feat(auto): equalizer folder in the browse tree, one toggle on playback

On-device feedback: two identical icons on the car's now-playing screen,
one of which looked dead. It worked -- but head units render custom
actions icon-first, so cycling six presets behind one static glyph was
invisible.

A monochrome icon cannot encode which of six presets is active. Android
Auto separates the idioms deliberately: custom actions for stateless
toggles, browsable lists for choosing among options.

- Playback screen keeps one action: equalizer on/off, state-aware icons
- New Ecualizador folder lists Desactivar plus the six presets by name,
  active one marked
- The preset-cycling action and its drawable are removed

Supersedes the redesign's no-equalizer-folder rule, which predated
knowing custom actions do not surface state in a car.

# Conflicts:
#	lib/l10n/app_ar.arb
#	lib/l10n/app_bn.arb
#	lib/l10n/app_de.arb
#	lib/l10n/app_en.arb
#	lib/l10n/app_es.arb
#	lib/l10n/app_fr.arb
#	lib/l10n/app_hi.arb
#	lib/l10n/app_id.arb
#	lib/l10n/app_it.arb
#	lib/l10n/app_ja.arb
#	lib/l10n/app_pt.arb
#	lib/l10n/app_ru.arb
#	lib/l10n/app_zh.arb

android/app/src/main/res/drawable/ic_auto_eq_off.xml

@@ -0,0 +1,3 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android" android:width="24dp" android:height="24dp" android:viewportWidth="24" android:viewportHeight="24">
+  <path android:fillColor="#FFFFFF" android:pathData="M3,5L21,5L21,7L3,7Z M14,3L17,3L17,9L14,9Z M3,11L21,11L21,13L3,13Z M7,9L10,9L10,15L7,15Z M3,17L21,17L21,19L3,19Z M17,15L20,15L20,21L17,21Z M2,20L4,22L22,4L20,2Z" />
+</vector>

android/app/src/main/res/drawable/ic_auto_eq_on.xml

@@ -0,0 +1,3 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android" android:width="24dp" android:height="24dp" android:viewportWidth="24" android:viewportHeight="24">
+  <path android:fillColor="#FFFFFF" android:pathData="M3,5L21,5L21,7L3,7Z M14,3L17,3L17,9L14,9Z M3,11L21,11L21,13L3,13Z M7,9L10,9L10,15L7,15Z M3,17L21,17L21,19L3,19Z M17,15L20,15L20,21L17,21Z" />
+</vector>

lib/l10n/app_ar.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "إصلاح",
   "alarmDiagnosticsIntentUnavailable": "تعذّر فتح شاشة الإعدادات هذه على هذا الهاتف. حاول البحث عنها يدويًا في الإعدادات.",
-  "alarmDiagnosticsUnavailableHint": "لم نتمكّن بعد من التحقق من إعدادات المنبه الخاصة بك."
+  "alarmDiagnosticsUnavailableHint": "لم نتمكّن بعد من التحقق من إعدادات المنبه الخاصة بك.",
+  "autoEqDisableOption": "تعطيل"
 }

lib/l10n/app_bn.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "সমাধান করুন",
   "alarmDiagnosticsIntentUnavailable": "এই ফোনে সেই সেটিংস স্ক্রিনটি খোলা যায়নি। সেটিংসে ম্যানুয়ালি খুঁজে দেখার চেষ্টা করুন।",
-  "alarmDiagnosticsUnavailableHint": "আমরা এখনও আপনার অ্যালার্ম সেটিংস পরীক্ষা করতে পারিনি।"
+  "alarmDiagnosticsUnavailableHint": "আমরা এখনও আপনার অ্যালার্ম সেটিংস পরীক্ষা করতে পারিনি।",
+  "autoEqDisableOption": "বন্ধ করুন"
 }

lib/l10n/app_de.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "Beheben",
   "alarmDiagnosticsIntentUnavailable": "Diese Einstellungsseite konnte auf diesem Telefon nicht geöffnet werden. Suche sie manuell in den Einstellungen.",
-  "alarmDiagnosticsUnavailableHint": "Wir konnten deine Alarmeinstellungen noch nicht prüfen."
+  "alarmDiagnosticsUnavailableHint": "Wir konnten deine Alarmeinstellungen noch nicht prüfen.",
+  "autoEqDisableOption": "Deaktivieren"
 }

lib/l10n/app_en.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "Fix this",
   "alarmDiagnosticsIntentUnavailable": "Couldn't open that settings screen on this phone. Try looking for it manually in Settings.",
-  "alarmDiagnosticsUnavailableHint": "We couldn't check your alarm settings yet."
+  "alarmDiagnosticsUnavailableHint": "We couldn't check your alarm settings yet.",
+  "autoEqDisableOption": "Disable"
 }

lib/l10n/app_es.arb

@@ -833,5 +833,6 @@
   },
   "alarmDiagnosticsFixAction": "Solucionar",
   "alarmDiagnosticsIntentUnavailable": "No se pudo abrir esa pantalla de ajustes en este teléfono. Buscala manualmente en Ajustes.",
-  "alarmDiagnosticsUnavailableHint": "Todavía no pudimos revisar tus ajustes de alarma."
+  "alarmDiagnosticsUnavailableHint": "Todavía no pudimos revisar tus ajustes de alarma.",
+  "autoEqDisableOption": "Desactivar"
 }

lib/l10n/app_fr.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "Corriger",
   "alarmDiagnosticsIntentUnavailable": "Impossible d'ouvrir cet écran de paramètres sur ce téléphone. Essayez de le trouver manuellement dans les Paramètres.",
-  "alarmDiagnosticsUnavailableHint": "Nous n'avons pas encore pu vérifier vos paramètres d'alarme."
+  "alarmDiagnosticsUnavailableHint": "Nous n'avons pas encore pu vérifier vos paramètres d'alarme.",
+  "autoEqDisableOption": "Désactiver"
 }

lib/l10n/app_hi.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "ठीक करें",
   "alarmDiagnosticsIntentUnavailable": "इस फ़ोन पर वह सेटिंग्स स्क्रीन नहीं खोली जा सकी। कृपया सेटिंग्स में इसे खुद ढूंढने की कोशिश करें।",
-  "alarmDiagnosticsUnavailableHint": "हम अभी तक आपकी अलार्म सेटिंग्स जांच नहीं पाए हैं।"
+  "alarmDiagnosticsUnavailableHint": "हम अभी तक आपकी अलार्म सेटिंग्स जांच नहीं पाए हैं।",
+  "autoEqDisableOption": "बंद करें"
 }

lib/l10n/app_id.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "Perbaiki",
   "alarmDiagnosticsIntentUnavailable": "Tidak bisa membuka layar pengaturan itu di ponsel ini. Coba cari secara manual di Pengaturan.",
-  "alarmDiagnosticsUnavailableHint": "Kami belum bisa memeriksa pengaturan alarmmu."
+  "alarmDiagnosticsUnavailableHint": "Kami belum bisa memeriksa pengaturan alarmmu.",
+  "autoEqDisableOption": "Nonaktifkan"
 }

lib/l10n/app_it.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "Risolvi",
   "alarmDiagnosticsIntentUnavailable": "Non è stato possibile aprire questa schermata delle impostazioni su questo telefono. Prova a cercarla manualmente nelle Impostazioni.",
-  "alarmDiagnosticsUnavailableHint": "Non abbiamo ancora potuto controllare le impostazioni della sveglia."
+  "alarmDiagnosticsUnavailableHint": "Non abbiamo ancora potuto controllare le impostazioni della sveglia.",
+  "autoEqDisableOption": "Disattiva"
 }

