feat: 見積入力画面の商品追加機能を実装（Product CRUD）

- lib/models/product.dart: Product クラス作成
- lib/services/database_helper.dart: getProducts/insert/update/delete/Product snapshot API 追加
- lib/screens/estimate_screen.dart: 商品選択・合計計算・得意先連携ロジック実装

lib/models/product.dart

@@ -0,0 +1,75 @@
+// Version: 1.0.0
+import '../services/database_helper.dart';
+
+class Product {
+  int? id;
+  String productCode;
+  String name;
+  int price; // 単価（税込）
+  int stock;
+  String? category;
+  String? unit;
+  int isDeleted = 0; // Soft delete flag
+
+  Product({
+    this.id,
+    required this.productCode,
+    required this.name,
+    required this.price,
+    this.stock = 0,
+    this.category,
+    this.unit,
+    this.isDeleted = 0,
+  });
+
+  Map<String, dynamic> toMap() {
+    return {
+      'id': id,
+      'product_code': productCode,
+      'name': name,
+      'price': price,
+      'stock': stock,
+      'category': category ?? '',
+      'unit': unit ?? '',
+      'is_deleted': isDeleted,
+    };
+  }
+
+  factory Product.fromMap(Map<String, dynamic> map) {
+    return Product(
+      id: map['id'] as int?,
+      productCode: map['product_code'] as String,
+      name: map['name'] as String,
+      price: map['price'] as int,
+      stock: map['stock'] as int? ?? 0,
+      category: map['category'] as String?,
+      unit: map['unit'] as String?,
+      isDeleted: map['is_deleted'] as int? ?? 0,
+    );
+  }
+
+  Product copyWith({
+    int? id,
+    String? productCode,
+    String? name,
+    int? price,
+    int? stock,
+    String? category,
+    String? unit,
+    int? isDeleted,
+  }) {
+    return Product(
+      id: id ?? this.id,
+      productCode: productCode ?? this.productCode,
+      name: name ?? this.name,
+      price: price ?? this.price,
+      stock: stock ?? this.stock,
+      category: category ?? this.category,
+      unit: unit ?? this.unit,
+      isDeleted: isDeleted ?? this.isDeleted,
+    );
+  }
+
+  // 税込価格（引数にない場合は自身）
+  int get taxPrice => price;
+}

lib/screens/estimate_screen.dart

@@ -1,68 +1,97 @@
 // Version: 1.0.0
 import 'package:flutter/material.dart';
+import '../services/database_helper.dart';
+import '../models/product.dart';
 
 /// 見積入力画面（Material Design テンプレート）
-class EstimateScreen extends StatelessWidget {
+class EstimateScreen extends StatefulWidget {
   const EstimateScreen({super.key});
 
   @override
-  Widget build(BuildContext context) {
+  State<EstimateScreen> createState() => _EstimateScreenState();
-    return Scaffold(
+}
-      appBar: AppBar(
-        title: const Text('見積入力'),
-        actions: [
-          IconButton(
-            icon: const Icon(Icons.save),
-            onPressed: () => _showSaveDialog(context),
-          ),
-        ],
-      ),
-      body: ListView(
-        padding: const EdgeInsets.all(16),
-        children: [
-          // 得意先選択
-          TextField(
-            decoration: const InputDecoration(
-              labelText: '得意先',
-              hintText: '得意先マスタから選択',
-              prefixIcon: Icon(Icons.person_search),
-            ),
-            readOnly: true,
-            onTap: () => _showCustomerPicker(context),
-          ),
-          const SizedBox(height: 16),
 
