add changeset comment tracking and message notification bubble on startup

lib/app_state.dart

@@ -176,6 +176,8 @@ class AppState extends ChangeNotifier {
   // Messages state
   int? get unreadMessageCount => _messagesState.unreadCount;
   bool get hasUnreadMessages => _messagesState.hasUnreadMessages;
+  bool get hasUnreadChangesetComments => _messagesState.hasUnreadChangesetComments;
+  bool get hasUnreadNotifications => _messagesState.hasUnreadNotifications;
   bool get isCheckingMessages => _messagesState.isChecking;
   
   // Tile provider state
@@ -331,6 +333,7 @@ class AppState extends ChangeNotifier {
     final accessToken = await _authState.getAccessToken();
     await _messagesState.checkMessages(
       accessToken: accessToken,
+      username: isLoggedIn ? username : null,
       uploadMode: uploadMode,
       forceRefresh: forceRefresh,
     );
@@ -340,10 +343,24 @@ class AppState extends ChangeNotifier {
     return _messagesState.getMessagesUrl(uploadMode);
   }
   
+  /// URL of the specific changeset with unread comments, on OSM's website,
+  /// or null if there are no unread changeset comments.
+  String? getUnreadChangesetUrl() {
+    return _messagesState.getUnreadChangesetUrl(uploadMode);
+  }
+  
   void clearMessages() {
     _messagesState.clearMessages();
   }
   
+  /// Mark changeset comments as read (called when user views the changeset on OSM)
+  Future<void> markChangesetCommentsRead() async {
+    await _messagesState.markChangesetCommentsRead(
+      username: isLoggedIn ? username : null,
+      uploadMode: uploadMode,
+    );
+  }
+  
   /// Check if the current OAuth token has required scopes for message notifications
   /// Returns true if re-authentication is needed
   Future<bool> needsReauthForMessages() async {

lib/localizations/de.json

@@ -235,7 +235,12 @@
     "reauthExplanation": "Sie müssen Ihre Authentifizierung aktualisieren, um OSM-Nachrichtenbenachrichtigungen über die App zu erhalten.",
     "reauthBenefit": "Dies ermöglicht Benachrichtigungspunkte, wenn Sie ungelesene Nachrichten auf OpenStreetMap haben.",
     "reauthNow": "Jetzt machen",
-    "reauthLater": "Später"
+    "newChangesetComments": "Neuer Changeset-Kommentar",
+    "newChangesetCommentsSubtitle": "Jemand hat einen oder mehrere Ihrer Changesets kommentiert",
+    "reauthLater": "Später",
+    "unreadNotificationsTitle": "Sie haben ungelesene Benachrichtigungen",
+    "unreadNotificationsMessage": "Sie haben ungelesene OSM-Nachrichten und/oder neue Kommentare zu Ihren Changesets.",
+    "unreadNotificationsView": "Jetzt ansehen"
   },
   "queue": {
     "title": "Upload-Warteschlange",

lib/localizations/en.json

@@ -267,11 +267,16 @@
     "viewMessages": "View Messages on OSM",
     "unreadMessagesCount": "You have {} unread messages",
     "noUnreadMessages": "No unread messages",
+    "newChangesetComments": "New Changeset Comment",
+    "newChangesetCommentsSubtitle": "Someone commented on one or more of your changesets",
     "reauthRequired": "Refresh Authentication",
     "reauthExplanation": "You must refresh your authentication to receive OSM message notifications through the app.",
     "reauthBenefit": "This will enable notification dots when you have unread messages on OpenStreetMap.",
     "reauthNow": "Do That Now",
-    "reauthLater": "Later"
+    "reauthLater": "Later",
+    "unreadNotificationsTitle": "You Have Unread Notifications",
+    "unreadNotificationsMessage": "You have unread OSM messages and/or new comments on your changesets.",
+    "unreadNotificationsView": "View Now"
   },
   "queue": {
     "title": "Upload Queue",

