fix(channel): use upstream model for account stats pricing and remove channel pricing fallback

- resolveAccountStatsCost now uses the final upstream model (after
  account-level mapping) to match custom pricing rules, fixing the
  issue where requested model (e.g. claude-sonnet-4-5) didn't match
  rules configured for upstream model (e.g. claude-opus-4-6)
- Remove tryChannelPricing fallback — only custom rules are applied,
  unmatched requests use default formula (total_cost × rate)
- Remove unused billingService and serviceTier parameters
- Update description: "启用后将支持自定义账号统计的模型价格"

backend/internal/service/account_stats_pricing.go

@@ -8,23 +8,18 @@ import (
 
 // resolveAccountStatsCost 计算账号统计定价费用。
 // 返回 nil 表示不覆盖，使用默认公式（total_cost × account_rate_multiplier）。
-//
-// 匹配优先级（先命中为准）：
-//  1. 自定义规则（AccountStatsPricingRules，按数组顺序遍历）
-//  2. 渠道已有的模型定价（ApplyPricingToAccountStats 开启时）
-//  3. nil → 走默认公式
+// 仅匹配自定义规则（AccountStatsPricingRules），按数组顺序先命中为准。
+// upstreamModel 是最终发往上游的模型 ID，用于匹配自定义规则中的模型定价。
 func resolveAccountStatsCost(
 	ctx context.Context,
 	channelService *ChannelService,
-	billingService *BillingService,
 	accountID int64,
 	groupID int64,
-	billingModel string,
+	upstreamModel string,
 	tokens UsageTokens,
 	requestCount int,
-	serviceTier string,
 ) *float64 {
-	if channelService == nil || billingService == nil {
+	if channelService == nil || upstreamModel == "" {
 		return nil
 	}
 	channel, err := channelService.GetChannelForGroup(ctx, groupID)
@@ -33,22 +28,15 @@ func resolveAccountStatsCost(
 	}
 
 	platform := channelService.GetGroupPlatform(ctx, groupID)
-	modelLower := strings.ToLower(billingModel)
-
-	// 优先级 1：自定义规则
-	if cost := tryCustomRules(channel, accountID, groupID, platform, modelLower, tokens, requestCount); cost != nil {
-		return cost
-	}
-
-	// 优先级 2：渠道已有模型定价
-	return tryChannelPricing(ctx, channelService, groupID, billingModel, tokens, requestCount)
+	return tryCustomRules(channel, accountID, groupID, platform, upstreamModel, tokens, requestCount)
 }
 
 // tryCustomRules 遍历自定义规则，按数组顺序先命中为准。
 func tryCustomRules(
 	channel *Channel, accountID, groupID int64,
-	platform, modelLower string, tokens UsageTokens, requestCount int,
+	platform, model string, tokens UsageTokens, requestCount int,
 ) *float64 {
+	modelLower := strings.ToLower(model)
 	for _, rule := range channel.AccountStatsPricingRules {
 		if !matchAccountStatsRule(&rule, accountID, groupID) {
 			continue
@@ -62,18 +50,6 @@ func tryCustomRules(
 	return nil
 }
 
-// tryChannelPricing 使用渠道已有的模型定价计算账号统计费用。
-func tryChannelPricing(
-	ctx context.Context, channelService *ChannelService,
-	groupID int64, billingModel string, tokens UsageTokens, requestCount int,
-) *float64 {
-	pricing := channelService.GetChannelModelPricing(ctx, groupID, billingModel)
-	if pricing == nil {
-		return nil
-	}
-	return calculateStatsCost(pricing, tokens, requestCount)
-}
-
 // matchAccountStatsRule 检查规则是否匹配指定的 accountID 和 groupID。
 // 匹配条件：accountID ∈ rule.AccountIDs 或 groupID ∈ rule.GroupIDs。
 // 如果规则的 AccountIDs 和 GroupIDs 都为空，视为不匹配。

backend/internal/service/gateway_service.go

@@ -7581,11 +7581,15 @@ func (s *GatewayService) recordUsageCore(ctx context.Context, input *recordUsage
 	usageLog := s.buildRecordUsageLog(ctx, input, result, apiKey, user, account, subscription,
 		requestedModel, multiplier, accountRateMultiplier, billingType, cacheTTLOverridden, cost, opts)
 
-	// 计算账号统计定价费用
+	// 计算账号统计定价费用（使用最终上游模型匹配自定义规则）
 	if apiKey.GroupID != nil {
+		upstreamModel := result.UpstreamModel
+		if upstreamModel == "" {
+			upstreamModel = result.Model
+		}
 		usageLog.AccountStatsCost = resolveAccountStatsCost(
-			ctx, s.channelService, s.billingService,
-			account.ID, *apiKey.GroupID, billingModel,
+			ctx, s.channelService,
+			account.ID, *apiKey.GroupID, upstreamModel,
 			UsageTokens{
 				InputTokens:         result.Usage.InputTokens,
 				OutputTokens:        result.Usage.OutputTokens,
@@ -7594,7 +7598,6 @@ func (s *GatewayService) recordUsageCore(ctx context.Context, input *recordUsage
 				ImageOutputTokens:   result.Usage.ImageOutputTokens,
 			},
 			1, // requestCount
-			"", // serviceTier: Anthropic 平台不使用 service tier
 		)
 	}
 

backend/internal/service/openai_gateway_service.go

@@ -4573,12 +4573,16 @@ func (s *OpenAIGatewayService) RecordUsage(ctx context.Context, input *OpenAIRec
 		usageLog.SubscriptionID = &subscription.ID
 	}
 
-	// 计算账号统计定价费用
+	// 计算账号统计定价费用（使用最终上游模型匹配自定义规则）
 	if apiKey.GroupID != nil {
+		statsModel := result.UpstreamModel
+		if statsModel == "" {
+			statsModel = result.Model
+		}
 		usageLog.AccountStatsCost = resolveAccountStatsCost(
-			ctx, s.channelService, s.billingService,
-			account.ID, *apiKey.GroupID, billingModel,
-			tokens, 1, serviceTier,
+			ctx, s.channelService,
+			account.ID, *apiKey.GroupID, statsModel,
+			tokens, 1,
 		)
 	}
 

frontend/src/i18n/locales/en.ts

@@ -1877,7 +1877,7 @@ export default {
         pricingEntry: 'Pricing Entry',
         noModels: 'No models added',
         applyPricingToAccountStats: 'Apply Pricing to Account Stats',
-        applyPricingToAccountStatsDesc: 'When enabled, account statistics cost will use channel model pricing. Account rate multiplier still applies.',
+        applyPricingToAccountStatsDesc: 'When enabled, custom account stats model pricing rules will be applied.',
         accountStatsPricingRules: 'Custom Account Stats Pricing Rules',
         addRule: 'Add Rule',
         noRulesConfigured: 'No custom rules configured. Channel model pricing above will be used.',

frontend/src/i18n/locales/zh.ts

@@ -1956,7 +1956,7 @@ export default {
         pricingEntry: '定价配置',
         noModels: '未添加模型',
         applyPricingToAccountStats: '应用模型定价到账号统计',
-        applyPricingToAccountStatsDesc: '启用后，账号统计费用将使用渠道模型定价计算。账号自身的统计倍率仍然生效。',
+        applyPricingToAccountStatsDesc: '启用后将支持自定义账号统计的模型价格',
         accountStatsPricingRules: '自定义账号统计定价规则',
         addRule: '添加规则',
         noRulesConfigured: '未配置自定义规则，将使用上方的模型定价。',