feat: decouple billing correctness from usage log batching

PR_REPORT_20260311_db_write_hotspots.md

@@ -0,0 +1,307 @@
+# PR Report: DB 写入热点与后台查询拥塞排查
+
+## 背景
+
+线上在高峰期出现了几类明显症状：
+
+- 管理后台仪表盘接口经常超时，`/api/v1/admin/dashboard/snapshot-v2` 一度达到 50s 以上
+- 管理后台充值接口 `/api/v1/admin/users/:id/balance` 出现 15s 以上超时
+- 登录态刷新、扣费、错误记录在高峰期出现大量 `context deadline exceeded`
+- PostgreSQL 曾出现连接打满，后续回退连接池后，主问题转为 WAL/刷盘拥塞
+
+本报告基于 `/home/ius/sub2api` 当前源码，目标是给出一份可直接拆成 PR 的修复方案。
+
+## 结论
+
+这次故障的主因不是单一“慢 SQL”，而是请求成功路径上的同步写库次数过多，叠加部分后台查询仍直接扫 `usage_logs`，最终把 PostgreSQL 的 WAL 刷盘、热点行更新和 outbox 重建链路一起放大。
+
+代码层面的核心问题有 6 个。
+
+### 1. 成功请求路径同步写库过多
+
+`backend/internal/service/gateway_service.go:6594` 的 `postUsageBilling` 在单次请求成功后，可能同步触发以下写操作：
+
+- `userRepo.DeductBalance`
+- `APIKeyService.UpdateQuotaUsed`
+- `APIKeyService.UpdateRateLimitUsage`
+- `accountRepo.IncrementQuotaUsed`
+- `deferredService.ScheduleLastUsedUpdate`（这一项已经做了延迟批量，是正确方向）
+
+也就是说，一次成功请求不是 1 次落库，而是 3 到 5 次写入。
+
+这和线上看到的现象是吻合的：
+
+- `UPDATE accounts SET extra = ...`
+- `INSERT INTO usage_logs ...`
+- `INSERT INTO ops_error_logs ...`
+- `scheduler_outbox` backlog
+
+### 2. API Key 配额更新存在额外读写放大
+
+`backend/internal/service/api_key_service.go:815` 的 `UpdateQuotaUsed` 当前流程是：
+
+1. `IncrementQuotaUsed`
+2. `GetByID`
+3. 如超限再 `Update`
+
+对应仓储实现：
+
+- `backend/internal/repository/api_key_repo.go:441` 只做自增
+- 然后 service 再回表读取完整 API Key
+- 之后可能再整行更新状态
+
+这让“每次扣费后更新 API Key 配额”从 1 条 SQL 变成了最多 3 次数据库交互。
+
+### 3. `accounts.extra` 被当成高频热写字段使用
+
+两个最重的热点都落在 `accounts.extra`：
+
+- `backend/internal/repository/account_repo.go:1159` `UpdateExtra`
+- `backend/internal/repository/account_repo.go:1683` `IncrementQuotaUsed`
+
+问题有两个：
+
+1. 两者都会重写整块 JSONB，并更新 `updated_at`
+2. `UpdateExtra` 每次写完都会额外插入一条 `scheduler_outbox`
+
+尤其 `UpdateExtra` 现在被多处高频调用：
+
+- `backend/internal/service/openai_gateway_service.go:4039` 持久化 Codex rate-limit snapshot
+- `backend/internal/service/ratelimit_service.go:903` 持久化 OpenAI Codex snapshot
+- `backend/internal/service/ratelimit_service.go:1013` / `1025` 更新 session window utilization
+
+这类“监控/额度快照”并不会改变账号是否可调度，却仍然走了：
+
+- JSONB 更新
+- `updated_at`
+- `scheduler_outbox`
+
+这是明显的写放大。
+
+### 4. `scheduler_outbox` 设计偏向“每次状态变更都写一条”，高峰期会反压调度器
+
+`backend/internal/repository/scheduler_outbox_repo.go:79` 的 `enqueueSchedulerOutbox` 非常轻，但它被大量调用。
+
+例如：
+
+- `UpdateExtra` 每次都 enqueue `AccountChanged`
+- `BatchUpdateLastUsed` 也会 enqueue 一条 `AccountLastUsed`
+- 各类账号限流、过载、错误状态切换也都会 enqueue
+
+对应的 outbox worker 在：
+
+- `backend/internal/service/scheduler_snapshot_service.go:199`
+- `backend/internal/service/scheduler_snapshot_service.go:219`
+
+它会不断拉取 outbox，再触发 `GetByID`、`rebuildBucket`、`loadAccountsFromDB`。
+
+所以当高频写入导致 outbox 增长时，系统不仅多了写，还会反向带出更多读和缓存重建。
+
+### 5. 仪表盘只有一部分走了预聚合，`models/groups/users-trend` 仍然直接扫 `usage_logs`
+
+好消息是，`dashboard stats` 本身已经接了预聚合表：
+
+- `backend/internal/repository/usage_log_repo.go:306`
+- `backend/internal/repository/usage_log_repo.go:420`
+- 预聚合表定义在 `backend/migrations/034_usage_dashboard_aggregation_tables.sql:1`
+
+但后台慢的不是只有 stats。
+
+`snapshot-v2` 默认会同时拉：
+
+- stats
+- trend
+- model stats
+
+见：
+
+- `backend/internal/handler/admin/dashboard_snapshot_v2_handler.go:68`
+
+其中：
+
+- `GetUsageTrendWithFilters` 只有“无过滤、day/hour”时才走预聚合，见 `usage_log_repo.go:1657`
+- `GetModelStatsWithFilters` 直接扫 `usage_logs`，见 `usage_log_repo.go:1805`
+- `GetGroupStatsWithFilters` 直接扫 `usage_logs`，见 `usage_log_repo.go:1872`
+- `GetUserUsageTrend` 直接扫 `usage_logs`，见 `usage_log_repo.go:1101`
+- `GetAPIKeyUsageTrend` 直接扫 `usage_logs`，见 `usage_log_repo.go:1046`
+
+所以线上会出现：
+
+- stats 快
+- 但 `snapshot-v2` 仍然慢
+- `/admin/dashboard/users-trend` 单独也慢
+
+这和你线上看到的日志完全一致。
+
+### 6. 管理后台充值是“读用户 -> 整体更新用户 -> 插审计记录”
+
+`backend/internal/service/admin_service.go:694` 的 `UpdateUserBalance` 当前流程：
+
+1. `GetByID`
+2. 在内存里改 balance
+3. `userRepo.Update`
+4. `redeemCodeRepo.Create` 记录 admin 调账历史
+
+而 `userRepo.Update` 是整用户对象更新，并同步 allowed groups 事务处理：
+
+- `backend/internal/repository/user_repo.go:118`
+
+这个接口平时不一定重，但在数据库已经抖动时，会比一个原子 `UPDATE users SET balance = balance + $1` 更脆弱。
+
+## 额外观察
+
+### `ops_error_logs` 虽然已异步化，但单条写入仍然很重
+
+错误日志中间件已经做了队列削峰：
+
+- `backend/internal/handler/ops_error_logger.go:69`
+- `backend/internal/handler/ops_error_logger.go:106`
+
+这点方向是对的。
+
+但落库表本身很重：
+
+- `backend/internal/repository/ops_repo.go:23`
+- `backend/migrations/033_ops_monitoring_vnext.sql:69`
+- `backend/migrations/033_ops_monitoring_vnext.sql:470`
+
+`ops_error_logs` 不仅列很多，还带了多组 B-Tree 和 trigram 索引。高错误率时，即使改成异步，也还是会把 WAL 和 I/O 压上去。
+
+## 建议的 PR 拆分
+
+建议拆成 4 个 PR，不要在一个 PR 里同时改数据库模型、后台查询和管理接口。
+
+### PR 1: 收缩成功请求路径的同步写库次数
+
+目标：把一次成功请求的同步写次数从 3 到 5 次，尽量压到 1 到 2 次。
+
+建议改动：
+
+1. 把 `APIKeyService.UpdateQuotaUsed` 改为单 SQL
+   - 新增 repo 方法，例如 `IncrementQuotaUsedAndMaybeExhaust`
+   - 在 SQL 里同时完成 `quota_used += ?` 和 `status = quota_exhausted`
+   - 返回 `key/status/quota/quota_used` 最小字段，直接失效缓存
+   - 删掉当前的 `Increment -> GetByID -> Update`
+
+2. 把账号 quota 计数从 `accounts.extra` 拆出去
+   - 最理想：新增结构化列或独立 `account_quota_counters` 表
+   - 次优：至少把 `quota_used/quota_daily_used/quota_weekly_used` 从 JSONB 中剥离
+
+3. 对“纯监控型 extra 字段”禁止 enqueue outbox
+   - 例如 codex snapshot、session_window_utilization
+   - 这些字段不影响调度，不应该触发 `SchedulerOutboxEventAccountChanged`
+
+4. 复用现有 `DeferredService` 思路
+   - `last_used` 已经是批量刷盘，见 `deferred_service.go:41`
+   - 可继续扩展 `deferred quota snapshot flush`
+
+预期收益：
+
+- 直接减少 WAL 写入量
+- 降低 `accounts` 热点行锁竞争
+- 降低 outbox 增长速度
+
+### PR 2: 给 dashboard 补齐预聚合/缓存，避免继续扫 `usage_logs`
+
+目标：后台仪表盘接口不再直接扫描大表。
+
+建议改动：
+
+1. 为 `users-trend` / `api-keys-trend` 增加小时/天级预聚合表
+2. 为 `model stats` / `group stats` 增加日级聚合表
+3. `snapshot-v2` 增加分段缓存
+   - `stats`
+   - `trend`
+   - `models`
+   - `groups`
+   - `users_trend`
+   避免一个 section miss 导致整份 snapshot 重新扫库
+4. 可选：把 `include_model_stats` 默认值从 `true` 改成 `false`
+   - 至少让默认仪表盘先恢复可用，再按需加载重模块
+
+预期收益：
+
+- `snapshot-v2`
+- `/admin/dashboard/users-trend`
+- `/admin/dashboard/api-keys-trend`
+
+这几类接口会从“随数据量线性恶化”变成“近似固定成本”。
+
+### PR 3: 简化管理后台充值链路
+
+目标：管理充值/扣余额不再依赖整用户对象更新。
+
+建议改动：
+
+1. 新增 repo 原子方法
+   - `SetBalance(userID, amount)`
+   - `AddBalance(userID, delta)`
+   - `SubtractBalance(userID, delta)`
+
+2. `UpdateUserBalance` 改为：
+   - 先执行原子 SQL
+   - 再读一次最小必要字段返回
+   - 审计记录改为异步或降级写
+
+3. 审计记录建议改名或独立表
+   - 现在把后台调账记录塞进 `redeem_codes`，语义上不干净
+
+预期收益：
+
+- `/api/v1/admin/users/:id/balance` 在库抖时更稳
+- 失败面缩小，不再被 allowed groups 同步事务拖累
+
+### PR 4: 为重写路径增加“丢弃策略”和“熔断指标”
+
+目标：高峰期先保护主链路，不让非核心写入拖死数据库。
+
+建议改动：
+
+1. `ops_error_logs`
+   - 增加采样或分级开关
+   - 对重复 429/5xx 做聚合计数而不是逐条插入
+   - 对 request body / headers 存储加更严格开关
+
+2. `scheduler_outbox`
+   - 增加 coalesce/merge 机制
+   - 同一账号短时间内多次 `AccountChanged` 合并为一条
+
+3. 指标补齐
+   - outbox backlog
+   - ops error queue dropped
+   - deferred flush lag
+   - account extra write QPS
+
+## 推荐实施顺序
+
+1. 先做 PR 1
+   - 这是这次线上故障的主链路
+2. 再做 PR 2
+   - 解决后台仪表盘慢
+3. 再做 PR 3
+   - 解决后台充值接口脆弱
+4. 最后做 PR 4
+   - 做长期保护
+
+## 验证方案
+
+每个 PR 合并前都建议做同一组验证：
+
+1. 压测成功请求链路，记录单请求 SQL 次数
+2. 观测 PostgreSQL：
+   - `pg_stat_activity`
+   - `pg_stat_statements`
+   - `WALWrite` / `WalSync`
+   - 每分钟 WAL 增量
+3. 观测接口：
+   - `/api/v1/auth/refresh`
+   - `/api/v1/admin/dashboard/snapshot-v2`
+   - `/api/v1/admin/dashboard/users-trend`
+   - `/api/v1/admin/users/:id/balance`
+4. 观测队列：
+   - `ops_error_logs` queue length / dropped
+   - `scheduler_outbox` backlog
+
+## 可直接作为 PR 描述的摘要
+
+This PR reduces database write amplification on the request success path and removes several hot-path writes from `accounts.extra` + `scheduler_outbox`. It also prepares dashboard endpoints to rely on pre-aggregated data instead of scanning `usage_logs` under load. The goal is to keep admin dashboard, balance update, auth refresh, and billing-related paths stable under sustained 500+ RPS traffic.

backend/cmd/server/wire_gen.go

@@ -81,6 +81,7 @@ func initializeApplication(buildInfo handler.BuildInfo) (*Application, error) {
 	userHandler := handler.NewUserHandler(userService)
 	apiKeyHandler := handler.NewAPIKeyHandler(apiKeyService)
 	usageLogRepository := repository.NewUsageLogRepository(client, db)
+	usageBillingRepository := repository.NewUsageBillingRepository(client, db)
 	usageService := service.NewUsageService(usageLogRepository, userRepository, client, apiKeyAuthCacheInvalidator)
 	usageHandler := handler.NewUsageHandler(usageService, apiKeyService)
 	redeemHandler := handler.NewRedeemHandler(redeemService)
@@ -162,9 +163,9 @@ func initializeApplication(buildInfo handler.BuildInfo) (*Application, error) {
 	deferredService := service.ProvideDeferredService(accountRepository, timingWheelService)
 	claudeTokenProvider := service.NewClaudeTokenProvider(accountRepository, geminiTokenCache, oAuthService)
 	digestSessionStore := service.NewDigestSessionStore()
-	gatewayService := service.NewGatewayService(accountRepository, groupRepository, usageLogRepository, userRepository, userSubscriptionRepository, userGroupRateRepository, gatewayCache, configConfig, schedulerSnapshotService, concurrencyService, billingService, rateLimitService, billingCacheService, identityService, httpUpstream, deferredService, claudeTokenProvider, sessionLimitCache, rpmCache, digestSessionStore, settingService)
+	gatewayService := service.NewGatewayService(accountRepository, groupRepository, usageLogRepository, usageBillingRepository, userRepository, userSubscriptionRepository, userGroupRateRepository, gatewayCache, configConfig, schedulerSnapshotService, concurrencyService, billingService, rateLimitService, billingCacheService, identityService, httpUpstream, deferredService, claudeTokenProvider, sessionLimitCache, rpmCache, digestSessionStore, settingService)
 	openAITokenProvider := service.NewOpenAITokenProvider(accountRepository, geminiTokenCache, openAIOAuthService)
-	openAIGatewayService := service.NewOpenAIGatewayService(accountRepository, usageLogRepository, userRepository, userSubscriptionRepository, userGroupRateRepository, gatewayCache, configConfig, schedulerSnapshotService, concurrencyService, billingService, rateLimitService, billingCacheService, httpUpstream, deferredService, openAITokenProvider)
+	openAIGatewayService := service.NewOpenAIGatewayService(accountRepository, usageLogRepository, usageBillingRepository, userRepository, userSubscriptionRepository, userGroupRateRepository, gatewayCache, configConfig, schedulerSnapshotService, concurrencyService, billingService, rateLimitService, billingCacheService, httpUpstream, deferredService, openAITokenProvider)
 	geminiMessagesCompatService := service.NewGeminiMessagesCompatService(accountRepository, groupRepository, gatewayCache, schedulerSnapshotService, geminiTokenProvider, rateLimitService, httpUpstream, antigravityGatewayService, configConfig)
 	opsSystemLogSink := service.ProvideOpsSystemLogSink(opsRepository)
 	opsService := service.NewOpsService(opsRepository, settingRepository, configConfig, accountRepository, userRepository, concurrencyService, gatewayService, openAIGatewayService, geminiMessagesCompatService, antigravityGatewayService, opsSystemLogSink)

backend/internal/config/config.go

@@ -934,9 +934,10 @@ type DashboardAggregationConfig struct {
 
 // DashboardAggregationRetentionConfig 预聚合保留窗口
 type DashboardAggregationRetentionConfig struct {
-	UsageLogsDays int `mapstructure:"usage_logs_days"`
+	UsageLogsDays         int `mapstructure:"usage_logs_days"`
-	HourlyDays    int `mapstructure:"hourly_days"`
+	UsageBillingDedupDays int `mapstructure:"usage_billing_dedup_days"`
-	DailyDays     int `mapstructure:"daily_days"`
+	HourlyDays            int `mapstructure:"hourly_days"`
+	DailyDays             int `mapstructure:"daily_days"`
 }
 