lib/localizations/es.json

@@ -272,7 +272,12 @@
     "reauthExplanation": "Debes actualizar tu autenticación para recibir notificaciones de mensajes OSM a través de la aplicación.",
     "reauthBenefit": "Esto habilitará puntos de notificación cuando tengas mensajes sin leer en OpenStreetMap.",
     "reauthNow": "Hazlo Ahora",
-    "reauthLater": "Más Tarde"
+    "newChangesetComments": "Nuevo Comentario en Changeset",
+    "newChangesetCommentsSubtitle": "Alguien comentó en uno o más de tus changesets",
+    "reauthLater": "Más Tarde",
+    "unreadNotificationsTitle": "Tienes Notificaciones Sin Leer",
+    "unreadNotificationsMessage": "Tienes mensajes de OSM sin leer y/o nuevos comentarios en tus changesets.",
+    "unreadNotificationsView": "Ver Ahora"
   },
   "queue": {
     "title": "Cola de Subida",

lib/localizations/fr.json

@@ -272,7 +272,12 @@
     "reauthExplanation": "Vous devez actualiser votre authentification pour recevoir des notifications de messages OSM via l'application.",
     "reauthBenefit": "Cela activera les points de notification lorsque vous avez des messages non lus sur OpenStreetMap.",
     "reauthNow": "Le Faire Maintenant",
-    "reauthLater": "Plus Tard"
+    "newChangesetComments": "Nouveau Commentaire de Changeset",
+    "newChangesetCommentsSubtitle": "Quelqu'un a commenté un ou plusieurs de vos changesets",
+    "reauthLater": "Plus Tard",
+    "unreadNotificationsTitle": "Vous Avez des Notifications Non Lues",
+    "unreadNotificationsMessage": "Vous avez des messages OSM non lus et/ou de nouveaux commentaires sur vos changesets.",
+    "unreadNotificationsView": "Voir Maintenant"
   },
   "queue": {
     "title": "File de Téléchargement",

lib/localizations/it.json

@@ -272,7 +272,12 @@
     "reauthExplanation": "Devi aggiornare la tua autenticazione per ricevere notifiche di messaggi OSM tramite l'app.",
     "reauthBenefit": "Questo abiliterà i punti di notifica quando hai messaggi non letti su OpenStreetMap.",
     "reauthNow": "Fallo Ora",
-    "reauthLater": "Più Tardi"
+    "newChangesetComments": "Nuovo Commento al Changeset",
+    "newChangesetCommentsSubtitle": "Qualcuno ha commentato uno o più dei tuoi changeset",
+    "reauthLater": "Più Tardi",
+    "unreadNotificationsTitle": "Hai Notifiche Non Lette",
+    "unreadNotificationsMessage": "Hai messaggi OSM non letti e/o nuovi commenti sui tuoi changeset.",
+    "unreadNotificationsView": "Visualizza Ora"
   },
   "queue": {
     "title": "Coda di Upload",

lib/localizations/nl.json

@@ -272,7 +272,12 @@
     "reauthExplanation": "U moet uw authenticatie verversen om OSM bericht meldingen te ontvangen via de app.",
     "reauthBenefit": "Dit zal melding stippen inschakelen wanneer u ongelezen berichten heeft op OpenStreetMap.",
     "reauthNow": "Doe Dat Nu",
-    "reauthLater": "Later"
+    "newChangesetComments": "Nieuwe Changeset-opmerking",
+    "newChangesetCommentsSubtitle": "Iemand heeft commentaar gegeven op een of meer van uw changesets",
+    "reauthLater": "Later",
+    "unreadNotificationsTitle": "U Heeft Ongelezen Meldingen",
+    "unreadNotificationsMessage": "U heeft ongelezen OSM-berichten en/of nieuwe opmerkingen op uw changesets.",
+    "unreadNotificationsView": "Nu Bekijken"
   },
   "queue": {
     "title": "Upload Wachtrij",

