diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..76d554a
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,25 @@
+# 更新日志
+
+## [1.1.0] - 2026-03-18
+
+### 新增
+- 后端模块化重构，拆分单体 server.js
+- 数据库迁移系统
+- 统一错误处理机制
+- 数据库索引优化
+- SWR 数据获取和缓存
+- 乐观更新支持
+- 错误边界组件
+- ESLint + Prettier 配置
+- Jest 测试框架
+
+### 优化
+- API 错误响应格式统一
+- 前端数据获取性能优化
+- 代码质量和一致性检查
+
+### 开发体验
+- 新增 `npm run dev` 同时启动前后端
+- 新增 `npm run migrate` 数据库迁移
+- 新增 `npm run lint` 代码检查
+- 新增 `npm test` 运行测试
diff --git a/SPEC.md b/SPEC.md
index 858b046..9a59635 100644
--- a/SPEC.md
+++ b/SPEC.md
@@ -203,3 +203,43 @@ npm run dev
 ```
 
 访问 http://你的IP:3500
+
+## 9. 项目结构
+
+### 后端目录结构
+```
+server/
+├── index.js              # 入口文件
+├── config/
+│   └── database.js       # 数据库配置
+├── middleware/
+│   ├── auth.js           # 认证中间件
+│   └── errorHandler.js   # 错误处理
+├── routes/
+│   ├── auth.js           # 认证路由
+│   ├── records.js        # 账目路由
+│   ├── stats.js          # 统计路由
+│   ├── recurring.js      # 周期性账单
+│   ├── categories.js     # 分类路由
+│   ├── export.js         # 导入导出
+│   └── search.js         # 搜索路由
+├── utils/
+│   └── validators.js     # 验证函数
+└── db/
+    ├── migrations/       # 数据库迁移
+    └── migrate.js        # 迁移脚本
+```
+
+### 前端优化
+- 使用 SWR 进行数据获取和缓存
+- 乐观更新支持
+- 错误边界组件
+- 统一加载状态
+
+### 新增功能
+- 数据库迁移系统 (`npm run migrate`)
+- 结构化日志
+- 统一错误处理
+- API 请求验证
+- 数据库索引优化
+
diff --git a/server.js.backup b/server.js.backup
new file mode 100644
index 0000000..a9c360b
--- /dev/null
+++ b/server.js.backup
@@ -0,0 +1,824 @@
+const express = require('express');
+const Database = require('better-sqlite3');
+const jwt = require('jsonwebtoken');
+const bcrypt = require('bcryptjs');
+const cors = require('cors');
+const path = require('path');
+
+const app = express();
+const PORT = 3501;
+const JWT_SECRET = process.env.JWT_SECRET || 'accountbook_secret_key_2024';
+
+// 中间件
+app.use(cors({
+  origin: ['http://localhost:3500', 'http://127.0.0.1:3500'],
+  credentials: true
+}));
+app.use(express.json());
+app.use(express.static(path.join(__dirname, 'public')));
+app.use(express.static(path.join(__dirname, 'frontend/.next')));
+app.use(express.static(path.join(__dirname, 'frontend/.next/server/pages')));
+
+// 数据库初始化
+const db = new Database('accountbook.db');
+
+// 创建表
+db.exec(`
+  CREATE TABLE IF NOT EXISTS users (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    username TEXT UNIQUE NOT NULL,
+    password TEXT NOT NULL,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
+  );
+
+  CREATE TABLE IF NOT EXISTS records (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER NOT NULL,
+    type TEXT NOT NULL CHECK(type IN ('income', 'expense')),
+    amount REAL NOT NULL,
+    category TEXT NOT NULL,
+    date DATETIME NOT NULL,
+    note TEXT,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    FOREIGN KEY (user_id) REFERENCES users(id)
+  );
+
+  CREATE TABLE IF NOT EXISTS recurring_bills (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER NOT NULL,
+    type TEXT NOT NULL CHECK(type IN ('income', 'expense')),
+    amount REAL NOT NULL,
+    category TEXT NOT NULL,
+    day INTEGER NOT NULL,
+    note TEXT,
+    is_active INTEGER DEFAULT 1,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    FOREIGN KEY (user_id) REFERENCES users(id)
+  );
+
+  CREATE TABLE IF NOT EXISTS categories (
+    id INTEGER PRIMARY KEY AUTOINCREMENT,
+    user_id INTEGER NOT NULL,