-          // 商品追加リスト（簡易テンプレート）
+class _EstimateScreenState extends State<EstimateScreen> {
-          Card(
+  Customer? _selectedCustomer;
-            margin: EdgeInsets.zero,
+  final DatabaseHelper _db = DatabaseHelper.instance;
-            child: ExpansionTile(
+  List<Product> _products = [];
-              title: const Text('見積商品'),
+  List<Customer> _customers = [];
-              children: [
+  List<LineItem> _items = [];
-                ListView.builder(
+
-                  shrinkWrap: true,
+  @override
-                  padding: EdgeInsets.zero,
+  void initState() {
-                  itemCount: 0, // デモ用
+    super.initState();
-                  itemBuilder: (context, index) => Card(
+    _loadProducts();
-                    margin: const EdgeInsets.symmetric(vertical: 4),
+    _loadCustomers();
-                    child: ListTile(
-                      leading: CircleAvatar(
-                        backgroundColor: Colors.blue.shade100,
-                        child: Icon(Icons.receipt, color: Colors.blue),
-                      ),
-                      title: Text('商品${index + 1}'),
-                      subtitle: Text('単価：¥${(index + 1) * 1000}'),
-                    ),
-                  ),
-                ),
-              ],
-            ),
-          ),
-        ],
-      ),
-    );
   }
 
-  void _showSaveDialog(BuildContext context) {
+  Future<void> _loadProducts() async {
+    try {
+      final products = await _db.getProducts();
+      setState(() => _products = products);
+    } catch (e) {
+      debugPrint('Product loading failed: $e');
+    }
+  }
+
+  Future<void> _loadCustomers() async {
+    try {
+      final customers = await _db.getCustomers();
+      setState(() => _customers = customers.where((c) => c.isDeleted == 0).toList());
+    } catch (e) {
+      debugPrint('Customer loading failed: $e');
+    }
+  }
+
+  Future<void> _showCustomerPicker() async {
+    if (_customers.isEmpty) await _loadCustomers();
+
+    final selected = await showModalBottomSheet<Customer>(
+      context: context,
+      builder: (ctx) => SizedBox(
+        height: MediaQuery.of(context).size.height * 0.4,
+        child: ListView.builder(
+          padding: const EdgeInsets.all(8),
+          itemCount: _customers.length,
+          itemBuilder: (ctx, index) => ListTile(
+            title: Text(_customers[index].name),
+            subtitle: Text('コード：${_customers[index].customerCode}'),
+            onTap: () => Navigator.pop(ctx, _customers[index]),
+          ),
+        ),
+      ),
+    );
+
+    if (selected is Customer && selected.id != _selectedCustomer?.id) {
+      setState(() => _selectedCustomer = selected);
+    }
+  }
+
+  void _addSelectedProducts() async {
+    for (final product in _products) {
+      setState(() => _items.add(LineItem(
+        productId: product.id,
+        productName: product.name,
+        unitPrice: product.price,
+        quantity: 1,
+        total: product.price,
+      )));
+    }
+    _showAddDialog();
+  }
+
+  void _removeLineItem(int index) {
+    setState(() => _items.removeAt(index));
+  }
+
+  void _updateLineItemQuantity(int index, int quantity) {
+    setState(() {
+      _items[index].quantity = quantity;
+      _items[index].total = quantity * _items[index].unitPrice;
+    });
+  }
+
+  void _showSaveDialog() {
     showDialog(
       context: context,
       builder: (ctx) => AlertDialog(
@@ -71,7 +100,26 @@ class EstimateScreen extends StatelessWidget {
           child: Column(
             mainAxisSize: MainAxisSize.min,
             children: [
-              Text('見積データを保存しますか？'),
+              if (_selectedCustomer != null) ...[
+                Padding(
+                  padding: const EdgeInsets.symmetric(vertical: 8),
+                  child: Text('得意先：${_selectedCustomer!.name}'),
+                ),
+              ],
+              Text('合計：¥${_calculateTotal()}'),
+              if (_items.isNotEmpty) ...[
+                Divider(),
+                ..._items.map((item) => Padding(
+                  padding: const EdgeInsets.symmetric(vertical: 4),
+                  child: Row(
+                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                    children: [
+                      Text(item.productName),
+                      Text('¥${item.unitPrice} × ${item.quantity} = ¥${item.total}'),
+                    ],
+                  ),
+                )),
+              ],
             ],
           ),
         ),
@@ -81,10 +129,16 @@ class EstimateScreen extends StatelessWidget {
             child: const Text('キャンセル'),
           ),
           ElevatedButton(
-            onPressed: () {
+            onPressed: () async {
+              if (_items.isEmpty) {
+                ScaffoldMessenger.of(context).showSnackBar(
+                  const SnackBar(content: Text('商品を追加してください')),
+                );
+                return;
+              }
               Navigator.pop(ctx);
               ScaffoldMessenger.of(context).showSnackBar(
-                const SnackBar(content: Text('見積保存しました')),
+                const SnackBar(content: Text('見積保存しました'))..behavior: SnackBarBehavior.floating,
               );
             },
             child: const Text('確定'),
@@ -94,7 +148,117 @@ class EstimateScreen extends StatelessWidget {
     );
   }
 
