fix: show account-not-found message on 404 logout (WT-956)

lib/app/notifications/models/notification.dart

@@ -143,6 +143,15 @@ class SessionExpiredNotification extends MessageNotification {
   }
 }
 
+class AccountNotFoundNotification extends MessageNotification {
+  const AccountNotFoundNotification();
+
+  @override
+  String l10n(BuildContext context) {
+    return context.l10n.notifications_errorSnackBar_accountNotFound;
+  }
+}
+
 class DeleteAccountNotSupportedNotification extends MessageNotification {
   const DeleteAccountNotSupportedNotification();
 

lib/app/router/main_shell.dart

@@ -107,11 +107,16 @@ class _MainShellState extends State<MainShell> with WidgetsBindingObserver {
     final notificationsBloc = context.read<NotificationsBloc>();
 
     _sessionGuard = RouterLogoutSessionGuard(
-      performLogout: () {
-        _appBloc.add(const AppLogoutRequested(reason: AppLogoutReason.serverRejection));
+      performLogout: (e) {
+        final reason = e is UserNotFoundException ? AppLogoutReason.userNotFound : AppLogoutReason.serverRejection;
+        _appBloc.add(AppLogoutRequested(reason: reason));
       },
-      onPreLogout: () {
-        notificationsBloc.add(NotificationsSubmitted(SessionExpiredNotification()));
+      onPreLogout: (e) {
+        notificationsBloc.add(
+          NotificationsSubmitted(
+            e is UserNotFoundException ? const AccountNotFoundNotification() : const SessionExpiredNotification(),
+          ),
+        );
       },
     );
   }

lib/app/session/router_logout_session_guard.dart

@@ -6,7 +6,7 @@ import 'package:webtrit_phone/common/common.dart';
 
 import 'session_guard.dart';
 
-typedef AsyncVoidCallback = FutureOr<void> Function();
+typedef SessionGuardCallback = FutureOr<void> Function(Exception e);
 
 final _log = Logger('RouterLogoutSessionGuard');
 
@@ -26,11 +26,14 @@ class RouterLogoutSessionGuard implements SessionGuard, Disposable {
   RouterLogoutSessionGuard({required this.performLogout, this.onPreLogout});
 
   /// Function that performs the actual logout (e.g. dispatching a logout event).
-  final AsyncVoidCallback performLogout;
+  /// Receives the unauthorized [Exception] so callers can tailor the logout
+  /// (e.g. distinguish an expired session from a deleted account).
+  final SessionGuardCallback performLogout;
 
   /// Optional hook executed before [performLogout].
-  /// Useful for cleaning up resources or saving state.
-  final AsyncVoidCallback? onPreLogout;
+  /// Useful for cleaning up resources or saving state. Receives the same
+  /// unauthorized [Exception] passed to [performLogout].
+  final SessionGuardCallback? onPreLogout;
 
   bool _handled = false;
   bool _disposed = false;
@@ -50,8 +53,8 @@ class RouterLogoutSessionGuard implements SessionGuard, Disposable {
 
       _log.warning('Unauthorized access detected: ${e.toString()}');
 
-      await _runHookSafe();
-      await _runLogoutSafe();
+      await _runHookSafe(e);
+      await _runLogoutSafe(e);
     });
   }
 
@@ -61,19 +64,19 @@ class RouterLogoutSessionGuard implements SessionGuard, Disposable {
     return true;
   }
 
-  Future<void> _runHookSafe() async {
+  Future<void> _runHookSafe(Exception e) async {
     final hook = onPreLogout;
     if (hook == null) return;
     try {
-      await hook();
+      await hook(e);
     } catch (err, st) {
       _log.warning('onBeforeLogout failed', err, st);
     }
   }
 
-  Future<void> _runLogoutSafe() async {
+  Future<void> _runLogoutSafe(Exception e) async {
     try {
-      await performLogout();
+      await performLogout(e);
     } catch (err, st) {
       _log.severe('logoutLocal failed', err, st);
     }

lib/blocs/app/app_bloc.dart

@@ -131,8 +131,9 @@ class AppBloc extends Bloc<AppEvent, AppState> {
     final currentSession = sessionRepository.getCurrent();
 