 // UsageCleanupConfig 使用记录清理任务配置
@@ -1301,6 +1302,7 @@ func setDefaults() {
 	viper.SetDefault("dashboard_aggregation.backfill_enabled", false)
 	viper.SetDefault("dashboard_aggregation.backfill_max_days", 31)
 	viper.SetDefault("dashboard_aggregation.retention.usage_logs_days", 90)
+	viper.SetDefault("dashboard_aggregation.retention.usage_billing_dedup_days", 365)
 	viper.SetDefault("dashboard_aggregation.retention.hourly_days", 180)
 	viper.SetDefault("dashboard_aggregation.retention.daily_days", 730)
 	viper.SetDefault("dashboard_aggregation.recompute_days", 2)
@@ -1758,6 +1760,12 @@ func (c *Config) Validate() error {
 		if c.DashboardAgg.Retention.UsageLogsDays <= 0 {
 			return fmt.Errorf("dashboard_aggregation.retention.usage_logs_days must be positive")
 		}
+		if c.DashboardAgg.Retention.UsageBillingDedupDays <= 0 {
+			return fmt.Errorf("dashboard_aggregation.retention.usage_billing_dedup_days must be positive")
+		}
+		if c.DashboardAgg.Retention.UsageBillingDedupDays < c.DashboardAgg.Retention.UsageLogsDays {
+			return fmt.Errorf("dashboard_aggregation.retention.usage_billing_dedup_days must be greater than or equal to usage_logs_days")
+		}
 		if c.DashboardAgg.Retention.HourlyDays <= 0 {
 			return fmt.Errorf("dashboard_aggregation.retention.hourly_days must be positive")
 		}
@@ -1780,6 +1788,14 @@ func (c *Config) Validate() error {
 		if c.DashboardAgg.Retention.UsageLogsDays < 0 {
 			return fmt.Errorf("dashboard_aggregation.retention.usage_logs_days must be non-negative")
 		}
+		if c.DashboardAgg.Retention.UsageBillingDedupDays < 0 {
+			return fmt.Errorf("dashboard_aggregation.retention.usage_billing_dedup_days must be non-negative")
+		}
+		if c.DashboardAgg.Retention.UsageBillingDedupDays > 0 &&
+			c.DashboardAgg.Retention.UsageLogsDays > 0 &&
+			c.DashboardAgg.Retention.UsageBillingDedupDays < c.DashboardAgg.Retention.UsageLogsDays {
+			return fmt.Errorf("dashboard_aggregation.retention.usage_billing_dedup_days must be greater than or equal to usage_logs_days")
+		}
 		if c.DashboardAgg.Retention.HourlyDays < 0 {
 			return fmt.Errorf("dashboard_aggregation.retention.hourly_days must be non-negative")
 		}

backend/internal/config/config_test.go

@@ -441,6 +441,9 @@ func TestLoadDefaultDashboardAggregationConfig(t *testing.T) {
 	if cfg.DashboardAgg.Retention.UsageLogsDays != 90 {
 		t.Fatalf("DashboardAgg.Retention.UsageLogsDays = %d, want 90", cfg.DashboardAgg.Retention.UsageLogsDays)
 	}
+	if cfg.DashboardAgg.Retention.UsageBillingDedupDays != 365 {
+		t.Fatalf("DashboardAgg.Retention.UsageBillingDedupDays = %d, want 365", cfg.DashboardAgg.Retention.UsageBillingDedupDays)
+	}
 	if cfg.DashboardAgg.Retention.HourlyDays != 180 {
 		t.Fatalf("DashboardAgg.Retention.HourlyDays = %d, want 180", cfg.DashboardAgg.Retention.HourlyDays)
 	}
@@ -1016,6 +1019,23 @@ func TestValidateConfigErrors(t *testing.T) {
 			mutate:  func(c *Config) { c.DashboardAgg.Enabled = true; c.DashboardAgg.Retention.UsageLogsDays = 0 },
 			wantErr: "dashboard_aggregation.retention.usage_logs_days",
 		},
+		{
+			name: "dashboard aggregation dedup retention",
+			mutate: func(c *Config) {
+				c.DashboardAgg.Enabled = true
+				c.DashboardAgg.Retention.UsageBillingDedupDays = 0
+			},
+			wantErr: "dashboard_aggregation.retention.usage_billing_dedup_days",
+		},
+		{
+			name: "dashboard aggregation dedup retention smaller than usage logs",
+			mutate: func(c *Config) {
+				c.DashboardAgg.Enabled = true
+				c.DashboardAgg.Retention.UsageLogsDays = 30
+				c.DashboardAgg.Retention.UsageBillingDedupDays = 29
+			},
+			wantErr: "dashboard_aggregation.retention.usage_billing_dedup_days",
+		},
 		{
 			name:    "dashboard aggregation disabled interval",
 			mutate:  func(c *Config) { c.DashboardAgg.Enabled = false; c.DashboardAgg.IntervalSeconds = -1 },

backend/internal/handler/gateway_handler.go

@@ -434,19 +434,21 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 			// 捕获请求信息（用于异步记录，避免在 goroutine 中访问 gin.Context）
 			userAgent := c.GetHeader("User-Agent")
 			clientIP := ip.GetClientIP(c)
+			requestPayloadHash := service.HashUsageRequestPayload(body)
 
 			// 使用量记录通过有界 worker 池提交，避免请求热路径创建无界 goroutine。
 			h.submitUsageRecordTask(func(ctx context.Context) {
 				if err := h.gatewayService.RecordUsage(ctx, &service.RecordUsageInput{
-					Result:            result,
+					Result:             result,
-					APIKey:            apiKey,
+					APIKey:             apiKey,
-					User:              apiKey.User,
+					User:               apiKey.User,
-					Account:           account,
+					Account:            account,
-					Subscription:      subscription,
+					Subscription:       subscription,
-					UserAgent:         userAgent,
+					UserAgent:          userAgent,
-					IPAddress:         clientIP,
+					IPAddress:          clientIP,
-					ForceCacheBilling: fs.ForceCacheBilling,
+					RequestPayloadHash: requestPayloadHash,
-					APIKeyService:     h.apiKeyService,
+					ForceCacheBilling:  fs.ForceCacheBilling,
+					APIKeyService:      h.apiKeyService,
 				}); err != nil {
 					logger.L().With(
 						zap.String("component", "handler.gateway.messages"),
@@ -736,19 +738,21 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 			// 捕获请求信息（用于异步记录，避免在 goroutine 中访问 gin.Context）
 			userAgent := c.GetHeader("User-Agent")
 			clientIP := ip.GetClientIP(c)
+			requestPayloadHash := service.HashUsageRequestPayload(body)
 
 			// 使用量记录通过有界 worker 池提交，避免请求热路径创建无界 goroutine。
 			h.submitUsageRecordTask(func(ctx context.Context) {
 				if err := h.gatewayService.RecordUsage(ctx, &service.RecordUsageInput{
-					Result:            result,
+					Result:             result,
-					APIKey:            currentAPIKey,
+					APIKey:             currentAPIKey,
-					User:              currentAPIKey.User,
+					User:               currentAPIKey.User,
-					Account:           account,
+					Account:            account,
-					Subscription:      currentSubscription,
+					Subscription:       currentSubscription,
-					UserAgent:         userAgent,
+					UserAgent:          userAgent,
-					IPAddress:         clientIP,
+					IPAddress:          clientIP,
-					ForceCacheBilling: fs.ForceCacheBilling,
+					RequestPayloadHash: requestPayloadHash,
-					APIKeyService:     h.apiKeyService,
+					ForceCacheBilling:  fs.ForceCacheBilling,
+					APIKeyService:      h.apiKeyService,
 				}); err != nil {
 					logger.L().With(
 						zap.String("component", "handler.gateway.messages"),

backend/internal/handler/gateway_handler_warmup_intercept_unit_test.go

@@ -139,6 +139,7 @@ func newTestGatewayHandler(t *testing.T, group *service.Group, accounts []*servi
 		nil, // accountRepo (not used: scheduler snapshot hit)
 		&fakeGroupRepo{group: group},
 		nil, // usageLogRepo
+		nil, // usageBillingRepo
 		nil, // userRepo
 		nil, // userSubRepo
 		nil, // userGroupRateRepo

backend/internal/handler/gemini_v1beta_handler.go

@@ -503,6 +503,7 @@ func (h *GatewayHandler) GeminiV1BetaModels(c *gin.Context) {
 		}
 
 		// 使用量记录通过有界 worker 池提交，避免请求热路径创建无界 goroutine。
+		requestPayloadHash := service.HashUsageRequestPayload(body)
 		h.submitUsageRecordTask(func(ctx context.Context) {
 			if err := h.gatewayService.RecordUsageWithLongContext(ctx, &service.RecordUsageLongContextInput{
 				Result:                result,
@@ -512,6 +513,7 @@ func (h *GatewayHandler) GeminiV1BetaModels(c *gin.Context) {
 				Subscription:          subscription,
 				UserAgent:             userAgent,
 				IPAddress:             clientIP,
+				RequestPayloadHash:    requestPayloadHash,
 				LongContextThreshold:  200000, // Gemini 200K 阈值
 				LongContextMultiplier: 2.0,    // 超出部分双倍计费
 				ForceCacheBilling:     fs.ForceCacheBilling,

backend/internal/handler/openai_gateway_handler.go

@@ -352,18 +352,20 @@ func (h *OpenAIGatewayHandler) Responses(c *gin.Context) {
 		// 捕获请求信息（用于异步记录，避免在 goroutine 中访问 gin.Context）
 		userAgent := c.GetHeader("User-Agent")
 		clientIP := ip.GetClientIP(c)
+		requestPayloadHash := service.HashUsageRequestPayload(body)
 
 		// 使用量记录通过有界 worker 池提交，避免请求热路径创建无界 goroutine。
 		h.submitUsageRecordTask(func(ctx context.Context) {
 			if err := h.gatewayService.RecordUsage(ctx, &service.OpenAIRecordUsageInput{
-				Result:        result,
+				Result:             result,
-				APIKey:        apiKey,
+				APIKey:             apiKey,
-				User:          apiKey.User,
+				User:               apiKey.User,
-				Account:       account,
+				Account:            account,
-				Subscription:  subscription,
+				Subscription:       subscription,
-				UserAgent:     userAgent,
+				UserAgent:          userAgent,
-				IPAddress:     clientIP,
+				IPAddress:          clientIP,
-				APIKeyService: h.apiKeyService,
+				RequestPayloadHash: requestPayloadHash,
+				APIKeyService:      h.apiKeyService,
 			}); err != nil {
 				logger.L().With(
 					zap.String("component", "handler.openai_gateway.responses"),
@@ -732,17 +734,19 @@ func (h *OpenAIGatewayHandler) Messages(c *gin.Context) {
 
 		userAgent := c.GetHeader("User-Agent")
 		clientIP := ip.GetClientIP(c)
+		requestPayloadHash := service.HashUsageRequestPayload(body)
 
 		h.submitUsageRecordTask(func(ctx context.Context) {
 			if err := h.gatewayService.RecordUsage(ctx, &service.OpenAIRecordUsageInput{
-				Result:        result,
+				Result:             result,
-				APIKey:        apiKey,
+				APIKey:             apiKey,
-				User:          apiKey.User,
+				User:               apiKey.User,
-				Account:       account,
+				Account:            account,
-				Subscription:  subscription,
+				Subscription:       subscription,
-				UserAgent:     userAgent,
+				UserAgent:          userAgent,
-				IPAddress:     clientIP,
+				IPAddress:          clientIP,
-				APIKeyService: h.apiKeyService,
+				RequestPayloadHash: requestPayloadHash,
+				APIKeyService:      h.apiKeyService,
 			}); err != nil {
 				logger.L().With(
 					zap.String("component", "handler.openai_gateway.messages"),
@@ -1231,14 +1235,15 @@ func (h *OpenAIGatewayHandler) ResponsesWebSocket(c *gin.Context) {
 			h.gatewayService.ReportOpenAIAccountScheduleResult(account.ID, true, result.FirstTokenMs)
 			h.submitUsageRecordTask(func(taskCtx context.Context) {
 				if err := h.gatewayService.RecordUsage(taskCtx, &service.OpenAIRecordUsageInput{
-					Result:        result,
+					Result:             result,
-					APIKey:        apiKey,
+					APIKey:             apiKey,
-					User:          apiKey.User,
+					User:               apiKey.User,
-					Account:       account,
+					Account:            account,
-					Subscription:  subscription,
+					Subscription:       subscription,
-					UserAgent:     userAgent,
+					UserAgent:          userAgent,
-					IPAddress:     clientIP,
+					IPAddress:          clientIP,
-					APIKeyService: h.apiKeyService,
+					RequestPayloadHash: service.HashUsageRequestPayload(firstMessage),
+					APIKeyService:      h.apiKeyService,
 				}); err != nil {
 					reqLog.Error("openai.websocket_record_usage_failed",
 						zap.Int64("account_id", account.ID),

backend/internal/handler/sora_client_handler_test.go

@@ -2206,7 +2206,7 @@ func (s *stubSoraClientForHandler) GetVideoTask(_ context.Context, _ *service.Ac
 // newMinimalGatewayService 创建仅包含 accountRepo 的最小 GatewayService（用于测试 SelectAccountForModel）。
 func newMinimalGatewayService(accountRepo service.AccountRepository) *service.GatewayService {
 	return service.NewGatewayService(
-		accountRepo, nil, nil, nil, nil, nil, nil, nil,
+		accountRepo, nil, nil, nil, nil, nil, nil, nil, nil,
 		nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil,
 	)
 }

backend/internal/handler/sora_gateway_handler.go

@@ -399,17 +399,19 @@ func (h *SoraGatewayHandler) ChatCompletions(c *gin.Context) {
 
 		userAgent := c.GetHeader("User-Agent")
 		clientIP := ip.GetClientIP(c)
+		requestPayloadHash := service.HashUsageRequestPayload(body)
 
 		// 使用量记录通过有界 worker 池提交，避免请求热路径创建无界 goroutine。
 		h.submitUsageRecordTask(func(ctx context.Context) {
 			if err := h.gatewayService.RecordUsage(ctx, &service.RecordUsageInput{
-				Result:       result,
+				Result:             result,
-				APIKey:       apiKey,
+				APIKey:             apiKey,
-				User:         apiKey.User,
+				User:               apiKey.User,
-				Account:      account,
+				Account:            account,
-				Subscription: subscription,
+				Subscription:       subscription,
-				UserAgent:    userAgent,
+				UserAgent:          userAgent,
-				IPAddress:    clientIP,
+				IPAddress:          clientIP,
+				RequestPayloadHash: requestPayloadHash,
 			}); err != nil {
 				logger.L().With(
 					zap.String("component", "handler.sora_gateway.chat_completions"),

backend/internal/handler/sora_gateway_handler_test.go

@@ -431,6 +431,7 @@ func TestSoraGatewayHandler_ChatCompletions(t *testing.T) {
 		nil,
 		nil,
 		nil,
+		nil,
 		testutil.StubGatewayCache{},
 		cfg,
 		nil,

backend/internal/repository/dashboard_aggregation_repo.go

@@ -17,6 +17,9 @@ type dashboardAggregationRepository struct {
 	sql sqlExecutor
 }
 
+const usageLogsCleanupBatchSize = 10000
+const usageBillingDedupCleanupBatchSize = 10000
+
 // NewDashboardAggregationRepository 创建仪表盘预聚合仓储。
 func NewDashboardAggregationRepository(sqlDB *sql.DB) service.DashboardAggregationRepository {
 	if sqlDB == nil {
@@ -42,6 +45,9 @@ func isPostgresDriver(db *sql.DB) bool {
 }
 
 func (r *dashboardAggregationRepository) AggregateRange(ctx context.Context, start, end time.Time) error {
+	if r == nil || r.sql == nil {
+		return nil
+	}
 	loc := timezone.Location()
 	startLocal := start.In(loc)
 	endLocal := end.In(loc)
@@ -61,6 +67,22 @@ func (r *dashboardAggregationRepository) AggregateRange(ctx context.Context, sta
 		dayEnd = dayEnd.Add(24 * time.Hour)
 	}
 
