+  description: string;
+  coverUrl: string;
+  songCount: number;
+}
+
 export interface Album {
   id: string;
   name: string;
@@ -77,4 +85,5 @@ export interface MusicProvider {
   getPersonalFm?(): Promise<Song[]>;
   getDailyRecommendSongs?(): Promise<Song[]>;
   getUserPlaylists?(): Promise<Playlist[]>;
+  getPlaylistDetail?(playlistId: string): Promise<PlaylistDetail | null>;
 }

src/music/qq.ts

@@ -3,6 +3,7 @@ import type {
   MusicProvider,
   Song,
   Playlist,
+  PlaylistDetail,
   LyricLine,
   SearchResult,
   QrCodeResult,
@@ -178,6 +179,21 @@ export class QQMusicProvider implements MusicProvider {
     }));
   }
 
+  async getPlaylistDetail(playlistId: string): Promise<PlaylistDetail | null> {
+    const res = await this.api.get("/getSongListDetail", {
+      params: { disstid: playlistId, ...this.cookieParams },
+    });
+    const cd = res.data?.response?.cdlist?.[0];
+    if (!cd) return null;
+    return {
+      id: String(cd.disstid ?? cd.dissid ?? ""),
+      name: cd.dissname ?? "",
+      description: cd.desc ?? "",
+      coverUrl: cd.logo ?? "",
+      songCount: cd.songnum ?? cd.total_song_num ?? 0,
+    };
+  }
+
   async getRecommendPlaylists(): Promise<Playlist[]> {
     const res = await this.api.get("/getSongLists", {
       params: { categoryId: 10000000, pageSize: 10, ...this.cookieParams },

src/web/api/music.ts

@@ -168,32 +168,16 @@ export function createMusicRouter(
   router.get("/playlist/:id/detail", async (req, res) => {
     try {
       const provider = getProvider(req.query.platform as string);
-      // Use the playlist songs endpoint to get basic info,
-      // but we also need detail info (name, cover, description).
-      // For netease, we access the underlying API directly.
-      const nProvider = provider as any;
-      if (nProvider.api) {
-        const cookieParams = nProvider.cookie
-          ? { cookie: nProvider.cookie }
-          : {};
-        const detailRes = await nProvider.api.get("/playlist/detail", {
-          params: { id: req.params.id, ...cookieParams },
-        });
-        const p = detailRes.data?.playlist;
-        if (p) {
-          res.json({
-            playlist: {
-              id: String(p.id),
-              name: p.name,
-              description: p.description ?? "",
-              coverUrl: p.coverImgUrl ?? "",
-              songCount: p.trackCount ?? 0,
-            },
-          });
+      if (!provider.getPlaylistDetail) {
+        res.status(501).json({ error: "Not supported by this provider" });
         return;
       }
-      }
+      const detail = await provider.getPlaylistDetail(req.params.id);
+      if (!detail) {
         res.status(404).json({ error: "Playlist not found" });
+        return;
+      }
+      res.json({ playlist: detail });
     } catch (err) {
       logger.error({ err }, "Get playlist detail failed");
       res.status(500).json({ error: (err as Error).message });