lib/localizations/pl.json

@@ -272,7 +272,12 @@
     "reauthExplanation": "Musisz odświeżyć uwierzytelnienie, aby otrzymywać powiadomienia o wiadomościach OSM przez aplikację.",
     "reauthBenefit": "To włączy kropki powiadomień, gdy masz nieprzeczytane wiadomości w OpenStreetMap.",
     "reauthNow": "Zrób To Teraz",
-    "reauthLater": "Później"
+    "newChangesetComments": "Nowy Komentarz do Zestawu Zmian",
+    "newChangesetCommentsSubtitle": "Ktoś skomentował jeden lub więcej Twoich zestawów zmian",
+    "reauthLater": "Później",
+    "unreadNotificationsTitle": "Masz Nieprzeczytane Powiadomienia",
+    "unreadNotificationsMessage": "Masz nieprzeczytane wiadomości OSM i/lub nowe komentarze do Twoich zestawów zmian.",
+    "unreadNotificationsView": "Zobacz Teraz"
   },
   "queue": {
     "title": "Kolejka Przesyłania",

lib/localizations/pt.json

@@ -272,7 +272,12 @@
     "reauthExplanation": "Você deve atualizar sua autenticação para receber notificações de mensagens OSM através do aplicativo.",
     "reauthBenefit": "Isso habilitará pontos de notificação quando você tiver mensagens não lidas no OpenStreetMap.",
     "reauthNow": "Fazer Agora",
-    "reauthLater": "Mais Tarde"
+    "newChangesetComments": "Novo Comentário no Changeset",
+    "newChangesetCommentsSubtitle": "Alguém comentou em um ou mais dos seus changesets",
+    "reauthLater": "Mais Tarde",
+    "unreadNotificationsTitle": "Você Tem Notificações Não Lidas",
+    "unreadNotificationsMessage": "Você tem mensagens OSM não lidas e/ou novos comentários nos seus changesets.",
+    "unreadNotificationsView": "Ver Agora"
   },
   "queue": {
     "title": "Fila de Upload",

lib/localizations/tr.json

@@ -272,7 +272,12 @@
     "reauthExplanation": "Uygulama üzerinden OSM mesaj bildirimlerini alabilmek için kimlik doğrulamanızı yenilemeniz gerekir.",
     "reauthBenefit": "Bu, OpenStreetMap'te okunmamış mesajlarınız olduğunda bildirim noktalarını etkinleştirecek.",
     "reauthNow": "Şimdi Yap",
-    "reauthLater": "Sonra"
+    "newChangesetComments": "Yeni Değişiklik Kümesi Yorumu",
+    "newChangesetCommentsSubtitle": "Biri değişiklik kümelerinizden birine veya birkaçına yorum yaptı",
+    "reauthLater": "Sonra",
+    "unreadNotificationsTitle": "Okunmamış Bildirimleriniz Var",
+    "unreadNotificationsMessage": "Okunmamış OSM mesajlarınız ve/veya değişiklik kümelerinize yapılan yeni yorumlar var.",
+    "unreadNotificationsView": "Şimdi Görüntüle"
   },
   "queue": {
     "title": "Yükleme Kuyruğu",

lib/localizations/uk.json

@@ -272,7 +272,12 @@
     "reauthExplanation": "Ви повинні оновити вашу автентифікацію, щоб отримувати сповіщення про повідомлення OSM через додаток.",
     "reauthBenefit": "Це дозволить показувати точки сповіщень, коли у вас є непрочитані повідомлення в OpenStreetMap.",
     "reauthNow": "Зробити Зараз",
-    "reauthLater": "Пізніше"
+    "newChangesetComments": "Новий Коментар до Набору Змін",
+    "newChangesetCommentsSubtitle": "Хтось прокоментував один або декілька ваших наборів змін",
+    "reauthLater": "Пізніше",
+    "unreadNotificationsTitle": "У Вас Є Непрочитані Сповіщення",
+    "unreadNotificationsMessage": "У вас є непрочитані повідомлення OSM та/або нові коментарі до ваших наборів змін.",
+    "unreadNotificationsView": "Переглянути Зараз"
   },
   "queue": {
     "title": "Черга Завантаження",