+	if db, ok := r.sql.(*sql.DB); ok {
+		tx, err := db.BeginTx(ctx, nil)
+		if err != nil {
+			return err
+		}
+		txRepo := newDashboardAggregationRepositoryWithSQL(tx)
+		if err := txRepo.aggregateRangeInTx(ctx, hourStart, hourEnd, dayStart, dayEnd); err != nil {
+			_ = tx.Rollback()
+			return err
+		}
+		return tx.Commit()
+	}
+	return r.aggregateRangeInTx(ctx, hourStart, hourEnd, dayStart, dayEnd)
+}
+
+func (r *dashboardAggregationRepository) aggregateRangeInTx(ctx context.Context, hourStart, hourEnd, dayStart, dayEnd time.Time) error {
 	// 以桶边界聚合，允许覆盖 end 所在桶的剩余区间。
 	if err := r.insertHourlyActiveUsers(ctx, hourStart, hourEnd); err != nil {
 		return err
@@ -195,8 +217,58 @@ func (r *dashboardAggregationRepository) CleanupUsageLogs(ctx context.Context, c
 	if isPartitioned {
 		return r.dropUsageLogsPartitions(ctx, cutoff)
 	}
-	_, err = r.sql.ExecContext(ctx, "DELETE FROM usage_logs WHERE created_at < $1", cutoff.UTC())
+	for {
-	return err
+		res, err := r.sql.ExecContext(ctx, `
+			WITH victims AS (
+				SELECT ctid
+				FROM usage_logs
+				WHERE created_at < $1
+				LIMIT $2
+			)
+			DELETE FROM usage_logs
+			WHERE ctid IN (SELECT ctid FROM victims)
+		`, cutoff.UTC(), usageLogsCleanupBatchSize)
+		if err != nil {
+			return err
+		}
+		affected, err := res.RowsAffected()
+		if err != nil {
+			return err
+		}
+		if affected < usageLogsCleanupBatchSize {
+			return nil
+		}
+	}
+}
+
+func (r *dashboardAggregationRepository) CleanupUsageBillingDedup(ctx context.Context, cutoff time.Time) error {
+	for {
+		res, err := r.sql.ExecContext(ctx, `
+			WITH victims AS (
+				SELECT ctid, request_id, api_key_id, request_fingerprint, created_at
+				FROM usage_billing_dedup
+				WHERE created_at < $1
+				LIMIT $2
+			), archived AS (
+				INSERT INTO usage_billing_dedup_archive (request_id, api_key_id, request_fingerprint, created_at)
+				SELECT request_id, api_key_id, request_fingerprint, created_at
+				FROM victims
+				ON CONFLICT (request_id, api_key_id) DO NOTHING
+			)
+			DELETE FROM usage_billing_dedup
+			WHERE ctid IN (SELECT ctid FROM victims)
+		`, cutoff.UTC(), usageBillingDedupCleanupBatchSize)
+		if err != nil {
+			return err
+		}
+		affected, err := res.RowsAffected()
+		if err != nil {
+			return err
+		}
+		if affected < usageBillingDedupCleanupBatchSize {
+			return nil
+		}
+	}
 }
 
 func (r *dashboardAggregationRepository) EnsureUsageLogsPartitions(ctx context.Context, now time.Time) error {

backend/internal/repository/migrations_schema_integration_test.go

@@ -45,6 +45,20 @@ func TestMigrationsRunner_IsIdempotent_AndSchemaIsUpToDate(t *testing.T) {
 	requireColumn(t, tx, "usage_logs", "request_type", "smallint", 0, false)
 	requireColumn(t, tx, "usage_logs", "openai_ws_mode", "boolean", 0, false)
 
+	// usage_billing_dedup: billing idempotency narrow table
+	var usageBillingDedupRegclass sql.NullString
+	require.NoError(t, tx.QueryRowContext(context.Background(), "SELECT to_regclass('public.usage_billing_dedup')").Scan(&usageBillingDedupRegclass))
+	require.True(t, usageBillingDedupRegclass.Valid, "expected usage_billing_dedup table to exist")
+	requireColumn(t, tx, "usage_billing_dedup", "request_fingerprint", "character varying", 64, false)
+	requireIndex(t, tx, "usage_billing_dedup", "idx_usage_billing_dedup_request_api_key")
+	requireIndex(t, tx, "usage_billing_dedup", "idx_usage_billing_dedup_created_at_brin")
+
+	var usageBillingDedupArchiveRegclass sql.NullString
+	require.NoError(t, tx.QueryRowContext(context.Background(), "SELECT to_regclass('public.usage_billing_dedup_archive')").Scan(&usageBillingDedupArchiveRegclass))
+	require.True(t, usageBillingDedupArchiveRegclass.Valid, "expected usage_billing_dedup_archive table to exist")
+	requireColumn(t, tx, "usage_billing_dedup_archive", "request_fingerprint", "character varying", 64, false)
+	requireIndex(t, tx, "usage_billing_dedup_archive", "usage_billing_dedup_archive_pkey")
+
 	// settings table should exist
 	var settingsRegclass sql.NullString
 	require.NoError(t, tx.QueryRowContext(context.Background(), "SELECT to_regclass('public.settings')").Scan(&settingsRegclass))
@@ -75,6 +89,23 @@ func TestMigrationsRunner_IsIdempotent_AndSchemaIsUpToDate(t *testing.T) {
 	requireColumn(t, tx, "user_allowed_groups", "created_at", "timestamp with time zone", 0, false)
 }
 
+func requireIndex(t *testing.T, tx *sql.Tx, table, index string) {
+	t.Helper()
+
+	var exists bool
+	err := tx.QueryRowContext(context.Background(), `
+SELECT EXISTS (
+	SELECT 1
+	FROM pg_indexes
+	WHERE schemaname = 'public'
+	  AND tablename = $1
+	  AND indexname = $2
+)
+`, table, index).Scan(&exists)
+	require.NoError(t, err, "query pg_indexes for %s.%s", table, index)
+	require.True(t, exists, "expected index %s on %s", index, table)
+}
+
 func requireColumn(t *testing.T, tx *sql.Tx, table, column, dataType string, maxLen int, nullable bool) {
 	t.Helper()
 

backend/internal/repository/usage_billing_repo.go

@@ -0,0 +1,308 @@
+package repository
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"strings"
+
+	dbent "github.com/Wei-Shaw/sub2api/ent"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/logger"
+	"github.com/Wei-Shaw/sub2api/internal/service"
+)
+
+type usageBillingRepository struct {
+	db *sql.DB
+}
+
+func NewUsageBillingRepository(_ *dbent.Client, sqlDB *sql.DB) service.UsageBillingRepository {
+	return &usageBillingRepository{db: sqlDB}
+}
+
+func (r *usageBillingRepository) Apply(ctx context.Context, cmd *service.UsageBillingCommand) (_ *service.UsageBillingApplyResult, err error) {
+	if cmd == nil {
+		return &service.UsageBillingApplyResult{}, nil
+	}
+	if r == nil || r.db == nil {
+		return nil, errors.New("usage billing repository db is nil")
+	}
+
+	cmd.Normalize()
+	if cmd.RequestID == "" {
+		return nil, service.ErrUsageBillingRequestIDRequired
+	}
+
+	tx, err := r.db.BeginTx(ctx, nil)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		if tx != nil {
+			_ = tx.Rollback()
+		}
+	}()
+
+	applied, err := r.claimUsageBillingKey(ctx, tx, cmd)
+	if err != nil {
+		return nil, err
+	}
+	if !applied {
+		return &service.UsageBillingApplyResult{Applied: false}, nil
+	}
+
+	result := &service.UsageBillingApplyResult{Applied: true}
+	if err := r.applyUsageBillingEffects(ctx, tx, cmd, result); err != nil {
+		return nil, err
+	}
+
+	if err := tx.Commit(); err != nil {
+		return nil, err
+	}
+	tx = nil
+	return result, nil
+}
+
+func (r *usageBillingRepository) claimUsageBillingKey(ctx context.Context, tx *sql.Tx, cmd *service.UsageBillingCommand) (bool, error) {
+	var id int64
+	err := tx.QueryRowContext(ctx, `
+		INSERT INTO usage_billing_dedup (request_id, api_key_id, request_fingerprint)
+		VALUES ($1, $2, $3)
+		ON CONFLICT (request_id, api_key_id) DO NOTHING
+		RETURNING id
+	`, cmd.RequestID, cmd.APIKeyID, cmd.RequestFingerprint).Scan(&id)
+	if errors.Is(err, sql.ErrNoRows) {
+		var existingFingerprint string
+		if err := tx.QueryRowContext(ctx, `
+			SELECT request_fingerprint
+			FROM usage_billing_dedup
+			WHERE request_id = $1 AND api_key_id = $2
+		`, cmd.RequestID, cmd.APIKeyID).Scan(&existingFingerprint); err != nil {
+			return false, err
+		}
+		if strings.TrimSpace(existingFingerprint) != strings.TrimSpace(cmd.RequestFingerprint) {
+			return false, service.ErrUsageBillingRequestConflict
+		}
+		return false, nil
+	}
+	if err != nil {
+		return false, err
+	}
+	var archivedFingerprint string
+	err = tx.QueryRowContext(ctx, `
+		SELECT request_fingerprint
+		FROM usage_billing_dedup_archive
+		WHERE request_id = $1 AND api_key_id = $2
+	`, cmd.RequestID, cmd.APIKeyID).Scan(&archivedFingerprint)
+	if err == nil {
+		if strings.TrimSpace(archivedFingerprint) != strings.TrimSpace(cmd.RequestFingerprint) {
+			return false, service.ErrUsageBillingRequestConflict
+		}
+		return false, nil
+	}
+	if !errors.Is(err, sql.ErrNoRows) {
+		return false, err
+	}
+	return true, nil
+}
+
+func (r *usageBillingRepository) applyUsageBillingEffects(ctx context.Context, tx *sql.Tx, cmd *service.UsageBillingCommand, result *service.UsageBillingApplyResult) error {
+	if cmd.SubscriptionCost > 0 && cmd.SubscriptionID != nil {
+		if err := incrementUsageBillingSubscription(ctx, tx, *cmd.SubscriptionID, cmd.SubscriptionCost); err != nil {
+			return err
+		}
+	}
+
+	if cmd.BalanceCost > 0 {
+		if err := deductUsageBillingBalance(ctx, tx, cmd.UserID, cmd.BalanceCost); err != nil {
+			return err
+		}
+	}
+
+	if cmd.APIKeyQuotaCost > 0 {
+		exhausted, err := incrementUsageBillingAPIKeyQuota(ctx, tx, cmd.APIKeyID, cmd.APIKeyQuotaCost)
+		if err != nil {
+			return err
+		}
+		result.APIKeyQuotaExhausted = exhausted
+	}
+
+	if cmd.APIKeyRateLimitCost > 0 {
+		if err := incrementUsageBillingAPIKeyRateLimit(ctx, tx, cmd.APIKeyID, cmd.APIKeyRateLimitCost); err != nil {
+			return err
+		}
+	}
+
+	if cmd.AccountQuotaCost > 0 && strings.EqualFold(cmd.AccountType, service.AccountTypeAPIKey) {
+		if err := incrementUsageBillingAccountQuota(ctx, tx, cmd.AccountID, cmd.AccountQuotaCost); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func incrementUsageBillingSubscription(ctx context.Context, tx *sql.Tx, subscriptionID int64, costUSD float64) error {
+	const updateSQL = `
+		UPDATE user_subscriptions us
+		SET
+			daily_usage_usd = us.daily_usage_usd + $1,
+			weekly_usage_usd = us.weekly_usage_usd + $1,
+			monthly_usage_usd = us.monthly_usage_usd + $1,
+			updated_at = NOW()
+		FROM groups g
+		WHERE us.id = $2
+			AND us.deleted_at IS NULL
+			AND us.group_id = g.id
+			AND g.deleted_at IS NULL
+	`
+	res, err := tx.ExecContext(ctx, updateSQL, costUSD, subscriptionID)
+	if err != nil {
+		return err
+	}
+	affected, err := res.RowsAffected()
+	if err != nil {
+		return err
+	}
+	if affected > 0 {
+		return nil
+	}
+	return service.ErrSubscriptionNotFound
+}
+
+func deductUsageBillingBalance(ctx context.Context, tx *sql.Tx, userID int64, amount float64) error {
+	res, err := tx.ExecContext(ctx, `
+		UPDATE users
+		SET balance = balance - $1,
+			updated_at = NOW()
+		WHERE id = $2 AND deleted_at IS NULL
+	`, amount, userID)
+	if err != nil {
+		return err
+	}
+	affected, err := res.RowsAffected()
+	if err != nil {
+		return err
+	}
+	if affected > 0 {
+		return nil
+	}
+	return service.ErrUserNotFound
+}
+
+func incrementUsageBillingAPIKeyQuota(ctx context.Context, tx *sql.Tx, apiKeyID int64, amount float64) (bool, error) {
+	var exhausted bool
+	err := tx.QueryRowContext(ctx, `
+		UPDATE api_keys
+		SET quota_used = quota_used + $1,
+			status = CASE
+				WHEN quota > 0
+					AND status = $3
+					AND quota_used < quota
+					AND quota_used + $1 >= quota
+				THEN $4
+				ELSE status
+			END,
+			updated_at = NOW()
+		WHERE id = $2 AND deleted_at IS NULL
+		RETURNING quota > 0 AND quota_used >= quota AND quota_used - $1 < quota
+	`, amount, apiKeyID, service.StatusAPIKeyActive, service.StatusAPIKeyQuotaExhausted).Scan(&exhausted)
+	if errors.Is(err, sql.ErrNoRows) {
+		return false, service.ErrAPIKeyNotFound
+	}
+	if err != nil {
+		return false, err
+	}
+	return exhausted, nil
+}
+
+func incrementUsageBillingAPIKeyRateLimit(ctx context.Context, tx *sql.Tx, apiKeyID int64, cost float64) error {
+	res, err := tx.ExecContext(ctx, `
+		UPDATE api_keys SET
+			usage_5h = CASE WHEN window_5h_start IS NOT NULL AND window_5h_start + INTERVAL '5 hours' <= NOW() THEN $1 ELSE usage_5h + $1 END,
+			usage_1d = CASE WHEN window_1d_start IS NOT NULL AND window_1d_start + INTERVAL '24 hours' <= NOW() THEN $1 ELSE usage_1d + $1 END,
+			usage_7d = CASE WHEN window_7d_start IS NOT NULL AND window_7d_start + INTERVAL '7 days' <= NOW() THEN $1 ELSE usage_7d + $1 END,
+			window_5h_start = CASE WHEN window_5h_start IS NULL OR window_5h_start + INTERVAL '5 hours' <= NOW() THEN NOW() ELSE window_5h_start END,
+			window_1d_start = CASE WHEN window_1d_start IS NULL OR window_1d_start + INTERVAL '24 hours' <= NOW() THEN date_trunc('day', NOW()) ELSE window_1d_start END,
+			window_7d_start = CASE WHEN window_7d_start IS NULL OR window_7d_start + INTERVAL '7 days' <= NOW() THEN date_trunc('day', NOW()) ELSE window_7d_start END,
+			updated_at = NOW()
+		WHERE id = $2 AND deleted_at IS NULL
+	`, cost, apiKeyID)
+	if err != nil {
+		return err
+	}
+	affected, err := res.RowsAffected()
+	if err != nil {
+		return err
+	}
+	if affected == 0 {
+		return service.ErrAPIKeyNotFound
+	}
+	return nil
+}
+
+func incrementUsageBillingAccountQuota(ctx context.Context, tx *sql.Tx, accountID int64, amount float64) error {
+	rows, err := tx.QueryContext(ctx,
+		`UPDATE accounts SET extra = (
+			COALESCE(extra, '{}'::jsonb)
+			|| jsonb_build_object('quota_used', COALESCE((extra->>'quota_used')::numeric, 0) + $1)
+			|| CASE WHEN COALESCE((extra->>'quota_daily_limit')::numeric, 0) > 0 THEN
+				jsonb_build_object(
+					'quota_daily_used',
+					CASE WHEN COALESCE((extra->>'quota_daily_start')::timestamptz, '1970-01-01'::timestamptz)
+						+ '24 hours'::interval <= NOW()
+					THEN $1
+					ELSE COALESCE((extra->>'quota_daily_used')::numeric, 0) + $1 END,
+					'quota_daily_start',
+					CASE WHEN COALESCE((extra->>'quota_daily_start')::timestamptz, '1970-01-01'::timestamptz)
+						+ '24 hours'::interval <= NOW()
+					THEN `+nowUTC+`
+					ELSE COALESCE(extra->>'quota_daily_start', `+nowUTC+`) END
+				)
+			ELSE '{}'::jsonb END
+			|| CASE WHEN COALESCE((extra->>'quota_weekly_limit')::numeric, 0) > 0 THEN
+				jsonb_build_object(
+					'quota_weekly_used',
+					CASE WHEN COALESCE((extra->>'quota_weekly_start')::timestamptz, '1970-01-01'::timestamptz)
+						+ '168 hours'::interval <= NOW()
+					THEN $1
+					ELSE COALESCE((extra->>'quota_weekly_used')::numeric, 0) + $1 END,
+					'quota_weekly_start',
+					CASE WHEN COALESCE((extra->>'quota_weekly_start')::timestamptz, '1970-01-01'::timestamptz)
+						+ '168 hours'::interval <= NOW()
+					THEN `+nowUTC+`
+					ELSE COALESCE(extra->>'quota_weekly_start', `+nowUTC+`) END
+				)
+			ELSE '{}'::jsonb END
+		), updated_at = NOW()
+		WHERE id = $2 AND deleted_at IS NULL
+		RETURNING
+			COALESCE((extra->>'quota_used')::numeric, 0),
+			COALESCE((extra->>'quota_limit')::numeric, 0)`,
+		amount, accountID)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = rows.Close() }()
+
+	var newUsed, limit float64
+	if rows.Next() {
+		if err := rows.Scan(&newUsed, &limit); err != nil {
+			return err
+		}
+	} else {
+		if err := rows.Err(); err != nil {
+			return err
+		}
+		return service.ErrAccountNotFound
+	}
+	if err := rows.Err(); err != nil {
+		return err
+	}
+	if limit > 0 && newUsed >= limit && (newUsed-amount) < limit {
+		if err := enqueueSchedulerOutbox(ctx, tx, service.SchedulerOutboxEventAccountChanged, &accountID, nil, nil); err != nil {
+			logger.LegacyPrintf("repository.usage_billing", "[SchedulerOutbox] enqueue quota exceeded failed: account=%d err=%v", accountID, err)
+			return err
+		}
+	}
+	return nil
+}

