feat(同步): 改进网易云音乐到Navidrome的播放列表同步逻辑

添加获取Navidrome播放列表歌曲ID的功能
确保同步时检查并补全缺失歌曲，避免重复添加
使用Set去重处理歌曲ID列表

Netease-sync/server.js

@@ -549,6 +549,18 @@ async function updateNavidromePlaylist(playlistId, songIdsToAdd) {
     }
 }
 
+async function getNavidromePlaylistSongIds(playlistId) {
+    try {
+        const result = await callSubsonicAPI('getPlaylist', { id: playlistId });
+        const entries = result.playlist?.entry || result.playlist?.song || [];
+        const list = Array.isArray(entries) ? entries : [entries];
+        return list.map(e => e?.id).filter(Boolean);
+    } catch (error) {
+        console.error('Get playlist error:', error.message);
+        return null;
+    }
+}
+
 async function findNavidromePlaylistByName(name) {
     try {
         const result = await callSubsonicAPI('getPlaylists');
@@ -690,23 +702,38 @@ async function syncPlaylist(playlist, cachedInfo = null) {
             }
         }
 
-        console.log(`[Sync] Matched ${allNavidromeIds.length} songs (New: ${newSongIds.length}). PlaylistID: ${playlist.navidromePlaylistId}`);
+        const uniqueAllNavidromeIds = Array.from(new Set(allNavidromeIds));
+
+        console.log(`[Sync] Matched ${uniqueAllNavidromeIds.length} songs (New: ${newSongIds.length}). PlaylistID: ${playlist.navidromePlaylistId}`);
 
         if (playlist.navidromePlaylistId) {
             // Playlist exists (either linked just now or before)
-            // Just append new songs if any
+            // Always check existing playlist content and补齐缺失歌曲
-            if (newSongIds.length > 0) {
+            let missingIds = [];
-                console.log(`[Sync] Adding ${newSongIds.length} new songs to existing playlist ${playlist.navidromePlaylistId}`);
+            if (uniqueAllNavidromeIds.length > 0) {
-                await updateNavidromePlaylist(playlist.navidromePlaylistId, newSongIds);
+                const existingIds = await getNavidromePlaylistSongIds(playlist.navidromePlaylistId);
+                if (Array.isArray(existingIds)) {
+                    const existingSet = new Set(existingIds.map(id => id?.toString()));
+                    missingIds = uniqueAllNavidromeIds.filter(id => !existingSet.has(id?.toString()));
+                    console.log(`[Sync] Existing playlist has ${existingIds.length} songs, missing ${missingIds.length}`);
+                } else {
+                    // Fallback: if无法读取，至少追加本次新匹配到的
+                    missingIds = newSongIds;
+                }
+            }
+
+            if (missingIds.length > 0) {
+                console.log(`[Sync] Adding ${missingIds.length} missing songs to existing playlist ${playlist.navidromePlaylistId}`);
+                await updateNavidromePlaylist(playlist.navidromePlaylistId, missingIds);
             } else {
-                console.log(`[Sync] No new songs to add to playlist ${playlist.navidromePlaylistId}`);
+                console.log(`[Sync] No missing songs to add to playlist ${playlist.navidromePlaylistId}`);
             }
         } else {
             // Playlist does NOT exist
             // Create it with ALL matched songs (if any)
-            if (allNavidromeIds.length > 0) {
+            if (uniqueAllNavidromeIds.length > 0) {
-                console.log(`[Sync] Creating new playlist '${playlist.name}' with ${allNavidromeIds.length} songs`);
+                console.log(`[Sync] Creating new playlist '${playlist.name}' with ${uniqueAllNavidromeIds.length} songs`);
-                const navidromePlaylistId = await createNavidromePlaylist(playlist.name, allNavidromeIds);
+                const navidromePlaylistId = await createNavidromePlaylist(playlist.name, uniqueAllNavidromeIds);
                 playlist.navidromePlaylistId = navidromePlaylistId;
             } else {
                 // Try creating empty playlist? Subsonic API usually requires songId.