fix(alarma-sonando): pulsing halo, hero-time metrics, art size, snooze icon

Tier 4 visual fidelity, audit 9.1/9.5/9.6/9.8 (t4 lines 411-428):

- 9.1: new _HaloPulsante renders the prototype's 420px amber radial
  gradient behind the hero content. Deliberately BOUNDED (one
  grow-and-settle cycle), not the prototype's literal `infinite` CSS
  animation: this screen's protected dismiss-guard test calls
  pumpAndSettle() after every mount/interaction, and a genuinely
  infinite AnimationController.repeat() would hang it forever with no
  way to fix it. Skips its Animate wrapper under reduced motion, same
  as every other entry animation in this app.
- 9.5: the hero time gets a local letterSpacing/height override
  (-4/0.95) instead of the shared heroTime token's -2.0/1.0 — the
  alarm editor's hour block is the token's other consumer and still
  wants height:1, so the shared style is untouched.
- 9.6: ringing-screen art grows from 168/radiusLg(30) to 180/36 (t4
  line 421), a local constant like the existing stop-button radius.
- 9.8: the POSPONER eyebrow regains its 19px warmCoral snooze icon.

All 5 protected files (including the dismiss-guard test) remain
empty-diff against main.

lib/pantallas/pantalla_alarma_sonando.dart

@@ -3,6 +3,7 @@ import 'dart:ui';
 
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
+import 'package:flutter_animate/flutter_animate.dart';
 import 'package:provider/provider.dart';
 
 import '../estado/estado_alarmas.dart';
@@ -199,6 +200,17 @@ class _PantallaAlarmaSonandoState extends State<PantallaAlarmaSonando> {
         fit: StackFit.expand,
         children: [
           _FondoArteDifuminado(tokens: tokens),
+          // Audit 9.1 (t4 line 411): the pulsing amber halo behind the
+          // hero content — see _HaloPulsante for why it is a BOUNDED pulse,
+          // not the prototype's literal `infinite` animation.
+          Positioned(
+            top: 150,
+            left: 0,
+            right: 0,
+            child: IgnorePointer(
+              child: Center(child: _HaloPulsante(tokens: tokens)),
+            ),
+          ),
           SafeArea(
             child: Padding(
               padding: const EdgeInsets.fromLTRB(24, 20, 24, 24),
@@ -218,7 +230,15 @@ class _PantallaAlarmaSonandoState extends State<PantallaAlarmaSonando> {
                     child: Text(
                       _hora(alarma),
                       key: const ValueKey('ringing-hero-time'),
-                      style: type.heroTime,
+                      // Audit 9.5 (t4 line 417): 88px/w800/ls-4/lh.95 on
+                      // THIS screen only — a local override, not a change
+                      // to the shared heroTime token (EditorHoraInline, the
+                      // alarm editor's hour block, is the other consumer
+                      // and wants height:1, t4 line 379).
+                      style: type.heroTime.copyWith(
+                        letterSpacing: -4,
+                        height: 0.95,
+                      ),
                     ),
                   ),
                   const SizedBox(height: 6),
@@ -229,11 +249,11 @@ class _PantallaAlarmaSonandoState extends State<PantallaAlarmaSonando> {
                   ),
                   const SizedBox(height: 22),
                   ClipRRect(
-                    borderRadius: BorderRadius.circular(tokens.radiusLg),
+                    borderRadius: BorderRadius.circular(_artworkRadio),
                     child: Image.asset(
                       'assets/icons/alarmas/alarm_music.png',
-                      width: 168,
+                      width: _artworkLado,
-                      height: 168,
+                      height: _artworkLado,
                       fit: BoxFit.cover,
                       errorBuilder:
                           (_, __, ___) => Icon(
@@ -280,11 +300,24 @@ class _PantallaAlarmaSonandoState extends State<PantallaAlarmaSonando> {
                   const Spacer(flex: 3),
                   Align(
                     alignment: Alignment.centerLeft,
-                    child: Text(
+                    child: Row(
-                      l10n.snoozeAction,
+                      mainAxisSize: MainAxisSize.min,
-                      style: type.eyebrowLabel.copyWith(
+                      children: [
-                        color: tokens.warmCoral,
+                        // Audit 9.8 (t4 line 428): the POSPONER eyebrow
-                      ),
+                        // lost its snooze icon.
+                        Icon(
+                          Icons.snooze_rounded,
+                          size: 19,
+                          color: tokens.warmCoral,
+                        ),
+                        const SizedBox(width: 8),
+                        Text(
+                          l10n.snoozeAction,
+                          style: type.eyebrowLabel.copyWith(
+                            color: tokens.warmCoral,
+                          ),
+                        ),
+                      ],
                     ),
                   ),
                   const SizedBox(height: 10),
@@ -377,6 +410,13 @@ String _hora(AlarmaMusical alarma) =>
 /// call site (mirrors `_ArteEscuchar._radio` in `pantalla_inicio.dart`).
 const _stopButtonRadius = 24.0;
 
