支持结账多轮协商与按实际消耗双比例结算

允许双方最多 6 轮修改结账方案；哈夫币按实际消耗与 buyer/seller 比例计价，打超从押金扣，押金不足禁止自动完结并引导人工争议。同步收紧结账明细展示密度。

backend/internal/modules/order/pricing.go

@@ -27,6 +27,8 @@ type checkoutSettlement struct {
 	RenterRefundCent        int64
 	PlatformFeeCent         int64
 	ActualRentAmountCent    int64
+	OvershootAmountCent     int64
+	ShortfallCent           int64
 }
 
 func orderDurationHours(order model.RentalOrder) int {
@@ -145,9 +147,6 @@ func buildCheckout(order model.RentalOrder, initiatedBy uint64, status string, c
 	if useExplicitDeduct {
 		deductAmountCent = explicitDeductCent
 	}
-	if deductAmountCent > order.DepositAmountCent {
-		return model.OrderCheckout{}, ErrInvalidCheckoutAmount
-	}
 	settlement := calculateCheckoutSettlement(order, consumableAmountCent, roundQuantity(coinConsumedM), deductAmountCent)
 	evidence, err := marshalStringList(evidenceURLS)
 	if err != nil {
@@ -164,9 +163,12 @@ func buildCheckout(order model.RentalOrder, initiatedBy uint64, status string, c
 		ConsumableAmountCent:    consumableAmountCent,
 		CoinConsumedM:           roundQuantity(coinConsumedM),
 		OtherAmountCent:         otherAmountCent,
-		DepositDeductAmountCent: settlement.DepositCompensationCent,
+		// 存用户申报的押金赔付（损坏等），打超由结算自动计入 shortfall/overshoot
+		DepositDeductAmountCent: deductAmountCent,
 		RenterRefundAmountCent:  settlement.RenterRefundCent,
 		OwnerIncomeAmountCent:   settlement.OwnerIncomeCent,
+		ShortfallCent:           settlement.ShortfallCent,
+		OvershootAmountCent:     settlement.OvershootAmountCent,
 		Content:                 content,
 		EvidenceURLS:            evidence,
 	}, nil
@@ -194,24 +196,61 @@ func calculateCheckoutSettlement(order model.RentalOrder, consumableAmountCent i
 		prepaidConsumablePriceCent = maxCent(orderRentAmountCent-buyerCoinBasePriceCent, 0)
 	}
 	prepaidOwnerConsumablePriceCent := maxCent(orderOwnerRentAmountCent-sellerCoinBasePriceCent, 0)
+
+	consumedM := roundQuantity(coinConsumedM)
 	totalCoinM := readOrderSnapshotCoinM(order.AccountSnapshot)
-	coinUseRatio := 1.0
-	if totalCoinM > 0 {
-		coinUseRatio = minRatio(maxRatio(roundQuantity(coinConsumedM)/totalCoinM, 0), 1)
+	buyerRatio := readOrderSnapshotPrice(order.AccountSnapshot, "buyer_ratio")
+	sellerRatio := readOrderSnapshotPrice(order.AccountSnapshot, "seller_ratio")
+
+	// 币费：优先按各自比例 × 实际消耗；无比例时回退到预收币基价 × (消耗/发布量)，允许 >1（打超）
+	// 无发布量快照时保持旧行为：按全额使用（ratio=1）
+	coinUseRatio := coinConsumptionRatio(consumedM, totalCoinM)
+	var usedBuyerCoinPriceCent, usedOwnerCoinPriceCent int64
+	if buyerRatio > 0 && (totalCoinM > 0 || consumedM > 0) {
+		// 价(元) = 消耗M×100 / ratio；分 = 元×100
+		usedBuyerCoinPriceCent = int64(math.Round(consumedM * 10000 / buyerRatio))
+	} else {
+		usedBuyerCoinPriceCent = int64(math.Round(float64(buyerCoinBasePriceCent) * coinUseRatio))
 	}
-	usedBuyerCoinPriceCent := int64(math.Round(float64(buyerCoinBasePriceCent) * coinUseRatio))
-	usedOwnerCoinPriceCent := int64(math.Round(float64(sellerCoinBasePriceCent) * coinUseRatio))
-	usedBuyerConsumablePriceCent := minCent(consumableAmountCent, prepaidConsumablePriceCent)
-	consumableUseRatio := 1.0
+	if sellerRatio > 0 && (totalCoinM > 0 || consumedM > 0) {
+		usedOwnerCoinPriceCent = int64(math.Round(consumedM * 10000 / sellerRatio))
+	} else {
+		usedOwnerCoinPriceCent = int64(math.Round(float64(sellerCoinBasePriceCent) * coinUseRatio))
+	}
+
+	// 消耗品按申报金额计价，允许超过预收；号主侧按预收消耗品占比线性外推
+	usedBuyerConsumablePriceCent := maxCent(consumableAmountCent, 0)
+	consumableUseRatio := 0.0
 	if prepaidConsumablePriceCent > 0 {
-		consumableUseRatio = minRatio(maxRatio(float64(usedBuyerConsumablePriceCent)/float64(prepaidConsumablePriceCent), 0), 1)
+		consumableUseRatio = maxRatio(float64(usedBuyerConsumablePriceCent)/float64(prepaidConsumablePriceCent), 0)
 	}
 	usedOwnerConsumablePriceCent := int64(math.Round(float64(prepaidOwnerConsumablePriceCent) * consumableUseRatio))
-	actualRentAmountCent := minCent(usedBuyerCoinPriceCent+usedBuyerConsumablePriceCent, orderRentAmountCent)
-	ownerRentIncomeCent := minCent(usedOwnerCoinPriceCent+usedOwnerConsumablePriceCent, orderOwnerRentAmountCent)
-	depositCompensationCent := minCent(depositDeductAmountCent, orderDepositAmountCent)
-	rentRefundCent := maxCent(orderRentAmountCent-actualRentAmountCent, 0)
-	depositRefundCent := maxCent(orderDepositAmountCent-depositCompensationCent, 0)
+
+	actualBuyerRentCent := usedBuyerCoinPriceCent + usedBuyerConsumablePriceCent
+	actualOwnerRentCent := usedOwnerCoinPriceCent + usedOwnerConsumablePriceCent
+	if actualOwnerRentCent > actualBuyerRentCent {
+		actualOwnerRentCent = actualBuyerRentCent
+	}
+
+	// 打超：实际租客侧费用超出预收租金的部分，从押金扣
+	overshootCent := maxCent(actualBuyerRentCent-orderRentAmountCent, 0)
+	damageRequestCent := maxCent(depositDeductAmountCent, 0)
+	// 押金先覆盖损坏赔付，再覆盖打超；不足记 shortfall，禁止自动完结
+	damageAppliedCent := minCent(damageRequestCent, orderDepositAmountCent)
+	depositLeftAfterDamage := maxCent(orderDepositAmountCent-damageAppliedCent, 0)
+	overshootCoveredCent := minCent(overshootCent, depositLeftAfterDamage)
+	shortfallCent := maxCent(damageRequestCent-damageAppliedCent, 0) + maxCent(overshootCent-overshootCoveredCent, 0)
+
+	rentFromPrepaidCent := minCent(actualBuyerRentCent, orderRentAmountCent)
+	rentRefundCent := maxCent(orderRentAmountCent-rentFromPrepaidCent, 0)
+	depositUsedCent := damageAppliedCent + overshootCoveredCent
+	depositRefundCent := maxCent(orderDepositAmountCent-depositUsedCent, 0)
+
+	// 可完结时租客实际承担的租金向金额；有 shortfall 时仍展示完整应付便于协商
+	actualRentAmountCent := actualBuyerRentCent
+	ownerRentIncomeCent := actualOwnerRentCent
+	platformFeeCent := maxCent(actualRentAmountCent-ownerRentIncomeCent, 0)
+	depositCompensationCent := damageAppliedCent
 