lib/localizations/zh.json

@@ -272,7 +272,12 @@
     "reauthExplanation": "您必须刷新身份验证才能通过应用接收 OSM 消息通知。",
     "reauthBenefit": "这将在您在 OpenStreetMap 上有未读消息时启用通知点。",
     "reauthNow": "现在执行",
-    "reauthLater": "稍后"
+    "newChangesetComments": "新的变更集评论",
+    "newChangesetCommentsSubtitle": "有人评论了您的一个或多个变更集",
+    "reauthLater": "稍后",
+    "unreadNotificationsTitle": "您有未读通知",
+    "unreadNotificationsMessage": "您有未读的 OSM 消息和/或对您变更集的新评论。",
+    "unreadNotificationsView": "立即查看"
   },
   "queue": {
     "title": "上传队列",

lib/screens/home_screen.dart

@@ -18,6 +18,7 @@ import '../widgets/search_bar.dart';
 import '../widgets/suspected_location_sheet.dart';
 import '../widgets/welcome_dialog.dart';
 import '../widgets/changelog_dialog.dart';
+import '../widgets/unread_notifications_dialog.dart';
 import '../models/osm_node.dart';
 import '../models/suspected_location.dart';
 import '../models/search_result.dart';
@@ -54,6 +55,9 @@ class _HomeScreenState extends State<HomeScreen> with TickerProviderStateMixin {
   // Track popup display to avoid showing multiple times
   bool _hasCheckedForPopup = false;
   
+  // Track whether we've shown the unread notifications popup this session
+  bool _hasShownUnreadNotificationsPopup = false;
+
   @override
   void initState() {
     super.initState();
@@ -247,6 +251,21 @@ class _HomeScreenState extends State<HomeScreen> with TickerProviderStateMixin {
     }
   }
 
+  void _showUnreadNotificationsDialog() {
+    if (!mounted) return;
+    showDialog(
+      context: context,
+      builder: (context) => UnreadNotificationsDialog(
+        onView: () {
+          Navigator.of(context).pushNamed('/settings/osm-account');
+        },
+        onDismiss: () {
+          // Just dismiss - badges remain visible until the user views them.
+        },
+      ),
+    );
+  }
+
   void _onStartRoute() {
     _navigationCoordinator.startRoute(
       context: context,
@@ -457,6 +476,19 @@ class _HomeScreenState extends State<HomeScreen> with TickerProviderStateMixin {
       });
     }
 
+    // Show a one-time popup this session if the user has unread messages
+    // and/or unread changeset comments. Gated on _hasCheckedForPopup so it
+    // doesn't race with the welcome/changelog dialog above.
+    if (_hasCheckedForPopup &&
+        !_hasShownUnreadNotificationsPopup &&
+        appState.isLoggedIn &&
+        appState.hasUnreadNotifications) {
+      _hasShownUnreadNotificationsPopup = true;
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        _showUnreadNotificationsDialog();
+      });
+    }
+
     // Auto-focus a node's details sheet right after it was submitted/edited/deleted,
     // behind kAutoOpenNodeSheetAfterSubmit (pending A/B testing/team feedback).
     if (kAutoOpenNodeSheetAfterSubmit) {
@@ -510,23 +542,9 @@ class _HomeScreenState extends State<HomeScreen> with TickerProviderStateMixin {
                 final appState = context.watch<AppState>();
                 return IconButton(
                   tooltip: LocalizationService.instance.settings,
-                  icon: Stack(
+                  icon: Badge(
-                    children: [
+                    isLabelVisible: appState.hasUnreadNotifications,
-                      const Icon(Icons.settings),
+                    child: const Icon(Icons.settings),
-                      if (appState.hasUnreadMessages)
-                        Positioned(
-                          right: 0,
-                          top: 0,
-                          child: Container(
-                            width: 10,
-                            height: 10,
-                            decoration: BoxDecoration(
-                              color: Theme.of(context).colorScheme.error,
-                              shape: BoxShape.circle,
-                            ),
-                          ),
-                        ),
-                    ],
                   ),
                   onPressed: () => Navigator.pushNamed(context, '/settings'),
                 );

lib/screens/osm_account_screen.dart

@@ -128,38 +128,46 @@ class _OSMAccountScreenState extends State<OSMAccountScreen> {
                           },
                         ),
                         
