From 7dae055f2afe4921ddb84d6634afa07dba436b8a Mon Sep 17 00:00:00 2001
From: IanShaw <131567472+IanShaw027@users.noreply.github.com>
Date: Wed, 19 Aug 2026 05:28:35 -0700
Subject: [PATCH] =?UTF-8?q?=E8=AE=A1=E8=B4=B9=EF=BC=9A=E8=AF=86=E5=88=AB?=
 =?UTF-8?q?=E5=B9=B6=E8=AE=B0=E5=BD=95=20Anthropic=20Fast=20=E8=AF=B7?=
 =?UTF-8?q?=E6=B1=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../channel_pricing_multipliers_test.go       | 288 ++++++++++++++++++
 backend/internal/service/gateway_forward.go   |  56 +++-
 backend/internal/service/gateway_request.go   |   5 +
 .../internal/service/gateway_request_test.go  |  16 +
 backend/internal/service/gateway_service.go   |   3 +
 .../internal/service/gateway_usage_billing.go |   5 +-
 backend/internal/service/usage_log.go         |   3 +-
 backend/internal/service/usage_log_helpers.go |   7 +
 8 files changed, 380 insertions(+), 3 deletions(-)
 create mode 100644 backend/internal/service/channel_pricing_multipliers_test.go

diff --git a/backend/internal/service/channel_pricing_multipliers_test.go b/backend/internal/service/channel_pricing_multipliers_test.go
new file mode 100644
index 0000000000..5b38fddec2
--- /dev/null
+++ b/backend/internal/service/channel_pricing_multipliers_test.go
@@ -0,0 +1,288 @@
+package service
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func pricingMultiplier(value float64) *float64 { return &value }
+
+func TestConfiguredServiceTierMultiplier(t *testing.T) {
+	tests := []struct {
+		name        string
+		serviceTier string
+		pricing     *ModelPricing
+		want        float64
+	}{
+		{name: "gpt-5.5 fast", serviceTier: "fast", pricing: &ModelPricing{FastMultiplier: pricingMultiplier(2.5)}, want: 2.5},
+		{name: "priority alias", serviceTier: "priority", pricing: &ModelPricing{FastMultiplier: pricingMultiplier(2)}, want: 2},
+		{name: "flex configured", serviceTier: "flex", pricing: &ModelPricing{FlexMultiplier: pricingMultiplier(0.4)}, want: 0.4},
+		{name: "legacy fast default", serviceTier: "fast", pricing: &ModelPricing{}, want: 2},
+		{name: "legacy flex default", serviceTier: "flex", pricing: &ModelPricing{}, want: 0.5},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			require.InDelta(t, tt.want, configuredServiceTierMultiplier(tt.serviceTier, tt.pricing), 1e-12)
+		})
+	}
+}
+
+func TestConfiguredServiceTierMultiplierAppliesToEveryTokenComponent(t *testing.T) {
+	pricing := &ModelPricing{
+		InputPricePerToken:         5e-6,
+		OutputPricePerToken:        30e-6,
+		CacheCreationPricePerToken: 6.25e-6,
+		CacheReadPricePerToken:     0.5e-6,
+		FastMultiplier:             pricingMultiplier(2.5),
+		FlexMultiplier:             pricingMultiplier(0.5),
+	}
+	tokens := UsageTokens{
+		InputTokens:         1_000_000,
+		OutputTokens:        1_000_000,
+		CacheCreationTokens: 1_000_000,
+		CacheReadTokens:     1_000_000,
+	}
+	service := &BillingService{}
+
+	fast := service.computeTokenBreakdown(pricing, tokens, 1, "fast", false)
+	require.InDelta(t, 12.5, fast.InputCost, 1e-12)
+	require.InDelta(t, 75, fast.OutputCost, 1e-12)
+	require.InDelta(t, 15.625, fast.CacheCreationCost, 1e-12)
+	require.InDelta(t, 1.25, fast.CacheReadCost, 1e-12)