backend/internal/repository/usage_billing_repo_integration_test.go

@@ -0,0 +1,279 @@
+//go:build integration
+
+package repository
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/require"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+)
+
+func TestUsageBillingRepositoryApply_DeduplicatesBalanceBilling(t *testing.T) {
+	ctx := context.Background()
+	client := testEntClient(t)
+	repo := NewUsageBillingRepository(client, integrationDB)
+
+	user := mustCreateUser(t, client, &service.User{
+		Email:        fmt.Sprintf("usage-billing-user-%d@example.com", time.Now().UnixNano()),
+		PasswordHash: "hash",
+		Balance:      100,
+	})
+	apiKey := mustCreateApiKey(t, client, &service.APIKey{
+		UserID: user.ID,
+		Key:    "sk-usage-billing-" + uuid.NewString(),
+		Name:   "billing",
+		Quota:  1,
+	})
+	account := mustCreateAccount(t, client, &service.Account{
+		Name: "usage-billing-account-" + uuid.NewString(),
+		Type: service.AccountTypeAPIKey,
+	})
+
+	requestID := uuid.NewString()
+	cmd := &service.UsageBillingCommand{
+		RequestID:           requestID,
+		APIKeyID:            apiKey.ID,
+		UserID:              user.ID,
+		AccountID:           account.ID,
+		AccountType:         service.AccountTypeAPIKey,
+		BalanceCost:         1.25,
+		APIKeyQuotaCost:     1.25,
+		APIKeyRateLimitCost: 1.25,
+	}
+
+	result1, err := repo.Apply(ctx, cmd)
+	require.NoError(t, err)
+	require.NotNil(t, result1)
+	require.True(t, result1.Applied)
+	require.True(t, result1.APIKeyQuotaExhausted)
+
+	result2, err := repo.Apply(ctx, cmd)
+	require.NoError(t, err)
+	require.NotNil(t, result2)
+	require.False(t, result2.Applied)
+
+	var balance float64
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT balance FROM users WHERE id = $1", user.ID).Scan(&balance))
+	require.InDelta(t, 98.75, balance, 0.000001)
+
+	var quotaUsed float64
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT quota_used FROM api_keys WHERE id = $1", apiKey.ID).Scan(&quotaUsed))
+	require.InDelta(t, 1.25, quotaUsed, 0.000001)
+
+	var usage5h float64
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT usage_5h FROM api_keys WHERE id = $1", apiKey.ID).Scan(&usage5h))
+	require.InDelta(t, 1.25, usage5h, 0.000001)
+
+	var status string
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT status FROM api_keys WHERE id = $1", apiKey.ID).Scan(&status))
+	require.Equal(t, service.StatusAPIKeyQuotaExhausted, status)
+
+	var dedupCount int
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT COUNT(*) FROM usage_billing_dedup WHERE request_id = $1 AND api_key_id = $2", requestID, apiKey.ID).Scan(&dedupCount))
+	require.Equal(t, 1, dedupCount)
+}
+
+func TestUsageBillingRepositoryApply_DeduplicatesSubscriptionBilling(t *testing.T) {
+	ctx := context.Background()
+	client := testEntClient(t)
+	repo := NewUsageBillingRepository(client, integrationDB)
+
+	user := mustCreateUser(t, client, &service.User{
+		Email:        fmt.Sprintf("usage-billing-sub-user-%d@example.com", time.Now().UnixNano()),
+		PasswordHash: "hash",
+	})
+	group := mustCreateGroup(t, client, &service.Group{
+		Name:             "usage-billing-group-" + uuid.NewString(),
+		Platform:         service.PlatformAnthropic,
+		SubscriptionType: service.SubscriptionTypeSubscription,
+	})
+	apiKey := mustCreateApiKey(t, client, &service.APIKey{
+		UserID:  user.ID,
+		GroupID: &group.ID,
+		Key:     "sk-usage-billing-sub-" + uuid.NewString(),
+		Name:    "billing-sub",
+	})
+	subscription := mustCreateSubscription(t, client, &service.UserSubscription{
+		UserID:  user.ID,
+		GroupID: group.ID,
+	})
+
+	requestID := uuid.NewString()
+	cmd := &service.UsageBillingCommand{
+		RequestID:        requestID,
+		APIKeyID:         apiKey.ID,
+		UserID:           user.ID,
+		AccountID:        0,
+		SubscriptionID:   &subscription.ID,
+		SubscriptionCost: 2.5,
+	}
+
+	result1, err := repo.Apply(ctx, cmd)
+	require.NoError(t, err)
+	require.True(t, result1.Applied)
+
+	result2, err := repo.Apply(ctx, cmd)
+	require.NoError(t, err)
+	require.False(t, result2.Applied)
+
+	var dailyUsage float64
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT daily_usage_usd FROM user_subscriptions WHERE id = $1", subscription.ID).Scan(&dailyUsage))
+	require.InDelta(t, 2.5, dailyUsage, 0.000001)
+}
+
+func TestUsageBillingRepositoryApply_RequestFingerprintConflict(t *testing.T) {
+	ctx := context.Background()
+	client := testEntClient(t)
+	repo := NewUsageBillingRepository(client, integrationDB)
+
+	user := mustCreateUser(t, client, &service.User{
+		Email:        fmt.Sprintf("usage-billing-conflict-user-%d@example.com", time.Now().UnixNano()),
+		PasswordHash: "hash",
+		Balance:      100,
+	})
+	apiKey := mustCreateApiKey(t, client, &service.APIKey{
+		UserID: user.ID,
+		Key:    "sk-usage-billing-conflict-" + uuid.NewString(),
+		Name:   "billing-conflict",
+	})
+
+	requestID := uuid.NewString()
+	_, err := repo.Apply(ctx, &service.UsageBillingCommand{
+		RequestID:   requestID,
+		APIKeyID:    apiKey.ID,
+		UserID:      user.ID,
+		BalanceCost: 1.25,
+	})
+	require.NoError(t, err)
+
+	_, err = repo.Apply(ctx, &service.UsageBillingCommand{
+		RequestID:   requestID,
+		APIKeyID:    apiKey.ID,
+		UserID:      user.ID,
+		BalanceCost: 2.50,
+	})
+	require.ErrorIs(t, err, service.ErrUsageBillingRequestConflict)
+}
+
+func TestUsageBillingRepositoryApply_UpdatesAccountQuota(t *testing.T) {
+	ctx := context.Background()
+	client := testEntClient(t)
+	repo := NewUsageBillingRepository(client, integrationDB)
+
+	user := mustCreateUser(t, client, &service.User{
+		Email:        fmt.Sprintf("usage-billing-account-user-%d@example.com", time.Now().UnixNano()),
+		PasswordHash: "hash",
+	})
+	apiKey := mustCreateApiKey(t, client, &service.APIKey{
+		UserID: user.ID,
+		Key:    "sk-usage-billing-account-" + uuid.NewString(),
+		Name:   "billing-account",
+	})
+	account := mustCreateAccount(t, client, &service.Account{
+		Name: "usage-billing-account-quota-" + uuid.NewString(),
+		Type: service.AccountTypeAPIKey,
+		Extra: map[string]any{
+			"quota_limit": 100.0,
+		},
+	})
+
+	_, err := repo.Apply(ctx, &service.UsageBillingCommand{
+		RequestID:        uuid.NewString(),
+		APIKeyID:         apiKey.ID,
+		UserID:           user.ID,
+		AccountID:        account.ID,
+		AccountType:      service.AccountTypeAPIKey,
+		AccountQuotaCost: 3.5,
+	})
+	require.NoError(t, err)
+
+	var quotaUsed float64
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT COALESCE((extra->>'quota_used')::numeric, 0) FROM accounts WHERE id = $1", account.ID).Scan(&quotaUsed))
+	require.InDelta(t, 3.5, quotaUsed, 0.000001)
+}
+
+func TestDashboardAggregationRepositoryCleanupUsageBillingDedup_BatchDeletesOldRows(t *testing.T) {
+	ctx := context.Background()
+	repo := newDashboardAggregationRepositoryWithSQL(integrationDB)
+
+	oldRequestID := "dedup-old-" + uuid.NewString()
+	newRequestID := "dedup-new-" + uuid.NewString()
+	oldCreatedAt := time.Now().UTC().AddDate(0, 0, -400)
+	newCreatedAt := time.Now().UTC().Add(-time.Hour)
+
+	_, err := integrationDB.ExecContext(ctx, `
+		INSERT INTO usage_billing_dedup (request_id, api_key_id, request_fingerprint, created_at)
+		VALUES ($1, 1, $2, $3), ($4, 1, $5, $6)
+	`,
+		oldRequestID, strings.Repeat("a", 64), oldCreatedAt,
+		newRequestID, strings.Repeat("b", 64), newCreatedAt,
+	)
+	require.NoError(t, err)
+
+	require.NoError(t, repo.CleanupUsageBillingDedup(ctx, time.Now().UTC().AddDate(0, 0, -365)))
+
+	var oldCount int
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT COUNT(*) FROM usage_billing_dedup WHERE request_id = $1", oldRequestID).Scan(&oldCount))
+	require.Equal(t, 0, oldCount)
+
+	var newCount int
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT COUNT(*) FROM usage_billing_dedup WHERE request_id = $1", newRequestID).Scan(&newCount))
+	require.Equal(t, 1, newCount)
+
+	var archivedCount int
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT COUNT(*) FROM usage_billing_dedup_archive WHERE request_id = $1", oldRequestID).Scan(&archivedCount))
+	require.Equal(t, 1, archivedCount)
+}
+
+func TestUsageBillingRepositoryApply_DeduplicatesAgainstArchivedKey(t *testing.T) {
+	ctx := context.Background()
+	client := testEntClient(t)
+	repo := NewUsageBillingRepository(client, integrationDB)
+	aggRepo := newDashboardAggregationRepositoryWithSQL(integrationDB)
+
+	user := mustCreateUser(t, client, &service.User{
+		Email:        fmt.Sprintf("usage-billing-archive-user-%d@example.com", time.Now().UnixNano()),
+		PasswordHash: "hash",
+		Balance:      100,
+	})
+	apiKey := mustCreateApiKey(t, client, &service.APIKey{
+		UserID: user.ID,
+		Key:    "sk-usage-billing-archive-" + uuid.NewString(),
+		Name:   "billing-archive",
+	})
+
+	requestID := uuid.NewString()
+	cmd := &service.UsageBillingCommand{
+		RequestID:   requestID,
+		APIKeyID:    apiKey.ID,
+		UserID:      user.ID,
+		BalanceCost: 1.25,
+	}
+
+	result1, err := repo.Apply(ctx, cmd)
+	require.NoError(t, err)
+	require.True(t, result1.Applied)
+
+	_, err = integrationDB.ExecContext(ctx, `
+		UPDATE usage_billing_dedup
+		SET created_at = $1
+		WHERE request_id = $2 AND api_key_id = $3
+	`, time.Now().UTC().AddDate(0, 0, -400), requestID, apiKey.ID)
+	require.NoError(t, err)
+	require.NoError(t, aggRepo.CleanupUsageBillingDedup(ctx, time.Now().UTC().AddDate(0, 0, -365)))
+
+	result2, err := repo.Apply(ctx, cmd)
+	require.NoError(t, err)
+	require.False(t, result2.Applied)
+
+	var balance float64
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT balance FROM users WHERE id = $1", user.ID).Scan(&balance))
+	require.InDelta(t, 98.75, balance, 0.000001)
+}

backend/internal/repository/usage_log_repo.go

@@ -3,12 +3,14 @@ package repository
 import (
 	"context"
 	"database/sql"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	dbent "github.com/Wei-Shaw/sub2api/ent"
@@ -17,11 +19,13 @@ import (
 	dbgroup "github.com/Wei-Shaw/sub2api/ent/group"
 	dbuser "github.com/Wei-Shaw/sub2api/ent/user"
 	dbusersub "github.com/Wei-Shaw/sub2api/ent/usersubscription"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/logger"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/pagination"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/timezone"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/usagestats"
 	"github.com/Wei-Shaw/sub2api/internal/service"
 	"github.com/lib/pq"
+	gocache "github.com/patrickmn/go-cache"
 )
 
 const usageLogSelectColumns = "id, user_id, api_key_id, account_id, request_id, model, group_id, subscription_id, input_tokens, output_tokens, cache_creation_tokens, cache_read_tokens, cache_creation_5m_tokens, cache_creation_1h_tokens, input_cost, output_cost, cache_creation_cost, cache_read_cost, total_cost, actual_cost, rate_multiplier, account_rate_multiplier, billing_type, request_type, stream, openai_ws_mode, duration_ms, first_token_ms, user_agent, ip_address, image_count, image_size, media_type, service_tier, reasoning_effort, cache_ttl_overridden, created_at"
@@ -47,18 +51,29 @@ type usageLogRepository struct {
 	sql    sqlExecutor
 	db     *sql.DB
 
-	createBatchOnce sync.Once
+	createBatchOnce     sync.Once
-	createBatchCh   chan usageLogCreateRequest
+	createBatchCh       chan usageLogCreateRequest
+	bestEffortBatchOnce sync.Once
+	bestEffortBatchCh   chan usageLogBestEffortRequest
+	bestEffortRecent    *gocache.Cache
 }
 
 const (
 	usageLogCreateBatchMaxSize  = 64
 	usageLogCreateBatchWindow   = 3 * time.Millisecond
 	usageLogCreateBatchQueueCap = 4096
+	usageLogCreateCancelWait    = 2 * time.Second
+
+	usageLogBestEffortBatchMaxSize  = 256
+	usageLogBestEffortBatchWindow   = 20 * time.Millisecond
+	usageLogBestEffortBatchQueueCap = 32768
+	usageLogBestEffortRecentTTL     = 30 * time.Second
 )
 
 type usageLogCreateRequest struct {
 	log      *service.UsageLog
+	prepared usageLogInsertPrepared
+	shared   *usageLogCreateShared
 	resultCh chan usageLogCreateResult
 }
 