 	return checkoutSettlement{
 		OwnerRentIncomeCent:     ownerRentIncomeCent,
@@ -220,8 +259,10 @@ func calculateCheckoutSettlement(order model.RentalOrder, consumableAmountCent i
 		RentRefundCent:          rentRefundCent,
 		DepositRefundCent:       depositRefundCent,
 		RenterRefundCent:        rentRefundCent + depositRefundCent,
-		PlatformFeeCent:         maxCent(actualRentAmountCent-ownerRentIncomeCent, 0),
+		PlatformFeeCent:         platformFeeCent,
 		ActualRentAmountCent:    actualRentAmountCent,
+		OvershootAmountCent:     overshootCent,
+		ShortfallCent:           shortfallCent,
 	}
 }
 
@@ -236,6 +277,15 @@ func readOrderSnapshotCoinM(raw datatypes.JSON) float64 {
 	return roundQuantity(readJSONNumber(snapshot["haf_coin_amount"]) / 1000000)
 }
 
+// coinConsumptionRatio 实际消耗相对发布量的比例，允许 >1 表示打超。
+// publishedM<=0 时视为无快照，回退为全额使用（兼容旧单测/无币价场景）。
+func coinConsumptionRatio(consumedM, publishedM float64) float64 {
+	if publishedM > 0 {
+		return maxRatio(roundQuantity(consumedM)/publishedM, 0)
+	}
+	return 1
+}
+
 func readOrderSnapshotAssetNumber(raw datatypes.JSON, key string) float64 {
 	if len(raw) == 0 {
 		return 0