+    type TEXT NOT NULL CHECK(type IN ('income', 'expense')),
+    name TEXT NOT NULL,
+    icon TEXT NOT NULL,
+    is_default INTEGER DEFAULT 0,
+    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
+    FOREIGN KEY (user_id) REFERENCES users(id)
+  );
+`);
+
+const VALID_RECORD_TYPES = ['income', 'expense'];
+const VALID_STATS_PERIODS = ['week', 'month', 'year'];
+const VALID_STATS_TYPES = ['income', 'expense', 'all'];
+const MONTH_PATTERN = /^\d{4}-\d{2}$/;
+const DATE_TIME_PATTERN = /^\d{4}-\d{2}-\d{2}( \d{2}:\d{2})?$/;
+
+function isNonEmptyString(value) {
+  return typeof value === 'string' && value.trim().length > 0;
+}
+
+function isValidMonth(value) {
+  return typeof value === 'string' && MONTH_PATTERN.test(value);
+}
+
+function isValidDateTime(value) {
+  return typeof value === 'string' && DATE_TIME_PATTERN.test(value);
+}
+
+function normalizeNote(value) {
+  return value === undefined || value === null ? '' : value;
+}
+
+function validateRecordPayload(payload) {
+  if (!payload || typeof payload !== 'object') {
+    return '请求数据格式错误';
+  }
+
+  const { type, amount, category, date, note } = payload;
+
+  if (!VALID_RECORD_TYPES.includes(type)) {
+    return '账目类型错误';
+  }
+
+  if (!Number.isFinite(amount) || amount <= 0) {
+    return '金额需大于0';
+  }
+
+  if (!isNonEmptyString(category)) {
+    return '请填写分类';
+  }
+
+  if (!isValidDateTime(date)) {
+    return '日期格式错误';
+  }
+
+  if (note !== undefined && note !== null && typeof note !== 'string') {
+    return '备注格式错误';
+  }
+
+  return null;
+}
+
+function validateRecurringPayload(payload) {
+  if (!payload || typeof payload !== 'object') {
+    return '请求数据格式错误';
+  }
+
+  const { type, amount, category, day, note, is_active } = payload;
+
+  if (!VALID_RECORD_TYPES.includes(type)) {
+    return '账单类型错误';
+  }
+
+  if (!Number.isFinite(amount) || amount <= 0) {
+    return '金额需大于0';
+  }
+
+  if (!isNonEmptyString(category)) {
+    return '请填写分类';
+  }
+
+  if (!Number.isInteger(day) || day < 1 || day > 28) {
+    return '日期需在1到28之间';
+  }
+
+  if (note !== undefined && note !== null && typeof note !== 'string') {
+    return '备注格式错误';
+  }
+
+  if (is_active !== undefined && ![0, 1, true, false].includes(is_active)) {
+    return '启用状态错误';
+  }
+
+  return null;
+}
+
+function validateCategoryPayload(payload) {
+  if (!payload || typeof payload !== 'object') {
+    return '请求数据格式错误';
+  }
+
+  const { type, name, icon } = payload;
+
+  if (!VALID_RECORD_TYPES.includes(type)) {
+    return '分类类型错误';
+  }
+
+  if (!isNonEmptyString(name)) {
+    return '请填写分类名称';
+  }
+
+  if (!isNonEmptyString(icon)) {
+    return '请选择分类图标';
+  }
+
+  return null;
+}
+
+function validateImportPayload(payload) {
+  if (!payload || typeof payload !== 'object' || Array.isArray(payload)) {
+    return '导入数据格式错误';
+  }
+
+  const { records, recurring, customCategories } = payload;
+
+  if (records !== undefined) {
+    if (!Array.isArray(records)) {
+      return 'records 必须是数组';
+    }
+
+    for (const record of records) {
+      const error = validateRecordPayload(record);
+      if (error) {
+        return `records 数据错误: ${error}`;
+      }
+    }
+  }
+
+  if (recurring !== undefined) {
+    if (!Array.isArray(recurring)) {
+      return 'recurring 必须是数组';
+    }
+
+    for (const bill of recurring) {
+      const error = validateRecurringPayload(bill);
+      if (error) {
+        return `recurring 数据错误: ${error}`;
+      }
+    }
+  }
+
