feat(scan+images): continuous scan loop and signed-url refresh fallback

- Add continuous scanner callback flow so detections are processed in-place
- Keep scanner open after add/lookup so users can continue scanning immediately
- Integrate scan processing with catalog branch logic without route round-trips
- Add signed URL refresh strategy for private image links on load failures
- Trigger signed-link regeneration from garage cards and detail view retry action
- Keep multi-select/move workflow and pagination compatible with refreshed image state

lib/scanner_screen.dart

@@ -10,7 +10,9 @@ import 'theme/app_colors.dart';
 ///
 /// The detected ID is returned via Navigator.pop(context, hwId).
 class ScannerScreen extends StatefulWidget {
-  const ScannerScreen({super.key});
+  final Future<bool> Function(String hwId)? onDetected;
+
+  const ScannerScreen({super.key, this.onDetected});
 
   @override
   State<ScannerScreen> createState() => _ScannerScreenState();
@@ -94,6 +96,9 @@ class _ScannerScreenState extends State<ScannerScreen> {
 
       if (found != null) {
         setState(() => _lastDetected = found);
+        if (widget.onDetected != null) {
+          await _submitDetected(found);
+        }
       } else {
         // Show all detected text so user knows what was seen.
         final allText = recognized.blocks.map((b) => b.text).join('\n');
@@ -118,6 +123,29 @@ class _ScannerScreenState extends State<ScannerScreen> {
     }
   }
 
+  Future<void> _submitDetected(String hwId) async {
+    if (widget.onDetected == null) {
+      if (mounted) Navigator.of(context).pop(hwId);
+      return;
+    }
+
+    try {
+      final keepScanning = await widget.onDetected!(hwId);
+      if (!mounted) return;
+
+      if (keepScanning) {
+        setState(() => _lastDetected = null);
+      } else {
+        Navigator.of(context).pop();
+      }
+    } catch (e) {
+      if (!mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(content: Text('Process error: $e'), backgroundColor: Colors.red),
+      );
+    }
+  }
+
   @override
   void dispose() {
     _cameraController?.dispose();
@@ -229,7 +257,9 @@ class _ScannerScreenState extends State<ScannerScreen> {
                     ),
                   ),
                   ElevatedButton(
-                    onPressed: () => Navigator.of(context).pop(_lastDetected),
+                    onPressed: _isBusy || _lastDetected == null
+                        ? null
+                        : () => _submitDetected(_lastDetected!),
                     child: const Text('Use This'),
                   ),
                 ],
@@ -298,7 +328,7 @@ class _ScannerScreenState extends State<ScannerScreen> {
     );
 
     if (result != null && context.mounted) {
-      Navigator.of(context).pop(result);
+      await _submitDetected(result);
     }
   }
 }

lib/screens/garage_screen.dart

@@ -40,6 +40,7 @@ class GarageScreenState extends State<GarageScreen> {
 
   bool _selectionMode = false;
   final Set<int> _selectedIds = <int>{};
+  final Set<int> _refreshingImageIds = <int>{};
 
   @override
   void initState() {
@@ -266,6 +267,7 @@ class GarageScreenState extends State<GarageScreen> {
                   (context, index) {
                     final car = _filteredCars[index];
                     final global = car['global_cars'] as Map<String, dynamic>?;
+                    final carId = car['id'] as int;
                     return CarCard(
                       hwId: car['hw_id'] as String? ?? '???',
                       name: global?['name'] as String?,
@@ -273,10 +275,11 @@ class GarageScreenState extends State<GarageScreen> {
                       year: global?['year'] as int?,
                       color: global?['color'] as String?,
                       imageUrl: car['signed_image_url'] as String?,
-                      isSelected: _selectedIds.contains(car['id'] as int),
+                      isSelected: _selectedIds.contains(carId),
                       addedAt: car['created_at'] != null
                           ? DateTime.tryParse(car['created_at'])
                           : null,
+                      onImageError: () => _refreshSignedUrlForCar(carId),
                       onTap: () => _selectionMode
                           ? _toggleCarSelection(car)
                           : _showCarDetails(car),
@@ -434,6 +437,30 @@ class GarageScreenState extends State<GarageScreen> {
     }
   }
 
+  Future<void> _refreshSignedUrlForCar(int carId) async {
+    if (_refreshingImageIds.contains(carId)) return;
+
+    final index = _cars.indexWhere((c) => c['id'] == carId);
+    if (index == -1) return;
+
+    final path = _cars[index]['user_image_url'] as String?;
+    if (path == null || path.isEmpty) return;
+
+    _refreshingImageIds.add(carId);
+    try {
+      final signed = await StorageService.createSignedUrl(path);
+      if (!mounted || signed == null) return;
+      setState(() {
+        _cars[index] = {
+          ..._cars[index],
+          'signed_image_url': signed,
+        };
+      });
+    } finally {
+      _refreshingImageIds.remove(carId);
+    }
+  }
+
   void _showCarDetails(Map<String, dynamic> car) {
     if (_selectionMode) {
       _toggleCarSelection(car);
@@ -485,7 +512,20 @@ class GarageScreenState extends State<GarageScreen> {
                     ? Image.network(
                         imageUrl,
                         fit: BoxFit.cover,
-                        errorBuilder: (context, error, stackTrace) => _imagePlaceholder(),
+                        errorBuilder: (context, error, stackTrace) => Column(
+                          mainAxisAlignment: MainAxisAlignment.center,
+                          children: [
+                            Expanded(child: _imagePlaceholder()),
+                            Padding(
+                              padding: const EdgeInsets.only(bottom: 10),
+                              child: TextButton.icon(
+                                onPressed: () => _refreshSignedUrlForCar(car['id'] as int),
+                                icon: const Icon(Icons.refresh, size: 16),
+                                label: const Text('Refresh image link'),
+                              ),
+                            ),
+                          ],
+                        ),
                       )
                     : _imagePlaceholder(),
               ),

