i18n(alarm): localize all native notification, channel and chooser texts

Centralize every native-side user-facing string in a single
AlarmNotificationStrings store written by Flutter via a new
setNotificationStrings MethodChannel whenever the app locale changes,
and read at notification/channel build time (with English fallbacks)
even when the engine is dead. This replaces the hardcoded Spanish text
in the ringing notification ("Alarma PluriWave", "Posponer", "Detener"),
the pre-notice notification ("Posponer", "Omitir esta vez"), both
notification channels (names + descriptions) and the file-action
choosers ("Abrir carpeta", "Abrir grabación").

The per-alarm preNoticeTemplate/snoozeCountdown template+label args are
dropped from scheduleAlarm and the persisted spec and folded into the
shared store, so a locale change now also relocalizes already-scheduled
alarms. Channels are re-created on each use so their name/description
refresh after a language switch.

Adds alarmRingingNotificationTitle, alarmFire/PreNoticeChannelName,
alarmFire/PreNoticeChannelDescription and openFolder/openRecording
chooser keys across all 13 locales (reusing snoozeAction, stopAlarmAction,
skipNextAction, snoozeAgainAction). Rewrites the template test around
setNotificationStrings. Kotlin is static-reviewed only; no Android build
environment available here.

android/app/src/main/kotlin/es/freetimelab/pluriwave/AlarmNotificationStrings.kt

@@ -0,0 +1,72 @@
+package es.freetimelab.pluriwave
+
+import android.content.Context
+
+/**
+ * Localized strings for native alarm notifications, channels and choosers.
+ *
+ * Flutter is the single source of truth for i18n: it pushes the current-locale
+ * strings via the `setNotificationStrings` MethodChannel whenever the app locale
+ * is (re)configured. They are persisted in device-protected storage so the
+ * native side can read them when building a notification or channel even while
+ * the Flutter engine is dead (alarm fired from a killed app, after reboot, in
+ * direct-boot). Every getter falls back to English when a value is unset.
+ */
+object AlarmNotificationStrings {
+    private const val PREFS = "pluriwave_alarm_strings"
+
+    const val KEY_RING_TITLE = "ringTitle"
+    const val KEY_SNOOZE = "snoozeLabel"
+    const val KEY_STOP = "stopLabel"
+    const val KEY_SKIP = "skipLabel"
+    const val KEY_SNOOZE_AGAIN = "snoozeAgainLabel"
+    const val KEY_FIRE_CHANNEL_NAME = "fireChannelName"
+    const val KEY_FIRE_CHANNEL_DESC = "fireChannelDescription"
+    const val KEY_PRE_NOTICE_CHANNEL_NAME = "preNoticeChannelName"
+    const val KEY_PRE_NOTICE_CHANNEL_DESC = "preNoticeChannelDescription"
+    const val KEY_PRE_NOTICE_TEMPLATE = "preNoticeTemplate"
+    const val KEY_SNOOZE_COUNTDOWN_TEMPLATE = "snoozeCountdownTemplate"
+    const val KEY_OPEN_FOLDER = "openFolderTitle"
+    const val KEY_OPEN_RECORDING = "openRecordingTitle"
+
+    /** Persists the localized strings pushed by Flutter. Blank values are removed. */
+    fun save(context: Context, values: Map<String, Any?>) {
+        val editor = prefs(context).edit()
+        for ((key, value) in values) {
+            val str = value as? String
+            if (str.isNullOrBlank()) editor.remove(key) else editor.putString(key, str)
+        }
+        editor.apply()
+    }
+
+    fun ringTitle(context: Context) = get(context, KEY_RING_TITLE, "PluriWave alarm")
+    fun snoozeLabel(context: Context) = get(context, KEY_SNOOZE, "Snooze")
+    fun stopLabel(context: Context) = get(context, KEY_STOP, "Stop")
+    fun skipLabel(context: Context) = get(context, KEY_SKIP, "Skip this time")
+    fun snoozeAgainLabel(context: Context) = get(context, KEY_SNOOZE_AGAIN, "Snooze again")
+    fun fireChannelName(context: Context) = get(context, KEY_FIRE_CHANNEL_NAME, "Ringing alarms")
+    fun fireChannelDescription(context: Context) =
+        get(context, KEY_FIRE_CHANNEL_DESC, "Urgent sound and screen when a music alarm must ring")
+    fun preNoticeChannelName(context: Context) =
+        get(context, KEY_PRE_NOTICE_CHANNEL_NAME, "Alarm reminders")
+    fun preNoticeChannelDescription(context: Context) =
+        get(context, KEY_PRE_NOTICE_CHANNEL_DESC, "Silent notifications before the alarm")
+    fun openFolderTitle(context: Context) = get(context, KEY_OPEN_FOLDER, "Open folder")
+    fun openRecordingTitle(context: Context) = get(context, KEY_OPEN_RECORDING, "Open recording")
+
+    fun preNoticeText(context: Context, minutes: Long): String =
+        format(get(context, KEY_PRE_NOTICE_TEMPLATE, "Starts in {minutes} min"), minutes)
+
+    fun snoozeCountdownText(context: Context, minutes: Long): String =
+        format(get(context, KEY_SNOOZE_COUNTDOWN_TEMPLATE, "Rings in {minutes} min"), minutes)
+
+    private fun format(template: String, minutes: Long): String =
+        template.replace("{minutes}", minutes.toString())
+
+    private fun get(context: Context, key: String, fallback: String): String =
+        prefs(context).getString(key, null)?.takeIf { it.isNotBlank() } ?: fallback
+
+    private fun prefs(context: Context) =
+        context.applicationContext.createDeviceProtectedStorageContext()
+            .getSharedPreferences(PREFS, Context.MODE_PRIVATE)
+}