+  if (customCategories !== undefined) {
+    if (!Array.isArray(customCategories)) {
+      return 'customCategories 必须是数组';
+    }
+
+    for (const category of customCategories) {
+      const error = validateCategoryPayload(category);
+      if (error) {
+        return `customCategories 数据错误: ${error}`;
+      }
+    }
+  }
+
+  return null;
+}
+
+// 认证中间件
+const authenticate = (req, res, next) => {
+  const token = req.headers.authorization?.split(' ')[1];
+  if (!token) {
+    return res.status(401).json({ error: '请先登录' });
+  }
+  try {
+    const decoded = jwt.verify(token, JWT_SECRET);
+    req.userId = decoded.userId;
+    next();
+  } catch (err) {
+    return res.status(401).json({ error: '登录已过期' });
+  }
+};
+
+// ============ 认证接口 ============
+
+// 注册
+app.post('/api/auth/register', async (req, res) => {
+  const { username, password } = req.body;
+
+  if (!username || !password) {
+    return res.status(400).json({ error: '请填写用户名和密码' });
+  }
+
+  if (username.length < 3 || username.length > 20) {
+    return res.status(400).json({ error: '用户名需3-20个字符' });
+  }
+
+  if (password.length < 6 || password.length > 20) {
+    return res.status(400).json({ error: '密码需6-20个字符' });
+  }
+
+  try {
+    const hashedPassword = await bcrypt.hash(password, 10);
+    const stmt = db.prepare('INSERT INTO users (username, password) VALUES (?, ?)');
+    const result = stmt.run(username, hashedPassword);
+
+    const token = jwt.sign({ userId: result.lastInsertRowid }, JWT_SECRET, { expiresIn: '7d' });
+    res.json({ token, username });
+  } catch (err) {
+    if (err.code === 'SQLITE_CONSTRAINT_UNIQUE') {
+      return res.status(400).json({ error: '用户名已存在' });
+    }
+    res.status(500).json({ error: '服务器错误' });
+  }
+});
+
+// 登录
+app.post('/api/auth/login', async (req, res) => {
+  const { username, password } = req.body;
+
+  if (!username || !password) {
+    return res.status(400).json({ error: '请填写用户名和密码' });
+  }
+
+  const stmt = db.prepare('SELECT * FROM users WHERE username = ?');
+  const user = stmt.get(username);
+
+  if (!user) {
+    return res.status(400).json({ error: '用户名或密码错误' });
+  }
+
+  const validPassword = await bcrypt.compare(password, user.password);
+  if (!validPassword) {
+    return res.status(400).json({ error: '用户名或密码错误' });
+  }
+
+  const token = jwt.sign({ userId: user.id }, JWT_SECRET, { expiresIn: '7d' });
+  res.json({ token, username: user.username });
+});
+
+// ============ 账目接口 ============
+
+// 获取账目列表
+app.get('/api/records', authenticate, (req, res) => {
+  const { month, type } = req.query;
+
+  let query = 'SELECT * FROM records WHERE user_id = ?';
+  const params = [req.userId];
+
+  if (month) {
+    query += ' AND date LIKE ?';
+    params.push(`${month}%`);
+  }
+
+  if (type && type !== 'all') {
+    query += ' AND type = ?';
+    params.push(type);
+  }
+
+  query += ' ORDER BY date DESC, id DESC';
+
+  const stmt = db.prepare(query);
+  const records = stmt.all(...params);
+
+  res.json(records);
+});
+
+// 新增账目
+app.post('/api/records', authenticate, (req, res) => {
+  const { type, amount, category, date, note } = req.body;
+
+  const validationError = validateRecordPayload(req.body);
+  if (validationError) {
+    return res.status(400).json({ error: validationError });
+  }
+
+  const stmt = db.prepare(`
+    INSERT INTO records (user_id, type, amount, category, date, note)
+    VALUES (?, ?, ?, ?, ?, ?)
