From 0fbc9a44d3cec5f9d0634d9a272844f37f6c48fc Mon Sep 17 00:00:00 2001
From: erio <asakifeng@gmail.com>
Date: Mon, 30 Mar 2026 23:04:48 +0800
Subject: [PATCH] =?UTF-8?q?fix(billing):=20=E6=8C=89=E6=AC=A1=E8=AE=A1?=
 =?UTF-8?q?=E8=B4=B9=E5=9B=9E=E9=80=80=E5=88=B0=E9=BB=98=E8=AE=A4=20PerReq?=
 =?UTF-8?q?uestPrice?=
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ResolvedPricing 新增 DefaultPerRequestPrice，当无层级匹配时使用渠道的默认按次价格
---
 backend/internal/service/billing_service.go        | 5 +++++
 backend/internal/service/model_pricing_resolver.go | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/backend/internal/service/billing_service.go b/backend/internal/service/billing_service.go
index d256102c..458788fd 100644
--- a/backend/internal/service/billing_service.go
+++ b/backend/internal/service/billing_service.go
@@ -542,6 +542,11 @@ func (s *BillingService) calculatePerRequestCost(resolved *ResolvedPricing, inpu
 		unitPrice = input.Resolver.GetRequestTierPriceByContext(resolved, totalContext)
 	}
 
+	// 回退到默认按次价格
+	if unitPrice == 0 {
+		unitPrice = resolved.DefaultPerRequestPrice
+	}
+
 	totalCost := unitPrice * float64(count)
 	actualCost := totalCost * input.RateMultiplier
 
diff --git a/backend/internal/service/model_pricing_resolver.go b/backend/internal/service/model_pricing_resolver.go
index 67f2684c..55387809 100644
--- a/backend/internal/service/model_pricing_resolver.go
+++ b/backend/internal/service/model_pricing_resolver.go
@@ -19,6 +19,9 @@ type ResolvedPricing struct {
 	// 按次/图片模式：分层定价
 	RequestTiers []PricingInterval
 
+	// 按次/图片模式：默认价格（未命中层级时使用）
+	DefaultPerRequestPrice float64
+
 	// 来源标识
 	Source string // "channel", "litellm", "fallback"
 
@@ -136,6 +139,9 @@ func (r *ModelPricingResolver) applyTokenOverrides(chPricing *ChannelModelPricin
 // applyRequestTierOverrides 应用按次/图片模式的渠道覆盖
 func (r *ModelPricingResolver) applyRequestTierOverrides(chPricing *ChannelModelPricing, resolved *ResolvedPricing) {
 	resolved.RequestTiers = chPricing.Intervals
+	if chPricing.PerRequestPrice != nil {
+		resolved.DefaultPerRequestPrice = *chPricing.PerRequestPrice
+	}
 }
 
 // GetIntervalPricing 根据 context token 数获取区间定价。