android/app/src/main/kotlin/es/freetimelab/pluriwave/AlarmScheduler.kt

@@ -42,11 +42,7 @@ class AlarmScheduler(private val context: Context) {
         snoozeMinutes: Int = 5,
         fallbackStationName: String? = null,
         fallbackStationUrl: String? = null,
-        fadeInSegundos: Int = 0,
-        preNoticeTemplate: String? = null,
-        snoozeCountdownTemplate: String? = null,
-        snoozeAgainLabel: String? = null,
-        snoozeStopLabel: String? = null
+        fadeInSegundos: Int = 0
     ): Boolean {
         val existing = readSpec(id)
         val preservedSnooze = preserveNativeSnooze(
@@ -77,11 +73,7 @@ class AlarmScheduler(private val context: Context) {
             fallbackSound = fallbackSound,
             volume = volume.coerceIn(0f, 1f),
             fadeInSegundos = fadeInSegundos.coerceIn(0, 60),
-            timezoneId = TimeZone.getDefault().id,
-            preNoticeTemplate = preNoticeTemplate,
-            snoozeCountdownTemplate = snoozeCountdownTemplate,
-            snoozeAgainLabel = snoozeAgainLabel,
-            snoozeStopLabel = snoozeStopLabel
+            timezoneId = TimeZone.getDefault().id
         )
         return scheduleSpec(spec, persistOnSuccess = true)
     }
@@ -168,7 +160,6 @@ class AlarmScheduler(private val context: Context) {
                                 PluriWaveAlarmReceiver.EXTRA_OCCURRENCE_AT,
                                 spec.snoozeOriginMillis ?: spec.triggerAtMillis
                             )
-                            putExtra(EXTRA_PRE_NOTICE_TEMPLATE, spec.preNoticeTemplate)
                         },
                         PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
                     )
@@ -189,7 +180,6 @@ class AlarmScheduler(private val context: Context) {
                         PluriWaveAlarmReceiver.EXTRA_OCCURRENCE_AT,
                         spec.snoozeOriginMillis ?: spec.triggerAtMillis
                     )
-                    putExtra(EXTRA_PRE_NOTICE_TEMPLATE, spec.preNoticeTemplate)
                 }
             )
             Log.d(tag, "alarm.schedule preNotice immediate id=${spec.id}")
@@ -483,11 +473,7 @@ class AlarmScheduler(private val context: Context) {
 
     private fun postSnoozeCountdownNotification(spec: NativeAlarmSpec, remaining: Long) {
         ensurePreNoticeChannel()
-        val text = if (spec.snoozeCountdownTemplate.isNullOrBlank()) {
-            "Rings in $remaining min"
-        } else {
-            spec.snoozeCountdownTemplate.replace("{minutes}", remaining.toString())
-        }
+        val text = AlarmNotificationStrings.snoozeCountdownText(appContext, remaining)
 
