diff --git a/lib/main.dart b/lib/main.dart
index d1a040b..abaf0e7 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -209,6 +209,7 @@ class _AuthGateState extends State<AuthGate> {
   bool _isInPasswordRecoveryFlow = false;
   Session? _session;
   String? _lastEnsuredUserId;
+  StreamSubscription<AuthState>? _authStateSubscription;
 
   @override
   void initState() {
@@ -217,7 +218,7 @@ class _AuthGateState extends State<AuthGate> {
     _session = supabase.auth.currentSession;
     _ensureDefaultCollectionIfNeeded();
 
-    supabase.auth.onAuthStateChange.listen(
+    _authStateSubscription = supabase.auth.onAuthStateChange.listen(
       (AuthState authState) {
         if (!mounted) return;
 
@@ -247,6 +248,12 @@ class _AuthGateState extends State<AuthGate> {
     setState(() => _isLoading = false);
   }
 
+  @override
+  void dispose() {
+    _authStateSubscription?.cancel();
+    super.dispose();
+  }
+
   Future<void> _ensureDefaultCollectionIfNeeded() async {
     final userId = _session?.user.id;
     if (userId == null || userId == _lastEnsuredUserId) return;
diff --git a/lib/services/collection_service.dart b/lib/services/collection_service.dart
index 023a52d..f5d298b 100644
--- a/lib/services/collection_service.dart
+++ b/lib/services/collection_service.dart
@@ -1,4 +1,5 @@
 //import 'package:supabase_flutter/supabase_flutter.dart';
+import 'package:flutter/foundation.dart';
 import '../main.dart';
 
 /// Data model for a collection.
@@ -120,7 +121,8 @@ class CollectionService {
           'p_collection_id': collectionId,
         });
         memberCounts[collectionId] = (rows as List).length;
-      } catch (_) {
+      } catch (e) {
+        debugPrint('CollectionService.getMyCollections member RPC error: $e');
       }
     }));
 
@@ -182,7 +184,9 @@ class CollectionService {
         if (collectionId == null) continue;
         itemCounts[collectionId] = (row['total_count'] as num?)?.toInt() ?? 0;
       }
-    } catch (_) {}
+    } catch (e) {
+      debugPrint('CollectionService.getCollectionItemCounts RPC error: $e');
+    }
 
     final unresolvedIds = collectionIds
         .where((collectionId) => !itemCounts.containsKey(collectionId))
@@ -211,7 +215,9 @@ class CollectionService {
           recent: (first['recent_count'] as num?)?.toInt() ?? 0,
         );
       }
-    } catch (_) {}
+    } catch (e) {
+      debugPrint('CollectionService.getCollectionStats RPC error: $e');
+    }
 
     final weekAgoIso = DateTime.now()
         .subtract(const Duration(days: 7))
@@ -269,11 +275,21 @@ class CollectionService {
         .single();
 
     // Add owner as a member.
-    await supabase.from('collection_members').insert({
-      'collection_id': row['id'],
-      'user_id': userId,
-      'role': 'owner',
-    });
+    try {
+      await supabase.from('collection_members').insert({
+        'collection_id': row['id'],
+        'user_id': userId,
+        'role': 'owner',
+      });
+    } catch (e) {
+      debugPrint('CollectionService.create member insert failed: $e');
+      try {
+        await supabase.from('collections').delete().eq('id', row['id']);
+      } catch (cleanupError) {
+        debugPrint('CollectionService.create rollback failed: $cleanupError');
+      }
+      rethrow;
+    }
 
     return Collection(
       id: row['id'] as String,
diff --git a/lib/services/storage_service.dart b/lib/services/storage_service.dart
index 5814152..73c3707 100644
--- a/lib/services/storage_service.dart
+++ b/lib/services/storage_service.dart
@@ -27,10 +27,6 @@ class StorageService {
     required int entryId,
     String? oldPath,
   }) async {
-    if (oldPath != null && oldPath.isNotEmpty) {
-      await deleteCarImage(oldPath);
-    }
-
     final user = supabase.auth.currentUser;
     if (user == null) {
       throw Exception('You must be signed in to upload images.');
@@ -50,6 +46,14 @@ class StorageService {
 
     _signedUrlCache.remove(path);
 
+    if (oldPath != null && oldPath.isNotEmpty && oldPath != path) {
+      try {
+        await deleteCarImage(oldPath);
+      } catch (e) {
+        debugPrint('StorageService.uploadCarImage cleanup error: $e');
+      }
+    }
+
     return path;
   }
 
diff --git a/test/widget_test.dart b/test/widget_test.dart
index f485109..8901f03 100644
--- a/test/widget_test.dart
+++ b/test/widget_test.dart
@@ -1,9 +1,54 @@
-// Basic smoke test placeholder — will be updated when UI is finalized.
-
+import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:hwhub/widgets/car_card.dart';
 
 void main() {
-  test('placeholder test', () {
-    expect(1 + 1, 2);
+  testWidgets('CarCard renders model id and metadata', (tester) async {
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: Scaffold(
+          body: Center(
+            child: SizedBox(
+              width: 220,
+              height: 360,
+              child: CarCard(
+                hwId: 'ABC12',
+                name: 'Die-Cast Model',
+                series: 'Collector Series',
+                year: 2024,
+                isVerified: true,
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('ABC12'), findsOneWidget);
+    expect(find.text('Die-Cast Model'), findsOneWidget);
+    expect(find.text('Collector Series'), findsOneWidget);
+    expect(find.text('2024'), findsOneWidget);
+    expect(find.text('Verified'), findsOneWidget);
+  });
+
+  testWidgets('CarCard shows selected state label', (tester) async {
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: Scaffold(
+          body: Center(
+            child: SizedBox(
+              width: 220,
+              height: 360,
+              child: CarCard(
+                hwId: 'XYZ99',
+                isSelected: true,
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('Selected'), findsOneWidget);
   });
 }