+
+	flex := service.computeTokenBreakdown(pricing, tokens, 1, "flex", false)
+	require.InDelta(t, 2.5, flex.InputCost, 1e-12)
+	require.InDelta(t, 15, flex.OutputCost, 1e-12)
+	require.InDelta(t, 3.125, flex.CacheCreationCost, 1e-12)
+	require.InDelta(t, 0.25, flex.CacheReadCost, 1e-12)
+}
+
+func TestChannelOverridePreservesCatalogFastRatioByDefault(t *testing.T) {
+	pricing := &ModelPricing{
+		InputPricePerToken:          2,
+		InputPricePerTokenPriority:  4,
+		OutputPricePerToken:         6,
+		OutputPricePerTokenPriority: 12,
+	}
+	applyChannelTokenPriceOverrides(pricing, &ChannelModelPricing{
+		InputPrice:  pricingMultiplier(3),
+		OutputPrice: pricingMultiplier(9),
+	})
+
+	require.InDelta(t, 3, pricing.InputPricePerToken, 1e-12)
+	require.InDelta(t, 6, pricing.InputPricePerTokenPriority, 1e-12)
+	require.InDelta(t, 9, pricing.OutputPricePerToken, 1e-12)
+	require.InDelta(t, 18, pricing.OutputPricePerTokenPriority, 1e-12)
+}
+
+func TestAnthropicFastUsesDefaultMultiplierWithoutCatalogTier(t *testing.T) {
+	pricing := &ModelPricing{InputPricePerToken: 5e-6, OutputPricePerToken: 25e-6}
+	cost := (&BillingService{}).computeTokenBreakdown(pricing, UsageTokens{
+		InputTokens: 1_000_000, OutputTokens: 1_000_000,
+	}, 1, "fast", false)
+
+	require.InDelta(t, 10, cost.InputCost, 1e-12)
+	require.InDelta(t, 50, cost.OutputCost, 1e-12)
+}
+
+func TestBuiltInModelFastDefaults(t *testing.T) {
+	service := &BillingService{fallbackPrices: make(map[string]*ModelPricing)}
+	service.initFallbackPricing()
+
+	for _, tt := range []struct {
+		model string
+		want  float64
+	}{
+		{model: "gpt-5.5", want: 2.5},
+		{model: "claude-opus-4.8", want: 2},
+		{model: "claude-opus-5", want: 2},
+	} {
+		pricing := service.fallbackPrices[tt.model]
+		require.NotNil(t, pricing)
+		require.InDelta(t, tt.want, pricing.InputPricePerTokenPriority/pricing.InputPricePerToken, 1e-12)
+		require.InDelta(t, tt.want, pricing.OutputPricePerTokenPriority/pricing.OutputPricePerToken, 1e-12)
+	}
+}
+
+func TestIntervalMultipliersApplyToChannelBase(t *testing.T) {
+	base := &ModelPricing{
+		InputPricePerToken:         5,
+		OutputPricePerToken:        30,
+		CacheCreationPricePerToken: 6.25,
+		CacheCreation5mPrice:       6.25,
+		CacheCreation1hPrice:       6.25,
+		CacheReadPricePerToken:     0.5,
+		FastMultiplier:             pricingMultiplier(2),
+		FlexMultiplier:             pricingMultiplier(0.5),
+	}
+	resolved := &ResolvedPricing{
+		BasePricing: base,
+		Intervals: []PricingInterval{{
+			MinTokens:            272000,
+			InputMultiplier:      pricingMultiplier(2),
+			OutputMultiplier:     pricingMultiplier(1.5),
+			CacheWriteMultiplier: pricingMultiplier(2),
+			CacheReadMultiplier:  pricingMultiplier(2),
+		}},
+	}
+
+	pricing := (&ModelPricingResolver{}).GetIntervalPricing(resolved, 272001)
+	require.InDelta(t, 10, pricing.InputPricePerToken, 1e-12)
+	require.InDelta(t, 45, pricing.OutputPricePerToken, 1e-12)
+	require.InDelta(t, 12.5, pricing.CacheCreationPricePerToken, 1e-12)
+	require.InDelta(t, 1, pricing.CacheReadPricePerToken, 1e-12)
+	require.Same(t, base, (&ModelPricingResolver{}).GetIntervalPricing(resolved, 272000))
+}
+