+/// Audit 9.6 (t4 line 421): the ringing screen's art is 180x180 with a 36
+/// corner radius — neither matches [PluriWaveTokens]'s three named radii
+/// (14/18/30), so this stays a local constant (same precedent as
+/// [_stopButtonRadius] above).
+const _artworkLado = 180.0;
+const _artworkRadio = 36.0;
+
 /// Audit 9.3: the schedule pill's text, built only from
 /// [AlarmaMusical.tipoProgramacion] and the fields it already carries per
 /// case (`diasSemana`, `fechaUnica`) — no new domain plumbing. Reuses the
@@ -458,6 +498,66 @@ class _PildoraProgramacion extends StatelessWidget {
   }
 }
 
+/// Pulsing amber halo (audit 9.1, t4 line 411): a 420x420 radial gradient
+/// centered behind the hero content, echoing the alarm's warmCoral accent.
+///
+/// BOUNDED, not infinite: the prototype's CSS is `animation: pw-pulse 2.4s
+/// ease-in-out infinite`, but this screen's dismiss guard
+/// (`pantalla_alarma_sonando_dismiss_guard_test.dart`, protected — must stay
+/// byte-identical to `main`) calls `pumpAndSettle()` after every mount and
+/// every interaction. A genuinely infinite `AnimationController.repeat()`
+/// anywhere in this widget's subtree would hang every one of those calls
+/// forever, with no way to fix it since that file cannot be edited (see
+/// `_EstadoSubidaVolumen` above for the same reasoning applied earlier on
+/// this exact screen). One grow-and-settle cycle, timed to the prototype's
+/// own 2.4s cadence, delivers the same "draws the eye" motion without ever
+/// leaving a frame scheduled forever. Respects reduced motion exactly like
+/// every other entry animation in this app (`PluriAnimate`).
+class _HaloPulsante extends StatelessWidget {
+  const _HaloPulsante({required this.tokens});
+
+  final PluriWaveTokens tokens;
+
+  static const _lado = 420.0;
+
+  @override
+  Widget build(BuildContext context) {
+    final halo = Container(
+      key: const ValueKey('ringing-pulse-halo'),
+      width: _lado,
+      height: _lado,
+      decoration: BoxDecoration(
+        shape: BoxShape.circle,
+        gradient: RadialGradient(
+          colors: [
+            tokens.warmCoral.withValues(alpha: 0.2),
+            tokens.warmCoral.withValues(alpha: 0),
+          ],
+          stops: const [0, 0.62],
+        ),
+      ),
+    );
+    if (MediaQuery.maybeDisableAnimationsOf(context) ?? false) {
+      return halo;
+    }
+    return halo
+        .animate()
+        .scaleXY(
+          begin: 1,
+          end: 1.08,
+          duration: 1200.ms,
+          curve: Curves.easeInOut,
+        )
+        .then()
+        .scaleXY(
+          begin: 1.08,
+          end: 1,
+          duration: 1200.ms,
+          curve: Curves.easeInOut,
+        );
+  }
+}
+
 /// Full-bleed blurred backdrop (WU11, replaces the `PluriGlassSurface` card
 /// container per task 11.3). This app has no per-station artwork/favicon
 /// safe to render here: `Emisora.favicon` is a network URL, and rendering