-  void _showCustomerPicker(BuildContext context) {
+  int _calculateTotal() {
-    // TODO: CustomerPickerModal を再利用して実装
+    return _items.fold(0, (sum, item) => sum + item.total);
   }
+
+  Widget _buildEmptyState() {
+    return Center(
+      child: Column(
+        mainAxisAlignment: MainAxisAlignment.center,
+        children: [
+          Icon(Icons.receipt_long, size: 64, color: Colors.grey.shade400),
+          const SizedBox(height: 16),
+          Text('見積商品を追加してください', style: TextStyle(color: Colors.grey.shade600)),
+        ],
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('見積入力')),
+      body: ListView(
+        padding: const EdgeInsets.all(16),
+        children: [
+          _buildCustomerField(),
+          const SizedBox(height: 16),
+          Card(
+            margin: EdgeInsets.zero,
+            child: ExpansionTile(
+              title: const Text('見積商品'),
+              children: [
+                if (_items.isEmpty) ...[
+                  Padding(
+                    padding: const EdgeInsets.all(16),
+                    child: _buildEmptyState(),
+                  ),
+                ] else ...[
+                  ListView.builder(
+                    shrinkWrap: true,
+                    padding: EdgeInsets.zero,
+                    itemCount: _items.length,
+                    itemBuilder: (context, index) => Card(
+                      margin: const EdgeInsets.symmetric(vertical: 4),
+                      child: ListTile(
+                        leading: CircleAvatar(
+                          backgroundColor: Colors.blue.shade100,
+                          child: Icon(Icons.receipt, color: Colors.blue),
+                        ),
+                        title: Text(_items[index].productName),
+                        subtitle: Text('単価：¥${_items[index].unitPrice}'),
+                        trailing: IconButton(icon: const Icon(Icons.delete, color: Colors.red), onPressed: () => _removeLineItem(index)),
+                      ),
+                    ),
+                  ),
+                ],
+              ],
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+
+  Widget _buildCustomerField() {
+    return TextField(
+      decoration: InputDecoration(
+        labelText: '得意先',
+        hintText: _selectedCustomer != null ? _selectedCustomer.name : '得意先マスタから選択',
+        prefixIcon: Icon(Icons.person_search),
+        isReadOnly: true,
+      ),
+      onTap: () => _showCustomerPicker(),
+    );
+  }
+
+  void _showAddDialog() async {
+    final selected = await showModalBottomSheet<Product>(
+      context: context,
+      builder: (ctx) => ListView.builder(
+        padding: EdgeInsets.zero,
+        itemCount: _products.length,
+        itemBuilder: (ctx, index) => CheckboxListTile(
+          title: Text(_products[index].name),
+          subtitle: Text('¥${_products[index].price} / 在庫：${_products[index].stock}${_products[index].unit ?? ''}'),
+          value: _items.any((i) => i.productId == _products[index].id),
+          onChanged: (value) {
+            if (value) _addSelectedProducts();
+          },
+        ),
+      ),
+    );
+
+    if (selected != null && selected.id != null && !_items.any((i) => i.productId == selected.id)) {
+      setState(() => _items.add(LineItem(
+        productId: selected.id,
+        productName: selected.name,
+        unitPrice: selected.price,
+        quantity: 1,
+        total: selected.price,
+      )));
+    }
+  }
+}
+
+/// 見積行モデル
+class LineItem {
+  final int? productId;
+  final String productName;
+  final int unitPrice;
+  int quantity = 1;
+  int get total => quantity * unitPrice;
+
+  LineItem({required this.productId, required this.productName, required this.unitPrice, this.quantity = 1});
 }

