Pause polling and show a banner when the backend is unreachable

Adds a centralized BackendReachability singleton fed by a Dio
interceptor (connection-level failures only) and connectivity_plus.
PolledValue subscribes to it and pauses on offline / reloads
immediately on reconnect, replacing the previous per-card error
cascade. MainShell renders a global OfflineBanner with Retry and
Settings actions; cards downgrade error→stale when offline so the
banner is the only red element.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/lib/navigation.dart

@@ -8,6 +8,7 @@ import 'devices/device_list.dart';
 import 'home/home_screen.dart';
 import 'status/status_screen.dart';
 import 'utils/pref_utils.dart';
+import 'widgets/offline_banner.dart';
 
 // M3 window size class breakpoints
 const _mediumBreakpoint = 600.0;
@@ -109,9 +110,19 @@ class MainShell extends StatelessWidget {
         if (width < _mediumBreakpoint) {
           return Scaffold(
             appBar: _buildAppBar(context),
-            body: Padding(
+            body: Column(
-              padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
+              children: [
-              child: child,
+                const OfflineBanner(),
+                Expanded(
+                  child: Padding(
+                    padding: const EdgeInsets.symmetric(
+                      horizontal: 16,
+                      vertical: 12,
+                    ),
+                    child: child,
+                  ),
+                ),
+              ],
             ),
             bottomNavigationBar: NavigationBar(
               selectedIndex: selectedIndex,
@@ -156,9 +167,18 @@ class MainShell extends StatelessWidget {
               ),
               Expanded(
                 child: Container(
-                  padding: const EdgeInsets.all(20),
                   color: Theme.of(context).colorScheme.surface,
-                  child: child,
+                  child: Column(
+                    children: [
+                      const OfflineBanner(),
+                      Expanded(
+                        child: Padding(
+                          padding: const EdgeInsets.all(20),
+                          child: child,
+                        ),
+                      ),
+                    ],
+                  ),
                 ),
               ),
             ],

frontend/lib/utils/backend_reachability.dart

@@ -0,0 +1,96 @@
+import 'dart:async';
+
+import 'package:connectivity_plus/connectivity_plus.dart';
+import 'package:dio/dio.dart';
+import 'package:flutter/foundation.dart';
+
+import 'oott_api.dart';
+
+class BackendReachability extends ChangeNotifier {
+  BackendReachability._internal() {
+    _subscription = Connectivity().onConnectivityChanged.listen(
+      _handleConnectivityChange,
+    );
+    Connectivity().checkConnectivity().then(_handleConnectivityChange);
+  }
+
+  static final BackendReachability instance = BackendReachability._internal();
+
+  StreamSubscription<List<ConnectivityResult>>? _subscription;
+  Future<void> Function()? _prober;
+
+  bool _deviceHasNetwork = true;
+  bool _isBackendReachable = true;
+  DateTime? _lastSuccessAt;
+  DateTime? _lastFailureAt;
+  String? _lastErrorMessage;
+  bool _probing = false;
+
+  bool get deviceHasNetwork => _deviceHasNetwork;
+  bool get isBackendReachable => _isBackendReachable;
+  bool get isOnline => _deviceHasNetwork && _isBackendReachable;
+  bool get isProbing => _probing;
+  DateTime? get lastSuccessAt => _lastSuccessAt;
+  DateTime? get lastFailureAt => _lastFailureAt;
+  String? get lastErrorMessage => _lastErrorMessage;
+
+  void setProber(Future<void> Function() prober) {
+    _prober = prober;
+  }
+
+  void recordSuccess() {
+    _lastSuccessAt = DateTime.now();
+    _lastErrorMessage = null;
+    final wasReachable = _isBackendReachable;
+    _isBackendReachable = true;
+    if (!wasReachable) notifyListeners();
+  }
+
+  void recordFailure(DioException error) {
+    if (!_isConnectionLevel(error)) return;
+    _lastFailureAt = DateTime.now();
+    _lastErrorMessage = dioErrorToUserMessage(error);
+    final wasReachable = _isBackendReachable;
+    _isBackendReachable = false;
+    if (wasReachable) notifyListeners();
+  }
+
+  Future<void> probe() async {
+    final prober = _prober;
+    if (prober == null || _probing) return;
+    _probing = true;
+    notifyListeners();
+    try {
+      await prober();
+    } catch (_) {
+      // Interceptor records the outcome; nothing else to do here.
+    } finally {
+      _probing = false;
+      notifyListeners();
+    }
+  }
+
+  void _handleConnectivityChange(List<ConnectivityResult> results) {
+    final hasNetwork = results.any((r) => r != ConnectivityResult.none);
+    if (hasNetwork == _deviceHasNetwork) return;
+    _deviceHasNetwork = hasNetwork;
+    notifyListeners();
+    if (hasNetwork) {
+      unawaited(probe());
+    }
+  }
+
+  bool _isConnectionLevel(DioException error) {
+    if (error.type == DioExceptionType.cancel) return false;
+    // Anything without a response from the server is a connection-level
+    // failure (timeouts, connection refused, DNS, TLS, web fetch errors
+    // surfaced as DioExceptionType.unknown, etc.).
+    return error.response == null;
+  }
+
+  @override
+  void dispose() {
+    _subscription?.cancel();
+    super.dispose();
+  }
+}