+                        // Unread changeset comments - links directly to the
+                        // specific changeset with the new comment, and only
+                        // appears when there is one.
+                        if (appState.hasUnreadChangesetComments) ...[
+                          const Divider(),
+                          ListTile(
+                            leading: Badge(
+                              isLabelVisible: true,
+                              child: const Icon(Icons.comment),
+                            ),
+                            title: Text(locService.t('auth.newChangesetComments')),
+                            subtitle: Text(locService.t('auth.newChangesetCommentsSubtitle')),
+                            trailing: const Icon(Icons.open_in_new),
+                            onTap: () async {
+                              final changesetUrl = appState.getUnreadChangesetUrl();
+                              if (changesetUrl == null) return;
+                              final url = Uri.parse(changesetUrl);
+                              if (await canLaunchUrl(url)) {
+                                await launchUrl(url, mode: LaunchMode.externalApplication);
+                                // The user has now had the opportunity to see the
+                                // new comment on OSM's website - clear our badge.
+                                appState.markChangesetCommentsRead();
+                              } else {
+                                if (context.mounted) {
+                                  ScaffoldMessenger.of(context).showSnackBar(
+                                    SnackBar(content: Text(locService.t('advancedEdit.couldNotOpenOSMWebsite'))),
+                                  );
+                                }
+                              }
+                            },
+                          ),
+                        ],
+                        
                         // Messages button - only show when not in simulate mode
                         const Divider(),
                       ListTile(
-                        leading: Stack(
+                        leading: Badge(
-                          children: [
+                          isLabelVisible: appState.hasUnreadMessages,
-                            const Icon(Icons.message),
+                          label: Text('${appState.unreadMessageCount ?? 0}'),
-                            if (appState.hasUnreadMessages)
+                          child: const Icon(Icons.message),
-                              Positioned(
-                                right: 0,
-                                top: 0,
-                                child: Container(
-                                  padding: const EdgeInsets.all(2),
-                                  decoration: BoxDecoration(
-                                    color: Theme.of(context).colorScheme.error,
-                                    shape: BoxShape.circle,
-                                  ),
-                                  constraints: const BoxConstraints(
-                                    minWidth: 12,
-                                    minHeight: 12,
-                                  ),
-                                  child: Text(
-                                    '${appState.unreadMessageCount}',
-                                    style: TextStyle(
-                                      color: Theme.of(context).colorScheme.onError,
-                                      fontSize: 10,
-                                      fontWeight: FontWeight.bold,
-                                    ),
-                                    textAlign: TextAlign.center,
-                                  ),
-                                ),
-                              ),
-                          ],
                         ),
                         title: Text(locService.t('auth.viewMessages')),
                         subtitle: Text(appState.hasUnreadMessages

lib/screens/settings_screen.dart

@@ -117,23 +117,9 @@ class SettingsScreen extends StatelessWidget {
     final appState = context.watch<AppState>();
     
     return ListTile(
-      leading: Stack(
+      leading: Badge(
-        children: [
+        isLabelVisible: appState.hasUnreadNotifications,
-          const Icon(Icons.account_circle),
+        child: const Icon(Icons.account_circle),
-          if (appState.hasUnreadMessages)
-            Positioned(
-              right: 0,
-              top: 0,
-              child: Container(
-                width: 10,
-                height: 10,
-                decoration: BoxDecoration(
-                  color: Theme.of(context).colorScheme.error,
-                  shape: BoxShape.circle,
-                ),
-              ),
-            ),
-        ],
       ),
       title: Text(locService.t('auth.osmAccountTitle')),
       subtitle: Text(locService.t('auth.osmAccountSubtitle')),