lib/l10n/app_ja.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "修正する",
   "alarmDiagnosticsIntentUnavailable": "この端末では設定画面を開けませんでした。設定アプリ内で手動で探してみてください。",
-  "alarmDiagnosticsUnavailableHint": "アラームの設定をまだ確認できていません。"
+  "alarmDiagnosticsUnavailableHint": "アラームの設定をまだ確認できていません。",
+  "autoEqDisableOption": "無効化"
 }

lib/l10n/app_pt.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "Resolver",
   "alarmDiagnosticsIntentUnavailable": "Não foi possível abrir essa tela de configurações neste telefone. Tente procurá-la manualmente nas Configurações.",
-  "alarmDiagnosticsUnavailableHint": "Ainda não conseguimos verificar as configurações do seu alarme."
+  "alarmDiagnosticsUnavailableHint": "Ainda não conseguimos verificar as configurações do seu alarme.",
+  "autoEqDisableOption": "Desativar"
 }

lib/l10n/app_ru.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "Исправить",
   "alarmDiagnosticsIntentUnavailable": "Не удалось открыть этот экран настроек на этом телефоне. Попробуйте найти его вручную в Настройках.",
-  "alarmDiagnosticsUnavailableHint": "Мы пока не смогли проверить настройки вашего будильника."
+  "alarmDiagnosticsUnavailableHint": "Мы пока не смогли проверить настройки вашего будильника.",
+  "autoEqDisableOption": "Отключить"
 }

lib/l10n/app_zh.arb

@@ -874,5 +874,6 @@
   },
   "alarmDiagnosticsFixAction": "解决",
   "alarmDiagnosticsIntentUnavailable": "无法在此手机上打开该设置界面。请尝试在设置中手动查找。",
-  "alarmDiagnosticsUnavailableHint": "我们还无法检查你的闹钟设置。"
+  "alarmDiagnosticsUnavailableHint": "我们还无法检查你的闹钟设置。",
+  "autoEqDisableOption": "关闭"
 }

lib/l10n/gen/app_localizations.dart

@@ -3187,6 +3187,12 @@ abstract class AppLocalizations {
   /// In es, this message translates to:
   /// **'Todavía no pudimos revisar tus ajustes de alarma.'**
   String get alarmDiagnosticsUnavailableHint;
+
+  /// No description provided for @autoEqDisableOption.
+  ///
+  /// In es, this message translates to:
+  /// **'Desactivar'**
+  String get autoEqDisableOption;
 }
 
 class _AppLocalizationsDelegate

lib/l10n/gen/app_localizations_ar.dart

@@ -1760,4 +1760,7 @@ class AppLocalizationsAr extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'لم نتمكّن بعد من التحقق من إعدادات المنبه الخاصة بك.';
+
+  @override
+  String get autoEqDisableOption => 'تعطيل';
 }

lib/l10n/gen/app_localizations_bn.dart

@@ -1768,4 +1768,7 @@ class AppLocalizationsBn extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'আমরা এখনও আপনার অ্যালার্ম সেটিংস পরীক্ষা করতে পারিনি।';
+
+  @override
+  String get autoEqDisableOption => 'বন্ধ করুন';
 }

lib/l10n/gen/app_localizations_de.dart

@@ -1782,4 +1782,7 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'Wir konnten deine Alarmeinstellungen noch nicht prüfen.';
+
+  @override
+  String get autoEqDisableOption => 'Deaktivieren';
 }

lib/l10n/gen/app_localizations_en.dart

@@ -1762,4 +1762,7 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'We couldn\'t check your alarm settings yet.';
+
+  @override
+  String get autoEqDisableOption => 'Disable';
 }

lib/l10n/gen/app_localizations_es.dart

@@ -1778,4 +1778,7 @@ class AppLocalizationsEs extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'Todavía no pudimos revisar tus ajustes de alarma.';
+
+  @override
+  String get autoEqDisableOption => 'Desactivar';
 }

lib/l10n/gen/app_localizations_fr.dart

@@ -1788,4 +1788,7 @@ class AppLocalizationsFr extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'Nous n\'avons pas encore pu vérifier vos paramètres d\'alarme.';
+
+  @override
+  String get autoEqDisableOption => 'Désactiver';
 }

lib/l10n/gen/app_localizations_hi.dart

@@ -1763,4 +1763,7 @@ class AppLocalizationsHi extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'हम अभी तक आपकी अलार्म सेटिंग्स जांच नहीं पाए हैं।';
+
+  @override
+  String get autoEqDisableOption => 'बंद करें';
 }

lib/l10n/gen/app_localizations_id.dart

@@ -1772,4 +1772,7 @@ class AppLocalizationsId extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'Kami belum bisa memeriksa pengaturan alarmmu.';
+
+  @override
+  String get autoEqDisableOption => 'Nonaktifkan';
 }

lib/l10n/gen/app_localizations_it.dart

@@ -1786,4 +1786,7 @@ class AppLocalizationsIt extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'Non abbiamo ancora potuto controllare le impostazioni della sveglia.';
+
+  @override
+  String get autoEqDisableOption => 'Disattiva';
 }

lib/l10n/gen/app_localizations_ja.dart

@@ -1711,4 +1711,7 @@ class AppLocalizationsJa extends AppLocalizations {
 
   @override
   String get alarmDiagnosticsUnavailableHint => 'アラームの設定をまだ確認できていません。';
+
+  @override
+  String get autoEqDisableOption => '無効化';
 }

lib/l10n/gen/app_localizations_pt.dart

@@ -1773,4 +1773,7 @@ class AppLocalizationsPt extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'Ainda não conseguimos verificar as configurações do seu alarme.';
+
+  @override
+  String get autoEqDisableOption => 'Desativar';
 }

lib/l10n/gen/app_localizations_ru.dart

@@ -1778,4 +1778,7 @@ class AppLocalizationsRu extends AppLocalizations {
   @override
   String get alarmDiagnosticsUnavailableHint =>
       'Мы пока не смогли проверить настройки вашего будильника.';
+
+  @override
+  String get autoEqDisableOption => 'Отключить';
 }

lib/l10n/gen/app_localizations_zh.dart

@@ -1699,4 +1699,7 @@ class AppLocalizationsZh extends AppLocalizations {
 
   @override
   String get alarmDiagnosticsUnavailableHint => '我们还无法检查你的闹钟设置。';
+
+  @override
+  String get autoEqDisableOption => '关闭';
 }

lib/servicios/navegacion_auto.dart

@@ -10,6 +10,7 @@ import '../estado/orden_emisoras.dart';
 import '../modelos/emisora.dart';
 import '../modelos/grupo_favoritos.dart';
 import '../modelos/pista_local.dart';
+import '../modelos/preset_ecualizador.dart';
 import 'musica_local_auto.dart';
 import 'persistencia_tolerante.dart';
 import 'servicio_favoritos.dart';
@@ -19,16 +20,22 @@ import 'servicio_favoritos.dart';
 /// no [NodoLocal] coupling — so a future paged folder type can reuse the
 /// slice arithmetic directly. An empty [items] or a [pagina] beyond the
 /// list's range returns `[]`, never throws.
-List<T> paginaDe<T>(List<T> items, {required int pagina, required int tamano}) =>
-    items.skip(pagina * tamano).take(tamano).toList();
+List<T> paginaDe<T>(
+  List<T> items, {
+  required int pagina,
+  required int tamano,
+}) => items.skip(pagina * tamano).take(tamano).toList();
 