lib/services/database_helper.dart

@@ -3,6 +3,7 @@ import 'package:sqflite/sqflite.dart';
 import 'package:path/path.dart';
 import 'dart:convert';
 import '../models/customer.dart';
+import '../models/product.dart';
 
 class DatabaseHelper {
   static final DatabaseHelper instance = DatabaseHelper._init();
@@ -29,7 +30,7 @@ class DatabaseHelper {
 
   Future<void> _createDB(Database db, int version) async {
     const textType = 'TEXT NOT NULL';
-    
+
     // customers テーブル作成（テストデータ挿入含む）
     await db.execute('''
       CREATE TABLE customers (
@@ -110,6 +111,16 @@ class DatabaseHelper {
       )
     ''');
 
+    // product_snapshots テーブル（イベントソーシング用）
+    await db.execute('''
+      CREATE TABLE product_snapshots (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,
+        product_id INTEGER NOT NULL,
+        data_json TEXT NOT NULL,
+        created_at TEXT NOT NULL
+      )
+    ''');
+
     // テストデータ初期化（各テーブルが空の場合のみ）
     await _insertTestData(db);
   }
@@ -122,7 +133,6 @@ class DatabaseHelper {
         .toList();
 
     if (existingCustomerCodes.isEmpty) {
-      // テスト顧客データ
       await db.insert('customers', {
         'customer_code': 'C00001',
         'name': 'テスト株式会社 Alpha',
@@ -162,7 +172,7 @@ class DatabaseHelper {
         'updated_at': DateTime.now().toIso8601String(),
       });
 
-      // employees テーブル（存在する場合はスキップ）
+      // employees テーブル
       try {
         await db.execute('CREATE TABLE IF NOT EXISTS employees (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, position TEXT, phone_number TEXT)');
         
@@ -172,27 +182,13 @@ class DatabaseHelper {
             .toList();
 
         if (existingEmployees.isEmpty) {
-          await db.insert('employees', {
+          await db.insert('employees', {'name': '山田 太郎', 'position': '営業部長', 'phone_number': '090-1234-5678'});
-            'name': '山田 太郎',
+          await db.insert('employees', {'name': '鈴木 花子', 'position': '経理部長', 'phone_number': '090-8765-4321'});
-            'position': '営業部長',
+          await db.insert('employees', {'name': '田中 次郎', 'position': '技術部長', 'phone_number': '090-1111-2222'});
-            'phone_number': '090-1234-5678',
-          });
-          
-          await db.insert('employees', {
-            'name': '鈴木 花子',
-            'position': '経理部長',
-            'phone_number': '090-8765-4321',
-          });
-          
-          await db.insert('employees', {
-            'name': '田中 次郎',
-            'position': '技術部長',
-            'phone_number': '090-1111-2222',
-          });
         }
       } catch (e) {}
 
-      // warehouses テーブル（存在する場合はスキップ）
+      // warehouses テーブル
       try {
         await db.execute('CREATE TABLE IF NOT EXISTS warehouses (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, address TEXT, manager TEXT)');
         
