diff --git a/lib/screens/camera_analysis_mixin.dart b/lib/screens/camera_analysis_mixin.dart
index d9c39fe..b957da3 100644
--- a/lib/screens/camera_analysis_mixin.dart
+++ b/lib/screens/camera_analysis_mixin.dart
@@ -381,9 +381,10 @@ mixin CameraAnalysisMixin<T extends ConsumerStatefulWidget> on ConsumerState<T>
         }
 
         debugPrint('Analysis error: $e');
+        final errDetail = _extractErrorCode(e.toString());
         messenger.showSnackBar(
           SnackBar(
-            content: const Text('解析に失敗しました。時間をおいて再試行してください。'),
+            content: Text('解析に失敗しました。時間をおいて再試行してください。$errDetail'),
             duration: const Duration(seconds: 5),
             backgroundColor: appColors.error,
           ),
@@ -395,6 +396,23 @@ mixin CameraAnalysisMixin<T extends ConsumerStatefulWidget> on ConsumerState<T>
     }
   }
 
+  /// エラー文字列から HTTP ステータスコードや既知キーワードを抽出して表示用の短い補足を返す。
+  /// ユーザーが画面を見たときに「どのエラーか」を把握できるようにするため。
+  String _extractErrorCode(String err) {
+    final patterns = {
+      RegExp(r'\b(4\d{2}|5\d{2})\b'): (Match m) => ' [${m.group(0)}]',
+      RegExp(r'API_KEY_INVALID|PERMISSION_DENIED'): (_) => ' [key?]',
+      RegExp(r'RESOURCE_EXHAUSTED'): (_) => ' [quota]',
+      RegExp(r'NOT_FOUND'): (_) => ' [model?]',
+      RegExp(r'timeout', caseSensitive: false): (_) => ' [timeout]',
+    };
+    for (final entry in patterns.entries) {
+      final m = entry.key.firstMatch(err);
+      if (m != null) return entry.value(m);
+    }
+    return '';
+  }
+
   /// さけのわ自動マッチング処理
   ///
   /// 登録後にバックグラウンドで実行。
diff --git a/lib/services/gemini_service.dart b/lib/services/gemini_service.dart
index 067f786..3324475 100644
--- a/lib/services/gemini_service.dart
+++ b/lib/services/gemini_service.dart
@@ -484,7 +484,7 @@ name・brand を出力する直前に以下を確認してください：
     }
 
     const primaryModel = 'gemini-2.5-flash';
-    const fallbackModel = 'gemini-2.0-flash';
+    const fallbackModel = 'gemini-2.5-flash-lite';
 
     final promptText = customPrompt ?? _mainAnalysisPrompt;
 
diff --git a/pubspec.yaml b/pubspec.yaml
index 9513065..ad73af8 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -16,7 +16,7 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 # https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
 # In Windows, build-name is used as the major, minor, and patch parts
 # of the product and file versions while build-number is used as the build suffix.
-version: 1.0.48+55
+version: 1.0.49+56
 
 environment:
   sdk: ^3.10.1