@@ -67,6 +82,12 @@ type usageLogCreateResult struct {
 	err      error
 }
 
+type usageLogBestEffortRequest struct {
+	prepared usageLogInsertPrepared
+	apiKeyID int64
+	resultCh chan error
+}
+
 type usageLogInsertPrepared struct {
 	createdAt      time.Time
 	requestID      string
@@ -80,6 +101,25 @@ type usageLogBatchState struct {
 	CreatedAt time.Time
 }
 
+type usageLogBatchRow struct {
+	RequestID string    `json:"request_id"`
+	APIKeyID  int64     `json:"api_key_id"`
+	ID        int64     `json:"id"`
+	CreatedAt time.Time `json:"created_at"`
+	Inserted  bool      `json:"inserted"`
+}
+
+type usageLogCreateShared struct {
+	state atomic.Int32
+}
+
+const (
+	usageLogCreateStateQueued int32 = iota
+	usageLogCreateStateProcessing
+	usageLogCreateStateCompleted
+	usageLogCreateStateCanceled
+)
+
 func NewUsageLogRepository(client *dbent.Client, sqlDB *sql.DB) service.UsageLogRepository {
 	return newUsageLogRepositoryWithSQL(client, sqlDB)
 }
@@ -90,6 +130,7 @@ func newUsageLogRepositoryWithSQL(client *dbent.Client, sqlq sqlExecutor) *usage
 	if db, ok := sqlq.(*sql.DB); ok {
 		repo.db = db
 	}
+	repo.bestEffortRecent = gocache.New(usageLogBestEffortRecentTTL, time.Minute)
 	return repo
 }
 
@@ -124,9 +165,6 @@ func (r *usageLogRepository) Create(ctx context.Context, log *service.UsageLog)
 	if tx := dbent.TxFromContext(ctx); tx != nil {
 		return r.createSingle(ctx, tx.Client(), log)
 	}
-	if r.db == nil {
-		return r.createSingle(ctx, r.sql, log)
-	}
 	requestID := strings.TrimSpace(log.RequestID)
 	if requestID == "" {
 		return r.createSingle(ctx, r.sql, log)
@@ -135,11 +173,61 @@ func (r *usageLogRepository) Create(ctx context.Context, log *service.UsageLog)
 	return r.createBatched(ctx, log)
 }
 
+func (r *usageLogRepository) CreateBestEffort(ctx context.Context, log *service.UsageLog) error {
+	if log == nil {
+		return nil
+	}
+
+	if tx := dbent.TxFromContext(ctx); tx != nil {
+		_, err := r.createSingle(ctx, tx.Client(), log)
+		return err
+	}
+	if r.db == nil {
+		_, err := r.createSingle(ctx, r.sql, log)
+		return err
+	}
+
+	r.ensureBestEffortBatcher()
+	if r.bestEffortBatchCh == nil {
+		_, err := r.createSingle(ctx, r.sql, log)
+		return err
+	}
+
+	req := usageLogBestEffortRequest{
+		prepared: prepareUsageLogInsert(log),
+		apiKeyID: log.APIKeyID,
+		resultCh: make(chan error, 1),
+	}
+	if key, ok := r.bestEffortRecentKey(req.prepared.requestID, req.apiKeyID); ok {
+		if _, exists := r.bestEffortRecent.Get(key); exists {
+			return nil
+		}
+	}
+
+	select {
+	case r.bestEffortBatchCh <- req:
+	case <-ctx.Done():
+		return ctx.Err()
+	default:
+		return errors.New("usage log best-effort queue full")
+	}
+
+	select {
+	case err := <-req.resultCh:
+		return err
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
 func (r *usageLogRepository) createSingle(ctx context.Context, sqlq sqlExecutor, log *service.UsageLog) (bool, error) {
 	prepared := prepareUsageLogInsert(log)
 	if sqlq == nil {
 		sqlq = r.sql
 	}
+	if ctx != nil && ctx.Err() != nil {
+		return false, service.MarkUsageLogCreateNotPersisted(ctx.Err())
+	}
 
 	query := `
 		INSERT INTO usage_logs (
@@ -218,13 +306,15 @@ func (r *usageLogRepository) createBatched(ctx context.Context, log *service.Usa
 
 	req := usageLogCreateRequest{
 		log:      log,
+		prepared: prepareUsageLogInsert(log),
+		shared:   &usageLogCreateShared{},
 		resultCh: make(chan usageLogCreateResult, 1),
 	}
 
 	select {
 	case r.createBatchCh <- req:
 	case <-ctx.Done():
-		return false, ctx.Err()
+		return false, service.MarkUsageLogCreateNotPersisted(ctx.Err())
 	default:
 		return r.createSingle(ctx, r.sql, log)
 	}
@@ -233,7 +323,17 @@ func (r *usageLogRepository) createBatched(ctx context.Context, log *service.Usa
 	case res := <-req.resultCh:
 		return res.inserted, res.err
 	case <-ctx.Done():
-		return false, ctx.Err()
+		if req.shared != nil && req.shared.state.CompareAndSwap(usageLogCreateStateQueued, usageLogCreateStateCanceled) {
+			return false, service.MarkUsageLogCreateNotPersisted(ctx.Err())
+		}
+		timer := time.NewTimer(usageLogCreateCancelWait)
+		defer timer.Stop()
+		select {
+		case res := <-req.resultCh:
+			return res.inserted, res.err
+		case <-timer.C:
+			return false, ctx.Err()
+		}
 	}
 }
 
@@ -247,6 +347,16 @@ func (r *usageLogRepository) ensureCreateBatcher() {
 	})
 }
 
+func (r *usageLogRepository) ensureBestEffortBatcher() {
+	if r == nil || r.db == nil {
+		return
+	}
+	r.bestEffortBatchOnce.Do(func() {
+		r.bestEffortBatchCh = make(chan usageLogBestEffortRequest, usageLogBestEffortBatchQueueCap)
+		go r.runBestEffortBatcher(r.db)
+	})
+}
+
 func (r *usageLogRepository) runCreateBatcher(db *sql.DB) {
 	for {
 		first, ok := <-r.createBatchCh
@@ -281,6 +391,40 @@ func (r *usageLogRepository) runCreateBatcher(db *sql.DB) {
 	}
 }
 
+func (r *usageLogRepository) runBestEffortBatcher(db *sql.DB) {
+	for {
+		first, ok := <-r.bestEffortBatchCh
+		if !ok {
+			return
+		}
+
+		batch := make([]usageLogBestEffortRequest, 0, usageLogBestEffortBatchMaxSize)
+		batch = append(batch, first)
+
+		timer := time.NewTimer(usageLogBestEffortBatchWindow)
+	bestEffortLoop:
+		for len(batch) < usageLogBestEffortBatchMaxSize {
+			select {
+			case req, ok := <-r.bestEffortBatchCh:
+				if !ok {
+					break bestEffortLoop
+				}
+				batch = append(batch, req)
+			case <-timer.C:
+				break bestEffortLoop
+			}
+		}
+		if !timer.Stop() {
+			select {
+			case <-timer.C:
+			default:
+			}
+		}
+
+		r.flushBestEffortBatch(db, batch)
+	}
+}
+
 func (r *usageLogRepository) flushCreateBatch(db *sql.DB, batch []usageLogCreateRequest) {
 	if len(batch) == 0 {
 		return
@@ -293,10 +437,19 @@ func (r *usageLogRepository) flushCreateBatch(db *sql.DB, batch []usageLogCreate
 
 	for _, req := range batch {
 		if req.log == nil {
-			sendUsageLogCreateResult(req.resultCh, usageLogCreateResult{inserted: false, err: nil})
+			completeUsageLogCreateRequest(req, usageLogCreateResult{inserted: false, err: nil})
 			continue
 		}
-		prepared := prepareUsageLogInsert(req.log)
+		if req.shared != nil && !req.shared.state.CompareAndSwap(usageLogCreateStateQueued, usageLogCreateStateProcessing) {
+			if req.shared.state.Load() == usageLogCreateStateCanceled {
+				completeUsageLogCreateRequest(req, usageLogCreateResult{
+					inserted: false,
+					err:      service.MarkUsageLogCreateNotPersisted(context.Canceled),
+				})
+				continue
+			}
+		}
+		prepared := req.prepared
 		if prepared.requestID == "" {
 			fallback = append(fallback, req)
 			continue
@@ -310,10 +463,37 @@ func (r *usageLogRepository) flushCreateBatch(db *sql.DB, batch []usageLogCreate
 	}
 
 	if len(uniqueOrder) > 0 {
-		insertedMap, stateMap, err := r.batchInsertUsageLogs(db, uniqueOrder, preparedByKey)
+		insertedMap, stateMap, safeFallback, err := r.batchInsertUsageLogs(db, uniqueOrder, preparedByKey)
 		if err != nil {
-			for _, key := range uniqueOrder {
+			if safeFallback {
-				fallback = append(fallback, requestsByKey[key]...)
+				for _, key := range uniqueOrder {
+					fallback = append(fallback, requestsByKey[key]...)
+				}
+			} else {
+				for _, key := range uniqueOrder {
+					reqs := requestsByKey[key]
+					state, hasState := stateMap[key]
+					inserted := insertedMap[key]
+					for idx, req := range reqs {
+						req.log.RateMultiplier = preparedByKey[key].rateMultiplier
+						if hasState {
+							req.log.ID = state.ID
+							req.log.CreatedAt = state.CreatedAt
+						}
+						switch {
+						case inserted && idx == 0:
+							completeUsageLogCreateRequest(req, usageLogCreateResult{inserted: true, err: nil})
+						case inserted:
+							completeUsageLogCreateRequest(req, usageLogCreateResult{inserted: false, err: nil})
+						case hasState:
+							completeUsageLogCreateRequest(req, usageLogCreateResult{inserted: false, err: nil})
+						case idx == 0:
+							completeUsageLogCreateRequest(req, usageLogCreateResult{inserted: false, err: err})
+						default:
+							completeUsageLogCreateRequest(req, usageLogCreateResult{inserted: false, err: nil})
+						}
+					}
+				}
 			}
 		} else {
 			for _, key := range uniqueOrder {
@@ -321,7 +501,7 @@ func (r *usageLogRepository) flushCreateBatch(db *sql.DB, batch []usageLogCreate
 				state, ok := stateMap[key]
 				if !ok {
 					for _, req := range reqs {
-						sendUsageLogCreateResult(req.resultCh, usageLogCreateResult{
+						completeUsageLogCreateRequest(req, usageLogCreateResult{
 							inserted: false,
 							err:      fmt.Errorf("usage log batch state missing for key=%s", key),
 						})
@@ -332,7 +512,7 @@ func (r *usageLogRepository) flushCreateBatch(db *sql.DB, batch []usageLogCreate
 					req.log.ID = state.ID
 					req.log.CreatedAt = state.CreatedAt
 					req.log.RateMultiplier = preparedByKey[key].rateMultiplier
-					sendUsageLogCreateResult(req.resultCh, usageLogCreateResult{
+					completeUsageLogCreateRequest(req, usageLogCreateResult{
 						inserted: idx == 0 && insertedMap[key],
 						err:      nil,
 					})
@@ -345,56 +525,366 @@ func (r *usageLogRepository) flushCreateBatch(db *sql.DB, batch []usageLogCreate
 		return
 	}
 
-	fallbackCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
-	defer cancel()
 	for _, req := range fallback {
+		fallbackCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 		inserted, err := r.createSingle(fallbackCtx, db, req.log)
-		sendUsageLogCreateResult(req.resultCh, usageLogCreateResult{inserted: inserted, err: err})
+		cancel()
+		completeUsageLogCreateRequest(req, usageLogCreateResult{inserted: inserted, err: err})
 	}
 }
 
-func (r *usageLogRepository) batchInsertUsageLogs(db *sql.DB, keys []string, preparedByKey map[string]usageLogInsertPrepared) (map[string]bool, map[string]usageLogBatchState, error) {
+func (r *usageLogRepository) flushBestEffortBatch(db *sql.DB, batch []usageLogBestEffortRequest) {
+	if len(batch) == 0 {
+		return
+	}
+
+	type bestEffortGroup struct {
+		prepared usageLogInsertPrepared
+		apiKeyID int64
+		key      string
+		reqs     []usageLogBestEffortRequest
+	}
+
+	groupsByKey := make(map[string]*bestEffortGroup, len(batch))
+	groupOrder := make([]*bestEffortGroup, 0, len(batch))
+	preparedList := make([]usageLogInsertPrepared, 0, len(batch))
+
+	for idx, req := range batch {
+		prepared := req.prepared
+		key := fmt.Sprintf("__best_effort_%d", idx)
+		if prepared.requestID != "" {
+			key = usageLogBatchKey(prepared.requestID, req.apiKeyID)
+		}
+		group, exists := groupsByKey[key]
+		if !exists {
+			group = &bestEffortGroup{
+				prepared: prepared,
+				apiKeyID: req.apiKeyID,
+				key:      key,
+			}
+			groupsByKey[key] = group
+			groupOrder = append(groupOrder, group)
+			preparedList = append(preparedList, prepared)
+		}
+		group.reqs = append(group.reqs, req)
+	}
+
+	if len(preparedList) == 0 {
+		for _, req := range batch {
+			sendUsageLogBestEffortResult(req.resultCh, nil)
+		}
+		return
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	query, args := buildUsageLogBestEffortInsertQuery(preparedList)
+	if _, err := db.ExecContext(ctx, query, args...); err != nil {
+		logger.LegacyPrintf("repository.usage_log", "best-effort batch insert failed: %v", err)
+		for _, group := range groupOrder {
+			singleErr := execUsageLogInsertNoResult(ctx, db, group.prepared)
+			if singleErr != nil {
+				logger.LegacyPrintf("repository.usage_log", "best-effort single fallback insert failed: %v", singleErr)
+			} else if group.prepared.requestID != "" && r != nil && r.bestEffortRecent != nil {
+				r.bestEffortRecent.SetDefault(group.key, struct{}{})
+			}
+			for _, req := range group.reqs {
+				sendUsageLogBestEffortResult(req.resultCh, singleErr)
+			}
+		}
+		return
+	}
+	for _, group := range groupOrder {
+		if group.prepared.requestID != "" && r != nil && r.bestEffortRecent != nil {
+			r.bestEffortRecent.SetDefault(group.key, struct{}{})
+		}
+		for _, req := range group.reqs {
+			sendUsageLogBestEffortResult(req.resultCh, nil)
+		}
+	}
+}
+
+func sendUsageLogBestEffortResult(ch chan error, err error) {
+	if ch == nil {
+		return
+	}
+	select {
+	case ch <- err:
+	default:
+	}
+}
+
+func completeUsageLogCreateRequest(req usageLogCreateRequest, res usageLogCreateResult) {
+	if req.shared != nil {
+		req.shared.state.Store(usageLogCreateStateCompleted)
+	}
+	sendUsageLogCreateResult(req.resultCh, res)
+}
+
+func (r *usageLogRepository) batchInsertUsageLogs(db *sql.DB, keys []string, preparedByKey map[string]usageLogInsertPrepared) (map[string]bool, map[string]usageLogBatchState, bool, error) {
 	if len(keys) == 0 {
-		return map[string]bool{}, map[string]usageLogBatchState{}, nil
+		return map[string]bool{}, map[string]usageLogBatchState{}, false, nil
 	}
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 
 	query, args := buildUsageLogBatchInsertQuery(keys, preparedByKey)
-	rows, err := db.QueryContext(ctx, query, args...)
+	var payload []byte
-	if err != nil {
+	if err := db.QueryRowContext(ctx, query, args...).Scan(&payload); err != nil {
-		return nil, nil, err
+		return nil, nil, true, err
+	}
+	var rows []usageLogBatchRow
+	if err := json.Unmarshal(payload, &rows); err != nil {
+		return nil, nil, false, err
 	}
 	insertedMap := make(map[string]bool, len(keys))
-	for rows.Next() {
+	stateMap := make(map[string]usageLogBatchState, len(keys))
-		var (
+	for _, row := range rows {
-			requestID string
+		key := usageLogBatchKey(row.RequestID, row.APIKeyID)
-			apiKeyID  int64
+		insertedMap[key] = row.Inserted
-			id        int64
+		stateMap[key] = usageLogBatchState{
-			createdAt time.Time
+			ID:        row.ID,
-		)
+			CreatedAt: row.CreatedAt,
-		if err := rows.Scan(&requestID, &apiKeyID, &id, &createdAt); err != nil {
-			_ = rows.Close()
-			return nil, nil, err
 		}
-		insertedMap[usageLogBatchKey(requestID, apiKeyID)] = true
 	}
-	if err := rows.Err(); err != nil {
+	if len(stateMap) != len(keys) {
-		_ = rows.Close()
+		return insertedMap, stateMap, false, fmt.Errorf("usage log batch state count mismatch: got=%d want=%d", len(stateMap), len(keys))
-		return nil, nil, err
 	}
-	_ = rows.Close()
+	return insertedMap, stateMap, false, nil
-
-	stateMap, err := loadUsageLogBatchStates(ctx, db, keys, preparedByKey)
-	if err != nil {
-		return nil, nil, err
-	}
-	return insertedMap, stateMap, nil
 }
 