 /// Whether a page after [pagina] exists for a list of [total] elements
 /// (Design ADR-6): `true` iff at least one element remains beyond the
 /// current page's slice. The exact-boundary case
 /// (`total == (pagina + 1) * tamano`) is `false` — nothing remains to
 /// reveal.
-bool hayPaginaSiguiente(int total, {required int pagina, required int tamano}) =>
-    total > (pagina + 1) * tamano;
+bool hayPaginaSiguiente(
+  int total, {
+  required int pagina,
+  required int tamano,
+}) => total > (pagina + 1) * tamano;
 
 /// Browse-tree ordering comparator for a local-music folder's children
 /// (Design "Directories before files", item 1): directories sort before
@@ -83,8 +90,7 @@ bool faviconUsable(String? favicon) {
   // even with an empty host (e.g. `Uri.parse('http://').hasAuthority` is
   // `true`) — check `host.isNotEmpty` explicitly to actually require a
   // non-empty authority host.
-  return (uri.scheme == 'http' || uri.scheme == 'https') &&
-      uri.host.isNotEmpty;
+  return (uri.scheme == 'http' || uri.scheme == 'https') && uri.host.isNotEmpty;
 }
 
 /// Deterministic rotation index over the 4 on-brand fallback arts, same
@@ -98,10 +104,11 @@ int indiceArtePara(String seed) =>
 /// drawable URI selected via [indiceArtePara] over `e.uuid` — the same
 /// on-brand art the phone UI would pick for this station (per-station
 /// parity), never a launcher-icon lookalike.
-String artUriPara(Emisora e) => faviconUsable(e.favicon)
-    ? e.favicon!
-    : 'android.resource://es.freetimelab.pluriwave/drawable/'
-        'station_art_${_nombresArte[indiceArtePara(e.uuid)]}';
+String artUriPara(Emisora e) =>
+    faviconUsable(e.favicon)
+        ? e.favicon!
+        : 'android.resource://es.freetimelab.pluriwave/drawable/'
+            'station_art_${_nombresArte[indiceArtePara(e.uuid)]}';
 
 /// Formats a human-readable audio-quality hint for the browse row's
 /// `displaySubtitle` (Design Decision "`displaySubtitle` quality format"):
@@ -212,6 +219,17 @@ class ConstructorArbolAuto {
   /// (Design "Local root hidden until a folder is configured").
   static const idMusicaLocal = 'musica_local';
 
+  /// Root folder id for the "Ecualizador" browsable folder (decision
+  /// `auto/ecualizador-diseno`): lists "Desactivar" plus the six factory
+  /// presets, the currently-active one marked. Deliberately NOT added to
+  /// [_idsCarpetas] -- like [idMusicaLocal], it has its own dedicated
+  /// children, built by `itemsEcualizadorAuto` in `servicio_audio.dart`
+  /// (which needs `AppLocalizations` -- this pure builder class does not
+  /// depend on it), not the generic station-list [hijos] path. Unlike
+  /// [idMusicaLocal], it is ALWAYS present in [raiz], never conditionally
+  /// hidden.
+  static const idEcualizador = 'ecualizador';
+
   static const _idsCarpetas = {idFavoritos, idTodas, idMisEmisoras};
   static const _maxItemsPorCarpeta = 50;
 
@@ -295,12 +313,23 @@ class ConstructorArbolAuto {
   };
 
   /// The root folders (Favoritos, Todas las emisoras, Mis emisoras,
-  /// optionally Música Local), all non-playable.
+  /// optionally Música Local, Ecualizador), all non-playable.
   ///
-  /// There is deliberately no equalizer folder: EQ is configured on the phone
-  /// only. The car still gets the right sound, because the per-device preset
-  /// is applied automatically when the output device changes — that lives in
-  /// `EstadoEcualizador`, not in this tree.
+  /// Decision `auto/ecualizador-diseno` SUPERSEDES the "no equalizer
+  /// folder" rule that used to live in this doc comment (commit `2403da3`,
+  /// mirroring the redesign mockup's "sin carpeta de ecualizador", turn t4
+  /// line 40). That rule was sound when written, but predated on-device
+  /// feedback showing that Android Auto custom actions don't surface
+  /// enough state for choosing among six presets: a monochrome icon cannot
+  /// legibly encode "which preset", and many head units render a custom
+  /// action icon-first, hiding its label. `Ecualizador` is a real
+  /// browsable folder again: "Desactivar" first, then the six factory
+  /// presets, the active one marked (children built by
+  /// `itemsEcualizadorAuto` in `servicio_audio.dart` -- this class stays
+  /// free of any `AppLocalizations` dependency, unlike that builder).
+  /// Always present, and LAST in the list (after Música Local, when
+  /// included) -- unlike [idMusicaLocal] it is never conditionally hidden.
+  /// Do not "restore" the no-folder rule without re-reading that decision.
   ///
   /// `Música Local` is OMITTED entirely (not just empty) unless
   /// [incluirMusicaLocal] is `true` (Design "Local root hidden until a folder
@@ -311,6 +340,7 @@ class ConstructorArbolAuto {
     _carpeta(idTodas, 'Todas las emisoras'),
     _carpeta(idMisEmisoras, 'Mis emisoras'),
     if (incluirMusicaLocal) _carpeta(idMusicaLocal, 'Música Local'),
+    _carpeta(idEcualizador, 'Ecualizador'),
   ];
 