lib/services/changeset_comments_service.dart

@@ -0,0 +1,182 @@
+import 'dart:convert';
+import 'package:shared_preferences/shared_preferences.dart';
+import '../state/settings_state.dart';
+import 'http_client.dart';
+
+/// Tracks unread comments on the user's own changesets.
+///
+/// The OSM API has no "read" concept for changeset comments, so we track it
+/// ourselves: we remember the `comments_count` we last saw for each of the
+/// user's recent changesets, and flag a changeset as having unread comments
+/// if it now has a higher count than what we last recorded.
+///
+/// This only looks at the user's most recent 100 changesets (the OSM API's
+/// max page size, and it doesn't support simple offset paging). If a
+/// changeset receives a new comment and then ages out of that window
+/// entirely before the next check, we will miss it - an accepted limitation
+/// of polling a bounded recent-activity window rather than a real
+/// notification feed.
+class ChangesetCommentsService {
+  static const _cacheDuration = Duration(minutes: 5);
+  final _client = UserAgentClient();
+
+  DateTime? _lastCheck;
+  int? _lastResult; // ID of changeset with unread comments, or null if none
+  bool _lastResultIsSet = false; // whether _lastResult holds a valid cached value
+  UploadMode? _lastMode;
+
+  /// Returns the ID of a changeset with more comments now than the last
+  /// time [markRead] was called for this upload mode, or null if there are
+  /// none (or if not logged in, in simulate mode, or on error). When
+  /// multiple changesets have new comments, returns the most recent one
+  /// (the API returns changesets newest-first).
+  Future<int?> getUnreadChangesetId({
+    required String? username,
+    required UploadMode uploadMode,
+    bool forceRefresh = false,
+  }) async {
+    if (uploadMode == UploadMode.simulate) return null;
+    if (username == null || username.isEmpty) return null;
+
+    if (!forceRefresh &&
+        _lastResultIsSet &&
+        _lastMode == uploadMode &&
+        _lastCheck != null &&
+        DateTime.now().difference(_lastCheck!) < _cacheDuration) {
+      return _lastResult;
+    }
+
+    try {
+      final current = await _fetchCommentCounts(username, uploadMode);
+      if (current == null) return null;
+
+      final seen = await _loadSeenCounts(uploadMode);
+      // current is built from the API response, which is ordered
+      // newest-first, so the first match found is the most recent one.
+      int? unreadId;
+      for (final entry in current.entries) {
+        if (entry.value > (seen[entry.key] ?? 0)) {
+          unreadId = entry.key;
+          break;
+        }
+      }
+
+      _lastCheck = DateTime.now();
+      _lastResult = unreadId;
+      _lastResultIsSet = true;
+      _lastMode = uploadMode;
+
+      return unreadId;
+    } catch (e) {
+      return null;
+    }
+  }
+
+  /// Mark all currently-visible changeset comments as read by saving the
+  /// current comment counts as the new baseline.
+  Future<void> markRead({
+    required String? username,
+    required UploadMode uploadMode,
+  }) async {
+    if (uploadMode == UploadMode.simulate) return;
+    if (username == null || username.isEmpty) return;
+
+    try {
+      final current = await _fetchCommentCounts(username, uploadMode);