+func TestIntervalExplicitPriceTakesPrecedenceOverMultiplier(t *testing.T) {
+	pricing := intervalToModelPricing(&PricingInterval{
+		InputPrice:      pricingMultiplier(7),
+		InputMultiplier: pricingMultiplier(2),
+	}, &ModelPricing{InputPricePerToken: 5}, nil)
+
+	require.InDelta(t, 7, pricing.InputPricePerToken, 1e-12)
+}
+
+func TestIntervalPricePreservesDefaultFastRatio(t *testing.T) {
+	pricing := intervalToModelPricing(&PricingInterval{
+		InputPrice: pricingMultiplier(7),
+	}, &ModelPricing{
+		InputPricePerToken:         5,
+		InputPricePerTokenPriority: 10,
+	}, nil)
+
+	require.InDelta(t, 7, pricing.InputPricePerToken, 1e-12)
+	require.InDelta(t, 14, pricing.InputPricePerTokenPriority, 1e-12)
+}
+
+func TestAnthropicSpeedServiceTier(t *testing.T) {
+	account := &Account{Platform: PlatformAnthropic}
+
+	for _, model := range []string{"claude-opus-5", "claude-opus-4-8", "claude-opus-4.8"} {
+		tier := anthropicSpeedServiceTier(account, "fast", model)
+		require.NotNil(t, tier, "model %s should bill as fast", model)
+		require.Equal(t, "fast", *tier)
+	}
+
+	require.Nil(t, anthropicSpeedServiceTier(&Account{Platform: PlatformOpenAI}, "fast", "claude-opus-5"))
+	require.Nil(t, anthropicSpeedServiceTier(account, "standard", "claude-opus-5"))
+}
+
+// fast mode 不存在于这些模型/承载上，即便客户端传了 speed=fast 也不能计 2x。
+func TestAnthropicSpeedServiceTierRejectsUnsupportedTargets(t *testing.T) {
+	account := &Account{Platform: PlatformAnthropic}
+
+	for _, model := range []string{
+		"claude-opus-4-7",  // fast mode 已被移除
+		"claude-opus-4-6",  //
+		"claude-opus-4-5",  // 不能被 "opus-5" 规则误判
+		"claude-sonnet-5",  // 非 Opus
+		"claude-haiku-4-5", //
+		"",                 //
+	} {
+		require.Nil(t, anthropicSpeedServiceTier(account, "fast", model),
+			"model %q must not bill as fast", model)
+	}
+
+	bedrock := &Account{Platform: PlatformAnthropic, Type: AccountTypeBedrock}
+	require.Nil(t, anthropicSpeedServiceTier(bedrock, "fast", "claude-opus-5"))
+}
+
+func TestAnthropicSpeedModelPrefersMappedUpstreamModel(t *testing.T) {
+	parsed := &ParsedRequest{Model: "claude-opus-5"}
+	require.Equal(t, "claude-opus-4-7", anthropicSpeedModel(parsed, &ForwardResult{
+		UpstreamModel: "claude-opus-4-7",
+	}))
+	require.Equal(t, "claude-opus-5", anthropicSpeedModel(parsed, &ForwardResult{}))
+}
+
+func TestMultiplierOnlyIntervalIsValid(t *testing.T) {
+	require.NoError(t, ValidateIntervals([]PricingInterval{{
+		MinTokens:       199999,
+		InputMultiplier: pricingMultiplier(2),
+	}}, BillingModeToken))
+	require.NoError(t, checkIntervalsHavePrices(ChannelModelPricing{
+		Models: []string{"grok-4.6"},
+		Intervals: []PricingInterval{{
+			MinTokens:       199999,
+			InputMultiplier: pricingMultiplier(2),
+		}},
+	}))
+}
+
+func TestChannelMultipliersMustBePositive(t *testing.T) {
+	zero := 0.0
+	require.Error(t, checkPricesNotNegative(ChannelModelPricing{FastMultiplier: &zero}))
+	require.Error(t, checkPricesNotNegative(ChannelModelPricing{FlexMultiplier: &zero}))
+	require.Error(t, ValidateIntervals([]PricingInterval{{
+		MinTokens:       100,
+		InputMultiplier: &zero,
+	}}, BillingModeToken))
+}
+
+func TestCalculateTokenCostContextTierEnablement(t *testing.T) {