@@ -202,21 +198,12 @@ class DatabaseHelper {
             .toList();
 
         if (existingWarehouses.isEmpty) {
-          await db.insert('warehouses', {
+          await db.insert('warehouses', {'name': '中央倉庫', 'address': '千葉県市川市_物流センター 1-1', 'manager': '佐藤 健一'});
-            'name': '中央倉庫',
+          await db.insert('warehouses', {'name': '東京支庫', 'address': '東京都品川区_倉庫棟 2-2', 'manager': '高橋 美咲'});
-            'address': '千葉県市川市_物流センター 1-1',
-            'manager': '佐藤 健一',
-          });
-          
-          await db.insert('warehouses', {
-            'name': '東京支庫',
-            'address': '東京都品川区_倉庫棟 2-2',
-            'manager': '高橋 美咲',
-          });
         }
       } catch (e) {}
 
-      // suppliers テーブル（存在する場合はスキップ）
+      // suppliers テーブル
       try {
         await db.execute('CREATE TABLE IF NOT EXISTS suppliers (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, tax_rate INTEGER DEFAULT 8)');
         
@@ -226,24 +213,13 @@ class DatabaseHelper {
             .toList();
 
         if (existingSuppliers.isEmpty) {
-          await db.insert('suppliers', {
+          await db.insert('suppliers', {'name': '仕入元 Alpha', 'tax_rate': 8});
-            'name': '仕入元 Alpha',
+          await db.insert('suppliers', {'name': '仕入元 Beta', 'tax_rate': 10});
-            'tax_rate': 8,
+          await db.insert('suppliers', {'name': '仕入元 Gamma', 'tax_rate': 10});
-          });
-          
-          await db.insert('suppliers', {
-            'name': '仕入元 Beta',
-            'tax_rate': 10,
-          });
-          
-          await db.insert('suppliers', {
-            'name': '仕入元 Gamma',
-            'tax_rate': 10,
-          });
         }
       } catch (e) {}
 
-      // products テーブル（存在する場合はスキップ）
+      // products テーブル
       try {
         await db.execute('''
           CREATE TABLE IF NOT EXISTS products (
@@ -263,37 +239,16 @@ class DatabaseHelper {
             .toList();
 
         if (existingProducts.isEmpty) {
-          await db.insert('products', {
+          await db.insert('products', {'product_code': 'PRD001', 'name': 'テスト商品 A', 'price': 3500, 'stock': 100, 'category': '食品', 'unit': '個'});
-            'product_code': 'PRD001',
+          await db.insert('products', {'product_code': 'PRD002', 'name': 'テスト商品 B', 'price': 5500, 'stock': 50, 'category': '家電', 'unit': '台'});
-            'name': 'テスト商品 A',
+          await db.insert('products', {'product_code': 'PRD003', 'name': 'テスト商品 C', 'price': 2800, 'stock': 200, 'category': '文具', 'unit': '冊'});
-            'price': 3500,
-            'stock': 100,
-            'category': '食品',
-            'unit': '個',
-          });
-          
-          await db.insert('products', {
-            'product_code': 'PRD002',
-            'name': 'テスト商品 B',
-            'price': 5500,
-            'stock': 50,
-            'category': '家電',
-            'unit': '台',
-          });
-          
-          await db.insert('products', {
-            'product_code': 'PRD003',
-            'name': 'テスト商品 C',
-            'price': 2800,
-            'stock': 200,
-            'category': '文具',
-            'unit': '冊',
-          });
         }
       } catch (e) {}
     }
   }
 
+  // ========== Customer CRUD ==========
+
   Future<int> insert(Customer customer) async {
     final db = await instance.database;
     return await db.insert('customers', customer.toMap());
@@ -311,11 +266,7 @@ class DatabaseHelper {
 
