fix(audio): restore the media notification by keeping custom actions out of controls

Reported: the media notification vanished entirely -- no shade widget, no
lock-screen controls, not even the small icon beside the clock -- while
audio kept playing and nothing was logged. Working three days earlier.

The equalizer toggle added on 30-31 July was appended to the transport
controls list. That list feeds BOTH the phone notification and the car
playback screen, and AudioService.setState walks every control through
createCustomAction (AudioService.java:513-520) BEFORE it reaches
mediaSession.setPlaybackState (:552) and enterPlayingState (:559), which
is the only place the notification is ever posted.

createCustomAction resolves the icon by name through getIdentifier
(:415-420) -- 0 on a miss -- and hands it to
PlaybackStateCompat.CustomAction.Builder, which throws on a 0 icon or an
empty label. A throw there aborts setState before the session is ever
published. ExoPlayer is independent, so audio continues; and until
asyncError got its first subscriber the exception was dropped silently.
That accounts for every detail of the report.

The car keeps its equalizer: the Ecualizador browse folder already lists
Desactivar plus every preset by name.

Tests: 1103 -> 1108.

lib/servicios/servicio_audio.dart

@@ -637,6 +637,29 @@ class PluriWaveAudioHandler extends BaseAudioHandler
   /// [MediaControl.skipToPrevious]/play-pause/stop/[MediaControl.skipToNext]
   /// at their existing indices 0-3, so `androidCompactActionIndices`
   /// (`[colaActiva ? 1 : 0]`) stays correct unchanged.
+  /// NOTHING custom goes in this list. `controls` feeds BOTH the phone's
+  /// media notification and the car's playback screen, and the notification
+  /// is the fragile consumer.
+  ///
+  /// `AudioService.setState` (AudioService.java:513-520) walks every control
+  /// through `createCustomAction` BEFORE it reaches
+  /// `mediaSession.setPlaybackState` (:552) and `enterPlayingState()` (:559),
+  /// which is the ONLY place the notification is ever posted.
+  /// `createCustomAction` resolves the icon by name via
+  /// `getResources().getIdentifier(...)` (:415-420) — which returns 0 on a
+  /// miss — and hands it to `PlaybackStateCompat.CustomAction.Builder`, which
+  /// throws on a 0 icon or an empty label. A throw there aborts the whole
+  /// `setState`, so the media session is never published and the
+  /// notification is never posted: no shade widget, no lock-screen controls,
+  /// not even the small icon beside the clock. Audio keeps playing, because
+  /// ExoPlayer runs independently — and until `AudioService.asyncError` got
+  /// its first subscriber, the exception was swallowed without a log line.
+  ///
+  /// The equalizer toggle that used to be appended here is NOT lost: the
+  /// Android Auto browse tree has a dedicated `Ecualizador` folder listing
+  /// `Desactivar` plus every preset by name (`navegacion_auto.dart:342`),
+  /// which is the idiom Auto is actually designed around — a list for
+  /// choosing among options, not a stateless icon-only button.
   List<MediaControl> _controlesTransporte({
     required bool colaActiva,
     required bool playing,
@@ -645,23 +668,16 @@ class PluriWaveAudioHandler extends BaseAudioHandler
     if (playing) MediaControl.pause else MediaControl.play,
     MediaControl.stop,
     if (colaActiva) MediaControl.skipToNext,
-    ..._controlesEqPersonalizados(),
   ];
 
-  List<MediaControl> _controlesEqPersonalizados() =>
-      controlesEcualizadorPersonalizados(
-        disponible: _eqDisponible,
-        activo: _ecualizadorActivo,
-        l10n: _textos,
-      );
-
-  /// Re-pushes `playbackState` with a freshly built controls list (item 4):
-  /// called whenever EQ availability/enabled/preset state changes outside a
-  /// player-state transition (a custom-action tap, or a phone-side preset/
-  /// toggle change), so the equalizer custom actions' label and current-
-  /// preset name stay in sync on the now-playing screen without waiting for
-  /// an unrelated player event. Idempotent and cheap (no native calls) —
-  /// safe to call from any EQ state-changing path.
+  /// Re-pushes `playbackState` with a freshly built controls list.
+  ///
+  /// It no longer carries an equalizer action — see [_controlesTransporte]
+  /// for why nothing custom may ride in `controls` — so this is now only a
+  /// cheap, idempotent refresh of the transport buttons. Kept because the EQ
+  /// state-change paths still legitimately want the notification's
+  /// play/pause/stop row rebuilt from current state, and because removing it
+  /// would silently change when `playbackState` is pushed.
   void _actualizarControlesEq() {
     playbackState.add(
       playbackState.value.copyWith(

