feat: add SimpMusic as a synced lyrics source

src/datasource/youtube/YouTubeMusicDataSource.ts

@@ -203,6 +203,10 @@ type BetterLyricsResponse = {
    was really decided by the order of an array literal. It is now the LYRICS_SOURCES table. */
 type LyricsProviderResult = Lyrics;
 
+type SimpMusicResponse = {
+  data?: Array<{ syncedLyrics?: string | null; vote?: number }>;
+};
+
 type RawLikeEndpoint = {
   status?: string;
   target?: string | {
@@ -4658,6 +4662,7 @@ export class YouTubeMusicDataSource extends DataSource {
       "lrclib-exact": () => this.fetchLrcLibExactLyrics(track),
       betterlyrics: () => this.fetchBetterLyrics(track),
       "lrclib-search": () => this.fetchLrcLibSearchLyrics(track),
+      simpmusic: () => this.fetchSimpMusicLyrics(track),
       "youtube-transcript": () => this.fetchYouTubeTranscriptLyrics(track),
       "youtube-music": () => this.fetchYouTubeMusicLyrics(track),
     };
@@ -4929,6 +4934,28 @@ export class YouTubeMusicDataSource extends DataSource {
     return null;
   }
 
+  // Keyed by video ID, so never another recording; ranked below LRCLIB because entries can be translations (#129).
+  private async fetchSimpMusicLyrics(track: Track): Promise<LyricsProviderResult | null> {
+    const response = await tauriFetch(
+      `https://api-lyrics.simpmusic.org/v1/${encodeURIComponent(track.id)}`,
+      { headers: this.getLyricsRequestHeaders(), timeoutMs: 3_500 },
+    );
+    if (!response.ok) return null;
+
+    const body = await response.json() as SimpMusicResponse;
+    const best = (body.data ?? [])
+      .filter((entry) => entry.syncedLyrics)
+      .sort((left, right) => (right.vote ?? 0) - (left.vote ?? 0))[0];
+    const lines = best?.syncedLyrics ? this.parseSyncedLyrics(best.syncedLyrics) : [];
+    if (lines.length === 0) return null;
+
+    logInternalInfo("YouTubeMusicDataSource.getLyrics SimpMusic success", {
+      trackId: track.id,
+      lineCount: lines.length,
+    });
+    return { lines, timing: "synced", sourceLabel: "SimpMusic" };
+  }
+
   private toLrcLibLyrics(
     track: Track,
     match: LrcLibTrack,

src/datasource/youtube/lyricsSources.check.ts

@@ -39,7 +39,7 @@ const synced = (count: number) => ({
   timing: "synced" as const,
 });
 
-equal(LYRICS_SOURCES.length, 5, "every source is in the table");
+equal(LYRICS_SOURCES.length, 6, "every source is in the table");
 check(
   rankOfSource("lrclib-exact") < rankOfSource("lrclib-search"),
   "a duration-exact match outranks a text search of the same corpus",
@@ -139,7 +139,7 @@ equal(
 
 const defaultWaves = planLyricsWaves();
 equal(defaultWaves.length, 2, "by default the expensive sources are held back to a second wave");
-equal(defaultWaves[0].length, 3, "three cheap sources race first");
+equal(defaultWaves[0].length, 4, "four cheap sources race first");
 check(
   defaultWaves[1].every((source) => source.wave === 2),
   "and only wave two sources are held back",
@@ -161,7 +161,7 @@ equal(
 );
 equal(
   planLyricsWaves("lrclib-exact")[0].length,
-  3,
+  4,
   "preferring a source already in wave one does not duplicate it",
 );
 

src/datasource/youtube/lyricsSources.ts

@@ -15,7 +15,7 @@ export interface LyricsSource {
    *
    * Declared here rather than left as an early `return null` inside the fetcher, because a
    * fetcher that quietly returns nothing is indistinguishable from one that searched and
-   * found nothing — which is how two of five sources went missing on every track without a
+   * found nothing — which is how two of the sources went missing on every track without a
    * duration while the UI cheerfully reported "No match".
    */
   requiresDuration?: boolean;
@@ -55,6 +55,13 @@ export const LYRICS_SOURCES: LyricsSource[] = [
     requiresDuration: true,
     note: "Same corpus, matched by text within two seconds of duration — can land on a different master.",
   },
+  {
+    id: "simpmusic",
+    label: "SimpMusic",
+    timeoutMs: 3_500,
+    wave: 1,
+    note: "Line-synced and keyed to this exact video, but community entries are sometimes translations.",
+  },
   {
     id: "youtube-transcript",
     label: "YouTube transcript",

src/ui/pages/LyricsView.tsx

@@ -778,7 +778,7 @@ const SyncedLine = memo(function SyncedLine({
  *
  * "No lyrics available" is the least useful sentence a music app can show — it gives the
  * listener nothing to act on and gives a bug report nothing to go on. This turns it into a
- * fact: which of the five ranked sources was asked, how long it took, and why it lost.
+ * fact: which of the ranked sources was asked, how long it took, and why it lost.
  */
 function LyricsSourcePanel({
   attempts,