+	base := &ModelPricing{InputPricePerToken: 1e-6}
+	resolved := &ResolvedPricing{
+		BasePricing: base,
+		Intervals: []PricingInterval{{
+			MinTokens:       100,
+			InputMultiplier: pricingMultiplier(2),
+		}},
+	}
+	resolver := &ModelPricingResolver{}
+	service := &BillingService{}
+	tokens := UsageTokens{InputTokens: 200}
+
+	t.Run("group disabled uses base tier", func(t *testing.T) {
+		resolved.longContextPricingEnabled = false
+		cost, err := service.calculateTokenCost(resolved, CostInput{
+			Model: "custom", Tokens: tokens, RateMultiplier: 1, Resolver: resolver,
+		})
+		require.NoError(t, err)
+		require.InDelta(t, 200e-6, cost.TotalCost, 1e-12)
+	})
+
+	t.Run("group enabled uses interval", func(t *testing.T) {
+		resolved.longContextPricingEnabled = true
+		accountDisabled := false
+		cost, err := service.calculateTokenCost(resolved, CostInput{
+			Model: "custom", Tokens: tokens, RateMultiplier: 1, Resolver: resolver,
+			LongContextBillingEnabled: &accountDisabled,
+		})
+		require.NoError(t, err)
+		require.InDelta(t, 400e-6, cost.TotalCost, 1e-12)
+	})
+
+	t.Run("account enabled overrides disabled group", func(t *testing.T) {
+		resolved.longContextPricingEnabled = false
+		accountEnabled := true
+		cost, err := service.calculateTokenCost(resolved, CostInput{
+			Model: "custom", Tokens: tokens, RateMultiplier: 1, Resolver: resolver,
+			LongContextBillingEnabled: &accountEnabled,
+		})
+		require.NoError(t, err)
+		require.InDelta(t, 400e-6, cost.TotalCost, 1e-12)
+	})
+}
+
+func TestCalculateTokenCostCombinesIntervalAndFastMultiplier(t *testing.T) {
+	resolved := &ResolvedPricing{
+		BasePricing: &ModelPricing{
+			InputPricePerToken: 1e-6,
+			FastMultiplier:     pricingMultiplier(2.5),
+		},
+		Intervals: []PricingInterval{{
+			MinTokens:       100,
+			InputMultiplier: pricingMultiplier(2),
+		}},
+		longContextPricingEnabled: true,
+	}
+	cost, err := (&BillingService{}).calculateTokenCost(resolved, CostInput{
+		Model: "custom", Tokens: UsageTokens{InputTokens: 200}, RateMultiplier: 1,
+		ServiceTier: "fast", Resolver: &ModelPricingResolver{},
+	})
+	require.NoError(t, err)
+	require.InDelta(t, 1e-3, cost.TotalCost, 1e-12)
+}
diff --git a/backend/internal/service/gateway_forward.go b/backend/internal/service/gateway_forward.go
index 863e4d2e83..d8a105c7d8 100644
--- a/backend/internal/service/gateway_forward.go
+++ b/backend/internal/service/gateway_forward.go
@@ -88,11 +88,21 @@ func sleepWithContext(ctx context.Context, d time.Duration) error {
 }
 
 // Forward 转发请求到Claude API
-func (s *GatewayService) Forward(ctx context.Context, c *gin.Context, account *Account, parsed *ParsedRequest) (*ForwardResult, error) {
+func (s *GatewayService) Forward(ctx context.Context, c *gin.Context, account *Account, parsed *ParsedRequest) (result *ForwardResult, err error) {
 	startTime := time.Now()
 	if parsed == nil {
 		return nil, fmt.Errorf("parse request: empty request")
 	}
+	// Anthropic Fast is requested with speed=fast rather than OpenAI's
+	// service_tier. Attach it at this shared boundary so passthrough, OAuth and
+	// partial-stream results all use the same billing and usage-log path.
