fix: tighten lyric placeholder detection

backend/src/main/java/com/music/service/LyricsService.java

@@ -127,6 +127,7 @@ public class LyricsService {
         String normalized = lyrics.replace("\uFEFF", "").replace("\r", "");
         int lines = 0;
         int chars = 0;
+        int timedLines = 0;
         for (String raw : normalized.split("\\n")) {
             String line = raw.trim();
             if (line.isEmpty() || line.matches("^\\[(?:ti|ar|al|by|re|ve|offset):.*$")) continue;
@@ -134,8 +135,10 @@ public class LyricsService {
             String body = timed.matches() ? timed.group(1).trim() : line;
             if (body.isEmpty() || META_LINE.matcher(body).matches()) continue;
             lines++;
+            if (timed.matches()) timedLines++;
             chars += body.replaceAll("\\s+", "").length();
         }
+        if (timedLines > 0) return lines >= 3 && chars >= 12;
         return lines >= 2 && chars >= 8;
     }
     private static byte[] readLimited(InputStream in) throws Exception { try (InputStream x = in; ByteArrayOutputStream b = new ByteArrayOutputStream()) { byte[] buf = new byte[8192]; int n, total = 0; while ((n = x.read(buf)) >= 0) { total += n; if (total > MAX_BYTES) throw new IllegalArgumentException("歌词响应过大"); b.write(buf, 0, n); } return b.toByteArray(); } }

backend/src/test/java/com/music/service/LibraryHealthServiceTest.java

@@ -30,7 +30,7 @@ class LibraryHealthServiceTest {
         Path album = root.resolve("Artist").resolve("Album");
         Files.createDirectories(album);
         Files.write(album.resolve("01 - Song.mp3"), new byte[]{1, 2, 3});
-        Files.write(album.resolve("01 - Song.lrc"), "[00:01]first line\n[00:02]second line".getBytes(StandardCharsets.UTF_8));
+        Files.write(album.resolve("01 - Song.lrc"), "[00:01]first line\n[00:02]second line\n[00:03]third line".getBytes(StandardCharsets.UTF_8));
         Files.write(album.resolve("orphan.lrc"), "[00:01]orphan".getBytes(StandardCharsets.UTF_8));
         Files.write(album.resolve("cover.jpg"), new byte[]{(byte) 0xFF, (byte) 0xD8, (byte) 0xFF});
         return album;
@@ -244,7 +244,7 @@ class LibraryHealthServiceTest {
             Files.createDirectories(album);
             // 大写 .LRC 侧车：既不应算缺歌词，也不应算孤立（与 orphan 判定保持一致）
             Files.write(album.resolve("01 - Song.mp3"), new byte[]{1, 2, 3});
-            Files.write(album.resolve("01 - Song.LRC"), "[00:01]first line\n[00:02]second line".getBytes(StandardCharsets.UTF_8));
+            Files.write(album.resolve("01 - Song.LRC"), "[00:01]first line\n[00:02]second line\n[00:03]third line".getBytes(StandardCharsets.UTF_8));
 
             LibraryHealthService svc = newService(root);
             LibraryHealthReport report = svc.scan(false);

backend/src/test/java/com/music/service/LyricsServiceTest.java

@@ -22,8 +22,8 @@ class LyricsServiceTest {
     @Test
     void selectsExactArtistInsteadOfFirstCoverCandidate() throws Exception {
         String json = "["
-                + "{\"title\":\"夜曲 (网易云音乐)\",\"artist\":\"Xai小爱\",\"lyrics\":\"[00:01]翻唱第一句\\n[00:02]翻唱第二句\",\"type\":\"lrc\",\"source\":\"netease\"},"
-                + "{\"title\":\"夜曲 (酷狗音乐)\",\"artist\":\"周杰伦\",\"lyrics\":\"[00:01]一群嗜血的蚂蚁\\n[00:02]被腐肉所吸引\",\"type\":\"lrc\",\"source\":\"kugou\",\"isComplete\":true}]";
+                + "{\"title\":\"夜曲 (网易云音乐)\",\"artist\":\"Xai小爱\",\"lyrics\":\"[00:01]翻唱第一句\\n[00:02]翻唱第二句\\n[00:03]翻唱第三句\",\"type\":\"lrc\",\"source\":\"netease\"},"
+                + "{\"title\":\"夜曲 (酷狗音乐)\",\"artist\":\"周杰伦\",\"lyrics\":\"[00:01]一群嗜血的蚂蚁\\n[00:02]被腐肉所吸引\\n[00:03]我面无表情\",\"type\":\"lrc\",\"source\":\"kugou\",\"isComplete\":true}]";
         start(json, 200);
         LyricsService.Candidate result = new LyricsService().lookup("夜曲", "周杰伦");
         assertNotNull(result);
@@ -45,7 +45,7 @@ class LyricsServiceTest {
 
     @Test
     void acceptsTimestampedLyrics() {
-        assertTrue(LyricsService.hasMeaningfulLyrics("[00:01.00]第一句歌词\n[00:03.00]第二句歌词\n"));
+        assertTrue(LyricsService.hasMeaningfulLyrics("[00:01.00]第一句歌词\n[00:03.00]第二句歌词\n[00:05.00]第三句歌词\n"));
     }
 
     private void start(String body, int status) throws Exception {