diff --git a/.gitignore b/.gitignore
index 892a386..2f94414 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,46 +3,28 @@
 *.log
 *.pyc
 *.swp
+*.swo
+*~
 .DS_Store
-.atom/
-.build/
-.buildlog/
-.history
-.svn/
-.swiftpm/
-migrate_working_dir/
 
-# IntelliJ related
-*.iml
-*.ipr
-*.iws
-.idea/
-
-# The .vscode folder contains launch configuration and tasks you configure in
-# VS Code which you may wish to be included in version control, so this line
-# is commented out by default.
-#.vscode/
-
-# Flutter/Dart/Pub related
-**/doc/api/
-**/ios/Flutter/.last_build_id
+# Dart
 .dart_tool/
-.flutter-plugins-dependencies
-.pub-cache/
-.pub/
-/build/
-/coverage/
+packages/
+pubspec.lock
 
-# Symbolication related
-app.*.symbols
+# Build outputs
+build/
+ios/iPhone*.xcodeproj/
+ios/Runner.xcworkspace/
+ios/Pods/
+libappbundle/
+*.apk
+*.aab
 
-# Obfuscation related
-app.*.map.json
+# Flutter tool
+.flutter-plugins
+.flutter-version
 
-# Android Studio will place build artifacts here
-/android/app/debug
-/android/app/profile
-/android/app/release
-
-# Local SQLite snapshots
-app.db
+# Environment variables
+.env
+.env.local
\ No newline at end of file
diff --git a/analysis_options.yaml b/analysis_options.yaml
new file mode 100644
index 0000000..acc41ca
--- /dev/null
+++ b/analysis_options.yaml
@@ -0,0 +1,16 @@
+include: package:flutter_lints/flutter.yaml
+
+linter:
+  rules:
+    - prefer_const_constructors
+    - prefer_const_declarations
+    - avoid_unnecessary_containers
+    - prefer_single_quotes
+    - sort_child_properties_last
+    - prefer_final_locals
+    - avoid_print
+
+analyzer:
+  exclude:
+    - '**/*.g.dart'
+    - '**/*.freezed.dart'
\ No newline at end of file
diff --git a/data/mothership/pubspec.yaml b/data/mothership/pubspec.yaml
new file mode 100644
index 0000000..f369aae
--- /dev/null
+++ b/data/mothership/pubspec.yaml
@@ -0,0 +1,18 @@
+// Version: 1.0.0
+name: mothership_server
+description: 母艦「お局様」用 HTTP サーバーアプリケーション
+publish_to: 'none'
+
+environment:
+  sdk: '>=3.0.0 <4.0.0'
+
+dependencies:
+  http: ^1.1.0
+  uuid: ^4.3.3
+  json_annotation: ^4.9.0
+  path_provider: ^2.1.1
+
+dev_dependencies:
+  build_runner: ^2.4.0
+  json_serializable: ^6.8.0
+  http_mock_adapter: ^0.7.0
\ No newline at end of file
diff --git a/lib/utils/build_expiry_info.dart b/lib/utils/build_expiry_info.dart
new file mode 100644
index 0000000..6161b82
--- /dev/null
+++ b/lib/utils/build_expiry_info.dart
@@ -0,0 +1,126 @@
+// Version: 1.0.0
+import 'package:flutter/foundation.dart';
+
+/// アプリのビルド lifetime を管理するクラス
+class BuildExpiryInfo {
+  /// バリッドな状態（90 日以内）
+  static const String statusValid = 'valid';
+  
+  /// 期限切れ状態
+  static const String statusExpired = 'expired';
+
+  /// ビルド時間を UTC 秒数として受け取り、残存寿命を判定する
+  /// [timestamp] は UTC タイムスタンプ（秒）
+  String getStatus(int timestamp) {
+    final now = DateTime.now().toUtc();
+    final buildTime = DateTime.fromMillisecondsSinceEpoch(
+      timestamp * 1000,
+      isUtc: true,
+    );
+    final expiryTime = _expiryTimestamp.buildDateTime;
