Harden app for 24-7 offline-first operation

lib/features/home/home_view.dart

@@ -44,12 +44,15 @@ class _HomeViewState extends ConsumerState<HomeView> {
   final List<LogicalKeyboardKey> _simulationShortcutKeys = [];
   Timer? _comboResetTimer;
   Timer? _simulationShortcutTimer;
+  Timer? _autoRefreshTimer;
+  bool _isAutoRefreshRunning = false;
 
   @override
   void initState() {
     super.initState();
     WidgetsBinding.instance.addPostFrameCallback((_) {
       _checkAutoSync();
+      _startAutoRefreshMonitor();
       if (mounted) {
         _homeFocusNode.requestFocus();
       }
@@ -60,21 +63,38 @@ class _HomeViewState extends ConsumerState<HomeView> {
   void dispose() {
     _comboResetTimer?.cancel();
     _simulationShortcutTimer?.cancel();
+    _autoRefreshTimer?.cancel();
     _homeFocusNode.dispose();
     super.dispose();
   }
 
+  void _startAutoRefreshMonitor() {
+    _autoRefreshTimer?.cancel();
+    _autoRefreshTimer = Timer.periodic(
+      const Duration(hours: 6),
+      (_) => _checkAutoSync(),
+    );
+  }
+
   Future<void> _checkAutoSync() async {
-    final schedule = ref.read(todayScheduleProvider);
-    if (schedule == null) {
-      debugPrint('[AutoSync] No schedule found for today! Starting auto-sync...');
-      final success = await SyncService.instance.syncMonthlyData();
-      if (success && mounted) {
-        debugPrint('[AutoSync] Success! Invalidating todayScheduleProvider.');
+    if (_isAutoRefreshRunning || !mounted) return;
+    _isAutoRefreshRunning = true;
+    try {
+      final result = await SyncService.instance.autoRefreshIfNeeded();
+      if (!mounted) return;
+
+      if (result.synced) {
+        debugPrint('[AutoSync] Cache refreshed successfully.');
         ref.invalidate(todayScheduleProvider);
-      } else {
-        debugPrint('[AutoSync] Failed or data remained empty.');
+        ref.invalidate(scheduleCacheStatusProvider);
+        return;
       }
+
+      if (result.attempted) {
+        debugPrint('[AutoSync] Refresh attempt failed. Staying on local cache.');
+      }
+    } finally {
+      _isAutoRefreshRunning = false;
     }
   }
 

lib/features/home/jumat_screen.dart

@@ -49,6 +49,7 @@ class JumatScreen extends ConsumerWidget {
                 fit: BoxFit.cover,
                 color: Colors.black.withValues(alpha: 0.55),
                 colorBlendMode: BlendMode.darken,
+                errorBuilder: (_, __, ___) => const UnsplashBackground(),
               ),
             )
           else

lib/features/home/main_screen.dart

@@ -53,6 +53,7 @@ class MainScreen extends ConsumerWidget {
                 fit: BoxFit.cover,
                 color: Colors.black.withValues(alpha: 0.55),
                 colorBlendMode: BlendMode.darken,
+                errorBuilder: (_, __, ___) => const UnsplashBackground(),
               ),
             )
           else

lib/features/home/unsplash_background.dart

@@ -96,6 +96,7 @@ class _UnsplashBackgroundState extends ConsumerState<UnsplashBackground> {
         // Soft opacity behind the MainScreen's dark glass vignette
         color: Colors.black.withValues(alpha: 0.5), 
         colorBlendMode: BlendMode.darken,
+        errorBuilder: (_, __, ___) => const SizedBox.shrink(),
       ),
     );
   }