+      if (current == null) return;
+
+      await _saveSeenCounts(uploadMode, current);
+
+      // Update in-memory cache so getUnreadChangesetId() doesn't need to
+      // re-fetch immediately after marking read.
+      _lastCheck = DateTime.now();
+      _lastResult = null;
+      _lastResultIsSet = true;
+      _lastMode = uploadMode;
+    } catch (e) {
+      // Best-effort - if this fails the badge will just persist until the
+      // next successful mark-read attempt.
+    }
+  }
+
+  /// Clear cached state (useful on logout or upload mode change).
+  void clearCache() {
+    _lastCheck = null;
+    _lastResult = null;
+    _lastResultIsSet = false;
+    _lastMode = null;
+  }
+
+  /// Build the URL to the given changeset on the OSM website for the given
+  /// upload mode.
+  String getChangesetUrl(int changesetId, UploadMode uploadMode) {
+    switch (uploadMode) {
+      case UploadMode.production:
+        return 'https://www.openstreetmap.org/changeset/$changesetId';
+      case UploadMode.sandbox:
+        return 'https://master.apis.dev.openstreetmap.org/changeset/$changesetId';
+      case UploadMode.simulate:
+        return 'https://www.openstreetmap.org/changeset/$changesetId';
+    }
+  }
+
+  /// Fetches the user's most recent changesets and returns a map of
+  /// changeset ID -> comments_count. Returns null on any error.
+  Future<Map<int, int>?> _fetchCommentCounts(
+    String username,
+    UploadMode uploadMode,
+  ) async {
+    final apiHost = _getApiHost(uploadMode);
+    final response = await _client.get(
+      Uri.parse('$apiHost/api/0.6/changesets.json?display_name=${Uri.encodeQueryComponent(username)}'),
+    );
+
+    if (response.statusCode != 200) return null;
+
+    final data = jsonDecode(response.body);
+    final changesets = data['changesets'];
+    if (changesets is! List) return null;
+
+    final result = <int, int>{};
+    for (final cs in changesets) {
+      final id = cs['id'];
+      final count = cs['comments_count'];
+      if (id is int && count is int) {
+        result[id] = count;
+      }
+    }
+    return result;
+  }
+
+  Future<Map<int, int>> _loadSeenCounts(UploadMode uploadMode) async {
+    final prefs = await SharedPreferences.getInstance();
+    final json = prefs.getString(_prefsKey(uploadMode));
+    if (json == null) return {};
+    try {
+      final decoded = jsonDecode(json) as Map<String, dynamic>;
+      return decoded.map((k, v) => MapEntry(int.parse(k), v as int));
+    } catch (e) {
+      return {};
+    }
+  }
+
+  Future<void> _saveSeenCounts(UploadMode uploadMode, Map<int, int> counts) async {
+    final prefs = await SharedPreferences.getInstance();
+    final encoded = jsonEncode(counts.map((k, v) => MapEntry(k.toString(), v)));
+    await prefs.setString(_prefsKey(uploadMode), encoded);
+  }
+
+  String _prefsKey(UploadMode uploadMode) =>
+      'changeset_comments_seen_${uploadMode.name}';
+
+  String _getApiHost(UploadMode uploadMode) {
+    switch (uploadMode) {
+      case UploadMode.production:
+        return 'https://api.openstreetmap.org';
+      case UploadMode.sandbox:
+        return 'https://api06.dev.openstreetmap.org';
+      case UploadMode.simulate:
+        return 'https://api.openstreetmap.org';
+    }
+  }
+}

