fix(billing): 修复复审发现的三处按次计费问题

- HIGH: GetByKeyForAuth 的 WithGroup 显式 Select 补 web_search_price_per_call 列，
  否则 auth 快照里分组覆盖价恒为 nil，覆盖价/免费配置在实际计费中静默失效
- MEDIUM: 按次搜索倍率改用不含高峰因子的基础倍率（与 image/video 按次不变式
  及分组表单价格预览承诺一致），calculateOpenAIRecordUsageCost 新增独立倍率参数
- LOW: 计费门槛从 <400 收紧为严格 2xx，1xx/3xx 透传不计费

backend/internal/repository/api_key_repo.go

@@ -190,6 +190,7 @@ func (r *apiKeyRepository) GetByKeyForAuth(ctx context.Context, key string) (*se
 				group.FieldVideoPrice480p,
 				group.FieldVideoPrice720p,
 				group.FieldVideoPrice1080p,
+				group.FieldWebSearchPricePerCall,
 				group.FieldClaudeCodeOnly,
 				group.FieldFallbackGroupID,
 				group.FieldFallbackGroupIDOnInvalidRequest,

backend/internal/service/openai_alpha_search.go

@@ -89,8 +89,8 @@ func (s *OpenAIGatewayService) ForwardAlphaSearch(ctx context.Context, c *gin.Co
 		contentType = "application/json"
 	}
 	c.Data(resp.StatusCode, contentType, respBody)
-	if resp.StatusCode >= http.StatusBadRequest {
-		// 上游错误已原样透传给客户端：不是一次成功的搜索，不计费。
+	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
+		// 非 2xx（错误/重定向）已原样透传给客户端：不是一次成功的搜索，不计费。
 		return nil, nil
 	}
 	return &OpenAIForwardResult{

backend/internal/service/openai_alpha_search_billing_test.go

@@ -46,10 +46,11 @@ func TestCalculateOpenAIRecordUsageCostWebSearchPerCall(t *testing.T) {
 	svc := &OpenAIGatewayService{billingService: &BillingService{}}
 	groupID := int64(11)
 
-	// 分组未配置单价：默认 0.01，倍率 2.0
+	// 分组未配置单价：默认 0.01。按次搜索使用不含高峰因子的基础倍率（第 4 个倍率参数 2.0），
+	// 即使 token 倍率（含高峰，3.0）更高也不采用。
 	apiKey := &APIKey{ID: 1, GroupID: &groupID, Group: &Group{ID: groupID, Platform: PlatformOpenAI}}
 	result := &OpenAIForwardResult{Model: "gpt-5.6-sol", UpstreamModel: "gpt-5.6-sol", WebSearchCalls: 1}
-	cost, err := svc.calculateOpenAIRecordUsageCost(context.Background(), result, apiKey, []string{"gpt-5.6-sol"}, 2.0, 1.0, 1.0, UsageTokens{}, "")
+	cost, err := svc.calculateOpenAIRecordUsageCost(context.Background(), result, apiKey, []string{"gpt-5.6-sol"}, 3.0, 1.0, 1.0, 2.0, UsageTokens{}, "")
 	require.NoError(t, err)
 	require.Equal(t, string(BillingModePerRequest), cost.BillingMode)
 	require.InDelta(t, 0.01, cost.TotalCost, 1e-12)
@@ -57,7 +58,7 @@ func TestCalculateOpenAIRecordUsageCostWebSearchPerCall(t *testing.T) {
 
 	// 分组配置单价 0.005
 	apiKey.Group.WebSearchPricePerCall = float64Ptr(0.005)
-	cost, err = svc.calculateOpenAIRecordUsageCost(context.Background(), result, apiKey, []string{"gpt-5.6-sol"}, 1.0, 1.0, 1.0, UsageTokens{}, "")
+	cost, err = svc.calculateOpenAIRecordUsageCost(context.Background(), result, apiKey, []string{"gpt-5.6-sol"}, 1.0, 1.0, 1.0, 1.0, UsageTokens{}, "")
 	require.NoError(t, err)
 	require.InDelta(t, 0.005, cost.TotalCost, 1e-12)
 	require.InDelta(t, 0.005, cost.ActualCost, 1e-12)
@@ -65,7 +66,7 @@ func TestCalculateOpenAIRecordUsageCostWebSearchPerCall(t *testing.T) {
 	// WebSearchCalls = 0 时不得走按次分支（无定价数据会返回 pricing 错误，
 	// 证明回落到了 token 路径而不是被按次分支吞掉）。
 	result.WebSearchCalls = 0
-	_, err = svc.calculateOpenAIRecordUsageCost(context.Background(), result, apiKey, []string{"gpt-5.6-sol"}, 1.0, 1.0, 1.0, UsageTokens{InputTokens: 10}, "")
+	_, err = svc.calculateOpenAIRecordUsageCost(context.Background(), result, apiKey, []string{"gpt-5.6-sol"}, 1.0, 1.0, 1.0, 1.0, UsageTokens{InputTokens: 10}, "")
 	require.Error(t, err)
 }
 

backend/internal/service/openai_gateway_usage.go

@@ -178,7 +178,7 @@ func (s *OpenAIGatewayService) RecordUsage(ctx context.Context, input *OpenAIRec
 	if result.ServiceTier != nil {
 		serviceTier = strings.TrimSpace(*result.ServiceTier)
 	}
-	cost, err = s.calculateOpenAIRecordUsageCost(ctx, result, apiKey, billingModels, multiplier, imageMultiplier, videoMultiplier, tokens, serviceTier)
+	cost, err = s.calculateOpenAIRecordUsageCost(ctx, result, apiKey, billingModels, multiplier, imageMultiplier, videoMultiplier, baseMultiplier, tokens, serviceTier)
 	if err != nil {
 		if !isUsagePricingUnavailableError(err) {
 			return err
@@ -363,14 +363,17 @@ func (s *OpenAIGatewayService) calculateOpenAIRecordUsageCost(
 	multiplier float64,
 	imageMultiplier float64,
 	videoMultiplier float64,
+	webSearchMultiplier float64,
 	tokens UsageTokens,
 	serviceTier string,
 ) (*CostBreakdown, error) {
 	billingModel := firstUsageBillingModel(billingModels)
 	if result != nil && result.WebSearchCalls > 0 {
-		// Codex alpha/search 网页搜索按次计费：上游不返回 usage/token 字段，
-		// 单价取分组覆盖价（nil 时默认 0.01 = 官方 $10/1000 次），倍率与 token 口径一致。
-		return s.billingService.CalculateWebSearchCost(result.WebSearchCalls, webSearchPricePerCallFromAPIKey(apiKey), multiplier), nil
+		// Codex alpha/search 网页搜索按次计费：上游不返回 usage/token 字段，单价只取
+		// 分组覆盖价（nil 时默认 0.01 = 官方 $10/1000 次），不参与渠道级模型定价。
+		// 倍率与 image/video 按次口径一致：使用不含高峰因子的基础倍率
+		//（用户专属 > 分组 rate_multiplier > 系统默认），与分组表单的价格预览承诺一致。
+		return s.billingService.CalculateWebSearchCost(result.WebSearchCalls, webSearchPricePerCallFromAPIKey(apiKey), webSearchMultiplier), nil
 	}
 	if isGrokVideoUsageResult(result, billingModels) {
 		if resolved := s.resolveOpenAIChannelPricing(ctx, billingModel, apiKey); resolved == nil || resolved.Mode != BillingModeToken {