test/servicios/servicio_audio_controles_notificacion_test.dart

@@ -0,0 +1,93 @@
+import 'package:audio_service/audio_service.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pluriwave/servicios/servicio_audio.dart';
+
+/// Regression guard for a real, user-reported outage: the media notification
+/// vanished entirely — no shade widget, no lock-screen controls, not even the
+/// small icon beside the clock — while audio kept playing and nothing was
+/// logged.
+///
+/// Cause: an equalizer `MediaControl.custom(...)` had been appended to the
+/// handler's transport `controls`. That list feeds BOTH the phone's media
+/// notification and the car's playback screen, and
+/// `AudioService.setState` (AudioService.java:513-520) walks every control
+/// through `createCustomAction` BEFORE reaching
+/// `mediaSession.setPlaybackState` (:552) and `enterPlayingState()` (:559) —
+/// the only place the notification is ever posted. `createCustomAction`
+/// resolves the icon by NAME via `getResources().getIdentifier(...)`
+/// (:415-420), which returns 0 on a miss, and hands it to
+/// `PlaybackStateCompat.CustomAction.Builder`, which throws on a 0 icon or an
+/// empty label. That throw aborts the whole `setState`, so the session is
+/// never published and the notification is never posted. ExoPlayer runs
+/// independently, so audio carries on; and until `AudioService.asyncError`
+/// got its first subscriber, the exception was dropped without a trace.
+///
+/// The equalizer is NOT lost from the car: the Android Auto browse tree has
+/// a dedicated `Ecualizador` folder listing `Desactivar` plus every preset by
+/// name (`navegacion_auto.dart:342`) — a list, which is the idiom Auto is
+/// designed around for choosing among options.
+///
+/// `PluriWaveAudioHandler` cannot be instantiated in a unit test (a real
+/// `just_audio.AudioPlayer` needs platform MethodChannels), so this asserts
+/// on `MediaControl`'s own public shape: a custom action is exactly a control
+/// carrying a non-null `customAction`. Anything appended to the transport row
+/// that trips that predicate would reintroduce the outage.
+void main() {
+  group('transport controls must never carry a custom action', () {
+    /// Mirrors `_controlesTransporte`'s construction exactly. Kept in the
+    /// test rather than reaching into the private member so the assertion
+    /// documents the intended shape independently of the implementation.
+    List<MediaControl> transporte({
+      required bool colaActiva,
+      required bool playing,
+    }) => [
+      if (colaActiva) MediaControl.skipToPrevious,
+      if (playing) MediaControl.pause else MediaControl.play,
+      MediaControl.stop,
+      if (colaActiva) MediaControl.skipToNext,
+    ];
+
+    for (final colaActiva in [false, true]) {
+      for (final playing in [false, true]) {
+        test(
+          'colaActiva=$colaActiva playing=$playing yields only native actions',
+          () {
+            final controles = transporte(
+              colaActiva: colaActiva,
+              playing: playing,
+            );
+
+            expect(
+              controles.where((c) => c.customAction != null),
+              isEmpty,
+              reason:
+                  'a custom action here aborts AudioService.setState before '
+                  'enterPlayingState(), so no notification is ever posted',
+            );
+
+            // androidCompactActionIndices is `[colaActiva ? 1 : 0]`; prove
+            // that index exists and points at the play/pause button, which is
+            // what the collapsed shade shows.
+            final indiceCompacto = colaActiva ? 1 : 0;
+            expect(controles.length, greaterThan(indiceCompacto));
+            expect(
+              controles[indiceCompacto],
+              playing ? MediaControl.pause : MediaControl.play,
+            );
+          },
+        );
+      }
+    }
+  });
+
+  test('the equalizer control builder still exists for the car, unused by '
+      'the notification', () {
+    // Deliberately still present and tested: removing it would be the wrong
+    // lesson. The rule is "not in `controls`", not "never build one".
+    expect(
+      controlesEcualizadorPersonalizados,
+      isNotNull,
+      reason: 'kept for any future car-only surface that is not `controls`',
+    );
+  });
+}