fix: [SDK-5608] reset language with '' on Android and standardize demo push UI

android/src/main/java/com/onesignal/flutter/OneSignalUser.java

@@ -63,9 +63,6 @@ private void handleMethodCall(MethodCall call, Result result) {
 
     private void setLanguage(MethodCall call, Result result) {
         String language = call.argument("language");
-        if (language != null && language.length() == 0) {
-            language = null;
-        }
         OneSignal.getUser().setLanguage(language);
         replySuccess(result, null);
     }

examples/build.md

@@ -140,7 +140,7 @@ if (_externalUserId != null) {
 }
 ```
 
-The cached `externalUserId` is the only value that drives an SDK call inside `loadInitialState()` -- it triggers `OneSignal.login(...)` so the SDK identity matches the persisted UI state. Push subscription id, opted-in flag, and permission are then read from the live SDK state, and the OneSignal ID is fetched via `OneSignal.User.getOnesignalId()`.
+The cached `externalUserId` is the only value that drives an SDK call inside `loadInitialState()` -- it triggers `OneSignal.login(...)` so the SDK identity matches the persisted UI state. Push subscription id, opted-in flag, token, and permission are then read from the live SDK state, and the OneSignal ID is fetched via `OneSignal.User.getOnesignalId()`.
 
 ### Observers
 
@@ -162,6 +162,13 @@ OneSignal.User.addObserver(...)
 - No global loading overlay. `vm.isLoading` is passed to `PairList(loading: ...)` in **aliases**, **emails**, **sms**, and **tags** sections only. `user_section.dart` has no loading UI.
 - The viewmodel uses a request-sequence counter (`_fetchSequence`) so stale REST results are dropped when a newer fetch is already in flight.
 
+### Push Status
+- The Push section shows a read-only **Status** row above the **Opted In** toggle: `Subscribed` when `pushSubscription.optedIn` is true, notification permission is granted, and a push token is present; otherwise `Unsubscribed`. `AppViewModel.isPushSubscribed` derives this from the push subscription and permission observers.
+
+### Language
+- The User section has a **Language** dropdown (`Device Default` plus the shared language list) after External ID. The selection is cached in `PreferencesService` and reset to `Device Default` on logout.
+- `Device Default` calls `OneSignal.User.setLanguage('')`, which the native SDK resolves to the device language.
+
 ### SnackBar Messages
 - `AppSnackBar` extension on `BuildContext` defined in `lib/theme.dart` exposes `context.showSnackBar(message)`.
 - The extension calls `ScaffoldMessenger.of(this)..hideCurrentSnackBar()..showSnackBar(SnackBar(content: Text(message), duration: _toastDuration))` for replace-on-show behavior.

examples/demo-pods/lib/services/preferences_service.dart

@@ -6,6 +6,7 @@ class PreferencesService {
   static const _keyExternalUserId = 'external_user_id';
   static const _keyLocationShared = 'location_shared';
   static const _keyIamPaused = 'iam_paused';
+  static const _keyLanguage = 'language';
 
   late final SharedPreferences _prefs;
 
@@ -39,4 +40,9 @@ class PreferencesService {
   bool get iamPaused => _prefs.getBool(_keyIamPaused) ?? false;
   Future<void> setIamPaused(bool value) =>
       _prefs.setBool(_keyIamPaused, value);
+
+  // Language
+  String get language => _prefs.getString(_keyLanguage) ?? '';
+  Future<void> setLanguage(String value) =>
+      _prefs.setString(_keyLanguage, value);
 }

examples/demo-pods/lib/viewmodels/app_viewmodel.dart

@@ -76,6 +76,17 @@ class AppViewModel extends ChangeNotifier {
   bool _hasNotificationPermission = false;
   bool get hasNotificationPermission => _hasNotificationPermission;
 
+  String? _pushToken;
+
+  bool get isPushSubscribed =>
+      _pushEnabled &&
+      _hasNotificationPermission &&
+      (_pushToken?.isNotEmpty ?? false);
+
+  // Empty means device default.
+  String _language = '';
+  String get language => _language;
+
   // IAM state
   bool _iamPaused = false;
   bool get iamPaused => _iamPaused;
@@ -132,13 +143,15 @@ class AppViewModel extends ChangeNotifier {
 
     _iamPaused = _prefs.iamPaused;
     _locationShared = _prefs.locationShared;
+    _language = _prefs.language;
 
     if (_externalUserId != null) {
       OneSignal.login(_externalUserId!);
     }
 
     _pushSubscriptionId = OneSignal.User.pushSubscription.id;
     _pushEnabled = OneSignal.User.pushSubscription.optedIn ?? false;
+    _pushToken = OneSignal.User.pushSubscription.token;
     _hasNotificationPermission = OneSignal.Notifications.permission;
 
     final onesignalId = await OneSignal.User.getOnesignalId();
@@ -165,6 +178,7 @@ class AppViewModel extends ChangeNotifier {
     OneSignal.User.pushSubscription.addObserver((state) {