   MediaItem _carpeta(String id, String titulo) => MediaItem(
@@ -457,10 +487,11 @@ class ConstructorArbolAuto {
     final construir = construirItem ?? _itemLocal;
     final ordenados = [...nodos]..sort(compararNodoLocalParaNavegacion);
     final paginaActual = paginaDe(ordenados, pagina: pagina, tamano: tamano);
-    final docIds = paginaActual
-        .where((n) => !n.esDirectorio)
-        .map((n) => n.documentId)
-        .toList();
+    final docIds =
+        paginaActual
+            .where((n) => !n.esDirectorio)
+            .map((n) => n.documentId)
+            .toList();
     final metadatos = await metadatosDe(docIds);
     final items = paginaActual.map((n) => construir(n, metadatos)).toList();
     if (hayPaginaSiguiente(ordenados.length, pagina: pagina, tamano: tamano)) {
@@ -486,8 +517,7 @@ class ConstructorArbolAuto {
         // (direct or nested), absent for a folder that is genuinely empty
         // even recursively (Spec "Folder has no tracks").
         if (hayContenidoReproducible) _itemReproducirCarpeta(documentIdPadre),
-        if (hayContenidoReproducible)
-          _itemReproducirAleatorio(documentIdPadre),
+        if (hayContenidoReproducible) _itemReproducirAleatorio(documentIdPadre),
         if (ofreceOrdenCalidad(totalPistas))
           _itemModoOrdenCalidad(documentIdPadre),
         if (ofreceBuckets(totalPistas))
@@ -725,10 +755,11 @@ class ConstructorArbolAuto {
     final ordenados = [...buckets[idxBucket].nodos]
       ..sort((a, b) => a.nombre.compareTo(b.nombre));
     final paginaActual = paginaDe(ordenados, pagina: pagina, tamano: tamano);
-    final docIds = paginaActual
-        .where((n) => !n.esDirectorio)
-        .map((n) => n.documentId)
-        .toList();
+    final docIds =
+        paginaActual
+            .where((n) => !n.esDirectorio)
+            .map((n) => n.documentId)
+            .toList();
     final metadatos = await metadatosDe(docIds);
     final items = paginaActual.map((n) => construir(n, metadatos)).toList();
     if (hayPaginaSiguiente(ordenados.length, pagina: pagina, tamano: tamano)) {
@@ -743,20 +774,21 @@ class ConstructorArbolAuto {
     }
     final meta = metadatos[nodo.documentId];
     final tituloMeta = meta?.titulo?.trim();
-    final titulo = (tituloMeta != null && tituloMeta.isNotEmpty)
-        ? tituloMeta
-        : _tituloDesdeNombre(nodo.nombre);
+    final titulo =
+        (tituloMeta != null && tituloMeta.isNotEmpty)
+            ? tituloMeta
+            : _tituloDesdeNombre(nodo.nombre);
     final artUriMeta = meta?.artUri?.trim();
-    final artUri = (artUriMeta != null && artUriMeta.isNotEmpty)
-        ? artUriMeta
-        : artUriLocal(nodo.documentId);
+    final artUri =
+        (artUriMeta != null && artUriMeta.isNotEmpty)
+            ? artUriMeta
+            : artUriLocal(nodo.documentId);
     final artistaMeta = meta?.artista?.trim();
     return MediaItem(
       id: '$_prefijoPista${nodo.documentId}',
       title: titulo,
-      artist: (artistaMeta != null && artistaMeta.isNotEmpty)
-          ? artistaMeta
-          : null,
+      artist:
+          (artistaMeta != null && artistaMeta.isNotEmpty) ? artistaMeta : null,
       playable: true,
       artUri: Uri.parse(artUri),
       displaySubtitle: subtituloCalidadLocal(meta),
@@ -777,15 +809,17 @@ class ConstructorArbolAuto {
     required List<GrupoFavoritos> grupos,
     required List<Emisora> favoritos,
   }) {
-    final carpetas = grupos
-        .where((g) => !g.esSinAsignar)
-        .where((g) => favoritos.any((e) => e.grupoFavoritosId == g.id))
-        .take(_maxGruposPorFavoritos)
-        .map(itemGrupo)
-        .toList();
-    final sinAsignar = favoritos
-        .where((e) => e.grupoFavoritosId == GrupoFavoritos.sinAsignarId)
-        .toList();
+    final carpetas =
+        grupos
+            .where((g) => !g.esSinAsignar)
+            .where((g) => favoritos.any((e) => e.grupoFavoritosId == g.id))
+            .take(_maxGruposPorFavoritos)
+            .map(itemGrupo)
+            .toList();
+    final sinAsignar =
+        favoritos
+            .where((e) => e.grupoFavoritosId == GrupoFavoritos.sinAsignarId)
+            .toList();
     return [...carpetas, ...hijos(idFavoritos, emisoras: sinAsignar)];
   }
 
@@ -801,13 +835,62 @@ class ConstructorArbolAuto {
     if (!esCarpetaGrupo(grupoMediaId)) return const [];
     final id = grupoMediaId.substring(_prefijoGrupo.length);
     if (id.isEmpty) return const [];
-    final miembros = favoritos
-        .where((e) => e.grupoFavoritosId == id)
-        .toList();
+    final miembros = favoritos.where((e) => e.grupoFavoritosId == id).toList();
     if (miembros.isEmpty) return const [];
     final ordenados = ordenarEmisoras(miembros, OrdenEmisoras.calidad);
     return ordenados.take(_maxItemsPorCarpeta).map(itemEmisora).toList();
   }
+
+  /// Equalizer preset-selection media-id prefix (decision
+  /// `auto/ecualizador-diseno`): `eq_preset:<rawPresetName>` for the six
+  /// factory presets, plus the reserved [_valorDesactivarEq] sentinel for
+  /// the "Desactivar" item ([idDesactivarEq]). Collision-free against every
+  /// other prefix/bare id in this class -- diverges from every sibling
+  /// prefix at the very first character ('e' vs 'g'/'c'/'p') and from every
+  /// bare folder id (none of which starts with "eq_preset:").
+  static const _prefijoPresetEq = 'eq_preset:';
+
+  /// Reserved sentinel raw value for the "Desactivar" item under
+  /// [_prefijoPresetEq] (decision `auto/ecualizador-diseno`) -- never
+  /// collides with a real [PresetEcualizador.nombre]; none of the six
+  /// factory presets is named this.
+  static const _valorDesactivarEq = '_off_';
+
+  /// The "Desactivar" item's media id: the reserved [_valorDesactivarEq]
+  /// sentinel under [_prefijoPresetEq].
+  static const idDesactivarEq = '$_prefijoPresetEq$_valorDesactivarEq';
+
+  /// Whether [id] identifies an item under the Ecualizador folder (a
+  /// factory preset OR "Desactivar").
+  bool esPresetEqMediaId(String id) => id.startsWith(_prefijoPresetEq);
+
+  /// Whether [id] is specifically the "Desactivar" item (not a factory
+  /// preset). Only meaningful alongside [esPresetEqMediaId].
+  bool esDesactivarEqMediaId(String id) => id == idDesactivarEq;
+
+  /// Builds a factory preset's selection media id, matched by raw
+  /// (untranslated) [PresetEcualizador.nombre] -- the SAME identity
+  /// [PresetEcualizador.presets] already uses for equality, so a locale
+  /// change never breaks resolution.
+  String idPresetEq(String nombrePreset) => '$_prefijoPresetEq$nombrePreset';
+
+  /// Resolves an `eq_preset:<nombre>` [id] to the matching factory
+  /// [PresetEcualizador] from [presets] (defaults to
+  /// [PresetEcualizador.presets]), comparing by raw `nombre`. Returns
+  /// `null` for the [_valorDesactivarEq] sentinel, an unresolvable name, or
+  /// any id that doesn't match [esPresetEqMediaId] -- never throws.
+  PresetEcualizador? resolverPresetEq(
+    String id, {
+    List<PresetEcualizador>? presets,
+  }) {
+    if (!esPresetEqMediaId(id) || esDesactivarEqMediaId(id)) return null;
+    final nombre = id.substring(_prefijoPresetEq.length);
+    final lista = presets ?? PresetEcualizador.presets;
+    for (final preset in lista) {
+      if (preset.nombre == nombre) return preset;
+    }
+    return null;
+  }
 }
 
 /// Routing seam between a car-tapped `emisora:<uuid>` media id and the
@@ -847,6 +930,43 @@ Future<void> reproducirPorMediaId(
   await reproducir(item);
 }
 
