feat: 新增周期性交易处理器及任务队列，实现周期性交易的自动处理、调度和幂等性保障。

internal/mq/recurring_handler.go

@@ -39,12 +39,27 @@ func NewRecurringTransactionHandler(
 }
 
 // Handle 处理周期性交易任务
+// 遵循 v7.0 规范：并发安全与幂等性
 func (h *RecurringTransactionHandler) Handle(ctx context.Context, task *DelayedTask) error {
 	payload, err := ParseRecurringPayload(task)
 	if err != nil {
 		return fmt.Errorf("failed to parse payload: %w", err)
 	}
 
+	// 幂等性检查：防止同一笔交易重复执行
+	// 使用 Redis SETNX 锁，锁 24 小时（足以覆盖重试窗口）
+	// TaskID 本身包含 recurringID 和执行时间戳，是天然的幂等 Key
+	lockKey := fmt.Sprintf("novault:lock:recurring:%s", task.ID)
+	// 使用 TaskQueue 提供的公开方法获取锁
+	isNew, err := h.taskQueue.AcquireLock(ctx, lockKey, 24*time.Hour)
+	if err != nil {
+		return fmt.Errorf("failed to check idempotency: %w", err)
+	}
+	if !isNew {
+		log.Printf("[RecurringHandler] Task %s already processed (idempotency check), skipping", task.ID)
+		return nil
+	}
+
 	log.Printf("[RecurringHandler] Processing recurring transaction %d for user %d",
 		payload.RecurringTransactionID, task.UserID)
 
@@ -94,23 +109,24 @@ func (h *RecurringTransactionHandler) Handle(ctx context.Context, task *DelayedT
 		return fmt.Errorf("failed to create transaction: %w", err)
 	}
 
-	// 更新账户余额
-	var account models.Account
-	if err := tx.First(&account, recurring.AccountID).Error; err != nil {
-		tx.Rollback()
-		return fmt.Errorf("failed to get account: %w", err)
-	}
-
+	// 更新账户余额 - 使用原子操作修复并发安全问题 (Race Condition Fix)
+	// UPDATE accounts SET balance = balance +/- ? WHERE id = ?
+	var updateExpr interface{}
 	switch recurring.Type {
 	case models.TransactionTypeIncome:
-		account.Balance += recurring.Amount
+		updateExpr = gorm.Expr("balance + ?", recurring.Amount)
 	case models.TransactionTypeExpense:
-		account.Balance -= recurring.Amount
+		updateExpr = gorm.Expr("balance - ?", recurring.Amount)
+	default:
+		tx.Rollback()
+		return fmt.Errorf("unknown transaction type: %s", recurring.Type)
 	}
 
-	if err := tx.Save(&account).Error; err != nil {
+	if err := tx.Model(&models.Account{}).
+		Where("id = ?", recurring.AccountID).
+		Update("balance", updateExpr).Error; err != nil {
 		tx.Rollback()
-		return fmt.Errorf("failed to update account balance: %w", err)
+		return fmt.Errorf("failed to update account balance atomic: %w", err)
 	}
 
 	// 计算下一次执行时间
@@ -140,7 +156,7 @@ func (h *RecurringTransactionHandler) Handle(ctx context.Context, task *DelayedT
 	if recurring.IsActive {
 		if err := h.scheduleNext(ctx, recurring); err != nil {
 			log.Printf("[RecurringHandler] Warning: failed to schedule next execution: %v", err)
-			// 不返回错误，当前任务已成功完成
+			// 不返回错误，当前任务已成功完成，仅仅是下次调度失败（会有补偿机制兜底）
 		}
 	}
 

internal/mq/task_queue.go

@@ -218,3 +218,8 @@ func (q *TaskQueue) GetPendingTasks(ctx context.Context, limit int64) ([]Delayed
 
 	return tasks, nil
 }
+
+// AcquireLock 尝试获取分布式锁（用于幂等性检查）
+func (q *TaskQueue) AcquireLock(ctx context.Context, key string, ttl time.Duration) (bool, error) {
+	return q.client.SetNX(ctx, key, "1", ttl).Result()
+}