         val openIntent = PendingIntent.getActivity(
             appContext,
@@ -531,8 +517,8 @@ class AlarmScheduler(private val context: Context) {
             .setOnlyAlertOnce(true)
             .setOngoing(true)
             .setContentIntent(openIntent)
-            .addAction(0, spec.snoozeAgainLabel ?: "Snooze again", againIntent)
-            .addAction(0, spec.snoozeStopLabel ?: "Stop", stopIntent)
+            .addAction(0, AlarmNotificationStrings.snoozeAgainLabel(appContext), againIntent)
+            .addAction(0, AlarmNotificationStrings.stopLabel(appContext), stopIntent)
             .build()
 
         try {
@@ -548,12 +534,14 @@ class AlarmScheduler(private val context: Context) {
     private fun ensurePreNoticeChannel() {
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) return
         val manager = appContext.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
-        if (manager.getNotificationChannel(PluriWaveAlarmReceiver.CHANNEL_ID) != null) return
+        // Re-create each time so the localized name/description refresh after a
+        // locale change (Android updates them on an existing channel).
         val channel = NotificationChannel(
             PluriWaveAlarmReceiver.CHANNEL_ID,
-            "Preavisos de alarmas",
+            AlarmNotificationStrings.preNoticeChannelName(appContext),
             NotificationManager.IMPORTANCE_LOW
         ).apply {
+            description = AlarmNotificationStrings.preNoticeChannelDescription(appContext)
             setSound(null, null)
             enableVibration(false)
         }
@@ -905,15 +893,7 @@ class AlarmScheduler(private val context: Context) {
         val fallbackSound: String?,
         val volume: Float,
         val fadeInSegundos: Int = 0,
-        val timezoneId: String,
-        // Nullable for backward compat: old persisted alarms without this field
-        // fall back to the English default in the receiver. Schema stays v3.
-        val preNoticeTemplate: String? = null,
-        // Localized template + button labels for the per-minute snooze countdown
-        // notification. Nullable so pre-existing persisted alarms keep working.
-        val snoozeCountdownTemplate: String? = null,
-        val snoozeAgainLabel: String? = null,
-        val snoozeStopLabel: String? = null
+        val timezoneId: String
     ) {
         fun toJson(): JSONObject = JSONObject().apply {
             put("schemaVersion", 3)
@@ -940,10 +920,6 @@ class AlarmScheduler(private val context: Context) {
             put("volume", volume)
             put("fadeInSegundos", fadeInSegundos)
             put("timezoneId", timezoneId)
-            put("preNoticeTemplate", preNoticeTemplate)
-            put("snoozeCountdownTemplate", snoozeCountdownTemplate)
-            put("snoozeAgainLabel", snoozeAgainLabel)
-            put("snoozeStopLabel", snoozeStopLabel)
         }
 
         companion object {
@@ -980,12 +956,7 @@ class AlarmScheduler(private val context: Context) {
                     fallbackSound = json.optString("fallbackSound").takeIf { it.isNotBlank() },
                     volume = json.optDouble("volume", 0.85).toFloat(),
                     fadeInSegundos = json.optInt("fadeInSegundos", 0).coerceIn(0, 60),
-                    timezoneId = json.optString("timezoneId", TimeZone.getDefault().id),
-                    preNoticeTemplate = json.optString("preNoticeTemplate").takeIf { it.isNotBlank() },
-                    snoozeCountdownTemplate =
-                        json.optString("snoozeCountdownTemplate").takeIf { it.isNotBlank() },
-                    snoozeAgainLabel = json.optString("snoozeAgainLabel").takeIf { it.isNotBlank() },
-                    snoozeStopLabel = json.optString("snoozeStopLabel").takeIf { it.isNotBlank() }
+                    timezoneId = json.optString("timezoneId", TimeZone.getDefault().id)
                 )
             }
         }
@@ -1000,9 +971,6 @@ class AlarmScheduler(private val context: Context) {
         private const val PRE_NOTICE_MILLIS = 30 * 60 * 1000L
         private const val SCHEDULE_UNICA = "unica"
         private const val SCHEDULE_DIAS_SEMANA = "diasSemana"
-        // Intent extra key for the localized pre-notice template string.
-        // Declared once here; PluriWaveAlarmReceiver reads it via this constant.
-        const val EXTRA_PRE_NOTICE_TEMPLATE = "preNoticeTemplate"
     }
 }
 