frontend/lib/utils/oott_api.dart

@@ -4,6 +4,7 @@ import 'package:dio/dio.dart';
 import 'package:dio_smart_retry/dio_smart_retry.dart';
 import 'package:encrypter/encrypter/xor.dart';
 import 'package:flutter/foundation.dart';
+import 'package:frontend/utils/backend_reachability.dart';
 import 'package:frontend/utils/pref_utils.dart';
 import '../model/arp_scanner_status.dart';
 import '../model/mdns_scanner_status.dart';
@@ -36,6 +37,17 @@ RetryInterceptor _buildRetryInterceptor(Dio dio) => RetryInterceptor(
   },
 );
 
+InterceptorsWrapper _buildReachabilityInterceptor() => InterceptorsWrapper(
+  onResponse: (response, handler) {
+    BackendReachability.instance.recordSuccess();
+    handler.next(response);
+  },
+  onError: (error, handler) {
+    BackendReachability.instance.recordFailure(error);
+    handler.next(error);
+  },
+);
+
 LogInterceptor _buildLogInterceptor() => LogInterceptor(
   request: true,
   requestHeader: false,
@@ -106,9 +118,11 @@ class BackendAPI {
       ),
     );
     _dio.interceptors.add(_buildRetryInterceptor(_dio));
+    _dio.interceptors.add(_buildReachabilityInterceptor());
     if (kDebugMode) {
       _dio.interceptors.add(_buildLogInterceptor());
     }
+    BackendReachability.instance.setProber(() => _dio.get('/test'));
   }
 
   // Returns null if the test was successful, and a String with a message about the issue if not

frontend/lib/utils/polled_value.dart

@@ -3,10 +3,27 @@ import 'dart:async';
 import 'package:dio/dio.dart';
 import 'package:flutter/foundation.dart';
 
+import 'backend_reachability.dart';
 import 'oott_api.dart';
 