+  `);
+
+  const result = stmt.run(req.userId, type, amount, category.trim(), date, normalizeNote(note));
+
+  res.json({ id: result.lastInsertRowid, message: '添加成功' });
+});
+
+// 更新账目
+app.put('/api/records/:id', authenticate, (req, res) => {
+  const { id } = req.params;
+  const { type, amount, category, date, note } = req.body;
+
+  const checkStmt = db.prepare('SELECT * FROM records WHERE id = ? AND user_id = ?');
+  const record = checkStmt.get(id, req.userId);
+
+  if (!record) {
+    return res.status(404).json({ error: '记录不存在' });
+  }
+
+  const validationError = validateRecordPayload(req.body);
+  if (validationError) {
+    return res.status(400).json({ error: validationError });
+  }
+
+  const stmt = db.prepare(`
+    UPDATE records SET type = ?, amount = ?, category = ?, date = ?, note = ?
+    WHERE id = ? AND user_id = ?
+  `);
+
+  stmt.run(type, amount, category.trim(), date, normalizeNote(note), id, req.userId);
+
+  res.json({ message: '更新成功' });
+});
+
+// 删除账目
+app.delete('/api/records/:id', authenticate, (req, res) => {
+  const { id } = req.params;
+
+  const checkStmt = db.prepare('SELECT * FROM records WHERE id = ? AND user_id = ?');
+  const record = checkStmt.get(id, req.userId);
+
+  if (!record) {
+    return res.status(404).json({ error: '记录不存在' });
+  }
+
+  const stmt = db.prepare('DELETE FROM records WHERE id = ? AND user_id = ?');
+  stmt.run(id, req.userId);
+
+  res.json({ message: '删除成功' });
+});
+
+// 批量删除指定分类的记录
+app.delete('/api/records/by-category/:category', authenticate, (req, res) => {
+  const { category } = req.params;
+
+  if (!category || typeof category !== 'string' || !category.trim()) {
+    return res.status(400).json({ error: '分类不能为空' });
+  }
+
+  const stmt = db.prepare('DELETE FROM records WHERE category = ? AND user_id = ?');
+  const result = stmt.run(category.trim(), req.userId);
+
+  res.json({ message: `已删除 ${result.changes} 条记录` });
+});
+
+// 获取月度统计
+app.get('/api/stats', authenticate, (req, res) => {
+  const { month } = req.query;
+
+  if (!month) {
+    return res.status(400).json({ error: '请指定月份' });
+  }
+
+  const stmt = db.prepare(`
+    SELECT
+      SUM(CASE WHEN type = 'income' THEN amount ELSE 0 END) as totalIncome,
+      SUM(CASE WHEN type = 'expense' THEN amount ELSE 0 END) as totalExpense
+    FROM records
+    WHERE user_id = ? AND date LIKE ?
+  `);
+
+  const result = stmt.get(req.userId, `${month}%`);
+
+  res.json({
+    income: result.totalIncome || 0,
+    expense: result.totalExpense || 0,
+    balance: (result.totalIncome || 0) - (result.totalExpense || 0)
+  });
+});
+
+// ============ 搜索接口 ============
+
+// 搜索账目
+app.get('/api/records/search', authenticate, (req, res) => {
+  const { q } = req.query;
+
+  if (!q) {
+    return res.status(400).json({ error: '请输入搜索关键词' });
+  }
+
+  const stmt = db.prepare(`
+    SELECT * FROM records
+    WHERE user_id = ? AND (category LIKE ? OR note LIKE ?)
+    ORDER BY date DESC, id DESC
+    LIMIT 50
+  `);
+
+  const records = stmt.all(req.userId, `%${q}%`, `%${q}%`);
+  res.json(records);
+});
+
+// ============ 统计接口 ============
+
+// 收支趋势统计
+app.get('/api/stats/trend', authenticate, (req, res) => {
+  const { period = 'month', month } = req.query;
+
+  if (!VALID_STATS_PERIODS.includes(period)) {
+    return res.status(400).json({ error: '统计周期错误' });
+  }
+
+  if (month && !isValidMonth(month)) {
+    return res.status(400).json({ error: '月份格式错误' });
+  }
+
+  let dateGroup;
+  if (period === 'year') {
+    dateGroup = "strftime('%Y', date)";
+  } else if (period === 'week') {
+    dateGroup = "strftime('%Y-%W', date)";
+  } else {
+    dateGroup = "strftime('%Y-%m', date)";
+  }
+
+  let query = `
+    SELECT
+      ${dateGroup} as period,
+      SUM(CASE WHEN type = 'income' THEN amount ELSE 0 END) as income,
+      SUM(CASE WHEN type = 'expense' THEN amount ELSE 0 END) as expense
+    FROM records
+    WHERE user_id = ?