lib/screens/scan_tab.dart

@@ -209,12 +209,13 @@ class ScanTabState extends State<ScanTab> {
   }
 
   Future<void> _openScanner() async {
-    final hwId = await navigatorKey.currentState!.push<String>(
+    await navigatorKey.currentState!.push<void>(
-      MaterialPageRoute(builder: (_) => const ScannerScreen()),
+      MaterialPageRoute(
+        builder: (_) => ScannerScreen(
+          onDetected: (hwId) => _processHwId(hwId),
+        ),
+      ),
     );
-
-    if (hwId == null || !mounted) return;
-    await _processHwId(hwId);
   }
 
   Future<void> _manualEntry() async {
@@ -253,9 +254,9 @@ class ScanTabState extends State<ScanTab> {
     await _processHwId(result);
   }
 
-  Future<void> _processHwId(String hwId) async {
+  Future<bool> _processHwId(String hwId) async {
     final collection = _selectedCollection;
-    if (collection == null) return;
+    if (collection == null) return false;
 
     setState(() => _isBusy = true);
 
@@ -268,10 +269,10 @@ class ScanTabState extends State<ScanTab> {
           .maybeSingle();
 
       if (existing != null) {
-        if (!mounted) return;
+        if (!mounted) return false;
         setState(() => _isBusy = false);
         await showDialog(
-          context: context,
+          context: navigatorKey.currentContext ?? context,
           builder: (_) => AlertDialog(
             icon: const Icon(Icons.check_circle,
                 color: AppColors.success, size: 48),
@@ -285,7 +286,7 @@ class ScanTabState extends State<ScanTab> {
             ],
           ),
         );
-        return;
+        return true;
       }
 
       final globalCar = await supabase
@@ -294,12 +295,12 @@ class ScanTabState extends State<ScanTab> {
           .eq('hw_id', hwId)
           .maybeSingle();
 
-      if (!mounted) return;
+      if (!mounted) return false;
       setState(() => _isBusy = false);
 
       if (globalCar != null) {
         final addConfirmed = await showModalBottomSheet<bool>(
-          context: context,
+          context: navigatorKey.currentContext ?? context,
           isScrollControlled: true,
           shape: const RoundedRectangleBorder(
             borderRadius: BorderRadius.vertical(top: Radius.circular(24)),
@@ -312,12 +313,12 @@ class ScanTabState extends State<ScanTab> {
 
         if (addConfirmed == true) {
           await _addToCollection(collection.id, hwId);
-          if (!mounted) return;
+          if (!mounted) return false;
           showGlobalSnackBar('$hwId added to "${collection.name}"! 🎉');
         }
       } else {
         final discovery = await showModalBottomSheet<_NewDiscoveryData>(
-          context: context,
+          context: navigatorKey.currentContext ?? context,
           isScrollControlled: true,
           shape: const RoundedRectangleBorder(
             borderRadius: BorderRadius.vertical(top: Radius.circular(24)),
@@ -336,13 +337,15 @@ class ScanTabState extends State<ScanTab> {
             year: discovery.year,
           );
           await _addToCollection(collection.id, hwId, notes: discovery.notes);
-          if (!mounted) return;
+          if (!mounted) return false;
           showGlobalSnackBar('$hwId added to "${collection.name}"! 🎉');
         }
       }
+      return true;
     } catch (e) {
       if (mounted) setState(() => _isBusy = false);
       showGlobalSnackBar('DB error: $e', isError: true);
+      return true;
     }
   }
 

lib/widgets/car_card.dart

@@ -12,6 +12,7 @@ class CarCard extends StatelessWidget {
   final DateTime? addedAt;
   final VoidCallback? onTap;
   final VoidCallback? onLongPress;
+  final VoidCallback? onImageError;
   final bool isSelected;
 
   const CarCard({
@@ -25,6 +26,7 @@ class CarCard extends StatelessWidget {
     this.addedAt,
     this.onTap,
     this.onLongPress,
+    this.onImageError,
     this.isSelected = false,
   });
 
@@ -65,8 +67,10 @@ class CarCard extends StatelessWidget {
                     ? Image.network(
                         imageUrl!,
                         fit: BoxFit.cover,
-                        errorBuilder: (context, error, stackTrace) =>
+                        errorBuilder: (context, error, stackTrace) {
-                      _PlaceholderIcon(isDark: isDark),
+                          onImageError?.call();
+                          return _PlaceholderIcon(isDark: isDark);
+                        },
                       )
                     : _PlaceholderIcon(isDark: isDark),
               ),