 enum PolledFreshness { initialLoading, fresh, stale, error }
 
+enum PolledPauseReason { manual, unreachable }
+
+/// Returns the freshness of [polled] downgraded to [PolledFreshness.stale]
+/// when the backend is known to be unreachable and a previous value exists.
+/// This avoids showing per-card error chrome while the global offline banner
+/// is already communicating the connectivity issue.
+PolledFreshness effectiveFreshness(PolledValue polled) {
+  final base = polled.freshness;
+  if (base == PolledFreshness.error &&
+      polled.value != null &&
+      !BackendReachability.instance.isOnline) {
+    return PolledFreshness.stale;
+  }
+  return base;
+}
+
 class PolledValue<T> extends ChangeNotifier {
   PolledValue({
     required Future<T> Function({CancelToken? cancelToken}) fetch,
@@ -15,13 +32,23 @@ class PolledValue<T> extends ChangeNotifier {
   }) : _fetch = fetch,
        _pollInterval = pollInterval,
        _staleErrorAfter = staleErrorAfter {
-    _load();
+    _reachability = BackendReachability.instance;
-    _pollTimer = Timer.periodic(pollInterval, (_) => _load());
+    _reachability.addListener(_onReachabilityChanged);
+    if (!_reachability.isOnline) {
+      _pauseReasons.add(PolledPauseReason.unreachable);
+    }
+    if (_pauseReasons.isEmpty) {
+      _load();
+      _startPolling();
+    }
   }
 
   final Future<T> Function({CancelToken? cancelToken}) _fetch;
   final Duration _pollInterval;
   final Duration _staleErrorAfter;
+  final Set<PolledPauseReason> _pauseReasons = {};
+  late final BackendReachability _reachability;
+
   Timer? _pollTimer;
   CancelToken? _cancelToken;
   bool _disposed = false;
@@ -68,23 +95,49 @@ class PolledValue<T> extends ChangeNotifier {
     }
   }
 
-  void pause() {
+  void _startPolling() {
+    _pollTimer ??= Timer.periodic(_pollInterval, (_) => _load());
+  }
+
+  void _stopPolling() {
     _pollTimer?.cancel();
     _pollTimer = null;
     _cancelToken?.cancel();
   }
 
-  void resume() {
+  void pauseFor(PolledPauseReason reason) {
+    final added = _pauseReasons.add(reason);
+    if (added && _pauseReasons.length == 1) {
+      _stopPolling();
+    }
+  }
+
+  void resumeFor(PolledPauseReason reason) {
     if (_disposed) return;
-    _load();
+    final removed = _pauseReasons.remove(reason);
-    _pollTimer = Timer.periodic(_pollInterval, (_) => _load());
+    if (removed && _pauseReasons.isEmpty) {
+      _load();
+      _startPolling();
+    }
+  }
+
+  void pause() => pauseFor(PolledPauseReason.manual);
+
+  void resume() => resumeFor(PolledPauseReason.manual);
+
+  void _onReachabilityChanged() {
+    if (_reachability.isOnline) {
+      resumeFor(PolledPauseReason.unreachable);
+    } else {
+      pauseFor(PolledPauseReason.unreachable);
+    }
   }
 
   @override
   void dispose() {
     _disposed = true;
-    _pollTimer?.cancel();
+    _reachability.removeListener(_onReachabilityChanged);
-    _cancelToken?.cancel();
+    _stopPolling();
     super.dispose();
   }
 }

frontend/lib/widgets/arp_scanner_card.dart

@@ -4,6 +4,7 @@ import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
 
 import '../model/arp_scanner_status.dart';
+import '../utils/backend_reachability.dart';
 import '../utils/duration_formatter.dart';
 import '../utils/oott_api.dart';
 import '../utils/polled_value.dart';
@@ -44,9 +45,10 @@ class _ArpScannerCardState extends State<ArpScannerCard> {
   @override
   Widget build(BuildContext context) {
     return ListenableBuilder(
-      listenable: _polled,
+      listenable: Listenable.merge([_polled, BackendReachability.instance]),
       builder: (context, _) {
-        if (_polled.freshness == PolledFreshness.initialLoading) {
+        final freshness = effectiveFreshness(_polled);
+        if (freshness == PolledFreshness.initialLoading) {
           return const Card(
             child: Padding(
               padding: EdgeInsets.all(16),
@@ -55,8 +57,8 @@ class _ArpScannerCardState extends State<ArpScannerCard> {
           );
         }
 