+  `;
+  const params = [req.userId];
+
+  if (month) {
+    query += ' AND date LIKE ?';
+    params.push(`${month}%`);
+  }
+
+  query += `
+    GROUP BY ${dateGroup}
+    ORDER BY period DESC
+    LIMIT 12
+  `;
+
+  const stmt = db.prepare(query);
+  const result = stmt.all(...params);
+  res.json(result.reverse());
+});
+
+// 分类统计
+app.get('/api/stats/category', authenticate, (req, res) => {
+  const { month, type = 'all' } = req.query;
+
+  if (!VALID_STATS_TYPES.includes(type)) {
+    return res.status(400).json({ error: '统计类型错误' });
+  }
+
+  if (month && !isValidMonth(month)) {
+    return res.status(400).json({ error: '月份格式错误' });
+  }
+
+  let query = `
+    SELECT
+      category,
+      SUM(amount) as total,
+      type
+    FROM records
+    WHERE user_id = ?
+  `;
+  const params = [req.userId];
+
+  if (month) {
+    query += ' AND date LIKE ?';
+    params.push(`${month}%`);
+  }
+
+  if (type !== 'all') {
+    query += ' AND type = ?';
+    params.push(type);
+  }
+
+  query += `
+    GROUP BY category, type
+    ORDER BY total DESC
+  `;
+
+  const stmt = db.prepare(query);
+  const result = stmt.all(...params);
+  res.json(result);
+});
+
+// ============ 周期性账单接口 ============
+
+// 获取周期性账单
+app.get('/api/recurring', authenticate, (req, res) => {
+  const stmt = db.prepare('SELECT * FROM recurring_bills WHERE user_id = ? ORDER BY day ASC');
+  const bills = stmt.all(req.userId);
+  res.json(bills);
+});
+
+// 新增周期性账单
+app.post('/api/recurring', authenticate, (req, res) => {
+  const { type, amount, category, day, note } = req.body;
+
+  const validationError = validateRecurringPayload(req.body);
+  if (validationError) {
+    return res.status(400).json({ error: validationError });
+  }
+
+  const stmt = db.prepare(`
+    INSERT INTO recurring_bills (user_id, type, amount, category, day, note)
+    VALUES (?, ?, ?, ?, ?, ?)
+  `);
+
+  const result = stmt.run(req.userId, type, amount, category.trim(), day, normalizeNote(note));
+  res.json({ id: result.lastInsertRowid, message: '添加成功' });
+});
+
+// 更新周期性账单
+app.put('/api/recurring/:id', authenticate, (req, res) => {
+  const { id } = req.params;
+  const { type, amount, category, day, note, is_active } = req.body;
+
+  const checkStmt = db.prepare('SELECT * FROM recurring_bills WHERE id = ? AND user_id = ?');
+  const bill = checkStmt.get(id, req.userId);
+
+  if (!bill) {
+    return res.status(404).json({ error: '账单不存在' });
+  }
+
+  const validationError = validateRecurringPayload(req.body);
+  if (validationError) {
+    return res.status(400).json({ error: validationError });
+  }
+
+  const stmt = db.prepare(`
+    UPDATE recurring_bills SET type = ?, amount = ?, category = ?, day = ?, note = ?, is_active = ?
+    WHERE id = ? AND user_id = ?