+/// Routing seam for a car-tapped `eq_preset:<...>` media id (decision
+/// `auto/ecualizador-diseno`, mirrors [reproducirPorMediaId]'s seam
+/// shape): dispatches "Desactivar" to [activarEcualizador]`(false)`, and a
+/// resolved factory preset to [aplicarPreset] -- turning the equalizer
+/// back ON via [activarEcualizador]`(true)` AFTERWARDS whenever [activo]
+/// is currently `false`, so tapping a preset while the equalizer is off
+/// both re-enables it AND applies the tapped preset's gains (Spec
+/// "selecting a preset while disabled enables it and applies it"), never
+/// silently just remembering the preset for later. [aplicarPreset] runs
+/// BEFORE the enable check so the native engine only ever pushes gains
+/// once, for the NEW preset -- never once for whatever was active before,
+/// then again for the new one.
+///
+/// A stale/unresolvable id, or any id that doesn't match
+/// [ConstructorArbolAuto.esPresetEqMediaId], is a no-op: neither callback
+/// runs and no exception propagates.
+Future<void> seleccionarPresetEqPorMediaId(
+  String id, {
+  required bool activo,
+  required Future<void> Function(PresetEcualizador) aplicarPreset,
+  required Future<void> Function(bool) activarEcualizador,
+}) async {
+  final constructor = ConstructorArbolAuto();
+  if (!constructor.esPresetEqMediaId(id)) return;
+
+  if (constructor.esDesactivarEqMediaId(id)) {
+    await activarEcualizador(false);
+    return;
+  }
+
+  final preset = constructor.resolverPresetEq(id);
+  if (preset == null) return;
+
+  await aplicarPreset(preset);
+  if (!activo) await activarEcualizador(true);
+}
+
 /// Fallback title (Design "Title = filename minus extension") for a blank
 /// or otherwise empty-after-stripping local filename — hardcoded Spanish,
 /// matching every other car-tree label in this file (`'Favoritos'`,
@@ -904,10 +1024,8 @@ List<NodoLocal> ordenarPorCalidadLocal(
 ) {
   final ordenados = List<NodoLocal>.from(nodos);
   ordenados.sort(
-    (a, b) => compararCalidadLocal(
-      metadatos[a.documentId],
-      metadatos[b.documentId],
-    ),
+    (a, b) =>
+        compararCalidadLocal(metadatos[a.documentId], metadatos[b.documentId]),
   );
   return ordenados;
 }
@@ -948,12 +1066,13 @@ List<BucketLocal> bucketsDe(List<NodoLocal> nodos) {
   final pistas = nodos.where((n) => !n.esDirectorio).toList();
   return _rangosBucket.map((rango) {
     final (etiqueta, desde, hasta) = rango;
-    final coincidencias = pistas.where((n) {
-      final recortado = n.nombre.trim();
-      if (recortado.isEmpty) return false;
-      final letra = recortado[0].toLowerCase();
-      return letra.compareTo(desde) >= 0 && letra.compareTo(hasta) <= 0;
-    }).toList();
+    final coincidencias =
+        pistas.where((n) {
+          final recortado = n.nombre.trim();
+          if (recortado.isEmpty) return false;
+          final letra = recortado[0].toLowerCase();
+          return letra.compareTo(desde) >= 0 && letra.compareTo(hasta) <= 0;
+        }).toList();
     return BucketLocal(etiqueta: etiqueta, nodos: coincidencias);
   }).toList();
 }
@@ -1119,9 +1238,10 @@ Future<void> reproducirCarpetaLocal(
   }
 
   final recolectadas = await pistasRecursivas(documentId, fuente: fuente);
-  final pistas = aleatorio
-      ? mezclarFisherYates(recolectadas, rng ?? Random())
-      : recolectadas;
+  final pistas =
+      aleatorio
+          ? mezclarFisherYates(recolectadas, rng ?? Random())
+          : recolectadas;
   if (pistas.isEmpty) return;
 
   await iniciarCola(pistas);

lib/servicios/servicio_audio.dart

@@ -66,7 +66,10 @@ void registrarFuenteMusicaLocal(FuenteMusicaLocalAuto fuente) {
 /// the browse tree and the car-tap path already show, instead of a blank
 /// tile on the car/lockscreen/notification. Pure — no [PluriWaveAudioHandler]
 /// dependency — so it is unit-testable without instantiating the handler.
-MediaItem mediaItemParaEmisora(Emisora emisora, {required AppLocalizations l10n}) {
+MediaItem mediaItemParaEmisora(
+  Emisora emisora, {
+  required AppLocalizations l10n,
+}) {
   return MediaItem(
     id: emisora.url,
     title: localizedStationName(l10n, emisora.nombre),
@@ -108,7 +111,6 @@ Emisora emisoraDesdeMediaItem(MediaItem mediaItem) {
 /// `MediaControl`/`customAction` namespace, never compared against a
 /// media id).
 const accionEqToggle = 'eq_toggle';
-const accionEqPresetSiguiente = 'eq_preset_siguiente';
 
 /// Advances to the NEXT factory preset after [actual] in [presets] order
 /// (Design "EQ custom actions — cycling presets", item 4): wraps around
@@ -151,38 +153,126 @@ String nombrePresetVisible(AppLocalizations l10n, String nombre) {
 }
 
