feat: add configurable payment amount precision

- add system.amount_precision setting with 2-6 validation

src/model/data/order_data.go

@@ -23,9 +23,14 @@ type PendingCallbackOrder struct {
 	UpdatedAt       carbon.Time `gorm:"column:updated_at"`
 }
 
+func normalizeAmount(amount float64, precision int) (int64, string) {
+	precision = NormalizeAmountPrecision(precision)
+	value := decimal.NewFromFloat(amount).Round(int32(precision))
+	return value.Shift(int32(precision)).IntPart(), value.StringFixed(int32(precision))
+}
+
 func normalizeLockAmount(amount float64) (int64, string) {
-	value := decimal.NewFromFloat(amount).Round(2)
-	return value.Shift(2).IntPart(), value.StringFixed(2)
+	return normalizeAmount(amount, GetAmountPrecision())
 }
 
 func normalizeLockNetwork(network string) string {
@@ -53,6 +58,30 @@ func applyLockAddressFilter(tx *gorm.DB, network, address string) *gorm.DB {
 	return tx.Where("address = ?", address)
 }
 
+func activeLocksForAddress(tx *gorm.DB, network, address, token string, now time.Time) *gorm.DB {
+	query := tx.Model(&mdb.TransactionLock{}).
+		Where("network = ?", normalizeLockNetwork(network)).
+		Where("token = ?", normalizeLockToken(token)).
+		Where("expires_at > ?", now)
+	return applyLockAddressFilter(query, network, address)
+}
+
+func lockMatchesAmount(lock mdb.TransactionLock, amount float64) bool {
+	precision := NormalizeAmountPrecision(lock.AmountPrecision)
+	scaledAmount, _ := normalizeAmount(amount, precision)
+	return lock.AmountScaled == scaledAmount
+}
+
+func lockAmountDecimal(lock mdb.TransactionLock) decimal.Decimal {
+	if strings.TrimSpace(lock.AmountText) != "" {
+		if value, err := decimal.NewFromString(lock.AmountText); err == nil {
+			return value
+		}
+	}
+	precision := NormalizeAmountPrecision(lock.AmountPrecision)
+	return decimal.NewFromInt(lock.AmountScaled).Shift(int32(-precision))
+}
+
 // GetOrderInfoByOrderId fetches an order by merchant order id.
 func GetOrderInfoByOrderId(orderId string) (*mdb.Orders, error) {
 	order := new(mdb.Orders)
@@ -278,45 +307,43 @@ func ExpireOrderByTradeId(tradeId string) error {
 func GetTradeIdByWalletAddressAndAmountAndToken(network string, address string, token string, amount float64) (string, error) {
 	network = normalizeLockNetwork(network)
 	address = normalizeLockAddress(network, address)
-	scaledAmount, _ := normalizeLockAmount(amount)
-	var lock mdb.TransactionLock
-	query := dao.RuntimeDB.Model(&mdb.TransactionLock{}).
-		Where("network = ?", network).
-		Where("token = ?", normalizeLockToken(token)).
-		Where("amount_scaled = ?", scaledAmount).
-		Where("expires_at > ?", time.Now())
-	query = applyLockAddressFilter(query, network, address)
-	err := query.Limit(1).Find(&lock).Error
+	var locks []mdb.TransactionLock
+	err := activeLocksForAddress(dao.RuntimeDB, network, address, token, time.Now()).
+		Order("created_at ASC").
+		Find(&locks).Error
 	if err != nil {
 		return "", err
 	}
-	if lock.ID <= 0 {
-		return "", nil
+	for _, lock := range locks {
+		if lockMatchesAmount(lock, amount) {
+			return lock.TradeId, nil
+		}
 	}
-	return lock.TradeId, nil
+	return "", nil
 }
 
 // LockTransaction reserves a network+address+token+amount pair in sqlite until expiration.
 func LockTransaction(network, address, token, tradeID string, amount float64, expirationTime time.Duration) error {
 	network = normalizeLockNetwork(network)
 	address = normalizeLockAddress(network, address)
-	scaledAmount, amountText := normalizeLockAmount(amount)
+	precision := GetAmountPrecision()
+	scaledAmount, amountText := normalizeAmount(amount, precision)
 	normalizedToken := normalizeLockToken(token)
 	now := time.Now()
 	lock := &mdb.TransactionLock{
-		Network:      network,
-		Address:      address,
-		Token:        normalizedToken,
-		AmountScaled: scaledAmount,
-		AmountText:   amountText,
-		TradeId:      tradeID,
-		ExpiresAt:    now.Add(expirationTime),
+		Network:         network,
+		Address:         address,
+		Token:           normalizedToken,
+		AmountScaled:    scaledAmount,
+		AmountText:      amountText,
+		AmountPrecision: precision,
+		TradeId:         tradeID,
+		ExpiresAt:       now.Add(expirationTime),
 	}
 
 	return dao.RuntimeDB.Transaction(func(tx *gorm.DB) error {
 		expiredQuery := tx.Where("network = ?", network).
 			Where("token = ?", normalizedToken).
-			Where("amount_scaled = ?", scaledAmount).
 			Where("expires_at <= ?", now)
 		expiredQuery = applyLockAddressFilter(expiredQuery, network, address)
 		if err := expiredQuery.Delete(&mdb.TransactionLock{}).Error; err != nil {
@@ -326,6 +353,18 @@ func LockTransaction(network, address, token, tradeID string, amount float64, ex
 			return err
 		}
 
+		var existing []mdb.TransactionLock
+		if err := activeLocksForAddress(tx, network, address, normalizedToken, now).
+			Find(&existing).Error; err != nil {
+			return err
+		}
+		candidateAmount := lockAmountDecimal(*lock)
+		for _, item := range existing {
+			if lockAmountDecimal(item).Equal(candidateAmount) {
+				return ErrTransactionLocked
+			}
+		}
+
 		result := tx.Clauses(clause.OnConflict{DoNothing: true}).Create(lock)
 		if result.Error != nil {
 			return result.Error
@@ -341,13 +380,21 @@ func LockTransaction(network, address, token, tradeID string, amount float64, ex
 func UnLockTransaction(network string, address string, token string, amount float64) error {
 	network = normalizeLockNetwork(network)
 	address = normalizeLockAddress(network, address)
-	scaledAmount, _ := normalizeLockAmount(amount)
-	query := dao.RuntimeDB.
-		Where("network = ?", network).
-		Where("token = ?", normalizeLockToken(token)).
-		Where("amount_scaled = ?", scaledAmount)
-	query = applyLockAddressFilter(query, network, address)
-	return query.Delete(&mdb.TransactionLock{}).Error
+	var locks []mdb.TransactionLock
+	if err := activeLocksForAddress(dao.RuntimeDB, network, address, token, time.Now()).
+		Find(&locks).Error; err != nil {
+		return err
+	}
+	ids := make([]uint64, 0, len(locks))
+	for _, lock := range locks {
+		if lockMatchesAmount(lock, amount) {
+			ids = append(ids, lock.ID)
+		}
+	}
+	if len(ids) == 0 {
+		return nil
+	}
+	return dao.RuntimeDB.Where("id IN ?", ids).Delete(&mdb.TransactionLock{}).Error
 }
 
 func UnLockTransactionByTradeId(tradeID string) error {