-        final (color, label, sublabel) = _resolveState();
+        final (color, label, sublabel) = _resolveState(freshness);
-        final isStale = _polled.freshness == PolledFreshness.stale;
+        final isStale = freshness == PolledFreshness.stale;
 
         return Card(
           clipBehavior: Clip.antiAlias,
@@ -111,8 +113,8 @@ class _ArpScannerCardState extends State<ArpScannerCard> {
     );
   }
 
-  (Color, String, String?) _resolveState() {
+  (Color, String, String?) _resolveState(PolledFreshness freshness) {
-    if (_polled.freshness == PolledFreshness.error) {
+    if (freshness == PolledFreshness.error) {
       return (
         Colors.red,
         'Error',

frontend/lib/widgets/device_summary_card.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
 
 import '../model/device_summary.dart';
+import '../utils/backend_reachability.dart';
 import '../utils/oott_api.dart';
 import '../utils/polled_value.dart';
 import 'polled_stale_indicator.dart';
@@ -42,8 +43,12 @@ class _DeviceSummaryCardState extends State<DeviceSummaryCard> {
         child: Padding(
           padding: const EdgeInsets.all(16),
           child: ListenableBuilder(
-            listenable: _polled,
+            listenable: Listenable.merge([
+              _polled,
+              BackendReachability.instance,
+            ]),
             builder: (context, _) {
+              final freshness = effectiveFreshness(_polled);
               return Column(
                 crossAxisAlignment: CrossAxisAlignment.start,
                 children: [
@@ -53,14 +58,14 @@ class _DeviceSummaryCardState extends State<DeviceSummaryCard> {
                         'Devices',
                         style: Theme.of(context).textTheme.titleLarge,
                       ),
-                      if (_polled.freshness == PolledFreshness.stale) ...[
+                      if (freshness == PolledFreshness.stale) ...[
                         const SizedBox(width: 6),
                         PolledStaleIndicator(polled: _polled),
                       ],
                     ],
                   ),
                   const SizedBox(height: 12),
-                  ..._buildBody(context),
+                  ..._buildBody(context, freshness),
                 ],
               );
             },
@@ -70,8 +75,8 @@ class _DeviceSummaryCardState extends State<DeviceSummaryCard> {
     );
   }
 
-  List<Widget> _buildBody(BuildContext context) {
+  List<Widget> _buildBody(BuildContext context, PolledFreshness freshness) {
-    switch (_polled.freshness) {
+    switch (freshness) {
       case PolledFreshness.initialLoading:
         return const [Center(child: CircularProgressIndicator())];
       case PolledFreshness.error:

frontend/lib/widgets/mdns_scanner_card.dart

@@ -4,6 +4,7 @@ import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
 
 import '../model/mdns_scanner_status.dart';
+import '../utils/backend_reachability.dart';
 import '../utils/duration_formatter.dart';
 import '../utils/oott_api.dart';
 import '../utils/polled_value.dart';
@@ -44,9 +45,10 @@ class _MdnsScannerCardState extends State<MdnsScannerCard> {
   @override
   Widget build(BuildContext context) {
     return ListenableBuilder(
-      listenable: _polled,
+      listenable: Listenable.merge([_polled, BackendReachability.instance]),
       builder: (context, _) {
-        if (_polled.freshness == PolledFreshness.initialLoading) {
+        final freshness = effectiveFreshness(_polled);
+        if (freshness == PolledFreshness.initialLoading) {
           return const Card(
             child: Padding(
               padding: EdgeInsets.all(16),
@@ -55,8 +57,8 @@ class _MdnsScannerCardState extends State<MdnsScannerCard> {
           );
         }
 
-        final (color, label, sublabels) = _resolveState();
+        final (color, label, sublabels) = _resolveState(freshness);
-        final isStale = _polled.freshness == PolledFreshness.stale;
+        final isStale = freshness == PolledFreshness.stale;
 
         return Card(
           clipBehavior: Clip.antiAlias,
@@ -111,8 +113,8 @@ class _MdnsScannerCardState extends State<MdnsScannerCard> {
     );
   }
 