 /// Builds the equalizer's custom-action `MediaControl`s for the now-playing
-/// screen (Design "EQ custom actions", item 4) — deliberately just 2: an
-/// on/off toggle plus a cycling-preset action, NOT one action per preset,
-/// since Android Auto only surfaces a limited number of custom actions.
+/// screen (decision `auto/ecualizador-diseno`) — exactly 1: an on/off
+/// toggle. The previous design paired this with a SECOND action that cycled
+/// through the six factory presets; that action is REMOVED. On-device
+/// feedback: many head units render custom actions icon-first, so two
+/// static, non-parametrized glyphs sitting side by side looked identical/
+/// dead even though the toggle's own icon DID change and the cycle action
+/// DID work — a monochrome icon simply cannot legibly encode "which of six
+/// presets" the way a browsable list's text rows can. Preset selection now
+/// lives in the "Ecualizador" browsable folder instead (see
+/// [itemsEcualizadorAuto]), which also frees this scarce custom-action
+/// slot. Do NOT re-add a preset-cycling custom action; extend the folder
+/// instead.
 /// Empty when [disponible] is false (gate on EQ availability, mirrors the
 /// existing `debeReaplicarEcualizador`/`_eqDisponible` gate) — a device
 /// without the native Equalizer effect gets no EQ actions at all, not
-/// broken ones. Reuses the SAME bundled `ic_stat_pluriwave` drawable the
-/// notification's own status-bar icon already uses (an equalizer-bars
-/// glyph) — zero new native assets. Pure, no handler dependency.
+/// broken ones.
+///
+/// On-device feedback follow-up: this action used to reuse the SAME
+/// `ic_stat_pluriwave` drawable as everything else and was visually
+/// indistinguishable on a car head unit, which foregrounds the icon over
+/// the label. It now gets its own dedicated drawables
+/// (`ic_auto_eq_on`/`ic_auto_eq_off`), and the icon itself reflects
+/// [activo] (not just its label) so on/off is legible at a glance. Pure, no
+/// handler dependency.
 List<MediaControl> controlesEcualizadorPersonalizados({
   required bool disponible,
   required bool activo,
-  required PresetEcualizador presetActual,
   required AppLocalizations l10n,
 }) {
   if (!disponible) return const [];
   return [
     MediaControl.custom(
-      androidIcon: 'drawable/ic_stat_pluriwave',
-      label: activo
-          ? l10n.eqCustomActionDisableLabel
-          : l10n.eqCustomActionEnableLabel,
+      androidIcon:
+          activo ? 'drawable/ic_auto_eq_on' : 'drawable/ic_auto_eq_off',
+      label:
+          activo
+              ? l10n.eqCustomActionDisableLabel
+              : l10n.eqCustomActionEnableLabel,
       name: accionEqToggle,
     ),
-    MediaControl.custom(
-      androidIcon: 'drawable/ic_stat_pluriwave',
-      label: l10n.eqCustomActionPresetLabel(
-        nombrePresetVisible(l10n, presetActual.nombre),
-      ),
-      name: accionEqPresetSiguiente,
+  ];
+}
+
+/// Content-style extras for the Ecualizador folder's items (decision
+/// `auto/ecualizador-diseno`), mirrors `ConstructorArbolAuto
+/// ._contentStyleLista` in `navegacion_auto.dart` — duplicated rather than
+/// exposed publicly (see [nombrePresetVisible]'s doc for why small pieces
+/// are deliberately duplicated across this handler/service layer and the
+/// pure browse-tree builder layer rather than cross-layer-shared). List
+/// style, not grid: these items are short text options with no artwork of
+/// their own, unlike a station or local-track tile.
+const _contentStyleListaEq = {
+  'android.media.browse.CONTENT_STYLE_BROWSABLE_HINT': 1,
+  'android.media.browse.CONTENT_STYLE_PLAYABLE_HINT': 1,
+};
+
+/// Marks the active Ecualizador-folder item by prefixing [titulo] with a
+/// checkmark glyph (decision `auto/ecualizador-diseno`, spec "the active
+/// preset must be visibly marked").
+///
+/// A `MediaItem.extras` completion-status flag (`androidx.media.utils.
+/// MediaConstants.DESCRIPTION_EXTRAS_KEY_COMPLETION_STATUS`) was considered
+/// and REJECTED as the marking mechanism: this project's `audio_service`
+/// version (0.18.18) has no Dart wrapper for it — only `AndroidContentStyle`
+/// 's list/grid hints are exposed — and the raw platform key itself is
+/// designed for playback-COMPLETION tracking (e.g. "this podcast episode
+/// was already listened to"), not item SELECTION; repurposing it here could
+/// render as "already played" on some head units, which would be actively
+/// misleading for a preset picker, and there is no way to verify its actual
+/// rendering on a real head unit from this environment. A plain-text
+/// marker renders identically and unambiguously on every head unit, which
+/// an unverifiable, semantically-mismatched extras key cannot guarantee.
+String _marcarActivoEq(String titulo, {required bool activo}) =>
+    activo ? '✓ $titulo' : titulo;
+
+/// Builds the "Ecualizador" folder's children for the Android Auto browse
+/// tree (decision `auto/ecualizador-diseno`): "Desactivar" FIRST, then the
+/// six factory presets in [PresetEcualizador.presets] order, each localized
+/// via [nombrePresetVisible] — the SAME helper the toggle's custom-action
+/// label already uses, so a preset's name reads identically whether the
+/// driver sees it in the now-playing screen's tooltip or in this folder.
+/// All items are playable: tapping one is dispatched through
+/// `playFromMediaId` -> `seleccionarPresetEqPorMediaId` (`navegacion_auto.
+/// dart`), the same seam every other browse-tree leaf already uses; this
+/// folder has no sub-browsing. Exactly one item is marked active via
+/// [_marcarActivoEq]: "Desactivar" when [activo] is `false`, otherwise
+/// whichever preset equals [presetActual] — never both at once, and never
+/// zero once this function is reached (an unresolvable [presetActual] with
+/// [activo] `true` simply marks nothing, which cannot happen in practice
+/// since [presetActual] always originates from [PresetEcualizador.presets]
+/// or a "Personalizado" tweak that would just leave every item unmarked
+/// rather than mis-marking one).
+List<MediaItem> itemsEcualizadorAuto({
+  required bool activo,
+  required PresetEcualizador presetActual,
+  required AppLocalizations l10n,
+}) {
+  final constructor = ConstructorArbolAuto();
+  final items = <MediaItem>[
+    MediaItem(
+      id: ConstructorArbolAuto.idDesactivarEq,
+      title: _marcarActivoEq(l10n.autoEqDisableOption, activo: !activo),
+      playable: true,
+      extras: _contentStyleListaEq,
     ),
   ];
+  for (final preset in PresetEcualizador.presets) {
+    items.add(
+      MediaItem(
+        id: constructor.idPresetEq(preset.nombre),
+        title: _marcarActivoEq(
+          nombrePresetVisible(l10n, preset.nombre),
+          activo: activo && preset == presetActual,
+        ),
+        playable: true,
+        extras: _contentStyleListaEq,
+      ),
+    );
+  }
+  return items;
 }
 
 /// Wrapper de alto nivel para el UI.
@@ -473,7 +563,6 @@ class PluriWaveAudioHandler extends BaseAudioHandler
       controlesEcualizadorPersonalizados(
         disponible: _eqDisponible,
         activo: _ecualizadorActivo,
-        presetActual: _presetActual,
         l10n: _textos,
       );
 
@@ -1081,14 +1170,17 @@ class PluriWaveAudioHandler extends BaseAudioHandler
     await _reproducirEntradaCola(anterior.actual);
   }
 
-  /// Dispatches the equalizer's 2 custom actions (item 4, Design "EQ custom
-  /// actions"): `accionEqToggle` flips on/off, `accionEqPresetSiguiente`
-  /// cycles to the next factory preset. Both delegate to the existing
-  /// [setEcualizadorActivo]/[aplicarPreset] — the SAME entry points the
+  /// Dispatches the equalizer's only custom action (decision
+  /// `auto/ecualizador-diseno`): `accionEqToggle` flips on/off, delegating
+  /// to the existing [setEcualizadorActivo] — the SAME entry point the
   /// phone settings screen uses via `EstadoEcualizador` — so a car tap and a
-  /// phone tap have identical effects and both refresh the custom action's
-  /// label via `_actualizarControlesEq()` (already wired into those two
-  /// methods). Any other [name] is a no-op — never throws.
+  /// phone tap have identical effects and both refresh the action's label
+  /// via `_actualizarControlesEq()` (already wired into that method). The
+  /// preset-cycling action that used to live here is REMOVED — preset
+  /// selection now goes through the "Ecualizador" browsable folder (see
+  /// `seleccionarPresetEqPorMediaId` in `navegacion_auto.dart`, dispatched
+  /// from [playFromMediaId] below). Any other [name] is a no-op — never
+  /// throws.
   @override
   Future<dynamic> customAction(
     String name, [
@@ -1097,8 +1189,6 @@ class PluriWaveAudioHandler extends BaseAudioHandler
     switch (name) {
       case accionEqToggle:
         await setEcualizadorActivo(!_ecualizadorActivo);
-      case accionEqPresetSiguiente:
-        await aplicarPreset(presetSiguiente(_presetActual));
     }
   }
 