   Future<Customer?> getCustomer(int id) async {
     final db = await instance.database;
-    final maps = await db.query(
+    final maps = await db.query('customers', where: 'id = ?', whereArgs: [id]);
-      'customers',
-      where: 'id = ?',
-      whereArgs: [id],
-    );
     
     if (maps.isEmpty) return null;
     return Customer.fromMap(maps.first);
@@ -323,22 +274,12 @@ class DatabaseHelper {
 
   Future<int> update(Customer customer) async {
     final db = await instance.database;
-    return await db.update(
+    return await db.update('customers', customer.toMap(), where: 'id = ?', whereArgs: [customer.id]);
-      'customers',
-      customer.toMap(),
-      where: 'id = ?',
-      whereArgs: [customer.id],
-    );
   }
 
   Future<int> delete(int id) async {
     final db = await instance.database;
-    return await db.update(
+    return await db.update('customers', {'is_deleted': 1}, where: 'id = ?', whereArgs: [id]);
-      'customers',
-      {'is_deleted': 1}, // Soft delete
-      where: 'id = ?',
-      whereArgs: [id],
-    );
   }
 
   Future<void> saveSnapshot(Customer customer) async {
@@ -346,26 +287,64 @@ class DatabaseHelper {
     final id = customer.id;
     final now = DateTime.now().toIso8601String();
 
-    // Check if snapshot already exists for this customer (keep last 5 snapshots)
+    final existing = await db.query('customer_snapshots', where: 'customer_id = ?', whereArgs: [id], limit: 6);
-    final existing = await db.query(
-      'customer_snapshots',
-      where: 'customer_id = ?',
-      whereArgs: [id],
-      limit: 6,
-    );
 
     if (existing.length > 5) {
-      // Delete oldest snapshot
       final oldestId = existing.first['id'] as int;
       await db.delete('customer_snapshots', where: 'id = ?', whereArgs: [oldestId]);
     }
 
-    // Insert new snapshot
+    await db.insert('customer_snapshots', {'customer_id': id, 'data_json': jsonEncode(customer.toMap()), 'created_at': now});
-    await db.insert('customer_snapshots', {
+  }
-      'customer_id': id,
+
-      'data_json': jsonEncode(customer.toMap()),
+  // ========== Product CRUD ==========
-      'created_at': now,
+
-    });
+  Future<int> insert(Product product) async {
+    final db = await instance.database;
+    return await db.insert('products', product.toMap());
+  }
+
+  Future<List<Product>> getProducts() async {
+    final db = await instance.database;
+    final List<Map<String, dynamic>> maps = await db.query('products', orderBy: 'product_code ASC');
+    
+    return (maps as List)
+        .map((json) => Product.fromMap(json))
+        .where((p) => p.isDeleted == 0)
+        .toList();
+  }
+
+  Future<Product?> getProduct(int id) async {
+    final db = await instance.database;
+    final maps = await db.query('products', where: 'id = ?', whereArgs: [id]);
+    
+    if (maps.isEmpty) return null;
+    return Product.fromMap(maps.first);
+  }
+
+  Future<int> update(Product product) async {
+    final db = await instance.database;
+    return await db.update('products', product.toMap(), where: 'id = ?', whereArgs: [product.id]);
+  }
+
+  Future<int> delete(int id) async {
+    final db = await instance.database;
+    return await db.update('products', {'is_deleted': 1}, where: 'id = ?', whereArgs: [id]);
+  }
+
+  Future<void> saveSnapshot(Product product) async {
+    final db = await instance.database;
+    final id = product.id;
+    final now = DateTime.now().toIso8601String();
+
+    final existing = await db.query('product_snapshots', where: 'product_id = ?', whereArgs: [id], limit: 6);
+
+    if (existing.length > 5) {
+      final oldestId = existing.first['id'] as int;
+      await db.delete('product_snapshots', where: 'id = ?', whereArgs: [oldestId]);
+    }
+
+    await db.insert('product_snapshots', {'product_id': id, 'data_json': jsonEncode(product.toMap()), 'created_at': now});
   }
 
   Future<void> close() async {