+    
+    if (now.isAfter(expiryTime)) {
+      return statusExpired;
+    }
+    return statusValid;
+  }
+
+  /// 残り寿命を DateTime オブジェクトとして返す（期限切れの場合 null）
+  DateTime? getRemainingExpiry(int timestamp) {
+    final now = DateTime.now().toUtc();
+    final expiryTime = _expiryTimestamp.buildDateTime;
+    
+    if (now.isAfter(expiryTime)) {
+      return null;
+    }
+    // 残り寿命を計算（例：90 日 + 15 日間延命用 buffer）
+    final daysRemaining = ((expiryTime.millisecondsSinceEpoch - now.millisecondsSinceEpoch) ~/ Duration.millisecondsPerDay);
+    return now.add(Duration(days: daysRemaining));
+  }
+
+  static BuildExpiryInfo get instance => _instance;
+  factory BuildExpiryInfo() => _instance;
+  
+  late final DateTime _expiryTimestamp;
+  String _appBuildTimestamp = '';
+
+  /// アプリのパッケージ情報からビルド時間を取得する
+  void initializeFromPackageInfo(PackageInfo packageInfo) async {
+    _appBuildTimestamp = (await packageInfo).version;
+  }
+
+  /// 寿命切れ画面を表示すべきかどうかを判定
+  bool get isExpired => getStatus(_parseTimestamp(_appBuildTimestamp));
+  
+  /// 寿命切れメッセージの取得
+  String get expiredMessage {
+    return '本アプリの有効期限が切れています。\n母艦（お局様）からの同期が必要となります。';
+  }
+}
+
+/// アプリ初期化時に呼ぶヘルパー
+class ExpiryInitHelper {
+  static Future<void> initialize(BuildContext context, PackageInfo packageInfo) async {
+    final expiry = BuildExpiryInfo();
+    
+    // パッケージ情報からビルド時間を含むバージョンをパース（例: "1.0.0+1234567890"）
+    final timestamp = int.tryParse(_extractTimestamp(packageInfo.version));
+    
+    if (timestamp != null) {
+      expiry._expiryTimestamp = DateTime.fromMillisecondsSinceEpoch(
+        timestamp * 1000,
+        isUtc: true,
+      ).add(const Duration(days: 90));
+      
+      // トランザクションで寿命チェックを実行
+      await context.mount<ExpiredApp>(
+        key: ExpiryInitHelper._routeName,
+        condition: () => expiry.isExpired,
+        builder: (context) => ExpiredApp(expiry: expiry),
+      );
+    }
+  }
+
+  static String _extractTimestamp(String version) {
+    // "1.0.0+1234567890" の形式の場合、+以降をパース
+    final parts = version.split('+');
+    if (parts.length > 1) {
+      return parts[1];
+    }
+    return '0';
+  }
+
+  static const String _routeName = '/expired_app_route';
+}
+
+class ExpiredApp extends StatelessWidget {
+  final BuildExpiryInfo expiry;
+  const ExpiredApp({super.key, required this.expiry});
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('有効期限切れ')),
+      body: Padding(
+        padding: const EdgeInsets.all(16.0),
+        child: Column(
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: [
+            const Icon(Icons.error_outline, size: 80, color: Colors.red),
+            const SizedBox(height: 24),
+            Text(
+              expiry.expiredMessage,
+              textAlign: TextAlign.center,
+              style: const TextStyle(fontSize: 16),
+            ),
+            const SizedBox(height: 32),
+            ElevatedButton(
+              onPressed: () => Navigator.of(context).pushNamedAndRemoveUntil('/', (route) => false),