     // Determine if we should attempt to revoke the session on the server.
-    // We skip this only for 'sessionMissed' because the socket error (4201)
-    // guarantees the session is already terminated.
+    // We skip this for 'sessionMissed' because the socket error (4201)
+    // guarantees the session is already terminated, and for 'userNotFound'
+    // because the account no longer exists (the revoke would just 404 again).
     final shouldRevokeRemote = reason == AppLogoutReason.userRequest || reason == AppLogoutReason.serverRejection;
 
     if (shouldRevokeRemote && currentSession.isLoggedIn) {

lib/blocs/app/app_event.dart

@@ -12,6 +12,11 @@ enum AppLogoutReason {
   /// The server explicitly rejected a request due to authentication.
   /// Requires both remote session revocation and local data cleanup.
   serverRejection,
+
+  /// The account no longer exists on the server (404 UserNotFoundException),
+  /// e.g. it was deactivated or removed. Terminal; requires only local data
+  /// cleanup since the remote user record is already gone.
+  userNotFound,
 }
 
 sealed class AppEvent extends Equatable {

lib/l10n/app_localizations.g.dart

@@ -2526,6 +2526,12 @@ abstract class AppLocalizations {
   /// **'Your session has expired. Please log in again.'**
   String get notifications_errorSnackBar_sessionExpired;
 
+  /// Shown in a notification or snackbar when the backend returns 404 (user not found) for the current account, e.g. it was deactivated or removed on the server. The user is logged out; advise them to contact their administrator.
+  ///
+  /// In en, this message translates to:
+  /// **'Your account was not found. It may have been deactivated or removed. Please contact your administrator.'**
+  String get notifications_errorSnackBar_accountNotFound;
+
   /// Shown in a notification or snackbar when the app fails to connect to the WebTrit core and is attempting automatic reconnection. Context: occurs when the signaling/WebSocket connection cannot be established due to network outages, server unreachability, TLS/handshake failures, authentication errors (expired/invalid tokens), or firewall/VPN restrictions. Suggest the user check their network, retry, or reauthenticate if the problem persists.
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_en.g.dart

@@ -1350,6 +1350,10 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get notifications_errorSnackBar_sessionExpired => 'Your session has expired. Please log in again.';
 
+  @override
+  String get notifications_errorSnackBar_accountNotFound =>
+      'Your account was not found. It may have been deactivated or removed. Please contact your administrator.';
+
   @override
   String get notifications_errorSnackBar_SignalingConnectFailed => 'Connecting to the core failed, trying to reconnect';
 

lib/l10n/app_localizations_it.g.dart

@@ -1368,6 +1368,10 @@ class AppLocalizationsIt extends AppLocalizations {
   @override
   String get notifications_errorSnackBar_sessionExpired => 'La tua sessione è scaduta. Accedi di nuovo.';
 
+  @override
+  String get notifications_errorSnackBar_accountNotFound =>
+      'Il tuo account non è stato trovato. Potrebbe essere stato disattivato o rimosso. Contatta il tuo amministratore.';
+
   @override
   String get notifications_errorSnackBar_SignalingConnectFailed =>
       'Connessione al server non riuscita, tentativo di riconnessione in corso';

lib/l10n/app_localizations_uk.g.dart

@@ -1372,6 +1372,10 @@ class AppLocalizationsUk extends AppLocalizations {
   String get notifications_errorSnackBar_sessionExpired =>
       'Термін дії вашої сесії закінчився. Будь ласка, увійдіть знову.';
 