@@ -1145,6 +1235,17 @@ class PluriWaveAudioHandler extends BaseAudioHandler
         fuente: fuenteLocal,
       );
       if (musicaLocal != null) return musicaLocal;
+      // Ecualizador folder (decision `auto/ecualizador-diseno`): needs no
+      // external data source, unlike every branch below it -- checked
+      // before the `_fuenteNavegacionGlobal` gate, mirroring how the
+      // local-music branch above is also resolved before that gate.
+      if (parentMediaId == ConstructorArbolAuto.idEcualizador) {
+        return itemsEcualizadorAuto(
+          activo: _ecualizadorActivo,
+          presetActual: _presetActual,
+          l10n: _textos,
+        );
+      }
       final fuente = _fuenteNavegacionGlobal;
       if (fuente == null) return const [];
       if (parentMediaId == ConstructorArbolAuto.idFavoritos) {
@@ -1215,14 +1316,24 @@ class PluriWaveAudioHandler extends BaseAudioHandler
         if (fuenteLocal == null) return;
         await reproducirCarpetaLocal(
           mediaId,
-          aleatorio: constructorArbol.esCarpetaLocalAleatorioMediaId(
-            mediaId,
-          ),
+          aleatorio: constructorArbol.esCarpetaLocalAleatorioMediaId(mediaId),
           fuente: fuenteLocal,
           iniciarCola: _iniciarColaLocal,
         );
         return;
       }
+      // Equalizer preset selection (decision `auto/ecualizador-diseno`):
+      // THIRD branch, same unconditional-return shape as the two above --
+      // an `eq_preset:` id never falls through to station routing.
+      if (constructorArbol.esPresetEqMediaId(mediaId)) {
+        await seleccionarPresetEqPorMediaId(
+          mediaId,
+          activo: _ecualizadorActivo,
+          aplicarPreset: aplicarPreset,
+          activarEcualizador: setEcualizadorActivo,
+        );
+        return;
+      }
       final fuente = _fuenteNavegacionGlobal;
       if (fuente == null) return;
       await reproducirPorMediaId(

test/servicios/servicio_audio_eq_custom_actions_test.dart

@@ -1,3 +1,4 @@
+import 'dart:io';
 import 'dart:ui' show Locale;
 
 import 'package:audio_service/audio_service.dart';
@@ -19,14 +20,8 @@ void main() {
 
   group('presetSiguiente (item 4 — cycling presets)', () {
     test('advances to the next preset in order', () {
-      expect(
-        presetSiguiente(PresetEcualizador.flat),
-        PresetEcualizador.rock,
-      );
-      expect(
-        presetSiguiente(PresetEcualizador.rock),
-        PresetEcualizador.pop,
-      );
+      expect(presetSiguiente(PresetEcualizador.flat), PresetEcualizador.rock);
+      expect(presetSiguiente(PresetEcualizador.rock), PresetEcualizador.pop);
     });
 
     test('wraps around after the last preset', () {
@@ -36,21 +31,15 @@ void main() {
       );
     });
 
-    test(
-      'an unknown/custom preset (e.g. a user-tweaked "Personalizado" band '
-      'set) starts from the FIRST preset instead of throwing',
-      () {
-        final personalizado = PresetEcualizador(
-          nombre: 'Personalizado',
-          bandas: [1.0, 2.0, 3.0, 4.0, 5.0],
-        );
+    test('an unknown/custom preset (e.g. a user-tweaked "Personalizado" band '
+        'set) starts from the FIRST preset instead of throwing', () {
+      final personalizado = PresetEcualizador(
+        nombre: 'Personalizado',
+        bandas: [1.0, 2.0, 3.0, 4.0, 5.0],
+      );
 
-        expect(
-          presetSiguiente(personalizado),
-          PresetEcualizador.presets.first,
-        );
-      },
-    );
+      expect(presetSiguiente(personalizado), PresetEcualizador.presets.first);
+    });
 
     test('respects an injected presets list instead of the default 6', () {
       final propios = [PresetEcualizador.jazz, PresetEcualizador.voz];
@@ -84,7 +73,10 @@ void main() {
     });
 
     test('an unrecognized name falls through verbatim', () {
-      expect(nombrePresetVisible(l10n, 'Mi Preset Guardado'), 'Mi Preset Guardado');
+      expect(
+        nombrePresetVisible(l10n, 'Mi Preset Guardado'),
+        'Mi Preset Guardado',
+      );
     });
   });
 
@@ -93,35 +85,32 @@ void main() {
       final controles = controlesEcualizadorPersonalizados(
         disponible: false,
         activo: true,
-        presetActual: PresetEcualizador.flat,
         l10n: l10n,
       );
 
       expect(controles, isEmpty);
     });
 
-    test(
-      'exactly 2 custom actions when available: on/off toggle + preset '
-      'cycle -- Android Auto shows a limited number of custom actions, so '
-      'this is deliberately NOT one action per preset',
-      () {
-        final controles = controlesEcualizadorPersonalizados(
-          disponible: true,
-          activo: true,
-          presetActual: PresetEcualizador.rock,
-          l10n: l10n,
-        );
+    test('exactly 1 custom action when available: the on/off toggle -- '
+        'decision `auto/ecualizador-diseno` REMOVES the preset-cycling '
+        'action that used to sit alongside it; preset selection now lives '
+        'in the "Ecualizador" browsable folder instead (see '
+        '`itemsEcualizadorAuto`)', () {
+      final controles = controlesEcualizadorPersonalizados(
+        disponible: true,
+        activo: true,
+        l10n: l10n,
+      );
 
-        expect(controles, hasLength(2));
-        expect(controles.every((c) => c.action == MediaAction.custom), isTrue);
-      },
-    );
+      expect(controles, hasLength(1));
+      expect(controles.single.action, MediaAction.custom);
+      expect(controles.single.customAction?.name, accionEqToggle);
+    });
 
     test('toggle label reflects ON -> shows "disable" action', () {
       final controles = controlesEcualizadorPersonalizados(
         disponible: true,
         activo: true,
-        presetActual: PresetEcualizador.flat,
         l10n: l10n,
       );
       final toggle = controles.firstWhere(
@@ -135,7 +124,6 @@ void main() {
       final controles = controlesEcualizadorPersonalizados(
         disponible: true,
         activo: false,
-        presetActual: PresetEcualizador.flat,
         l10n: l10n,
       );
       final toggle = controles.firstWhere(
@@ -145,45 +133,68 @@ void main() {
       expect(toggle.label, l10n.eqCustomActionEnableLabel);
     });
 
-    test('preset-cycle label shows the CURRENT preset localized name', () {
-      final controles = controlesEcualizadorPersonalizados(
+    test('toggle icon reflects EQ state: ON uses ic_auto_eq_on, OFF uses '
+        'ic_auto_eq_off -- a car head unit foregrounds the icon over the '
+        'label, so the icon itself must change, not just the text', () {
+      final activado = controlesEcualizadorPersonalizados(
         disponible: true,
         activo: true,
-        presetActual: PresetEcualizador.jazz,
         l10n: l10n,
-      );
-      final ciclo = controles.firstWhere(
-        (c) => c.customAction?.name == accionEqPresetSiguiente,
-      );
-
-      expect(
-        ciclo.label,
-        l10n.eqCustomActionPresetLabel(l10n.equalizerPresetJazz),
-      );
-    });
-
-    test('both actions reuse the bundled notification drawable (zero new '
-        'native assets)', () {
-      final controles = controlesEcualizadorPersonalizados(
+      ).firstWhere((c) => c.customAction?.name == accionEqToggle);
+      final desactivado = controlesEcualizadorPersonalizados(
         disponible: true,
-        activo: true,
-        presetActual: PresetEcualizador.flat,
+        activo: false,
         l10n: l10n,
-      );
+      ).firstWhere((c) => c.customAction?.name == accionEqToggle);
 