test/pantallas/pantalla_alarma_sonando_scaffold_test.dart

@@ -146,7 +146,8 @@ void main() {
 
   group('WU11 — restyle a pantalla completa', () {
     testWidgets(
-      'el tiempo gigante usa PluriWaveTypography.heroTime envuelto en '
+      'el tiempo gigante usa PluriWaveTypography.heroTime (con un ajuste '
+      'local de letter-spacing/height, audit 9.5) envuelto en '
       'FittedBox(scaleDown)',
       (tester) async {
         await _montarPantalla(tester);
@@ -155,7 +156,22 @@ void main() {
         expect(heroFinder, findsOneWidget);
         final texto = tester.widget<Text>(heroFinder);
         final contexto = tester.element(heroFinder);
-        expect(texto.style, contexto.pluriType.heroTime);
+        final base = contexto.pluriType.heroTime;
+        // Audit 9.5 (t4 line 417): the prototype wants 88px/w800/ls-4/lh.95
+        // on THIS screen only. heroTime itself must stay ls-2.0/height 1.0
+        // — EditorHoraInline (the alarm editor's hour block) is the other
+        // consumer and wants height:1 (t4 line 379) — so this is a LOCAL
+        // copyWith override, not a change to the shared token.
+        expect(texto.style?.fontSize, base.fontSize);
+        expect(texto.style?.fontWeight, base.fontWeight);
+        expect(texto.style?.letterSpacing, -4);
+        expect(texto.style?.height, 0.95);
+        expect(
+          base.letterSpacing,
+          -2.0,
+          reason: 'the shared token is unchanged',
+        );
+        expect(base.height, 1.0, reason: 'the shared token is unchanged');
         expect(
           find.ancestor(of: heroFinder, matching: find.byType(FittedBox)),
           findsOneWidget,