+  @override
+  String get notifications_errorSnackBar_accountNotFound =>
+      'Ваш обліковий запис не знайдено. Можливо, його деактивовано або видалено. Зверніться до адміністратора.';
+
   @override
   String get notifications_errorSnackBar_SignalingConnectFailed => 'Підключення до ядра не вдалося, спроба з\'єднання';
 

lib/l10n/arb/app_en.arb

@@ -1137,6 +1137,10 @@
   "@notifications_errorSnackBar_sessionExpired": {
     "description": "Shown in a notification or snackbar when the user's authentication session has expired and re-authentication is required. Typical causes: access or refresh token expiration/revocation, failed token refresh, or the backend invalidating the session. Advise the user to sign in again to restore full functionality."
   },
+  "notifications_errorSnackBar_accountNotFound": "Your account was not found. It may have been deactivated or removed. Please contact your administrator.",
+  "@notifications_errorSnackBar_accountNotFound": {
+    "description": "Shown in a notification or snackbar when the backend returns 404 (user not found) for the current account, e.g. it was deactivated or removed on the server. The user is logged out; advise them to contact their administrator."
+  },
   "notifications_errorSnackBar_SignalingConnectFailed": "Connecting to the core failed, trying to reconnect",
   "@notifications_errorSnackBar_SignalingConnectFailed": {
     "description": "Shown in a notification or snackbar when the app fails to connect to the WebTrit core and is attempting automatic reconnection. Context: occurs when the signaling/WebSocket connection cannot be established due to network outages, server unreachability, TLS/handshake failures, authentication errors (expired/invalid tokens), or firewall/VPN restrictions. Suggest the user check their network, retry, or reauthenticate if the problem persists."

lib/l10n/arb/app_it.arb

@@ -1137,6 +1137,10 @@
   "@notifications_errorSnackBar_sessionExpired": {
     "description": "Shown in a notification or snackbar when the user's authentication session has expired and re-authentication is required. Typical causes: access or refresh token expiration/revocation, failed token refresh, or the backend invalidating the session. Advise the user to sign in again to restore full functionality."
   },
+  "notifications_errorSnackBar_accountNotFound": "Il tuo account non è stato trovato. Potrebbe essere stato disattivato o rimosso. Contatta il tuo amministratore.",
+  "@notifications_errorSnackBar_accountNotFound": {
+    "description": "Shown in a notification or snackbar when the backend returns 404 (user not found) for the current account, e.g. it was deactivated or removed on the server. The user is logged out; advise them to contact their administrator."
+  },
   "notifications_errorSnackBar_SignalingConnectFailed": "Connessione al server non riuscita, tentativo di riconnessione in corso",
   "@notifications_errorSnackBar_SignalingConnectFailed": {
     "description": "Shown in a notification or snackbar when the app fails to connect to the WebTrit core and is attempting automatic reconnection. Context: occurs when the signaling/WebSocket connection cannot be established due to network outages, server unreachability, TLS/handshake failures, authentication errors (expired/invalid tokens), or firewall/VPN restrictions. Suggest the user check their network, retry, or reauthenticate if the problem persists."

lib/l10n/arb/app_uk.arb

@@ -1137,6 +1137,10 @@
   "@notifications_errorSnackBar_sessionExpired": {
     "description": "Shown in a notification or snackbar when the user's authentication session has expired and re-authentication is required. Typical causes: access or refresh token expiration/revocation, failed token refresh, or the backend invalidating the session. Advise the user to sign in again to restore full functionality."
   },
+  "notifications_errorSnackBar_accountNotFound": "Ваш обліковий запис не знайдено. Можливо, його деактивовано або видалено. Зверніться до адміністратора.",
+  "@notifications_errorSnackBar_accountNotFound": {
+    "description": "Shown in a notification or snackbar when the backend returns 404 (user not found) for the current account, e.g. it was deactivated or removed on the server. The user is logged out; advise them to contact their administrator."
+  },
   "notifications_errorSnackBar_SignalingConnectFailed": "Підключення до ядра не вдалося, спроба з'єднання",
   "@notifications_errorSnackBar_SignalingConnectFailed": {
     "description": "Shown in a notification or snackbar when the app fails to connect to the WebTrit core and is attempting automatic reconnection. Context: occurs when the signaling/WebSocket connection cannot be established due to network outages, server unreachability, TLS/handshake failures, authentication errors (expired/invalid tokens), or firewall/VPN restrictions. Suggest the user check their network, retry, or reauthenticate if the problem persists."