android/app/src/main/kotlin/es/freetimelab/pluriwave/MainActivity.kt

@@ -115,11 +115,7 @@ class MainActivity : AudioServiceActivity() {
                             snoozeMinutes = call.argument<Int>("snoozeMinutes") ?: 5,
                             fallbackStationName = call.argument<String>("fallbackStationName"),
                             fallbackStationUrl = call.argument<String>("fallbackStationUrl"),
-                            fadeInSegundos = call.argument<Int>("fadeInSegundos") ?: 0,
-                            preNoticeTemplate = call.argument<String>("preNoticeTemplate"),
-                            snoozeCountdownTemplate = call.argument<String>("snoozeCountdownTemplate"),
-                            snoozeAgainLabel = call.argument<String>("snoozeAgainLabel"),
-                            snoozeStopLabel = call.argument<String>("snoozeStopLabel")
+                            fadeInSegundos = call.argument<Int>("fadeInSegundos") ?: 0
                         )
                         result.success(scheduled)
                     }
@@ -209,6 +205,16 @@ class MainActivity : AudioServiceActivity() {
                     Log.d(tag, "alarm.channel getNativeSnoozeState")
                     result.success(alarmScheduler.nativeSnoozeStates())
                 }
+                "setNotificationStrings" -> {
+                    val args = call.arguments as? Map<*, *>
+                    if (args != null) {
+                        AlarmNotificationStrings.save(
+                            this,
+                            args.entries.associate { (k, v) -> k.toString() to v }
+                        )
+                    }
+                    result.success(null)
+                }
                 else -> result.notImplemented()
             }
         }
@@ -427,7 +433,9 @@ class MainActivity : AudioServiceActivity() {
 
         for (intent in candidates) {
             try {
-                startActivity(Intent.createChooser(intent, "Abrir carpeta"))
+                startActivity(
+                    Intent.createChooser(intent, AlarmNotificationStrings.openFolderTitle(this))
+                )
                 Log.d(tag, "file_actions.viewDirectory launched path=$path")
                 return true
             } catch (_: ActivityNotFoundException) {
@@ -471,7 +479,9 @@ class MainActivity : AudioServiceActivity() {
                 clipData = ClipData.newUri(contentResolver, "recording", uri)
                 addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
             }
-            startActivity(Intent.createChooser(intent, "Abrir grabación"))
+            startActivity(
+                Intent.createChooser(intent, AlarmNotificationStrings.openRecordingTitle(this))
+            )
             Log.d(tag, "file_actions.openFile launched path=$path")
             true
         } catch (_: ActivityNotFoundException) {

android/app/src/main/kotlin/es/freetimelab/pluriwave/PluriWaveAlarmReceiver.kt

@@ -51,8 +51,7 @@ class PluriWaveAlarmReceiver : BroadcastReceiver() {
                     title,
                     snoozeMinutes,
                     intent.getLongExtra(EXTRA_TRIGGER_AT, 0L),
-                    intent.getLongExtra(EXTRA_OCCURRENCE_AT, 0L),
-                    intent.getStringExtra(AlarmScheduler.EXTRA_PRE_NOTICE_TEMPLATE)
+                    intent.getLongExtra(EXTRA_OCCURRENCE_AT, 0L)
                 )
             }
             ACTION_POSTPONE_NEXT -> {
@@ -135,13 +134,12 @@ class PluriWaveAlarmReceiver : BroadcastReceiver() {
         title: String,
         snoozeMinutes: Int,
         triggerAtMillis: Long,
-        occurrenceAtMillis: Long,
-        preNoticeTemplate: String? = null
+        occurrenceAtMillis: Long
     ) {
         ensureChannel(context)
 
         val remaining = computeRemainingMinutes(triggerAtMillis)
-        val contentText = formatPreNoticeText(preNoticeTemplate, remaining)
+        val contentText = AlarmNotificationStrings.preNoticeText(context, remaining)
 