+	defer func() {
+		if result != nil {
+			if tier := anthropicSpeedServiceTier(account, parsed.Speed, anthropicSpeedModel(parsed, result)); tier != nil {
+				result.ServiceTier = tier
+			}
+		}
+	}()
 	beginUpstreamResponseModelObservation(c)
 
 	// Web Search 模拟：纯 web_search 请求时，直接调用搜索 API 构造响应
@@ -885,6 +895,50 @@ func (s *GatewayService) Forward(ctx context.Context, c *gin.Context, account *A
 	}, nil
 }
 
+func anthropicSpeedModel(parsed *ParsedRequest, result *ForwardResult) string {
+	if result != nil {
+		if upstreamModel := strings.TrimSpace(result.UpstreamModel); upstreamModel != "" {
+			return upstreamModel
+		}
+	}
+	if parsed == nil {
+		return ""
+	}
+	return parsed.Model
+}
+
+// anthropicSpeedServiceTier 把 Anthropic 的 speed=fast 归一成可计费的 "fast" tier。
+//
+// Fast mode 目前只在 Claude Opus 5 / Opus 4.8 上存在，且不支持 Bedrock 等第三方
+// 承载（Opus 4.7 的 fast mode 已被移除，传 speed=fast 会直接报错）。这里按模型和
+// 平台收紧，避免上游根本没跑 fast 时仍然按 2x 计费——宁可漏收也不能多收。
+//
+// 注：判据是请求参数而非响应里的 usage.speed。等 usage 解析链路统一暴露该字段后，
+// 应改为以响应为准。
+func anthropicSpeedServiceTier(account *Account, speed, model string) *string {
+	if account == nil || account.Platform != PlatformAnthropic || speed != "fast" {
+		return nil
+	}
+	if account.IsBedrock() || !modelSupportsAnthropicFastMode(model) {
+		return nil
+	}
+	tier := "fast"
+	return &tier
+}
+
+// modelSupportsAnthropicFastMode 判断模型是否属于支持 fast mode 的 Opus 5 / Opus 4.8。
+func modelSupportsAnthropicFastMode(model string) bool {
+	modelLower := strings.ToLower(strings.TrimSpace(model))
+	if !strings.Contains(modelLower, "opus") {
+		return false
+	}
+	// "opus-5" 必须先判：不能用裸 "5" 匹配，否则 claude-opus-4-5 会被误判。
+	if strings.Contains(modelLower, "opus-5") || strings.Contains(modelLower, "opus5") {
+		return true
+	}
+	return strings.Contains(modelLower, "4.8") || strings.Contains(modelLower, "4-8")
+}
+
 // ResolveChannelMapping 委托渠道服务解析模型映射
 func (s *GatewayService) ResolveChannelMapping(ctx context.Context, groupID int64, model string) ChannelMappingResult {
 	if s.channelService == nil {
diff --git a/backend/internal/service/gateway_request.go b/backend/internal/service/gateway_request.go
index 4ffd5ee8e9..111b807f2f 100644
--- a/backend/internal/service/gateway_request.go
+++ b/backend/internal/service/gateway_request.go
@@ -117,6 +117,7 @@ func clearGatewayRequestDerivedState(parsed *ParsedRequest) {
 	parsed.HasSystem = false
 	parsed.ThinkingEnabled = false
 	parsed.OutputEffort = ""
+	parsed.Speed = ""
 	parsed.MaxTokens = 0
 	parsed.systemRange = missingJSONRange()
 	parsed.messagesRange = missingJSONRange()