lib/state/messages_state.dart

@@ -1,22 +1,28 @@
 import 'package:flutter/material.dart';
 import '../services/osm_messages_service.dart';
+import '../services/changeset_comments_service.dart';
 import 'settings_state.dart';
 
-/// State management for OSM message notifications
+/// State management for OSM message and changeset comment notifications
 class MessagesState extends ChangeNotifier {
   final OSMMessagesService _messagesService = OSMMessagesService();
+  final ChangesetCommentsService _changesetCommentsService = ChangesetCommentsService();
   
   int? _unreadCount;
+  int? _unreadChangesetId; // ID of a changeset with unread comments, if any
   bool _isChecking = false;
   
   // Getters
   int? get unreadCount => _unreadCount;
   bool get hasUnreadMessages => (_unreadCount ?? 0) > 0;
+  bool get hasUnreadChangesetComments => _unreadChangesetId != null;
+  bool get hasUnreadNotifications => hasUnreadMessages || hasUnreadChangesetComments;
   bool get isChecking => _isChecking;
   
-  /// Check for unread messages
+  /// Check for unread messages and changeset comments
   Future<void> checkMessages({
     required String? accessToken,
+    required String? username,
     required UploadMode uploadMode,
     bool forceRefresh = false,
   }) async {
@@ -26,18 +32,29 @@ class MessagesState extends ChangeNotifier {
     notifyListeners();
     
     try {
-      final count = await _messagesService.getUnreadMessageCount(
+      final results = await Future.wait([
+        _messagesService.getUnreadMessageCount(
           accessToken: accessToken,
           uploadMode: uploadMode,
           forceRefresh: forceRefresh,
-      );
+        ),
+        _changesetCommentsService.getUnreadChangesetId(
+          username: username,
+          uploadMode: uploadMode,
+          forceRefresh: forceRefresh,
+        ),
+      ]);
       
-      if (_unreadCount != count) {
+      final count = results[0] as int?;
+      final unreadChangesetId = results[1] as int?;
+      
+      if (_unreadCount != count || _unreadChangesetId != unreadChangesetId) {
         _unreadCount = count;
+        _unreadChangesetId = unreadChangesetId;
         notifyListeners();
       }
     } catch (e) {
-      // Silently handle errors - messages are not critical
+      // Silently handle errors - notifications are not critical
       debugPrint('MessagesState: Error checking messages: $e');
     } finally {
       _isChecking = false;
@@ -45,6 +62,26 @@ class MessagesState extends ChangeNotifier {
     }
   }
   
+  /// URL of the changeset with unread comments, on OSM's website, or null
+  /// if there are no unread changeset comments.
+  String? getUnreadChangesetUrl(UploadMode uploadMode) {
+    final id = _unreadChangesetId;
+    if (id == null) return null;
+    return _changesetCommentsService.getChangesetUrl(id, uploadMode);
+  }
+  
+  /// Mark changeset comments as read (called when user views the changeset on OSM)
+  Future<void> markChangesetCommentsRead({
+    required String? username,
+    required UploadMode uploadMode,
+  }) async {
+    await _changesetCommentsService.markRead(username: username, uploadMode: uploadMode);
+    if (_unreadChangesetId != null) {
+      _unreadChangesetId = null;
+      notifyListeners();
+    }
+  }
+  
   /// Get the URL to view messages
   String getMessagesUrl(UploadMode uploadMode) {
     return _messagesService.getMessagesUrl(uploadMode);
@@ -53,7 +90,9 @@ class MessagesState extends ChangeNotifier {
   /// Clear message state (when user logs out or changes mode)
   void clearMessages() {
     _unreadCount = null;
+    _unreadChangesetId = null;
     _messagesService.clearCache();
+    _changesetCommentsService.clearCache();
     notifyListeners();
   }
 }

lib/widgets/unread_notifications_dialog.dart

@@ -0,0 +1,54 @@
+import 'package:flutter/material.dart';
+import '../services/localization_service.dart';
+
+/// Dialog shown once per session when the user has unread OSM messages
+/// and/or unread changeset comments, prompting them to view their OSM
+/// account details.
+class UnreadNotificationsDialog extends StatelessWidget {
+  final VoidCallback onView;
+  final VoidCallback onDismiss;
+
+  const UnreadNotificationsDialog({
+    super.key,
+    required this.onView,
+    required this.onDismiss,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final locService = LocalizationService.instance;
+
+    return AlertDialog(
+      title: Row(
+        children: [
+          Icon(
+            Icons.notifications_active_outlined,
+            color: Theme.of(context).colorScheme.primary,
+          ),
+          const SizedBox(width: 8),
+          Expanded(
+            child: Text(locService.t('auth.unreadNotificationsTitle')),
+          ),
+        ],
+      ),
+      content: Text(locService.t('auth.unreadNotificationsMessage')),
+      actions: [
+        TextButton(
+          onPressed: () {
+            Navigator.of(context).pop();
+            onDismiss();
+          },
+          child: Text(locService.t('auth.reauthLater')),
+        ),
+        FilledButton.icon(
+          onPressed: () {
+            Navigator.of(context).pop();
+            onView();
+          },
+          icon: const Icon(Icons.arrow_forward, size: 18),
+          label: Text(locService.t('auth.unreadNotificationsView')),
+        ),
+      ],
+    );
+  }
+}