 func buildUsageLogBatchInsertQuery(keys []string, preparedByKey map[string]usageLogInsertPrepared) (string, []any) {
 	var query strings.Builder
 	_, _ = query.WriteString(`
+		WITH input (
+			input_idx,
+			user_id,
+			api_key_id,
+			account_id,
+			request_id,
+			model,
+			group_id,
+			subscription_id,
+			input_tokens,
+			output_tokens,
+			cache_creation_tokens,
+			cache_read_tokens,
+			cache_creation_5m_tokens,
+			cache_creation_1h_tokens,
+			input_cost,
+			output_cost,
+			cache_creation_cost,
+			cache_read_cost,
+			total_cost,
+			actual_cost,
+			rate_multiplier,
+			account_rate_multiplier,
+			billing_type,
+			request_type,
+			stream,
+			openai_ws_mode,
+			duration_ms,
+			first_token_ms,
+			user_agent,
+			ip_address,
+			image_count,
+			image_size,
+			media_type,
+			service_tier,
+			reasoning_effort,
+			cache_ttl_overridden,
+			created_at
+		) AS (VALUES `)
+
+	args := make([]any, 0, len(keys)*37)
+	argPos := 1
+	for idx, key := range keys {
+		if idx > 0 {
+			_, _ = query.WriteString(",")
+		}
+		_, _ = query.WriteString("(")
+		_, _ = query.WriteString("$")
+		_, _ = query.WriteString(strconv.Itoa(argPos))
+		args = append(args, idx)
+		argPos++
+		prepared := preparedByKey[key]
+		for i := 0; i < len(prepared.args); i++ {
+			_, _ = query.WriteString(",")
+			_, _ = query.WriteString("$")
+			_, _ = query.WriteString(strconv.Itoa(argPos))
+			argPos++
+		}
+		_, _ = query.WriteString(")")
+		args = append(args, prepared.args...)
+	}
+	_, _ = query.WriteString(`
+		),
+		inserted AS (
+			INSERT INTO usage_logs (
+				user_id,
+				api_key_id,
+				account_id,
+				request_id,
+				model,
+				group_id,
+				subscription_id,
+				input_tokens,
+				output_tokens,
+				cache_creation_tokens,
+				cache_read_tokens,
+				cache_creation_5m_tokens,
+				cache_creation_1h_tokens,
+				input_cost,
+				output_cost,
+				cache_creation_cost,
+				cache_read_cost,
+				total_cost,
+				actual_cost,
+				rate_multiplier,
+				account_rate_multiplier,
+				billing_type,
+				request_type,
+				stream,
+				openai_ws_mode,
+				duration_ms,
+				first_token_ms,
+				user_agent,
+				ip_address,
+				image_count,
+				image_size,
+				media_type,
+				service_tier,
+				reasoning_effort,
+				cache_ttl_overridden,
+				created_at
+			)
+			SELECT
+				user_id,
+				api_key_id,
+				account_id,
+				request_id,
+				model,
+				group_id,
+				subscription_id,
+				input_tokens,
+				output_tokens,
+				cache_creation_tokens,
+				cache_read_tokens,
+				cache_creation_5m_tokens,
+				cache_creation_1h_tokens,
+				input_cost,
+				output_cost,
+				cache_creation_cost,
+				cache_read_cost,
+				total_cost,
+				actual_cost,
+				rate_multiplier,
+				account_rate_multiplier,
+				billing_type,
+				request_type,
+				stream,
+				openai_ws_mode,
+				duration_ms,
+				first_token_ms,
+				user_agent,
+				ip_address,
+				image_count,
+				image_size,
+				media_type,
+				service_tier,
+				reasoning_effort,
+				cache_ttl_overridden,
+				created_at
+			FROM input
+			ON CONFLICT (request_id, api_key_id) DO UPDATE
+			SET request_id = usage_logs.request_id
+			RETURNING request_id, api_key_id, id, created_at, (xmax = 0) AS inserted
+		)
+		SELECT COALESCE(
+			json_agg(
+				json_build_object(
+					'request_id', inserted.request_id,
+					'api_key_id', inserted.api_key_id,
+					'id', inserted.id,
+					'created_at', inserted.created_at,
+					'inserted', inserted.inserted
+				)
+				ORDER BY input.input_idx
+			),
+			'[]'::json
+		)
+		FROM input
+		JOIN inserted
+			ON inserted.request_id = input.request_id
+			AND inserted.api_key_id = input.api_key_id
+	`)
+	return query.String(), args
+}
+
+func buildUsageLogBestEffortInsertQuery(preparedList []usageLogInsertPrepared) (string, []any) {
+	var query strings.Builder
+	_, _ = query.WriteString(`
+		WITH input (
+			user_id,
+			api_key_id,
+			account_id,
+			request_id,
+			model,
+			group_id,
+			subscription_id,
+			input_tokens,
+			output_tokens,
+			cache_creation_tokens,
+			cache_read_tokens,
+			cache_creation_5m_tokens,
+			cache_creation_1h_tokens,
+			input_cost,
+			output_cost,
+			cache_creation_cost,
+			cache_read_cost,
+			total_cost,
+			actual_cost,
+			rate_multiplier,
+			account_rate_multiplier,
+			billing_type,
+			request_type,
+			stream,
+			openai_ws_mode,
+			duration_ms,
+			first_token_ms,
+			user_agent,
+			ip_address,
+			image_count,
+			image_size,
+			media_type,
+			service_tier,
+			reasoning_effort,
+			cache_ttl_overridden,
+			created_at
+		) AS (VALUES `)
+
+	args := make([]any, 0, len(preparedList)*36)
+	argPos := 1
+	for idx, prepared := range preparedList {
+		if idx > 0 {
+			_, _ = query.WriteString(",")
+		}
+		_, _ = query.WriteString("(")
+		for i := 0; i < len(prepared.args); i++ {
+			if i > 0 {
+				_, _ = query.WriteString(",")
+			}
+			_, _ = query.WriteString("$")
+			_, _ = query.WriteString(strconv.Itoa(argPos))
+			argPos++
+		}
+		_, _ = query.WriteString(")")
+		args = append(args, prepared.args...)
+	}
+
+	_, _ = query.WriteString(`
+		)
 		INSERT INTO usage_logs (
 			user_id,
 			api_key_id,
@@ -432,80 +922,101 @@ func buildUsageLogBatchInsertQuery(keys []string, preparedByKey map[string]usage
 			reasoning_effort,
 			cache_ttl_overridden,
 			created_at
-		) VALUES `)
+		)
-
+		SELECT
-	args := make([]any, 0, len(keys)*36)
+			user_id,
-	argPos := 1
+			api_key_id,
-	for idx, key := range keys {
+			account_id,
-		if idx > 0 {
+			request_id,
-			_, _ = query.WriteString(",")
+			model,
-		}
+			group_id,
-		_, _ = query.WriteString("(")
+			subscription_id,
-		prepared := preparedByKey[key]
+			input_tokens,
-		for i := 0; i < len(prepared.args); i++ {
+			output_tokens,
-			if i > 0 {
+			cache_creation_tokens,
-				_, _ = query.WriteString(",")
+			cache_read_tokens,
-			}
+			cache_creation_5m_tokens,
-			_, _ = query.WriteString("$")
+			cache_creation_1h_tokens,
-			_, _ = query.WriteString(strconv.Itoa(argPos))
+			input_cost,
-			argPos++
+			output_cost,
-		}
+			cache_creation_cost,
-		_, _ = query.WriteString(")")
+			cache_read_cost,
-		args = append(args, prepared.args...)
+			total_cost,
-	}
+			actual_cost,
-	_, _ = query.WriteString(`
+			rate_multiplier,
+			account_rate_multiplier,
+			billing_type,
+			request_type,
+			stream,
+			openai_ws_mode,
+			duration_ms,
+			first_token_ms,
+			user_agent,
+			ip_address,
+			image_count,
+			image_size,
+			media_type,
+			service_tier,
+			reasoning_effort,
+			cache_ttl_overridden,
+			created_at
+		FROM input
 		ON CONFLICT (request_id, api_key_id) DO NOTHING
-		RETURNING request_id, api_key_id, id, created_at
 	`)
+
 	return query.String(), args
 }
 
-func loadUsageLogBatchStates(ctx context.Context, db *sql.DB, keys []string, preparedByKey map[string]usageLogInsertPrepared) (map[string]usageLogBatchState, error) {
+func execUsageLogInsertNoResult(ctx context.Context, sqlq sqlExecutor, prepared usageLogInsertPrepared) error {
-	var query strings.Builder
+	_, err := sqlq.ExecContext(ctx, `
-	_, _ = query.WriteString(`SELECT request_id, api_key_id, id, created_at FROM usage_logs WHERE `)
+		INSERT INTO usage_logs (
-	args := make([]any, 0, len(keys)*2)
+			user_id,
-	argPos := 1
+			api_key_id,
-	for idx, key := range keys {
+			account_id,
-		if idx > 0 {
+			request_id,
-			_, _ = query.WriteString(" OR ")
+			model,
-		}
+			group_id,
-		prepared := preparedByKey[key]
+			subscription_id,
-		apiKeyID := prepared.args[1]
+			input_tokens,
-		_, _ = query.WriteString("(request_id = $")
+			output_tokens,
-		_, _ = query.WriteString(strconv.Itoa(argPos))
+			cache_creation_tokens,
-		_, _ = query.WriteString(" AND api_key_id = $")
+			cache_read_tokens,
-		_, _ = query.WriteString(strconv.Itoa(argPos + 1))
+			cache_creation_5m_tokens,
-		_, _ = query.WriteString(")")
+			cache_creation_1h_tokens,
-		args = append(args, prepared.requestID, apiKeyID)
+			input_cost,
-		argPos += 2
+			output_cost,
-	}
+			cache_creation_cost,
-
+			cache_read_cost,
-	rows, err := db.QueryContext(ctx, query.String(), args...)
+			total_cost,
-	if err != nil {
+			actual_cost,
-		return nil, err
+			rate_multiplier,
-	}
+			account_rate_multiplier,
-	defer func() { _ = rows.Close() }()
+			billing_type,
-
+			request_type,
-	stateMap := make(map[string]usageLogBatchState, len(keys))
+			stream,
-	for rows.Next() {
+			openai_ws_mode,
-		var (
+			duration_ms,
-			requestID string
+			first_token_ms,
-			apiKeyID  int64
+			user_agent,
-			id        int64
+			ip_address,
-			createdAt time.Time
+			image_count,
+			image_size,
+			media_type,
+			service_tier,
+			reasoning_effort,
+			cache_ttl_overridden,
+			created_at
+		) VALUES (
+			$1, $2, $3, $4, $5,
+			$6, $7,
+			$8, $9, $10, $11,
+			$12, $13,
+			$14, $15, $16, $17, $18, $19,
+			$20, $21, $22, $23, $24, $25, $26, $27, $28, $29, $30, $31, $32, $33, $34, $35, $36
 		)
-		if err := rows.Scan(&requestID, &apiKeyID, &id, &createdAt); err != nil {
+		ON CONFLICT (request_id, api_key_id) DO NOTHING
-			return nil, err
+	`, prepared.args...)
-		}
+	return err
-		stateMap[usageLogBatchKey(requestID, apiKeyID)] = usageLogBatchState{
-			ID:        id,
-			CreatedAt: createdAt,
-		}
-	}
-	if err := rows.Err(); err != nil {
-		return nil, err
-	}
-	return stateMap, nil
 }
 
 func prepareUsageLogInsert(log *service.UsageLog) usageLogInsertPrepared {
@@ -597,6 +1108,14 @@ func sendUsageLogCreateResult(ch chan usageLogCreateResult, res usageLogCreateRe
 	}
 }
 
+func (r *usageLogRepository) bestEffortRecentKey(requestID string, apiKeyID int64) (string, bool) {
+	requestID = strings.TrimSpace(requestID)
+	if requestID == "" || r == nil || r.bestEffortRecent == nil {
+		return "", false
+	}
+	return usageLogBatchKey(requestID, apiKeyID), true
+}
+
 func (r *usageLogRepository) GetByID(ctx context.Context, id int64) (log *service.UsageLog, err error) {
 	query := "SELECT " + usageLogSelectColumns + " FROM usage_logs WHERE id = $1"
 	rows, err := r.sql.QueryContext(ctx, query, id)

backend/internal/repository/usage_log_repo_integration_test.go

@@ -183,6 +183,214 @@ func TestUsageLogRepositoryCreate_BatchPathDuplicateRequestID(t *testing.T) {
 	require.Equal(t, 1, count)
 }
 