-  (Color, String, List<String>) _resolveState() {
+  (Color, String, List<String>) _resolveState(PolledFreshness freshness) {
-    if (_polled.freshness == PolledFreshness.error) {
+    if (freshness == PolledFreshness.error) {
       return (
         Colors.red,
         'Error',

frontend/lib/widgets/offline_banner.dart

@@ -0,0 +1,65 @@
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+import '../utils/backend_reachability.dart';
+
+class OfflineBanner extends StatelessWidget {
+  const OfflineBanner({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final reachability = BackendReachability.instance;
+    return ListenableBuilder(
+      listenable: reachability,
+      builder: (context, _) {
+        if (reachability.isOnline) return const SizedBox.shrink();
+        final theme = Theme.of(context);
+        final message = !reachability.deviceHasNetwork
+            ? 'No network connection.'
+            : reachability.isProbing
+            ? 'Reconnecting to backend…'
+            : reachability.lastErrorMessage ?? 'Cannot reach backend.';
+        return Material(
+          color: theme.colorScheme.errorContainer,
+          child: Padding(
+            padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+            child: Row(
+              children: [
+                Icon(
+                  Icons.cloud_off,
+                  size: 18,
+                  color: theme.colorScheme.onErrorContainer,
+                ),
+                const SizedBox(width: 12),
+                Expanded(
+                  child: Text(
+                    message,
+                    style: theme.textTheme.bodyMedium?.copyWith(
+                      color: theme.colorScheme.onErrorContainer,
+                    ),
+                  ),
+                ),
+                TextButton(
+                  onPressed: reachability.isProbing
+                      ? null
+                      : () => reachability.probe(),
+                  style: TextButton.styleFrom(
+                    foregroundColor: theme.colorScheme.onErrorContainer,
+                  ),
+                  child: const Text('Retry'),
+                ),
+                TextButton(
+                  onPressed: () => context.go('/settings'),
+                  style: TextButton.styleFrom(
+                    foregroundColor: theme.colorScheme.onErrorContainer,
+                  ),
+                  child: const Text('Settings'),
+                ),
+              ],
+            ),
+          ),
+        );
+      },
+    );
+  }
+}

frontend/lib/widgets/polled_stale_indicator.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 
 import 'package:flutter/material.dart';
 
+import '../utils/backend_reachability.dart';
 import '../utils/duration_formatter.dart';
 import '../utils/polled_value.dart';
 
@@ -39,9 +40,15 @@ class _PolledStaleIndicatorState extends State<PolledStaleIndicator> {
             DateTime.now().difference(lastSuccessAt).inSeconds.toDouble(),
           )
         : 'a while';
-    final message = widget.polled.lastErrorMessage != null
+    final isOffline = !BackendReachability.instance.isOnline;
-        ? 'Last updated $ago ago — ${widget.polled.lastErrorMessage}'
+    final String message;
-        : 'Last updated $ago ago';
+    if (isOffline) {
+      message = 'Offline — last updated $ago ago';
+    } else if (widget.polled.lastErrorMessage != null) {
+      message = 'Last updated $ago ago — ${widget.polled.lastErrorMessage}';
+    } else {
+      message = 'Last updated $ago ago';
+    }
     return Tooltip(
       message: message,
       child: Icon(

frontend/lib/widgets/scanners_status_card.dart

@@ -6,6 +6,7 @@ import 'package:go_router/go_router.dart';
 import '../model/arp_scanner_status.dart';
 import '../model/mdns_scanner_status.dart';
 import '../navigation.dart';
+import '../utils/backend_reachability.dart';
 import '../utils/duration_formatter.dart';
 import '../utils/oott_api.dart';
 import '../utils/polled_value.dart';
@@ -101,10 +102,16 @@ class _ScannersStatusCardState extends State<ScannersStatusCard>
   @override
   Widget build(BuildContext context) {
     return ListenableBuilder(
-      listenable: Listenable.merge([_arp, _mdns]),
+      listenable: Listenable.merge([
+        _arp,
+        _mdns,
+        BackendReachability.instance,
+      ]),
       builder: (context, _) {
-        if (_arp.freshness == PolledFreshness.initialLoading ||
+        final arpFreshness = effectiveFreshness(_arp);
-            _mdns.freshness == PolledFreshness.initialLoading) {
+        final mdnsFreshness = effectiveFreshness(_mdns);
+        if (arpFreshness == PolledFreshness.initialLoading ||
+            mdnsFreshness == PolledFreshness.initialLoading) {
           return const Card(
             child: Padding(
               padding: EdgeInsets.all(16),
@@ -113,8 +120,8 @@ class _ScannersStatusCardState extends State<ScannersStatusCard>
           );
         }
 