+  `);
+
+  stmt.run(type, amount, category.trim(), day, normalizeNote(note), is_active !== undefined ? is_active : 1, id, req.userId);
+  res.json({ message: '更新成功' });
+});
+
+// 删除周期性账单
+app.delete('/api/recurring/:id', authenticate, (req, res) => {
+  const { id } = req.params;
+
+  const checkStmt = db.prepare('SELECT * FROM recurring_bills WHERE id = ? AND user_id = ?');
+  const bill = checkStmt.get(id, req.userId);
+
+  if (!bill) {
+    return res.status(404).json({ error: '账单不存在' });
+  }
+
+  const stmt = db.prepare('DELETE FROM recurring_bills WHERE id = ? AND user_id = ?');
+  stmt.run(id, req.userId);
+  res.json({ message: '删除成功' });
+});
+
+// 应用周期性账单
+app.post('/api/recurring/:id/apply', authenticate, (req, res) => {
+  const { id } = req.params;
+
+  const checkStmt = db.prepare('SELECT * FROM recurring_bills WHERE id = ? AND user_id = ? AND is_active = 1');
+  const bill = checkStmt.get(id, req.userId);
+
+  if (!bill) {
+    return res.status(404).json({ error: '账单不存在或已禁用' });
+  }
+
+  // 创建当前日期的账目
+  const today = new Date();
+  const dateStr = today.toISOString().split('T')[0] + ' ' + today.toTimeString().slice(0, 5);
+
+  const insertStmt = db.prepare(`
+    INSERT INTO records (user_id, type, amount, category, date, note)
+    VALUES (?, ?, ?, ?, ?, ?)
+  `);
+
+  insertStmt.run(req.userId, bill.type, bill.amount, bill.category, dateStr, bill.note || '');
+  res.json({ message: '应用成功' });
+});
+
+// ============ 分类接口 ============
+
+// 获取分类列表
+app.get('/api/categories', authenticate, (req, res) => {
+  const stmt = db.prepare('SELECT * FROM categories WHERE user_id = ? ORDER BY type, id');
+  const customCategories = stmt.all(req.userId);
+
+  const defaultCategories = {
+    expense: [
+      { name: '餐饮', icon: '🍜' },
+      { name: '买菜', icon: '🥬' },
+      { name: '交通', icon: '🚗' },
+      { name: '购物', icon: '🛒' },
+      { name: '娱乐', icon: '🎮' },
+      { name: '房租', icon: '🏠' },
+      { name: '房贷', icon: '🏦' },
+      { name: '水电', icon: '💧' },
+      { name: '衣服', icon: '👔' },
+      { name: '通讯', icon: '📱' },
+      { name: '日用品', icon: '🧴' },
+      { name: '美妆', icon: '💄' },
+      { name: '医疗', icon: '🏥' },
+      { name: '养娃', icon: '👶' },
+      { name: '家电', icon: '📺' },
+      { name: '家具', icon: '🛋️' },
+      { name: '装修', icon: '🔨' },
+      { name: '宠物', icon: '🐕' },
+      { name: '其他', icon: '📝' }
+    ],
+    income: [
+      { name: '工资', icon: '💰' },
+      { name: '奖金', icon: '🎁' },
+      { name: '理财', icon: '📈' },
+      { name: '红包', icon: '🧧' },
+      { name: '其他', icon: '📝' }
+    ]
+  };
+
+  // 合并默认分类和自定义分类
+  const categories = {
+    expense: [
+      ...defaultCategories.expense.map(c => ({ ...c, is_default: true })),
+      ...customCategories.filter(c => c.type === 'expense')
+    ],
+    income: [
+      ...defaultCategories.income.map(c => ({ ...c, is_default: true })),
+      ...customCategories.filter(c => c.type === 'income')
+    ]
+  };
+
+  res.json(categories);
+});
+
+// 新增自定义分类
+app.post('/api/categories', authenticate, (req, res) => {
+  const { type, name, icon } = req.body;
+
+  const validationError = validateCategoryPayload(req.body);
+  if (validationError) {
+    return res.status(400).json({ error: validationError });
+  }
+
+  const stmt = db.prepare(`
+    INSERT INTO categories (user_id, type, name, icon, is_default)
+    VALUES (?, ?, ?, ?, 0)
+  `);
+
+  const result = stmt.run(req.userId, type, name.trim(), icon.trim());
+  res.json({ id: result.lastInsertRowid, message: '添加成功' });
+});
+
+// 删除自定义分类
+app.delete('/api/categories/:id', authenticate, (req, res) => {
+  const { id } = req.params;
+
+  const checkStmt = db.prepare('SELECT * FROM categories WHERE id = ? AND user_id = ? AND is_default = 0');
+  const category = checkStmt.get(id, req.userId);
+
+  if (!category) {