       _pushSubscriptionId = state.current.id;
       _pushEnabled = state.current.optedIn;
+      _pushToken = state.current.token;
 
       String fmtToken(String? t) {
         if (t == null || t.isEmpty) return 'null';
@@ -255,12 +269,29 @@ class AppViewModel extends ChangeNotifier {
     try {
       await OneSignal.logout();
       await _prefs.setExternalUserId(null);
+      await setLanguage('');
       debugPrint('Logged out');
     } catch (e) {
       debugPrint('Logout error: $e');
     }
   }
 
+  // Language
+  Future<void> setLanguage(String language) async {
+    _language = language;
+    notifyListeners();
+
+    try {
+      await OneSignal.User.setLanguage(language);
+      await _prefs.setLanguage(language);
+      debugPrint(
+        'Language set to: ${language.isEmpty ? 'device default' : language}',
+      );
+    } catch (e) {
+      debugPrint('Set language error: $e');
+    }
+  }
+
   // Consent
   Future<void> setConsentRequired(bool value) async {
     _consentRequired = value;

examples/demo-pods/lib/widgets/sections/push_section.dart

@@ -51,8 +51,26 @@ class PushSection extends StatelessWidget {
                     ],
                   ),
                   const Divider(),
+                  Row(
+                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                    children: [
+                      Text(
+                        'Status',
+                        style: Theme.of(context).textTheme.bodyMedium,
+                      ),
+                      Semantics(
+                        identifier: 'push_subscription_status',
+                        container: true,
+                        child: Text(
+                          vm.isPushSubscribed ? 'Subscribed' : 'Unsubscribed',
+                          style: Theme.of(context).textTheme.bodySmall,
+                        ),
+                      ),
+                    ],
+                  ),
+                  const Divider(),
                   ToggleRow(
-                    label: 'Enabled',
+                    label: 'Opted In',
                     value: vm.pushEnabled,
                     semanticsLabel: 'push_enabled_toggle',
                     onChanged: vm.hasNotificationPermission

examples/demo-pods/lib/widgets/sections/user_section.dart

@@ -7,6 +7,53 @@ import '../dialogs.dart';
 import '../action_button.dart';
 import '../section_card.dart';
 
+const _languageOptions = [
+  ('Device Default', ''),
+  ('English', 'en'),
+  ('Arabic', 'ar'),
+  ('Azerbaijani', 'az'),
+  ('Bosnian', 'bs'),
+  ('Catalan', 'ca'),
+  ('Chinese (Simplified)', 'zh-Hans'),
+  ('Chinese (Traditional)', 'zh-Hant'),
+  ('Croatian', 'hr'),
+  ('Czech', 'cs'),
+  ('Danish', 'da'),
+  ('Dutch', 'nl'),
+  ('Estonian', 'et'),
+  ('Finnish', 'fi'),
+  ('French', 'fr'),
+  ('Georgian', 'ka'),
+  ('Bulgarian', 'bg'),
+  ('German', 'de'),
+  ('Greek', 'el'),
+  ('Hindi', 'hi'),
+  ('Hebrew', 'he'),
+  ('Hungarian', 'hu'),
+  ('Indonesian', 'id'),
+  ('Italian', 'it'),
+  ('Japanese', 'ja'),
+  ('Korean', 'ko'),
+  ('Latvian', 'lv'),
+  ('Lithuanian', 'lt'),
+  ('Malay', 'ms'),
+  ('Norwegian', 'nb'),
+  ('Persian', 'fa'),
+  ('Polish', 'pl'),
+  ('Portuguese', 'pt'),
+  ('Punjabi', 'pa'),
+  ('Romanian', 'ro'),
+  ('Russian', 'ru'),
+  ('Serbian', 'sr'),
+  ('Slovak', 'sk'),
+  ('Spanish', 'es'),
+  ('Swedish', 'sv'),
+  ('Thai', 'th'),
+  ('Turkish', 'tr'),
+  ('Ukrainian', 'uk'),
+  ('Vietnamese', 'vi'),
+];
+
 class UserSection extends StatelessWidget {
   final VoidCallback? onInfoTap;
 
@@ -68,6 +115,38 @@ class UserSection extends StatelessWidget {
                       ),
                     ],
                   ),
+                  const Divider(),
+                  Row(
+                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                    children: [
+                      Text(
+                        'Language',
+                        style: Theme.of(context).textTheme.bodyMedium,
+                      ),
+                      Semantics(
+                        identifier: 'user_language_dropdown',
+                        container: true,
+                        child: DropdownButton<String>(
+                          value:
+                              _languageOptions.any((o) => o.$2 == vm.language)
+                                  ? vm.language
+                                  : '',
+                          isDense: true,
+                          menuMaxHeight: 320,
+                          alignment: AlignmentDirectional.centerEnd,
+                          underline: const SizedBox.shrink(),
+                          style: Theme.of(context).textTheme.bodySmall,
+                          items: [