+func TestUsageLogRepositoryFlushCreateBatch_DeduplicatesSameKeyInMemory(t *testing.T) {
+	ctx := context.Background()
+	client := testEntClient(t)
+	repo := newUsageLogRepositoryWithSQL(client, integrationDB)
+
+	user := mustCreateUser(t, client, &service.User{Email: fmt.Sprintf("usage-batch-memdup-%d@example.com", time.Now().UnixNano())})
+	apiKey := mustCreateApiKey(t, client, &service.APIKey{UserID: user.ID, Key: "sk-usage-batch-memdup-" + uuid.NewString(), Name: "k"})
+	account := mustCreateAccount(t, client, &service.Account{Name: "acc-usage-batch-memdup-" + uuid.NewString()})
+	requestID := uuid.NewString()
+
+	const total = 8
+	batch := make([]usageLogCreateRequest, 0, total)
+	logs := make([]*service.UsageLog, 0, total)
+
+	for i := 0; i < total; i++ {
+		log := &service.UsageLog{
+			UserID:       user.ID,
+			APIKeyID:     apiKey.ID,
+			AccountID:    account.ID,
+			RequestID:    requestID,
+			Model:        "claude-3",
+			InputTokens:  10 + i,
+			OutputTokens: 20 + i,
+			TotalCost:    0.5,
+			ActualCost:   0.5,
+			CreatedAt:    time.Now().UTC(),
+		}
+		logs = append(logs, log)
+		batch = append(batch, usageLogCreateRequest{
+			log:      log,
+			prepared: prepareUsageLogInsert(log),
+			resultCh: make(chan usageLogCreateResult, 1),
+		})
+	}
+
+	repo.flushCreateBatch(integrationDB, batch)
+
+	insertedCount := 0
+	var firstID int64
+	for idx, req := range batch {
+		res := <-req.resultCh
+		require.NoError(t, res.err)
+		if res.inserted {
+			insertedCount++
+		}
+		require.NotZero(t, logs[idx].ID)
+		if idx == 0 {
+			firstID = logs[idx].ID
+		} else {
+			require.Equal(t, firstID, logs[idx].ID)
+		}
+	}
+
+	require.Equal(t, 1, insertedCount)
+
+	var count int
+	require.NoError(t, integrationDB.QueryRowContext(ctx, "SELECT COUNT(*) FROM usage_logs WHERE request_id = $1 AND api_key_id = $2", requestID, apiKey.ID).Scan(&count))
+	require.Equal(t, 1, count)
+}
+
+func TestUsageLogRepositoryCreateBestEffort_BatchPathDuplicateRequestID(t *testing.T) {
+	ctx := context.Background()
+	client := testEntClient(t)
+	repo := newUsageLogRepositoryWithSQL(client, integrationDB)
+
+	user := mustCreateUser(t, client, &service.User{Email: fmt.Sprintf("usage-best-effort-dup-%d@example.com", time.Now().UnixNano())})
+	apiKey := mustCreateApiKey(t, client, &service.APIKey{UserID: user.ID, Key: "sk-usage-best-effort-dup-" + uuid.NewString(), Name: "k"})
+	account := mustCreateAccount(t, client, &service.Account{Name: "acc-usage-best-effort-dup-" + uuid.NewString()})
+	requestID := uuid.NewString()
+
+	log1 := &service.UsageLog{
+		UserID:       user.ID,
+		APIKeyID:     apiKey.ID,
+		AccountID:    account.ID,
+		RequestID:    requestID,
+		Model:        "claude-3",
+		InputTokens:  10,
+		OutputTokens: 20,
+		TotalCost:    0.5,
+		ActualCost:   0.5,
+		CreatedAt:    time.Now().UTC(),
+	}
+	log2 := &service.UsageLog{
+		UserID:       user.ID,
+		APIKeyID:     apiKey.ID,
+		AccountID:    account.ID,
+		RequestID:    requestID,
+		Model:        "claude-3",
+		InputTokens:  10,
+		OutputTokens: 20,
+		TotalCost:    0.5,
+		ActualCost:   0.5,
+		CreatedAt:    time.Now().UTC(),
+	}
+
+	require.NoError(t, repo.CreateBestEffort(ctx, log1))
+	require.NoError(t, repo.CreateBestEffort(ctx, log2))
+
+	require.Eventually(t, func() bool {
+		var count int
+		err := integrationDB.QueryRowContext(ctx, "SELECT COUNT(*) FROM usage_logs WHERE request_id = $1 AND api_key_id = $2", requestID, apiKey.ID).Scan(&count)
+		return err == nil && count == 1
+	}, 3*time.Second, 20*time.Millisecond)
+}
+
+func TestUsageLogRepositoryCreate_BatchPathCanceledContextMarksNotPersisted(t *testing.T) {
+	client := testEntClient(t)
+	repo := newUsageLogRepositoryWithSQL(client, integrationDB)
+
+	user := mustCreateUser(t, client, &service.User{Email: fmt.Sprintf("usage-cancel-%d@example.com", time.Now().UnixNano())})
+	apiKey := mustCreateApiKey(t, client, &service.APIKey{UserID: user.ID, Key: "sk-usage-cancel-" + uuid.NewString(), Name: "k"})
+	account := mustCreateAccount(t, client, &service.Account{Name: "acc-usage-cancel-" + uuid.NewString()})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	inserted, err := repo.Create(ctx, &service.UsageLog{
+		UserID:       user.ID,
+		APIKeyID:     apiKey.ID,
+		AccountID:    account.ID,
+		RequestID:    uuid.NewString(),
+		Model:        "claude-3",
+		InputTokens:  10,
+		OutputTokens: 20,
+		TotalCost:    0.5,
+		ActualCost:   0.5,
+		CreatedAt:    time.Now().UTC(),
+	})
+
+	require.False(t, inserted)
+	require.Error(t, err)
+	require.True(t, service.IsUsageLogCreateNotPersisted(err))
+}
+
+func TestUsageLogRepositoryCreate_BatchPathCanceledAfterQueueMarksNotPersisted(t *testing.T) {
+	client := testEntClient(t)
+	repo := newUsageLogRepositoryWithSQL(client, integrationDB)
+	repo.createBatchCh = make(chan usageLogCreateRequest, 1)
+
+	user := mustCreateUser(t, client, &service.User{Email: fmt.Sprintf("usage-cancel-queued-%d@example.com", time.Now().UnixNano())})
+	apiKey := mustCreateApiKey(t, client, &service.APIKey{UserID: user.ID, Key: "sk-usage-cancel-queued-" + uuid.NewString(), Name: "k"})
+	account := mustCreateAccount(t, client, &service.Account{Name: "acc-usage-cancel-queued-" + uuid.NewString()})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	errCh := make(chan error, 1)
+
+	go func() {
+		_, err := repo.createBatched(ctx, &service.UsageLog{
+			UserID:       user.ID,
+			APIKeyID:     apiKey.ID,
+			AccountID:    account.ID,
+			RequestID:    uuid.NewString(),
+			Model:        "claude-3",
+			InputTokens:  10,
+			OutputTokens: 20,
+			TotalCost:    0.5,
+			ActualCost:   0.5,
+			CreatedAt:    time.Now().UTC(),
+		})
+		errCh <- err
+	}()
+
+	req := <-repo.createBatchCh
+	require.NotNil(t, req.shared)
+	cancel()
+
+	err := <-errCh
+	require.Error(t, err)
+	require.True(t, service.IsUsageLogCreateNotPersisted(err))
+	completeUsageLogCreateRequest(req, usageLogCreateResult{inserted: false, err: service.MarkUsageLogCreateNotPersisted(context.Canceled)})
+}
+
+func TestUsageLogRepositoryFlushCreateBatch_CanceledRequestReturnsNotPersisted(t *testing.T) {
+	client := testEntClient(t)
+	repo := newUsageLogRepositoryWithSQL(client, integrationDB)
+
+	user := mustCreateUser(t, client, &service.User{Email: fmt.Sprintf("usage-flush-cancel-%d@example.com", time.Now().UnixNano())})
+	apiKey := mustCreateApiKey(t, client, &service.APIKey{UserID: user.ID, Key: "sk-usage-flush-cancel-" + uuid.NewString(), Name: "k"})
+	account := mustCreateAccount(t, client, &service.Account{Name: "acc-usage-flush-cancel-" + uuid.NewString()})
+
+	log := &service.UsageLog{
+		UserID:       user.ID,
+		APIKeyID:     apiKey.ID,
+		AccountID:    account.ID,
+		RequestID:    uuid.NewString(),
+		Model:        "claude-3",
+		InputTokens:  10,
+		OutputTokens: 20,
+		TotalCost:    0.5,
+		ActualCost:   0.5,
+		CreatedAt:    time.Now().UTC(),
+	}
+	req := usageLogCreateRequest{
+		log:      log,
+		prepared: prepareUsageLogInsert(log),
+		shared:   &usageLogCreateShared{},
+		resultCh: make(chan usageLogCreateResult, 1),
+	}
+	req.shared.state.Store(usageLogCreateStateCanceled)
+
+	repo.flushCreateBatch(integrationDB, []usageLogCreateRequest{req})
+
+	res := <-req.resultCh
+	require.False(t, res.inserted)
+	require.Error(t, res.err)
+	require.True(t, service.IsUsageLogCreateNotPersisted(res.err))
+}
+
 func (s *UsageLogRepoSuite) TestGetByID() {
 	user := mustCreateUser(s.T(), s.client, &service.User{Email: "getbyid@test.com"})
 	apiKey := mustCreateApiKey(s.T(), s.client, &service.APIKey{UserID: user.ID, Key: "sk-getbyid", Name: "k"})

backend/internal/repository/wire.go

@@ -62,6 +62,7 @@ var ProviderSet = wire.NewSet(
 	NewAnnouncementRepository,
 	NewAnnouncementReadRepository,
 	NewUsageLogRepository,
+	NewUsageBillingRepository,
 	NewIdempotencyRepository,
 	NewUsageCleanupRepository,
 	NewDashboardAggregationRepository,

backend/internal/service/dashboard_aggregation_service.go

@@ -35,6 +35,7 @@ type DashboardAggregationRepository interface {
 	UpdateAggregationWatermark(ctx context.Context, aggregatedAt time.Time) error
 	CleanupAggregates(ctx context.Context, hourlyCutoff, dailyCutoff time.Time) error
 	CleanupUsageLogs(ctx context.Context, cutoff time.Time) error
+	CleanupUsageBillingDedup(ctx context.Context, cutoff time.Time) error
 	EnsureUsageLogsPartitions(ctx context.Context, now time.Time) error
 }
 
@@ -296,6 +297,7 @@ func (s *DashboardAggregationService) maybeCleanupRetention(ctx context.Context,
 	hourlyCutoff := now.AddDate(0, 0, -s.cfg.Retention.HourlyDays)
 	dailyCutoff := now.AddDate(0, 0, -s.cfg.Retention.DailyDays)
 	usageCutoff := now.AddDate(0, 0, -s.cfg.Retention.UsageLogsDays)
+	dedupCutoff := now.AddDate(0, 0, -s.cfg.Retention.UsageBillingDedupDays)
 
 	aggErr := s.repo.CleanupAggregates(ctx, hourlyCutoff, dailyCutoff)
 	if aggErr != nil {
@@ -305,7 +307,11 @@ func (s *DashboardAggregationService) maybeCleanupRetention(ctx context.Context,
 	if usageErr != nil {
 		logger.LegacyPrintf("service.dashboard_aggregation", "[DashboardAggregation] usage_logs 保留清理失败: %v", usageErr)
 	}
-	if aggErr == nil && usageErr == nil {
+	dedupErr := s.repo.CleanupUsageBillingDedup(ctx, dedupCutoff)
+	if dedupErr != nil {
+		logger.LegacyPrintf("service.dashboard_aggregation", "[DashboardAggregation] usage_billing_dedup 保留清理失败: %v", dedupErr)
+	}
+	if aggErr == nil && usageErr == nil && dedupErr == nil {
 		s.lastRetentionCleanup.Store(now)
 	}
 }

backend/internal/service/dashboard_aggregation_service_test.go

@@ -12,12 +12,18 @@ import (
 
 type dashboardAggregationRepoTestStub struct {
 	aggregateCalls       int
+	recomputeCalls       int
+	cleanupUsageCalls    int
+	cleanupDedupCalls    int
+	ensurePartitionCalls int
 	lastStart            time.Time
 	lastEnd              time.Time
 	watermark            time.Time
 	aggregateErr         error
 	cleanupAggregatesErr error
 	cleanupUsageErr      error
+	cleanupDedupErr      error
+	ensurePartitionErr   error
 }
 
 func (s *dashboardAggregationRepoTestStub) AggregateRange(ctx context.Context, start, end time.Time) error {
@@ -28,6 +34,7 @@ func (s *dashboardAggregationRepoTestStub) AggregateRange(ctx context.Context, s
 }
 
 func (s *dashboardAggregationRepoTestStub) RecomputeRange(ctx context.Context, start, end time.Time) error {
+	s.recomputeCalls++
 	return s.AggregateRange(ctx, start, end)
 }
 
@@ -44,11 +51,18 @@ func (s *dashboardAggregationRepoTestStub) CleanupAggregates(ctx context.Context
 }
 
 func (s *dashboardAggregationRepoTestStub) CleanupUsageLogs(ctx context.Context, cutoff time.Time) error {
+	s.cleanupUsageCalls++
 	return s.cleanupUsageErr
 }
 
+func (s *dashboardAggregationRepoTestStub) CleanupUsageBillingDedup(ctx context.Context, cutoff time.Time) error {
+	s.cleanupDedupCalls++
+	return s.cleanupDedupErr
+}
+
 func (s *dashboardAggregationRepoTestStub) EnsureUsageLogsPartitions(ctx context.Context, now time.Time) error {
-	return nil
+	s.ensurePartitionCalls++
+	return s.ensurePartitionErr
 }
 
 func TestDashboardAggregationService_RunScheduledAggregation_EpochUsesRetentionStart(t *testing.T) {
@@ -90,6 +104,50 @@ func TestDashboardAggregationService_CleanupRetentionFailure_DoesNotRecord(t *te
 	svc.maybeCleanupRetention(context.Background(), time.Now().UTC())
 
 	require.Nil(t, svc.lastRetentionCleanup.Load())
+	require.Equal(t, 1, repo.cleanupUsageCalls)
+	require.Equal(t, 1, repo.cleanupDedupCalls)
+}
+
+func TestDashboardAggregationService_CleanupDedupFailure_DoesNotRecord(t *testing.T) {
+	repo := &dashboardAggregationRepoTestStub{cleanupDedupErr: errors.New("dedup cleanup failed")}
+	svc := &DashboardAggregationService{
+		repo: repo,
+		cfg: config.DashboardAggregationConfig{
+			Retention: config.DashboardAggregationRetentionConfig{
+				UsageLogsDays: 1,
+				HourlyDays:    1,
+				DailyDays:     1,
+			},
+		},
+	}
+
+	svc.maybeCleanupRetention(context.Background(), time.Now().UTC())
+
+	require.Nil(t, svc.lastRetentionCleanup.Load())
+	require.Equal(t, 1, repo.cleanupDedupCalls)
+}
+
+func TestDashboardAggregationService_PartitionFailure_DoesNotAggregate(t *testing.T) {
+	repo := &dashboardAggregationRepoTestStub{ensurePartitionErr: errors.New("partition failed")}
+	svc := &DashboardAggregationService{
+		repo: repo,
+		cfg: config.DashboardAggregationConfig{
+			Enabled:         true,
+			IntervalSeconds: 60,
+			LookbackSeconds: 120,
+			Retention: config.DashboardAggregationRetentionConfig{
+				UsageLogsDays:         1,
+				UsageBillingDedupDays: 2,
+				HourlyDays:            1,
+				DailyDays:             1,
+			},
+		},
+	}
+
+	svc.runScheduledAggregation()
+
+	require.Equal(t, 1, repo.ensurePartitionCalls)
+	require.Equal(t, 1, repo.aggregateCalls)
 }
 
 func TestDashboardAggregationService_TriggerBackfill_TooLarge(t *testing.T) {

backend/internal/service/dashboard_service_test.go

@@ -124,6 +124,10 @@ func (s *dashboardAggregationRepoStub) CleanupUsageLogs(ctx context.Context, cut
 	return nil
 }
 
+func (s *dashboardAggregationRepoStub) CleanupUsageBillingDedup(ctx context.Context, cutoff time.Time) error {
+	return nil
+}
+
 func (s *dashboardAggregationRepoStub) EnsureUsageLogsPartitions(ctx context.Context, now time.Time) error {
 	return nil
 }

backend/internal/service/gateway_anthropic_apikey_passthrough_test.go

@@ -136,16 +136,18 @@ func TestGatewayService_AnthropicAPIKeyPassthrough_ForwardStreamPreservesBodyAnd
 		},
 	}
 
-	svc := &GatewayService{
+	cfg := &config.Config{
-		cfg: &config.Config{
+		Gateway: config.GatewayConfig{
-			Gateway: config.GatewayConfig{
+			MaxLineSize: defaultMaxLineSize,
-				MaxLineSize: defaultMaxLineSize,
-			},
 		},
-		httpUpstream:        upstream,
+	}
-		rateLimitService:    &RateLimitService{},
+	svc := &GatewayService{
-		deferredService:     &DeferredService{},
+		cfg:                  cfg,
-		billingCacheService: nil,
+		responseHeaderFilter: compileResponseHeaderFilter(cfg),
+		httpUpstream:         upstream,
+		rateLimitService:     &RateLimitService{},
+		deferredService:      &DeferredService{},
+		billingCacheService:  nil,
 	}
 
 	account := &Account{
@@ -221,14 +223,16 @@ func TestGatewayService_AnthropicAPIKeyPassthrough_ForwardCountTokensPreservesBo
 		},
 	}
 
-	svc := &GatewayService{
+	cfg := &config.Config{
-		cfg: &config.Config{
+		Gateway: config.GatewayConfig{
-			Gateway: config.GatewayConfig{
+			MaxLineSize: defaultMaxLineSize,
-				MaxLineSize: defaultMaxLineSize,
-			},
 		},
-		httpUpstream:     upstream,
+	}
-		rateLimitService: &RateLimitService{},
+	svc := &GatewayService{
+		cfg:                  cfg,
+		responseHeaderFilter: compileResponseHeaderFilter(cfg),
+		httpUpstream:         upstream,
+		rateLimitService:     &RateLimitService{},
 	}
 
 	account := &Account{
@@ -727,6 +731,39 @@ func TestGatewayService_AnthropicAPIKeyPassthrough_StreamingStillCollectsUsageAf
 	require.Equal(t, 5, result.usage.OutputTokens)
 }
 
+func TestGatewayService_AnthropicAPIKeyPassthrough_MissingTerminalEventReturnsError(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+	c.Request = httptest.NewRequest(http.MethodPost, "/v1/messages", nil)
+
+	svc := &GatewayService{
+		cfg: &config.Config{
+			Gateway: config.GatewayConfig{
+				MaxLineSize: defaultMaxLineSize,
+			},
+		},
+		rateLimitService: &RateLimitService{},
+	}
+
+	resp := &http.Response{
+		StatusCode: http.StatusOK,
+		Header:     http.Header{"Content-Type": []string{"text/event-stream"}},
+		Body: io.NopCloser(strings.NewReader(strings.Join([]string{
+			`data: {"type":"message_start","message":{"usage":{"input_tokens":11}}}`,
+			"",
+			`data: {"type":"message_delta","usage":{"output_tokens":5}}`,
+			"",
+		}, "\n"))),
+	}
+
+	result, err := svc.handleStreamingResponseAnthropicAPIKeyPassthrough(context.Background(), resp, c, &Account{ID: 1}, time.Now(), "claude-3-7-sonnet-20250219")
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "missing terminal event")
+	require.NotNil(t, result)
+}
+
 func TestGatewayService_AnthropicAPIKeyPassthrough_ForwardDirect_NonStreamingSuccess(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	rec := httptest.NewRecorder()
@@ -1074,7 +1111,8 @@ func TestGatewayService_AnthropicAPIKeyPassthrough_StreamingTimeoutAfterClientDi
 	_ = pr.Close()
 	<-done
 
