feat: 完善使用记录端点可观测性与分布统计

将入站、上游与路径三类端点分布统一到使用记录页的一致化卡片交互中，并补齐端点元数据与统计链路，提升排障与流量分析效率。

backend/internal/service/account_usage_service.go

@@ -45,6 +45,8 @@ type UsageLogRepository interface {
 	GetDashboardStats(ctx context.Context) (*usagestats.DashboardStats, error)
 	GetUsageTrendWithFilters(ctx context.Context, startTime, endTime time.Time, granularity string, userID, apiKeyID, accountID, groupID int64, model string, requestType *int16, stream *bool, billingType *int8) ([]usagestats.TrendDataPoint, error)
 	GetModelStatsWithFilters(ctx context.Context, startTime, endTime time.Time, userID, apiKeyID, accountID, groupID int64, requestType *int16, stream *bool, billingType *int8) ([]usagestats.ModelStat, error)
+	GetEndpointStatsWithFilters(ctx context.Context, startTime, endTime time.Time, userID, apiKeyID, accountID, groupID int64, model string, requestType *int16, stream *bool, billingType *int8) ([]usagestats.EndpointStat, error)
+	GetUpstreamEndpointStatsWithFilters(ctx context.Context, startTime, endTime time.Time, userID, apiKeyID, accountID, groupID int64, model string, requestType *int16, stream *bool, billingType *int8) ([]usagestats.EndpointStat, error)
 	GetGroupStatsWithFilters(ctx context.Context, startTime, endTime time.Time, userID, apiKeyID, accountID, groupID int64, requestType *int16, stream *bool, billingType *int8) ([]usagestats.GroupStat, error)
 	GetAPIKeyUsageTrend(ctx context.Context, startTime, endTime time.Time, granularity string, limit int) ([]usagestats.APIKeyUsageTrendPoint, error)
 	GetUserUsageTrend(ctx context.Context, startTime, endTime time.Time, granularity string, limit int) ([]usagestats.UserUsageTrendPoint, error)

backend/internal/service/openai_gateway_record_usage_test.go

@@ -226,6 +226,41 @@ func TestOpenAIGatewayServiceRecordUsage_UsesUserSpecificGroupRate(t *testing.T)
 	require.Equal(t, 1, userRepo.deductCalls)
 }
 
+func TestOpenAIGatewayServiceRecordUsage_IncludesEndpointMetadata(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{inserted: true}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	rateRepo := &openAIUserGroupRateRepoStub{}
+	svc := newOpenAIRecordUsageServiceForTest(usageRepo, userRepo, subRepo, rateRepo)
+
+	err := svc.RecordUsage(context.Background(), &OpenAIRecordUsageInput{
+		Result: &OpenAIForwardResult{
+			RequestID: "resp_endpoint_metadata",
+			Usage: OpenAIUsage{
+				InputTokens:  8,
+				OutputTokens: 2,
+			},
+			Model:    "gpt-5.1",
+			Duration: time.Second,
+		},
+		APIKey: &APIKey{
+			ID:    1002,
+			Group: &Group{RateMultiplier: 1},
+		},
+		User:             &User{ID: 2002},
+		Account:          &Account{ID: 3002},
+		InboundEndpoint:  " /v1/chat/completions ",
+		UpstreamEndpoint: " /v1/responses ",
+	})
+
+	require.NoError(t, err)
+	require.NotNil(t, usageRepo.lastLog)
+	require.NotNil(t, usageRepo.lastLog.InboundEndpoint)
+	require.Equal(t, "/v1/chat/completions", *usageRepo.lastLog.InboundEndpoint)
+	require.NotNil(t, usageRepo.lastLog.UpstreamEndpoint)
+	require.Equal(t, "/v1/responses", *usageRepo.lastLog.UpstreamEndpoint)
+}
+
 func TestOpenAIGatewayServiceRecordUsage_FallsBackToGroupDefaultRateOnResolverError(t *testing.T) {
 	groupID := int64(12)
 	groupRate := 1.6

backend/internal/service/openai_gateway_service.go

@@ -4028,6 +4028,8 @@ type OpenAIRecordUsageInput struct {
 	User               *User
 	Account            *Account
 	Subscription       *UserSubscription
+	InboundEndpoint    string
+	UpstreamEndpoint   string
 	UserAgent          string // 请求的 User-Agent
 	IPAddress          string // 请求的客户端 IP 地址
 	RequestPayloadHash string
@@ -4106,6 +4108,8 @@ func (s *OpenAIGatewayService) RecordUsage(ctx context.Context, input *OpenAIRec
 		Model:                 billingModel,
 		ServiceTier:           result.ServiceTier,
 		ReasoningEffort:       result.ReasoningEffort,
+		InboundEndpoint:       optionalTrimmedStringPtr(input.InboundEndpoint),
+		UpstreamEndpoint:      optionalTrimmedStringPtr(input.UpstreamEndpoint),
 		InputTokens:           actualInputTokens,
 		OutputTokens:          result.Usage.OutputTokens,
 		CacheCreationTokens:   result.Usage.CacheCreationInputTokens,
@@ -4125,7 +4129,6 @@ func (s *OpenAIGatewayService) RecordUsage(ctx context.Context, input *OpenAIRec
 		FirstTokenMs:          result.FirstTokenMs,
 		CreatedAt:             time.Now(),
 	}
-
 	// 添加 UserAgent
 	if input.UserAgent != "" {
 		usageLog.UserAgent = &input.UserAgent
@@ -4668,3 +4671,11 @@ func normalizeOpenAIReasoningEffort(raw string) string {
 		return ""
 	}
 }
+
+func optionalTrimmedStringPtr(raw string) *string {
+	trimmed := strings.TrimSpace(raw)
+	if trimmed == "" {
+		return nil
+	}
+	return &trimmed
+}

backend/internal/service/usage_log.go

@@ -103,6 +103,10 @@ type UsageLog struct {
 	// ReasoningEffort is the request's reasoning effort level (OpenAI Responses API),
 	// e.g. "low" / "medium" / "high" / "xhigh". Nil means not provided / not applicable.
 	ReasoningEffort *string
+	// InboundEndpoint is the client-facing API endpoint path, e.g. /v1/chat/completions.
+	InboundEndpoint *string
+	// UpstreamEndpoint is the normalized upstream endpoint path, e.g. /v1/responses.
+	UpstreamEndpoint *string
 
 	GroupID        *int64
 	SubscriptionID *int64