test/pantallas/pantalla_alarma_sonando_tier4_test.dart

@@ -0,0 +1,189 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_animate/flutter_animate.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pluriwave/estado/estado_alarmas.dart';
+import 'package:pluriwave/estado/estado_radio.dart';
+import 'package:pluriwave/l10n/gen/app_localizations.dart';
+import 'package:pluriwave/modelos/alarma_musical.dart';
+import 'package:pluriwave/modelos/emisora.dart';
+import 'package:pluriwave/pantallas/pantalla_alarma_sonando.dart';
+import 'package:pluriwave/servicios/servicio_alarmas.dart';
+import 'package:pluriwave/servicios/servicio_audio.dart';
+import 'package:pluriwave/tema/pluriwave_theme.dart';
+import 'package:provider/provider.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+import '../helpers/fakes.dart';
+import '../helpers/fakes_alarmas.dart';
+
+/// Tier 4 visual fidelity, ringing screen: 9.1 (pulsing amber halo), 9.6
+/// (art geometry), 9.8 (snooze eyebrow icon). Item 9.5 (hero time metrics)
+/// is covered in `pantalla_alarma_sonando_scaffold_test.dart`, which already
+/// owned the pre-existing `heroTime`-equality assertion that item revises.
+///
+/// 9.1 is the one with real hazard: the prototype's halo is a literal CSS
+/// `animation: pw-pulse 2.4s ease-in-out infinite`. This screen's dismiss
+/// guard (`pantalla_alarma_sonando_dismiss_guard_test.dart`, protected,
+/// byte-identical to `main`) calls `pumpAndSettle()` after every mount and
+/// every interaction — an actually-infinite `AnimationController.repeat()`
+/// anywhere in this widget's subtree would hang every one of those calls
+/// forever, with no way to fix it since that file cannot be touched. The
+/// halo below is a BOUNDED pulse (one grow/settle cycle, no `.repeat()`) —
+/// genuine animated motion, but one that always finishes.
+Future<void> _montarPantalla(
+  WidgetTester tester, {
+  bool disableAnimations = false,
+}) async {
+  tester.view.physicalSize = const Size(1440, 3200);
+  tester.view.devicePixelRatio = 1.0;
+  addTearDown(tester.view.resetPhysicalSize);
+  addTearDown(tester.view.resetDevicePixelRatio);
+
+  final audio = FakeServicioAudio();
+  audio.emitirEstado(EstadoReproduccion.reproduciendo);
+  final radio = EstadoRadio(
+    audio: audio,
+    favoritos: FakeServicioFavoritos(),
+    radio: FakeServicioRadio(),
+    servicioEcualizador: FakeServicioEcualizador(),
+    servicioGrabacion: FakeServicioGrabacionRadioInactiva(),
+    iniciarAutomaticamente: false,
+  );
+  addTearDown(radio.dispose);
+
+  final android = FakePuertoAlarmasAndroid();
+  final estadoAlarmas = EstadoAlarmas(
+    servicio: ServicioAlarmas(reloj: () => DateTime(2026, 6, 11, 7, 0)),
+    android: android,
+    iniciarAutomaticamente: false,
+  );
+  addTearDown(estadoAlarmas.dispose);
+  addTearDown(android.dispose);
+  await estadoAlarmas.guardarAlarma(
+    const AlarmaMusical(
+      id: 'tier4-1',
+      nombre: 'Despertar',
+      hora: 7,
+      minuto: 30,
+      tipoProgramacion: TipoProgramacionAlarma.diaria,
+      diasSemana: [],
+      emisora: Emisora(
+        uuid: 'e1',
+        nombre: 'Radio Uno',
+        url: 'https://radio.example/stream',
+      ),
+    ),
+  );
+
+  await tester.pumpWidget(
+    MultiProvider(
+      providers: [
+        ChangeNotifierProvider<EstadoRadio>.value(value: radio),
+        ChangeNotifierProvider<EstadoAlarmas>.value(value: estadoAlarmas),
+      ],
+      child: MaterialApp(
+        locale: const Locale('es'),
+        localizationsDelegates: AppLocalizations.localizationsDelegates,
+        supportedLocales: AppLocalizations.supportedLocales,
+        theme: PluriWaveTheme.dark(),
+        builder:
+            (context, child) => MediaQuery(
+              data: MediaQuery.of(
+                context,
+              ).copyWith(disableAnimations: disableAnimations),
+              child: child!,
+            ),
+        home: const SizedBox.shrink(),
+      ),
+    ),
+  );
+  final navigator = tester.state<NavigatorState>(find.byType(Navigator));
+  unawaited(
+    navigator.push(
+      MaterialPageRoute<void>(
+        builder:
+            (_) => PantallaAlarmaSonando(alarma: estadoAlarmas.alarmas.single),
+        fullscreenDialog: true,
+      ),
+    ),
+  );
+  await tester.pump();
+  await tester.pump(const Duration(milliseconds: 50));
+}
+
+void main() {
+  setUp(() {
+    SharedPreferences.setMockInitialValues({});
+  });
+
+  testWidgets(
+    'visual fidelity (audit 9.1): a pulsing amber halo renders behind the '
+    'hero content, and settling it NEVER hangs (protects the dismiss-guard '
+    "test's repeated pumpAndSettle calls)",
+    (tester) async {
+      await _montarPantalla(tester);
+
+      expect(find.byKey(const ValueKey('ringing-pulse-halo')), findsOneWidget);
+
+      // The critical regression guard: this must COMPLETE. An infinite
+      // AnimationController.repeat() here would hang every pumpAndSettle()
+      // call in the protected dismiss-guard test forever.
+      await tester.pumpAndSettle();
+    },
+  );
+
+  testWidgets(
+    'visual fidelity (audit 9.1): the halo skips its Animate wrapper under '
+    'reduced motion (matches every other entry animation in this app)',
+    (tester) async {
+      await _montarPantalla(tester, disableAnimations: true);
+
+      expect(find.byType(Animate), findsNothing);
+      expect(find.byKey(const ValueKey('ringing-pulse-halo')), findsOneWidget);
+    },
+  );
+
+  testWidgets(
+    'visual fidelity (audit 9.6): the ringing art is 180 square with a 36 '
+    'corner radius, not 168/30',
+    (tester) async {
+      await _montarPantalla(tester);
+
+      final art = tester
+          .widgetList<Image>(find.byType(Image))
+          .where((img) => img.width == 180 && img.height == 180);
+      expect(
+        art,
+        isNotEmpty,
+        reason: 'prototype t4 line 421 sizes the ringing-screen art at 180',
+      );
+
+      final clip = tester.widget<ClipRRect>(
+        find.ancestor(
+          of: find.byWidgetPredicate(
+            (w) => w is Image && w.width == 180 && w.height == 180,
+          ),
+          matching: find.byType(ClipRRect),
+        ),
+      );
+      expect(
+        (clip.borderRadius as BorderRadius).topLeft,
+        const Radius.circular(36),
+      );
+    },
+  );
+
+  testWidgets(
+    'visual fidelity (audit 9.8): the POSPONER eyebrow keeps its snooze '
+    'icon at 19px warmCoral',
+    (tester) async {
+      await _montarPantalla(tester);
+
+      final icon = tester.widget<Icon>(find.byIcon(Icons.snooze_rounded));
+      expect(icon.size, 19);
+      expect(icon.color, const Color(0xFFF4B860));
+    },
+  );
+}