@@ -224,6 +225,9 @@ func parseGatewayRequestCurrentBody(parsed *ParsedRequest, protocol string) erro
 	parsed.ThinkingEnabled = thinkingType == "enabled" || thinkingType == "adaptive"
 
 	parsed.OutputEffort = strings.TrimSpace(gjson.Get(jsonStr, "output_config.effort").String())
+	if protocol == domain.PlatformAnthropic {
+		parsed.Speed = strings.ToLower(strings.TrimSpace(gjson.Get(jsonStr, "speed").String()))
+	}
 
 	maxTokensResult := gjson.Get(jsonStr, "max_tokens")
 	if maxTokensResult.Exists() && maxTokensResult.Type == gjson.Number {
@@ -282,6 +286,7 @@ type ParsedRequest struct {
 	HasSystem       bool            // 是否包含 system 字段（包含 null 也视为显式传入）
 	ThinkingEnabled bool            // 是否开启 thinking（部分平台会影响最终模型名）
 	OutputEffort    string          // output_config.effort（Claude API 的推理强度控制）
+	Speed           string          // Anthropic speed（当前可计费值为 "fast"）
 	MaxTokens       int             // max_tokens 值（用于探测请求拦截）
 	SessionContext  *SessionContext // 可选：请求上下文区分因子（nil 时行为不变）
 
diff --git a/backend/internal/service/gateway_request_test.go b/backend/internal/service/gateway_request_test.go
index d4e010a5e8..6074c02991 100644
--- a/backend/internal/service/gateway_request_test.go
+++ b/backend/internal/service/gateway_request_test.go
@@ -42,6 +42,22 @@ func TestParseGatewayRequest_ThinkingAdaptiveEnabled(t *testing.T) {
 	require.True(t, parsed.ThinkingEnabled)
 }
 
+func TestParseGatewayRequest_AnthropicFastSpeed(t *testing.T) {
+	parsed, err := ParseGatewayRequest(
+		NewRequestBodyRef([]byte(`{"model":"claude-opus-4-8","speed":" FAST "}`)),
+		domain.PlatformAnthropic,
+	)
+	require.NoError(t, err)
+	require.Equal(t, "fast", parsed.Speed)
+
+	nonAnthropic, err := ParseGatewayRequest(
+		NewRequestBodyRef([]byte(`{"model":"gpt-5.4","speed":"fast"}`)),
+		"responses",
+	)
+	require.NoError(t, err)
+	require.Empty(t, nonAnthropic.Speed)
+}
+
 func TestParseGatewayRequest_MaxTokens(t *testing.T) {
 	body := []byte(`{"model":"claude-haiku-4-5","max_tokens":1}`)
 	parsed, err := ParseGatewayRequest(NewRequestBodyRef(body), "")
diff --git a/backend/internal/service/gateway_service.go b/backend/internal/service/gateway_service.go
index 2578d59b1d..20e7e5b9e6 100644
--- a/backend/internal/service/gateway_service.go
+++ b/backend/internal/service/gateway_service.go
@@ -619,6 +619,9 @@ type ForwardResult struct {
 	FirstTokenMs                  *int // 首字时间（流式请求）
 	ClientDisconnect              bool // 客户端是否在流式传输过程中断开
 	ReasoningEffort               *string
+	// ServiceTier records the billable request tier. OpenAI uses service_tier;
+	// Anthropic speed=fast is normalized to "fast".