+              child: const Text('設定画面へ戻る'),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
\ No newline at end of file
diff --git a/pubspec.yaml b/pubspec.yaml
new file mode 100644
index 0000000..2e32637
--- /dev/null
+++ b/pubspec.yaml
@@ -0,0 +1,32 @@
+name: sales_assist_1
+description: オフライン単体で見積・納品・請求・レジ業務まで完結できる販売アシスタント
+publish_to: 'none'
+
+version: 1.0.0+4
+
+environment:
+  sdk: '>=3.0.0 <4.0.0'
+
+dependencies:
+  flutter:
+    sdk: flutter
+  cupertino_icons: ^1.0.6
+  
+  # SQLite データ永続化
+  sqflite: ^2.3.3
+  path_provider: ^2.1.1
+  
+  # Google エコシステム連携
+  google_sign_in: ^6.1.0
+  http: ^1.1.0
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+  flutter_lints: ^3.0.0
+
+flutter:
+  uses-material-design: true
+  
+  assets:
+    - assets/
\ No newline at end of file
diff --git a/scripts/build_with_expiry.sh b/scripts/build_with_expiry.sh
new file mode 100644
index 0000000..3b3a8e5
--- /dev/null
+++ b/scripts/build_with_expiry.sh
@@ -0,0 +1,70 @@
+#!/bin/bash
+# Version: 1.0.0
+#
+# 販売アシスト 1 号用の APK ビルドスクリプト
+# 自動的な BUILD_TIMESTAMP（UTC タイムスタンプ）を付与し、90 日寿命チェックされた APK を生成
+
+set -e
+
+PROJECT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+FLUTTER="${FLUTTER:-flutter}"
+BUILD_TYPE="${1:-release}"  # debug|profile|release（デフォルト：release）
+
+echo "=== 販売アシスト 1 号 APK ビルドスクリプト ==="
+echo "ビルドモード: ${BUILD_TYPE}"
+echo ""
+
+# プロジェクトディレクトリへ cd
+cd "$PROJECT_DIR"
+
+# パッケージ名を取得
+PACKAGE_NAME=$(grep '^name:' pubspec.yaml | cut -d' ' -f2)
+
+# 環境チェック
+if [ ! -f "pubspec.lock" ]; then
+    echo "[エラー] pubspec.lock を発見できません。flutter pub get を実行してください。"
+    exit 1
+fi
+
+echo "[情報] パッケージ名: ${PACKAGE_NAME}"
+
+# flutter analyze を実行（オプション：--no-fatal-warnings は必要に応じて）
+echo "[実装] flutter analyze..."
+$FLUTTER analyze --no-fatal-warnings || true  # エラーを警告として扱う
+
+# ビルドタインプスタンプの自動付与
+BUILD_TIMESTAMP=$(date -u +%s)
+DART_DEFINE="--dart-define=APP_BUILD_TIMESTAMP=${BUILD_TIMESTAMP}"
+
+echo "[情報] BUILD_TIMESTAMP: ${BUILD_TIMESTAMP}"
+echo "          有効期限（UTC）: $(date -u -d "@${BUILD_TIMESTAMP}" "+%Y-%m-%d %H:%M:%S")"
+echo "          90 日後の期限：$(date -u -d "@${BUILD_TIMESTAMP} + 90 days" "+%Y-%m-%d %H:%M:%S")"
+
+# APK ビルド実行（リリースビルドモードが推奨）
+echo ""
+echo "[実装] flutter build apk ${DART_DEFINE} --release..."
+$FLUTTER build apk $DART_DEFINE \
+    --dart-define=APP_BUILD_TIMESTAMP=$BUILD_TIMESTAMP \
+    --release \
+    --build-number=$((date +%s))  # ビルド番号を秒数（ビルド毎に異なる）
+
+# バイナリ出力先を確認
+APK_PATH=""
+if [ -f "$PROJECT_DIR/build/app/outputs/flutter-apk/app-release.apk" ]; then
+    APK_PATH="$PROJECT_DIR/build/app/outputs/flutter-apk/app-release.apk"
+elif [ -f "$PROJECT_DIR/build/app/outputs/bundle/release/app-release.aab" ]; then
+    # 必要に応じて AAB（Google Play）も出力可
+    APK_PATH="$PROJECT_DIR/build/app/outputs/bundle/release/app-release.aab"
+fi
+
+if [ ! -z "$APK_PATH" ]; then
+    echo ""
+    echo "[成功] APK 生成完了："
+    echo "  ファイル: ${APK_PATH}"
+    echo "  サイズ：$(ls -lh "$APK_PATH" | awk '{print $5}')"
+else
+    echo "[警告] バイナリ出力先が見つかりませんでした。"
+fi
+
+echo ""
+echo "=== ビルド完了 ==="
\ No newline at end of file