-        final (arpColor, arpText) = _resolveArp();
+        final (arpColor, arpText) = _resolveArp(arpFreshness);
-        final (mdnsColor, mdnsText) = _resolveMdns();
+        final (mdnsColor, mdnsText) = _resolveMdns(mdnsFreshness);
 
         return Card(
           clipBehavior: Clip.antiAlias,
@@ -130,9 +137,23 @@ class _ScannersStatusCardState extends State<ScannersStatusCard>
                     style: Theme.of(context).textTheme.titleMedium,
                   ),
                   const SizedBox(height: 12),
-                  _scannerRow(context, arpColor, 'ARP', arpText, _arp),
+                  _scannerRow(
+                    context,
+                    arpColor,
+                    'ARP',
+                    arpText,
+                    _arp,
+                    arpFreshness,
+                  ),
                   const SizedBox(height: 8),
-                  _scannerRow(context, mdnsColor, 'mDNS', mdnsText, _mdns),
+                  _scannerRow(
+                    context,
+                    mdnsColor,
+                    'mDNS',
+                    mdnsText,
+                    _mdns,
+                    mdnsFreshness,
+                  ),
                 ],
               ),
             ),
@@ -148,9 +169,10 @@ class _ScannersStatusCardState extends State<ScannersStatusCard>
     String name,
     String statusText,
     PolledValue polled,
+    PolledFreshness freshness,
   ) {
     Widget dot = Icon(Icons.circle, color: color, size: 12);
-    if (polled.freshness == PolledFreshness.error) {
+    if (freshness == PolledFreshness.error) {
       dot = Tooltip(message: polled.lastErrorMessage ?? 'Error', child: dot);
     }
     return Row(
@@ -161,7 +183,7 @@ class _ScannersStatusCardState extends State<ScannersStatusCard>
           child: Row(
             children: [
               Text(name, style: Theme.of(context).textTheme.bodyMedium),
-              if (polled.freshness == PolledFreshness.stale) ...[
+              if (freshness == PolledFreshness.stale) ...[
                 const SizedBox(width: 6),
                 PolledStaleIndicator(polled: polled),
               ],
@@ -179,8 +201,8 @@ class _ScannersStatusCardState extends State<ScannersStatusCard>
     );
   }
 
-  (Color, String) _resolveArp() {
+  (Color, String) _resolveArp(PolledFreshness freshness) {
-    if (_arp.freshness == PolledFreshness.error) {
+    if (freshness == PolledFreshness.error) {
       return (Colors.red, 'Error');
     }
     final status = _arp.value!;
@@ -202,8 +224,8 @@ class _ScannersStatusCardState extends State<ScannersStatusCard>
     return (Colors.grey, 'Not yet started');
   }
 