+	ServiceTier *string
 
 	// 图片生成计费字段（图片生成模型使用）
 	ImageCount         int    // 生成的图片数量
diff --git a/backend/internal/service/gateway_usage_billing.go b/backend/internal/service/gateway_usage_billing.go
index c9671328be..e1fac3d6cf 100644
--- a/backend/internal/service/gateway_usage_billing.go
+++ b/backend/internal/service/gateway_usage_billing.go
@@ -1157,6 +1157,7 @@ func (s *GatewayService) calculateTokenCost(
 			RequestCount:   1,
 			RateMultiplier: multiplier,
 			PricingAt:      pricingAt,
+			ServiceTier:    optionalStringValue(result.ServiceTier),
 			Resolver:       s.resolver,
 			Resolved:       resolved,
 		})
@@ -1167,7 +1168,8 @@ func (s *GatewayService) calculateTokenCost(
 		gid := apiKey.Group.ID
 		cost, err = s.billingService.CalculateCostUnified(CostInput{
 			Ctx: ctx, Model: billingModel, GroupID: &gid, Group: apiKey.Group,
-			Tokens: tokens, RequestCount: 1, RateMultiplier: multiplier, PricingAt: pricingAt, Resolver: s.resolver,
+			Tokens: tokens, RequestCount: 1, RateMultiplier: multiplier, PricingAt: pricingAt,
+			ServiceTier: optionalStringValue(result.ServiceTier), Resolver: s.resolver,
 		})
 	} else {
 		cost, err = s.billingService.CalculateCost(billingModel, tokens, multiplier)
@@ -1219,6 +1221,7 @@ func (s *GatewayService) buildRecordUsageLog(
 		UpstreamModel:         optionalTrimmedStringPtr(result.UpstreamModel),
 		UpstreamResponseModel: optionalTrimmedStringPtr(result.UpstreamResponseModel),
 		UpstreamModelMismatch: upstreamModelMismatch(sentModel, result.UpstreamResponseModel),
+		ServiceTier:           result.ServiceTier,
 		ReasoningEffort:       result.ReasoningEffort,
 		InboundEndpoint:       optionalTrimmedStringPtr(input.InboundEndpoint),
 		UpstreamEndpoint:      optionalTrimmedStringPtr(input.UpstreamEndpoint),
diff --git a/backend/internal/service/usage_log.go b/backend/internal/service/usage_log.go
index 7a41555ece..b6dc2a9d0e 100644
--- a/backend/internal/service/usage_log.go
+++ b/backend/internal/service/usage_log.go
@@ -128,7 +128,8 @@ type UsageLog struct {
 	BillingTier *string
 	// BillingMode 计费模式：token/image
 	BillingMode *string
-	// ServiceTier records the OpenAI service tier used for billing, e.g. "priority" / "flex".
+	// ServiceTier records the billable request tier, e.g. OpenAI "priority" / "flex"
+	// or Anthropic "fast".
 	ServiceTier *string
 	// ReasoningEffort is the request's reasoning effort level.
 	// OpenAI: "low" / "medium" / "high" / "xhigh"; Claude: "low" / "medium" / "high" / "max".
diff --git a/backend/internal/service/usage_log_helpers.go b/backend/internal/service/usage_log_helpers.go
index b431b50aef..deb102e736 100644
--- a/backend/internal/service/usage_log_helpers.go
+++ b/backend/internal/service/usage_log_helpers.go
@@ -10,6 +10,13 @@ func optionalTrimmedStringPtr(raw string) *string {
 	return &trimmed
 }
 
+func optionalStringValue(value *string) string {
+	if value == nil {
+		return ""
+	}
+	return strings.TrimSpace(*value)
+}
+
 func forwardResultBillingModel(requestedModel, upstreamModel string) string {
 	if trimmed := strings.TrimSpace(requestedModel); trimmed != "" {
 		return trimmed