         val openAppIntent = PendingIntent.getActivity(
             context,
@@ -189,8 +187,8 @@ class PluriWaveAlarmReceiver : BroadcastReceiver() {
             .setSilent(true)
             .setAutoCancel(true)
             .setContentIntent(openAppIntent)
-            .addAction(0, "Posponer", postponeNextIntent)
-            .addAction(0, "Omitir esta vez", skipNextIntent)
+            .addAction(0, AlarmNotificationStrings.snoozeLabel(context), postponeNextIntent)
+            .addAction(0, AlarmNotificationStrings.skipLabel(context), skipNextIntent)
             .build()
 
         try {
@@ -208,30 +206,17 @@ class PluriWaveAlarmReceiver : BroadcastReceiver() {
     private fun computeRemainingMinutes(triggerAtMillis: Long): Long =
         maxOf(1L, (triggerAtMillis - System.currentTimeMillis()) / 60_000L)
 
-    /**
-     * Formats the pre-notice notification text by replacing the `{minutes}`
-     * placeholder in [template] with [remaining]. Falls back to an English
-     * default if [template] is null or blank.
-     */
-    private fun formatPreNoticeText(template: String?, remaining: Long): String {
-        if (template.isNullOrBlank()) {
-            return "Starts in $remaining min"
-        }
-        return template.replace("{minutes}", remaining.toString())
-    }
-
     private fun ensureChannel(context: Context) {
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) return
         val manager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
-        val existing = manager.getNotificationChannel(CHANNEL_ID)
-        if (existing != null) return
-
+        // Re-create each time so the localized name/description refresh after a
+        // locale change (Android updates them on an existing channel).
         val channel = NotificationChannel(
             CHANNEL_ID,
-            "Preavisos de alarmas",
+            AlarmNotificationStrings.preNoticeChannelName(context),
             NotificationManager.IMPORTANCE_LOW
         ).apply {
-            description = "Notificaciones silenciosas 30 minutos antes de la alarma"
+            description = AlarmNotificationStrings.preNoticeChannelDescription(context)
             setSound(null, null)
             enableVibration(false)
         }

android/app/src/main/kotlin/es/freetimelab/pluriwave/PluriWaveAlarmService.kt

@@ -388,7 +388,7 @@ class PluriWaveAlarmService : Service() {
     ) =
         NotificationCompat.Builder(this, CHANNEL_ID)
             .setSmallIcon(android.R.drawable.ic_lock_idle_alarm)
-            .setContentTitle("Alarma PluriWave")
+            .setContentTitle(AlarmNotificationStrings.ringTitle(this))
             .setContentText(
                 if (stationName.isNullOrBlank()) title else "$title - $stationName"
             )
@@ -399,8 +399,8 @@ class PluriWaveAlarmService : Service() {
             .setAutoCancel(false)
             .setFullScreenIntent(openAlarmPendingIntent(alarmId, title, snoozeMinutes), true)
             .setContentIntent(openAlarmPendingIntent(alarmId, title, snoozeMinutes))
-            .addAction(0, "Posponer", snoozePendingIntent(alarmId, snoozeMinutes))
-            .addAction(0, "Detener", stopPendingIntent(alarmId))
+            .addAction(0, AlarmNotificationStrings.snoozeLabel(this), snoozePendingIntent(alarmId, snoozeMinutes))
+            .addAction(0, AlarmNotificationStrings.stopLabel(this), stopPendingIntent(alarmId))
             .build()
 
     private fun openAlarmPendingIntent(
@@ -553,13 +553,16 @@ class PluriWaveAlarmService : Service() {
             if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) return
             val manager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
             migrateLegacyChannels(context, manager)
-            if (manager.getNotificationChannel(CHANNEL_ID) != null) return
+            // Re-create each time (not early-returning when present) so the
+            // localized name/description refresh after a locale change. Android
+            // updates name + description on an existing channel; importance and
+            // sound stay fixed from first creation.
             val channel = NotificationChannel(
                 CHANNEL_ID,
-                "Alarmas sonando",
+                AlarmNotificationStrings.fireChannelName(context),
                 NotificationManager.IMPORTANCE_HIGH
             ).apply {
-                description = "Sonido y pantalla urgente cuando una alarma musical debe sonar"
+                description = AlarmNotificationStrings.fireChannelDescription(context)
                 enableVibration(true)
                 setSound(
                     Settings.System.DEFAULT_ALARM_ALERT_URI,