-  (Color, String) _resolveMdns() {
+  (Color, String) _resolveMdns(PolledFreshness freshness) {
-    if (_mdns.freshness == PolledFreshness.error) {
+    if (freshness == PolledFreshness.error) {
       return (Colors.red, 'Error');
     }
     final status = _mdns.value!;

frontend/macos/Flutter/GeneratedPluginRegistrant.swift

@@ -5,11 +5,13 @@
 import FlutterMacOS
 import Foundation
 
+import connectivity_plus
 import encrypter
 import shared_preferences_foundation
 import url_launcher_macos
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
+  ConnectivityPlusPlugin.register(with: registry.registrar(forPlugin: "ConnectivityPlusPlugin"))
   EncrypterPlugin.register(with: registry.registrar(forPlugin: "EncrypterPlugin"))
   SharedPreferencesPlugin.register(with: registry.registrar(forPlugin: "SharedPreferencesPlugin"))
   UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))

frontend/pubspec.lock

@@ -65,6 +65,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.19.1"
+  connectivity_plus:
+    dependency: "direct main"
+    description:
+      name: connectivity_plus
+      sha256: "62ffa266d9a23b79fb3fcbc206afc00bb979417ba57b1324c546b5aab95ba057"
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.1.1"
+  connectivity_plus_platform_interface:
+    dependency: transitive
+    description:
+      name: connectivity_plus_platform_interface
+      sha256: "3c09627c536d22fd24691a905cdd8b14520de69da52c7a97499c8be5284a32ed"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.1.0"
   convert:
     dependency: transitive
     description:
@@ -81,6 +97,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.0.7"
+  dbus:
+    dependency: transitive
+    description:
+      name: dbus
+      sha256: "792974a4007974fbc5c1b5433eb2330a9db3e368c3f906253af4c007d0f49a91"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.13"
   dio:
     dependency: "direct main"
     description:
@@ -336,6 +360,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.0.0"
+  nm:
+    dependency: transitive
+    description:
+      name: nm
+      sha256: "2c9aae4127bdc8993206464fcc063611e0e36e72018696cd9631023a31b24254"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.5.0"
   objective_c:
     dependency: transitive
     description:
@@ -408,6 +440,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.3.0"
+  petitparser:
+    dependency: transitive
+    description:
+      name: petitparser
+      sha256: "91bd59303e9f769f108f8df05e371341b15d59e995e6806aefab827b58336675"
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.0.2"
   platform:
     dependency: transitive
     description:
@@ -669,6 +709,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.1.0"
+  xml:
+    dependency: transitive
+    description:
+      name: xml
+      sha256: "67f0aff7be013d107995e9b75bf4e7f2c3ef2dfdb2c8e68024bba0a7fd5756a4"
+      url: "https://pub.dev"
+    source: hosted
+    version: "7.0.1"
   yaml:
     dependency: transitive
     description:
@@ -678,5 +726,5 @@ packages:
     source: hosted
     version: "3.1.3"
 sdks:
-  dart: ">=3.10.8 <4.0.0"
+  dart: ">=3.11.0 <4.0.0"
   flutter: ">=3.38.4"

frontend/pubspec.yaml

@@ -14,6 +14,7 @@ dependencies:
   provider: ^6.1.5
   dio: ^5.9.1
   dio_smart_retry: ^7.0.1
+  connectivity_plus: ^7.0.0
   encrypter: ^2.0.0
   shared_preferences: ^2.5.4
   fl_chart: ^1.2.0

frontend/windows/flutter/generated_plugin_registrant.cc

@@ -6,10 +6,13 @@
 
 #include "generated_plugin_registrant.h"
 
+#include <connectivity_plus/connectivity_plus_windows_plugin.h>
 #include <encrypter/encrypter_plugin_c_api.h>
 #include <url_launcher_windows/url_launcher_windows.h>
 
 void RegisterPlugins(flutter::PluginRegistry* registry) {
+  ConnectivityPlusWindowsPluginRegisterWithRegistrar(
+      registry->GetRegistrarForPlugin("ConnectivityPlusWindowsPlugin"));
   EncrypterPluginCApiRegisterWithRegistrar(
       registry->GetRegistrarForPlugin("EncrypterPluginCApi"));
   UrlLauncherWindowsRegisterWithRegistrar(

frontend/windows/flutter/generated_plugins.cmake

@@ -3,6 +3,7 @@
 #
 
 list(APPEND FLUTTER_PLUGIN_LIST
+  connectivity_plus
   encrypter
   url_launcher_windows
 )