-      expect(
-        controles.every((c) => c.androidIcon == 'drawable/ic_stat_pluriwave'),
-        isTrue,
-      );
+      expect(activado.androidIcon, 'drawable/ic_auto_eq_on');
+      expect(desactivado.androidIcon, 'drawable/ic_auto_eq_off');
     });
   });
 
-  group('action name constants (item 4 — collision-free with car-tree ids)', () {
-    test('names are non-empty, distinct, and do not collide with any '
-        'existing browse-tree media-id prefix', () {
-      expect(accionEqToggle, isNotEmpty);
-      expect(accionEqPresetSiguiente, isNotEmpty);
-      expect(accionEqToggle, isNot(equals(accionEqPresetSiguiente)));
+  group(
+    'action name constants (item 4 -- collision-free with car-tree ids)',
+    () {
+      test('accionEqToggle is non-empty and does not collide with any '
+          'existing browse-tree media-id prefix -- accionEqPresetSiguiente '
+          '(decision `auto/ecualizador-diseno`: removed, superseded by the '
+          '"Ecualizador" browsable folder) no longer exists as a symbol at '
+          'all, which this file compiling proves on its own', () {
+        expect(accionEqToggle, isNotEmpty);
+      });
+    },
+  );
+
+  group('equalizer drawable assets on disk (on-device feedback follow-up: the '
+      'two custom actions used to share one drawable and were visually '
+      'indistinguishable)', () {
+    test('ic_auto_eq_on and ic_auto_eq_off exist under '
+        'android/app/src/main/res/drawable/ -- a missing drawable is not a '
+        'build error, it silently renders blank/default on the head unit, '
+        'so this is the only safety net that would have caught the '
+        'original duplication. ic_auto_eq_preset is deliberately NOT '
+        'checked here anymore -- decision `auto/ecualizador-diseno` '
+        'removes the preset-cycling action and its drawable', () {
+      for (final nombre in ['ic_auto_eq_on', 'ic_auto_eq_off']) {
+        final archivo = File('android/app/src/main/res/drawable/$nombre.xml');
+        expect(
+          archivo.existsSync(),
+          isTrue,
+          reason:
+              '$nombre.xml must exist under '
+              'android/app/src/main/res/drawable/',
+        );
+      }
+      expect(
+        File(
+          'android/app/src/main/res/drawable/ic_auto_eq_preset.xml',
+        ).existsSync(),
+        isFalse,
+        reason:
+            'ic_auto_eq_preset.xml must be REMOVED -- decision '
+            '`auto/ecualizador-diseno` retires the preset-cycling '
+            'custom action it belonged to',
+      );
     });
   });
 }

test/servicios/servicio_audio_eq_folder_test.dart

@@ -0,0 +1,123 @@
+import 'dart:ui' show Locale;
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pluriwave/l10n/gen/app_localizations.dart';
+import 'package:pluriwave/modelos/preset_ecualizador.dart';
+import 'package:pluriwave/servicios/navegacion_auto.dart';
+import 'package:pluriwave/servicios/servicio_audio.dart';
+
+/// Decision `auto/ecualizador-diseno` -- the "Ecualizador" browsable
+/// folder's item-building (`itemsEcualizadorAuto`), the pure,
+/// `AppLocalizations`-dependent half of the folder feature. Lives in a
+/// dedicated file, separate from `servicio_audio_eq_custom_actions_test.dart`
+/// (which covers the now-playing screen's on/off toggle) because this is a
+/// different car UI surface: a browsable folder, not a custom action.
+void main() {
+  final l10n = lookupAppLocalizations(const Locale('es'));
+
+  group('itemsEcualizadorAuto (decision `auto/ecualizador-diseno`)', () {
+    test('devuelve exactamente 7 items: Desactivar primero, luego los 6 '
+        'presets de fábrica, todos playable', () {
+      final items = itemsEcualizadorAuto(
+        activo: true,
+        presetActual: PresetEcualizador.flat,
+        l10n: l10n,
+      );
+
+      expect(items, hasLength(7));
+      expect(items.first.id, ConstructorArbolAuto.idDesactivarEq);
+      for (final item in items) {
+        expect(item.playable, isTrue);
+      }
+    });
+
+    test('los 6 presets aparecen en el mismo orden que '
+        'PresetEcualizador.presets, cada uno con su id eq_preset:<nombre>', () {
+      final items = itemsEcualizadorAuto(
+        activo: true,
+        presetActual: PresetEcualizador.flat,
+        l10n: l10n,
+      );
+      final builder = ConstructorArbolAuto();
+
+      final idsPresets = items.skip(1).map((i) => i.id).toList();
+      final idsEsperados =
+          PresetEcualizador.presets
+              .map((p) => builder.idPresetEq(p.nombre))
+              .toList();
+
+      expect(idsPresets, idsEsperados);
+    });
+
+    test('los nombres de preset están localizados vía nombrePresetVisible, '
+        'no crudos', () {
+      final items = itemsEcualizadorAuto(
+        activo: true,
+        presetActual: PresetEcualizador.flat,
+        l10n: l10n,
+      );
+      final builder = ConstructorArbolAuto();
+
+      final rock = items.firstWhere(
+        (i) => i.id == builder.idPresetEq(PresetEcualizador.rock.nombre),
+      );
+
+      expect(rock.title, contains(nombrePresetVisible(l10n, 'Rock')));
+    });
+
+    test('con el ecualizador ACTIVO, el preset actual queda marcado y '
+        'Desactivar NO', () {
+      final items = itemsEcualizadorAuto(
+        activo: true,
+        presetActual: PresetEcualizador.jazz,
+        l10n: l10n,
+      );
+      final builder = ConstructorArbolAuto();
+
+      final desactivar = items.firstWhere(
+        (i) => i.id == ConstructorArbolAuto.idDesactivarEq,
+      );
+      final jazz = items.firstWhere(
+        (i) => i.id == builder.idPresetEq(PresetEcualizador.jazz.nombre),
+      );
+      final marcados = items.where((i) => i.title.contains('✓')).toList();
+
+      expect(desactivar.title, isNot(contains('✓')));
+      expect(jazz.title, contains('✓'));
+      expect(marcados, hasLength(1));
+      expect(marcados.single.id, jazz.id);
+    });
+
+    test('con el ecualizador DESACTIVADO, Desactivar queda marcado y NINGÚN '
+        'preset lo está', () {
+      final items = itemsEcualizadorAuto(
+        activo: false,
+        presetActual: PresetEcualizador.rock,
+        l10n: l10n,
+      );
+
+      final desactivar = items.firstWhere(
+        (i) => i.id == ConstructorArbolAuto.idDesactivarEq,
+      );
+      final marcados = items.where((i) => i.title.contains('✓')).toList();
+
+      expect(desactivar.title, contains('✓'));
+      expect(marcados, hasLength(1));
+      expect(marcados.single.id, ConstructorArbolAuto.idDesactivarEq);
+    });
+
+    test('el label de Desactivar usa l10n.autoEqDisableOption', () {
+      final items = itemsEcualizadorAuto(
+        activo: false,
+        presetActual: PresetEcualizador.flat,
+        l10n: l10n,
+      );
+
+      final desactivar = items.firstWhere(
+        (i) => i.id == ConstructorArbolAuto.idDesactivarEq,
+      );
+
+      expect(desactivar.title, contains(l10n.autoEqDisableOption));
+    });
+  });
+}