+    return res.status(404).json({ error: '分类不存在或无法删除' });
+  }
+
+  const stmt = db.prepare('DELETE FROM categories WHERE id = ? AND user_id = ?');
+  stmt.run(id, req.userId);
+  res.json({ message: '删除成功' });
+});
+
+// ============ 数据导入导出接口 ============
+
+// 导出数据
+app.get('/api/export', authenticate, (req, res) => {
+  const recordsStmt = db.prepare('SELECT * FROM records WHERE user_id = ? ORDER BY date DESC');
+  const records = recordsStmt.all(req.userId);
+
+  const recurringStmt = db.prepare('SELECT * FROM recurring_bills WHERE user_id = ?');
+  const recurring = recurringStmt.all(req.userId);
+
+  const categoriesStmt = db.prepare('SELECT * FROM categories WHERE user_id = ?');
+  const categories = categoriesStmt.all(req.userId);
+
+  res.json({
+    version: '1.0',
+    exportDate: new Date().toISOString(),
+    records,
+    recurring,
+    customCategories: categories
+  });
+});
+
+// 导入数据
+app.post('/api/import', authenticate, (req, res) => {
+  const { records: importRecords, recurring: importRecurring, customCategories: importCategories } = req.body;
+
+  const validationError = validateImportPayload(req.body);
+  if (validationError) {
+    return res.status(400).json({ error: validationError });
+  }
+
+  try {
+    if (importRecords && Array.isArray(importRecords)) {
+      const insertRecord = db.prepare(`
+        INSERT INTO records (user_id, type, amount, category, date, note, created_at)
+        VALUES (?, ?, ?, ?, ?, ?, ?)
+      `);
+
+      const insertMany = db.transaction((records) => {
+        for (const r of records) {
+          insertRecord.run(req.userId, r.type, r.amount, r.category.trim(), r.date, normalizeNote(r.note), r.created_at || new Date().toISOString());
+        }
+      });
+      insertMany(importRecords);
+    }
+
+    if (importRecurring && Array.isArray(importRecurring)) {
+      const insertRecurring = db.prepare(`
+        INSERT INTO recurring_bills (user_id, type, amount, category, day, note, is_active, created_at)
+        VALUES (?, ?, ?, ?, ?, ?, ?, ?)
+      `);
+
+      const insertRecurringMany = db.transaction((bills) => {
+        for (const b of bills) {
+          insertRecurring.run(req.userId, b.type, b.amount, b.category.trim(), b.day, normalizeNote(b.note), b.is_active !== undefined ? b.is_active : 1, b.created_at || new Date().toISOString());
+        }
+      });
+      insertRecurringMany(importRecurring);
+    }
+
+    if (importCategories && Array.isArray(importCategories)) {
+      const insertCategory = db.prepare(`
+        INSERT INTO categories (user_id, type, name, icon, is_default, created_at)
+        VALUES (?, ?, ?, ?, 0, ?)
+      `);
+
+      const insertCategoryMany = db.transaction((cats) => {
+        for (const c of cats) {
+          insertCategory.run(req.userId, c.type, c.name.trim(), c.icon.trim(), c.created_at || new Date().toISOString());
+        }
+      });
+      insertCategoryMany(importCategories);
+    }
+
+    res.json({ message: '导入成功' });
+  } catch (err) {
+    res.status(500).json({ error: '导入失败: ' + err.message });
+  }
+});
+
+// 前端路由 - 优先处理 Next.js 静态文件
+app.get('/_next/static/:path(*)', (req, res) => {
+  const filePath = path.join(__dirname, 'frontend/.next/static', req.params.path);
+  res.sendFile(filePath, (err) => {
+    if (err) res.status(404).send('Not found');
+  });
+});
+
+app.get('*', (req, res) => {
+  // 检查是否是 Next.js 预渲染的页面
+  let pagePath = req.path === '/' ? '/index.html' : req.path + '.html';
+  const nextPagePath = path.join(__dirname, 'frontend/.next/server/pages', pagePath);
+
+  res.sendFile(nextPagePath, (err) => {
+    if (err) {
+      // 如果找不到，返回首页
+      res.sendFile(path.join(__dirname, 'frontend/.next/server/pages/index.html'));
+    }
+  });
+});
+
+app.listen(PORT, '0.0.0.0', () => {
+  console.log(`记账本服务已启动: http://0.0.0.0:${PORT}`);
+});