fix(library): multi-genre local index with track_genre and backfill (#1059)

* fix(library): multi-genre local index with track_genre and backfill

Restore atomic genre browse, filters, and counts via track_genre:
OpenSubsonic genres[] first with Navidrome-default split fallback, sync
write path, read-path query switches, blocking startup backfill with
progress, and v12 repair migration for DBs that recorded legacy 002–011.
TS fallback adds genreTagsFor and migration gate i18n across locales.

* fix(library): address multi-genre review — robust TS genres and scope join

genreTagsFor routes raw genres through parseItemGenres (single-object
Subsonic quirk and bare strings). Library-scoped genre browse/counts join
track for raw_json library_id fallback. Statistics keeps empty-genre bucket.

* docs: CHANGELOG and credits for multi-genre local index (PR #1059)

* docs(changelog): credit HiveMind on Discord for multi-genre report (PR #1059)

src/api/library.ts

@@ -892,3 +892,24 @@ export function subscribeLibrarySyncIdle(
     handler(payload),
   );
 }
+
+// ── Genre tags startup backfill (multi-genre local index) ───────────────
+
+export interface GenreTagsInspectDto {
+  needed: boolean;
+  totalTracks: number;
+  doneTracks: number;
+}
+
+export interface GenreTagsProgressEvent {
+  done: number;
+  total: number;
+}
+
+export function libraryGenreTagsInspect(): Promise<GenreTagsInspectDto> {
+  return invoke<GenreTagsInspectDto>('library_genre_tags_inspect');
+}
+
+export function libraryGenreTagsRun(): Promise<void> {
+  return invoke<void>('library_genre_tags_run');
+}

src/api/navidromeBrowse.ts

@@ -1,4 +1,5 @@
 import type { SubsonicAlbum, SubsonicArtist, SubsonicSong } from './subsonicTypes';
+import { parseItemGenres } from '../utils/library/genreTags';
 import { invoke } from '@tauri-apps/api/core';
 import { useAuthStore } from '../store/authStore';
 import { ndLogin } from './navidromeAdmin';
@@ -54,6 +55,7 @@ function mapNdSong(o: Record<string, unknown>): SubsonicSong {
     userRating: asNumber(o.rating),
     starred: o.starred ? asString(o.starredAt) || 'true' : undefined,
     genre: typeof o.genre === 'string' ? o.genre : undefined,
+    genres: parseItemGenres(o.genres),
     bitRate: asNumber(o.bitRate),
     suffix: typeof o.suffix === 'string' ? o.suffix : undefined,
     contentType: typeof o.contentType === 'string' ? o.contentType : undefined,
@@ -166,6 +168,7 @@ function mapNdAlbum(o: Record<string, unknown>): SubsonicAlbum {
     duration: asNumber(o.duration) ?? 0,
     year: asNumber(o.maxYear) ?? asNumber(o.year),
     genre: typeof o.genre === 'string' ? o.genre : undefined,
+    genres: parseItemGenres(o.genres),
     starred: starredFlag ? (starredAt ?? 'true') : undefined,
     userRating: asNumber(o.rating),
     isCompilation: o.compilation === true,
@@ -383,6 +386,7 @@ export async function ndListLosslessAlbumsPage(req: NdLosslessPageRequest): Prom
         duration: 0,
         year: asNumber(o.year),
         genre: typeof o.genre === 'string' ? o.genre : undefined,
+        genres: parseItemGenres(o.genres),
       };
       pageEntries.push({ album, bitDepth, sampleRate: asNumber(o.sampleRate) ?? 0 });
     }

src/api/subsonicStatistics.ts

@@ -1,4 +1,5 @@
 import { useAuthStore } from '../store/authStore';
+import { genreTagsFor } from '../utils/library/genreTags';
 import { getArtists } from './subsonicArtists';
 import { getAlbumList, getRandomSongs } from './subsonicLibrary';
 import type {
@@ -54,14 +55,17 @@ export async function fetchStatisticsLibraryAggregates(): Promise<StatisticsLibr
         albumsCounted += 1;
         const sc = a.songCount ?? 0;
         songsCounted += sc;
-        const label = (a.genre?.trim()) ? a.genre.trim() : '';
-        let g = genreAgg.get(label);
-        if (!g) {
-          g = { songCount: 0, albumCount: 0 };
-          genreAgg.set(label, g);
+        const tags = genreTagsFor(a);
+        const labels = tags.length > 0 ? tags : [''];
+        for (const label of labels) {
+          let g = genreAgg.get(label);
+          if (!g) {
+            g = { songCount: 0, albumCount: 0 };
+            genreAgg.set(label, g);
+          }
+          g.songCount += sc;
+          g.albumCount += 1;
         }
-        g.songCount += sc;
-        g.albumCount += 1;
       }
       if (albums.length < pageSize) break;
       offset += pageSize;

src/api/subsonicTypes.ts

@@ -1,5 +1,10 @@
 import type { SubsonicServerIdentity } from '../utils/server/subsonicServerIdentity';
 
+/** OpenSubsonic `ItemGenre` on songs/albums (atomic genres from the server). */
+export interface SubsonicItemGenre {
+  name: string;
+}
+
 export interface SubsonicAlbum {
   id: string;
   name: string;
@@ -11,6 +16,8 @@ export interface SubsonicAlbum {
   playCount?: number;
   year?: number;
   genre?: string;
+  /** OpenSubsonic atomic genres — preferred over splitting `genre`. */
+  genres?: SubsonicItemGenre[];
   starred?: string;
   recordLabel?: string;
   created?: string;
@@ -72,6 +79,8 @@ export interface SubsonicSong {
   channelCount?: number;
   starred?: string;
   genre?: string;
+  /** OpenSubsonic atomic genres — preferred over splitting `genre`. */
+  genres?: SubsonicItemGenre[];
   path?: string;
   albumArtist?: string;
   /** OpenSubsonic: single-string album-artist for display (mirrors `albumArtists` joined). */