+                            for (final (name, code) in _languageOptions)
+                              DropdownMenuItem(value: code, child: Text(name)),
+                          ],
+                          onChanged: (code) {
+                            if (code != null) vm.setLanguage(code);
+                          },
+                        ),
+                      ),
+                    ],
+                  ),
                 ],
               ),
             ),

examples/demo/lib/services/preferences_service.dart

@@ -6,6 +6,7 @@ class PreferencesService {
   static const _keyExternalUserId = 'external_user_id';
   static const _keyLocationShared = 'location_shared';
   static const _keyIamPaused = 'iam_paused';
+  static const _keyLanguage = 'language';
 
   late final SharedPreferences _prefs;
 
@@ -39,4 +40,9 @@ class PreferencesService {
   bool get iamPaused => _prefs.getBool(_keyIamPaused) ?? false;
   Future<void> setIamPaused(bool value) =>
       _prefs.setBool(_keyIamPaused, value);
+
+  // Language
+  String get language => _prefs.getString(_keyLanguage) ?? '';
+  Future<void> setLanguage(String value) =>
+      _prefs.setString(_keyLanguage, value);
 }

examples/demo/lib/viewmodels/app_viewmodel.dart

@@ -88,6 +88,17 @@ class AppViewModel extends ChangeNotifier {
   bool _hasNotificationPermission = false;
   bool get hasNotificationPermission => _hasNotificationPermission;
 
+  String? _pushToken;
+
+  bool get isPushSubscribed =>
+      _pushEnabled &&
+      _hasNotificationPermission &&
+      (_pushToken?.isNotEmpty ?? false);
+
+  // Empty means device default.
+  String _language = '';
+  String get language => _language;
+
   // IAM state
   bool _iamPaused = false;
   bool get iamPaused => _iamPaused;
@@ -144,13 +155,15 @@ class AppViewModel extends ChangeNotifier {
 
     _iamPaused = _prefs.iamPaused;
     _locationShared = _prefs.locationShared;
+    _language = _prefs.language;
 
     if (_externalUserId != null) {
       OneSignal.login(_externalUserId!);
     }
 
     _pushSubscriptionId = OneSignal.User.pushSubscription.id;
     _pushEnabled = OneSignal.User.pushSubscription.optedIn ?? false;
+    _pushToken = OneSignal.User.pushSubscription.token;
     _hasNotificationPermission = OneSignal.Notifications.permission;
 
     final onesignalId = await OneSignal.User.getOnesignalId();
@@ -171,6 +184,7 @@ class AppViewModel extends ChangeNotifier {
     OneSignal.User.pushSubscription.addObserver((state) {
       _pushSubscriptionId = state.current.id;
       _pushEnabled = state.current.optedIn;
+      _pushToken = state.current.token;
 
       String fmtToken(String? t) {
         if (t == null || t.isEmpty) return 'null';
@@ -291,12 +305,29 @@ class AppViewModel extends ChangeNotifier {
     try {
       await OneSignal.logout();
       await _prefs.setExternalUserId(null);
+      await setLanguage('');
       LogService.info('Logged out');
     } catch (e) {
       LogService.error('Logout error: $e');
     }
   }
 
+  // Language
+  Future<void> setLanguage(String language) async {
+    _language = language;
+    notifyListeners();
+
+    try {
+      await OneSignal.User.setLanguage(language);
+      await _prefs.setLanguage(language);
+      LogService.info(
+        'Language set to: ${language.isEmpty ? 'device default' : language}',
+      );
+    } catch (e) {
+      LogService.error('Set language error: $e');
+    }
+  }
+
   // Consent
   Future<void> setConsentRequired(bool value) async {
     _consentRequired = value;

examples/demo/lib/widgets/sections/push_section.dart

@@ -51,8 +51,26 @@ class PushSection extends StatelessWidget {
                     ],
                   ),
                   const Divider(),
+                  Row(
+                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                    children: [
+                      Text(
+                        'Status',
+                        style: Theme.of(context).textTheme.bodyMedium,
+                      ),
+                      Semantics(
+                        identifier: 'push_subscription_status',
+                        container: true,
+                        child: Text(
+                          vm.isPushSubscribed ? 'Subscribed' : 'Unsubscribed',
+                          style: Theme.of(context).textTheme.bodySmall,
+                        ),
+                      ),
+                    ],
+                  ),
+                  const Divider(),
                   ToggleRow(
-                    label: 'Enabled',
+                    label: 'Opted In',
                     value: vm.pushEnabled,
                     semanticsLabel: 'push_enabled_toggle',
                     onChanged: vm.hasNotificationPermission