-	require.NoError(t, err)
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "stream usage incomplete after timeout")
 	require.NotNil(t, result)
 	require.True(t, result.clientDisconnect)
 	require.Equal(t, 9, result.usage.InputTokens)
@@ -1103,7 +1141,8 @@ func TestGatewayService_AnthropicAPIKeyPassthrough_StreamingContextCanceled(t *t
 	}
 
 	result, err := svc.handleStreamingResponseAnthropicAPIKeyPassthrough(context.Background(), resp, c, &Account{ID: 3}, time.Now(), "claude-3-7-sonnet-20250219")
-	require.NoError(t, err)
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "stream usage incomplete")
 	require.NotNil(t, result)
 	require.True(t, result.clientDisconnect)
 }
@@ -1133,7 +1172,8 @@ func TestGatewayService_AnthropicAPIKeyPassthrough_StreamingUpstreamReadErrorAft
 	}
 
 	result, err := svc.handleStreamingResponseAnthropicAPIKeyPassthrough(context.Background(), resp, c, &Account{ID: 4}, time.Now(), "claude-3-7-sonnet-20250219")
-	require.NoError(t, err)
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "stream usage incomplete after disconnect")
 	require.NotNil(t, result)
 	require.True(t, result.clientDisconnect)
 	require.Equal(t, 8, result.usage.InputTokens)

backend/internal/service/gateway_record_usage_test.go

@@ -0,0 +1,261 @@
+//go:build unit
+
+package service
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/ctxkey"
+	"github.com/stretchr/testify/require"
+)
+
+func newGatewayRecordUsageServiceForTest(usageRepo UsageLogRepository, userRepo UserRepository, subRepo UserSubscriptionRepository) *GatewayService {
+	cfg := &config.Config{}
+	cfg.Default.RateMultiplier = 1.1
+	return NewGatewayService(
+		nil,
+		nil,
+		usageRepo,
+		nil,
+		userRepo,
+		subRepo,
+		nil,
+		nil,
+		cfg,
+		nil,
+		nil,
+		NewBillingService(cfg, nil),
+		nil,
+		&BillingCacheService{},
+		nil,
+		nil,
+		&DeferredService{},
+		nil,
+		nil,
+		nil,
+		nil,
+		nil,
+	)
+}
+
+func newGatewayRecordUsageServiceWithBillingRepoForTest(usageRepo UsageLogRepository, billingRepo UsageBillingRepository, userRepo UserRepository, subRepo UserSubscriptionRepository) *GatewayService {
+	svc := newGatewayRecordUsageServiceForTest(usageRepo, userRepo, subRepo)
+	svc.usageBillingRepo = billingRepo
+	return svc
+}
+
+func TestGatewayServiceRecordUsage_BillingUsesDetachedContext(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{inserted: false, err: context.DeadlineExceeded}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	quotaSvc := &openAIRecordUsageAPIKeyQuotaStub{}
+	svc := newGatewayRecordUsageServiceForTest(usageRepo, userRepo, subRepo)
+
+	reqCtx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	err := svc.RecordUsage(reqCtx, &RecordUsageInput{
+		Result: &ForwardResult{
+			RequestID: "gateway_detached_ctx",
+			Usage: ClaudeUsage{
+				InputTokens:  10,
+				OutputTokens: 6,
+			},
+			Model:    "claude-sonnet-4",
+			Duration: time.Second,
+		},
+		APIKey: &APIKey{
+			ID:    501,
+			Quota: 100,
+		},
+		User:          &User{ID: 601},
+		Account:       &Account{ID: 701},
+		APIKeyService: quotaSvc,
+	})
+
+	require.NoError(t, err)
+	require.Equal(t, 1, usageRepo.calls)
+	require.Equal(t, 1, userRepo.deductCalls)
+	require.NoError(t, userRepo.lastCtxErr)
+	require.Equal(t, 1, quotaSvc.quotaCalls)
+	require.NoError(t, quotaSvc.lastQuotaCtxErr)
+}
+
+func TestGatewayServiceRecordUsage_BillingFingerprintIncludesRequestPayloadHash(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{}
+	billingRepo := &openAIRecordUsageBillingRepoStub{result: &UsageBillingApplyResult{Applied: true}}
+	svc := newGatewayRecordUsageServiceWithBillingRepoForTest(usageRepo, billingRepo, &openAIRecordUsageUserRepoStub{}, &openAIRecordUsageSubRepoStub{})
+
+	payloadHash := HashUsageRequestPayload([]byte(`{"messages":[{"role":"user","content":"hello"}]}`))
+	err := svc.RecordUsage(context.Background(), &RecordUsageInput{
+		Result: &ForwardResult{
+			RequestID: "gateway_payload_hash",
+			Usage: ClaudeUsage{
+				InputTokens:  10,
+				OutputTokens: 6,
+			},
+			Model:    "claude-sonnet-4",
+			Duration: time.Second,
+		},
+		APIKey:             &APIKey{ID: 501, Quota: 100},
+		User:               &User{ID: 601},
+		Account:            &Account{ID: 701},
+		RequestPayloadHash: payloadHash,
+	})
+	require.NoError(t, err)
+	require.NotNil(t, billingRepo.lastCmd)
+	require.Equal(t, payloadHash, billingRepo.lastCmd.RequestPayloadHash)
+}
+
+func TestGatewayServiceRecordUsage_BillingFingerprintFallsBackToContextRequestID(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{}
+	billingRepo := &openAIRecordUsageBillingRepoStub{result: &UsageBillingApplyResult{Applied: true}}
+	svc := newGatewayRecordUsageServiceWithBillingRepoForTest(usageRepo, billingRepo, &openAIRecordUsageUserRepoStub{}, &openAIRecordUsageSubRepoStub{})
+
+	ctx := context.WithValue(context.Background(), ctxkey.RequestID, "req-local-123")
+	err := svc.RecordUsage(ctx, &RecordUsageInput{
+		Result: &ForwardResult{
+			RequestID: "gateway_payload_fallback",
+			Usage: ClaudeUsage{
+				InputTokens:  10,
+				OutputTokens: 6,
+			},
+			Model:    "claude-sonnet-4",
+			Duration: time.Second,
+		},
+		APIKey:  &APIKey{ID: 501, Quota: 100},
+		User:    &User{ID: 601},
+		Account: &Account{ID: 701},
+	})
+	require.NoError(t, err)
+	require.NotNil(t, billingRepo.lastCmd)
+	require.Equal(t, "local:req-local-123", billingRepo.lastCmd.RequestPayloadHash)
+}
+
+func TestGatewayServiceRecordUsage_UsageLogWriteErrorDoesNotSkipBilling(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{inserted: false, err: MarkUsageLogCreateNotPersisted(context.Canceled)}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	quotaSvc := &openAIRecordUsageAPIKeyQuotaStub{}
+	svc := newGatewayRecordUsageServiceForTest(usageRepo, userRepo, subRepo)
+
+	err := svc.RecordUsage(context.Background(), &RecordUsageInput{
+		Result: &ForwardResult{
+			RequestID: "gateway_not_persisted",
+			Usage: ClaudeUsage{
+				InputTokens:  10,
+				OutputTokens: 6,
+			},
+			Model:    "claude-sonnet-4",
+			Duration: time.Second,
+		},
+		APIKey: &APIKey{
+			ID:    503,
+			Quota: 100,
+		},
+		User:          &User{ID: 603},
+		Account:       &Account{ID: 703},
+		APIKeyService: quotaSvc,
+	})
+
+	require.NoError(t, err)
+	require.Equal(t, 1, usageRepo.calls)
+	require.Equal(t, 1, userRepo.deductCalls)
+	require.Equal(t, 1, quotaSvc.quotaCalls)
+}
+
+func TestGatewayServiceRecordUsageWithLongContext_BillingUsesDetachedContext(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{inserted: false, err: context.DeadlineExceeded}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	quotaSvc := &openAIRecordUsageAPIKeyQuotaStub{}
+	svc := newGatewayRecordUsageServiceForTest(usageRepo, userRepo, subRepo)
+
+	reqCtx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	err := svc.RecordUsageWithLongContext(reqCtx, &RecordUsageLongContextInput{
+		Result: &ForwardResult{
+			RequestID: "gateway_long_context_detached_ctx",
+			Usage: ClaudeUsage{
+				InputTokens:  12,
+				OutputTokens: 8,
+			},
+			Model:    "claude-sonnet-4",
+			Duration: time.Second,
+		},
+		APIKey: &APIKey{
+			ID:    502,
+			Quota: 100,
+		},
+		User:                  &User{ID: 602},
+		Account:               &Account{ID: 702},
+		LongContextThreshold:  200000,
+		LongContextMultiplier: 2,
+		APIKeyService:         quotaSvc,
+	})
+
+	require.NoError(t, err)
+	require.Equal(t, 1, usageRepo.calls)
+	require.Equal(t, 1, userRepo.deductCalls)
+	require.NoError(t, userRepo.lastCtxErr)
+	require.Equal(t, 1, quotaSvc.quotaCalls)
+	require.NoError(t, quotaSvc.lastQuotaCtxErr)
+}
+
+func TestGatewayServiceRecordUsage_UsesFallbackRequestIDForUsageLog(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	svc := newGatewayRecordUsageServiceForTest(usageRepo, userRepo, subRepo)
+
+	ctx := context.WithValue(context.Background(), ctxkey.RequestID, "gateway-local-fallback")
+	err := svc.RecordUsage(ctx, &RecordUsageInput{
+		Result: &ForwardResult{
+			RequestID: "",
+			Usage: ClaudeUsage{
+				InputTokens:  10,
+				OutputTokens: 6,
+			},
+			Model:    "claude-sonnet-4",
+			Duration: time.Second,
+		},
+		APIKey:  &APIKey{ID: 504},
+		User:    &User{ID: 604},
+		Account: &Account{ID: 704},
+	})
+
+	require.NoError(t, err)
+	require.NotNil(t, usageRepo.lastLog)
+	require.Equal(t, "local:gateway-local-fallback", usageRepo.lastLog.RequestID)
+}
+
+func TestGatewayServiceRecordUsage_BillingErrorSkipsUsageLogWrite(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{}
+	billingRepo := &openAIRecordUsageBillingRepoStub{err: context.DeadlineExceeded}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	svc := newGatewayRecordUsageServiceWithBillingRepoForTest(usageRepo, billingRepo, userRepo, subRepo)
+
+	err := svc.RecordUsage(context.Background(), &RecordUsageInput{
+		Result: &ForwardResult{
+			RequestID: "gateway_billing_fail",
+			Usage: ClaudeUsage{
+				InputTokens:  10,
+				OutputTokens: 6,
+			},
+			Model:    "claude-sonnet-4",
+			Duration: time.Second,
+		},
+		APIKey:  &APIKey{ID: 505},
+		User:    &User{ID: 605},
+		Account: &Account{ID: 705},
+	})
+
+	require.Error(t, err)
+	require.Equal(t, 1, billingRepo.calls)
+	require.Equal(t, 0, usageRepo.calls)
+}

backend/internal/service/gateway_service.go

@@ -50,6 +50,7 @@ const (
 
 	defaultUserGroupRateCacheTTL = 30 * time.Second
 	defaultModelsListCacheTTL    = 15 * time.Second
+	postUsageBillingTimeout      = 15 * time.Second
 )
 
 const (
@@ -106,6 +107,52 @@ func GatewayModelsListCacheStats() (cacheHit, cacheMiss, store int64) {
 	return modelsListCacheHitTotal.Load(), modelsListCacheMissTotal.Load(), modelsListCacheStoreTotal.Load()
 }
 
+func claudeUsageHasAnyTokens(usage *ClaudeUsage) bool {
+	return usage != nil && (usage.InputTokens > 0 ||
+		usage.OutputTokens > 0 ||
+		usage.CacheCreationInputTokens > 0 ||
+		usage.CacheReadInputTokens > 0 ||
+		usage.CacheCreation5mTokens > 0 ||
+		usage.CacheCreation1hTokens > 0)
+}
+
+func openAIUsageHasAnyTokens(usage *OpenAIUsage) bool {
+	return usage != nil && (usage.InputTokens > 0 ||
+		usage.OutputTokens > 0 ||
+		usage.CacheCreationInputTokens > 0 ||
+		usage.CacheReadInputTokens > 0)
+}
+
+func openAIStreamEventIsTerminal(data string) bool {
+	trimmed := strings.TrimSpace(data)
+	if trimmed == "" {
+		return false
+	}
+	if trimmed == "[DONE]" {
+		return true
+	}
+	switch gjson.Get(trimmed, "type").String() {
+	case "response.completed", "response.done", "response.failed":
+		return true
+	default:
+		return false
+	}
+}
+
+func anthropicStreamEventIsTerminal(eventName, data string) bool {
+	if strings.EqualFold(strings.TrimSpace(eventName), "message_stop") {
+		return true
+	}
+	trimmed := strings.TrimSpace(data)
+	if trimmed == "" {
+		return false
+	}
+	if trimmed == "[DONE]" {
+		return true
+	}
+	return gjson.Get(trimmed, "type").String() == "message_stop"
+}
+
 func cloneStringSlice(src []string) []string {
 	if len(src) == 0 {
 		return nil
@@ -504,6 +551,7 @@ type GatewayService struct {
 	accountRepo           AccountRepository
 	groupRepo             GroupRepository
 	usageLogRepo          UsageLogRepository
+	usageBillingRepo      UsageBillingRepository
 	userRepo              UserRepository
 	userSubRepo           UserSubscriptionRepository
 	userGroupRateRepo     UserGroupRateRepository
@@ -537,6 +585,7 @@ func NewGatewayService(
 	accountRepo AccountRepository,
 	groupRepo GroupRepository,
 	usageLogRepo UsageLogRepository,
+	usageBillingRepo UsageBillingRepository,
 	userRepo UserRepository,
 	userSubRepo UserSubscriptionRepository,
 	userGroupRateRepo UserGroupRateRepository,
@@ -563,6 +612,7 @@ func NewGatewayService(
 		accountRepo:          accountRepo,
 		groupRepo:            groupRepo,
 		usageLogRepo:         usageLogRepo,
+		usageBillingRepo:     usageBillingRepo,
 		userRepo:             userRepo,
 		userSubRepo:          userSubRepo,
 		userGroupRateRepo:    userGroupRateRepo,
@@ -4049,7 +4099,9 @@ func (s *GatewayService) Forward(ctx context.Context, c *gin.Context, account *A
 	retryStart := time.Now()
 	for attempt := 1; attempt <= maxRetryAttempts; attempt++ {
 		// 构建上游请求（每次重试需要重新构建，因为请求体需要重新读取）
-		upstreamReq, err := s.buildUpstreamRequest(ctx, c, account, body, token, tokenType, reqModel, reqStream, shouldMimicClaudeCode)
+		upstreamCtx, releaseUpstreamCtx := detachStreamUpstreamContext(ctx, reqStream)
+		upstreamReq, err := s.buildUpstreamRequest(upstreamCtx, c, account, body, token, tokenType, reqModel, reqStream, shouldMimicClaudeCode)
+		releaseUpstreamCtx()
 		if err != nil {
 			return nil, err
 		}
@@ -4127,7 +4179,9 @@ func (s *GatewayService) Forward(ctx context.Context, c *gin.Context, account *A
 					//    also downgrade tool_use/tool_result blocks to text.
 
 					filteredBody := FilterThinkingBlocksForRetry(body)
-					retryReq, buildErr := s.buildUpstreamRequest(ctx, c, account, filteredBody, token, tokenType, reqModel, reqStream, shouldMimicClaudeCode)
+					retryCtx, releaseRetryCtx := detachStreamUpstreamContext(ctx, reqStream)
+					retryReq, buildErr := s.buildUpstreamRequest(retryCtx, c, account, filteredBody, token, tokenType, reqModel, reqStream, shouldMimicClaudeCode)
+					releaseRetryCtx()
 					if buildErr == nil {
 						retryResp, retryErr := s.httpUpstream.DoWithTLS(retryReq, proxyURL, account.ID, account.Concurrency, account.IsTLSFingerprintEnabled())
 						if retryErr == nil {
@@ -4159,7 +4213,9 @@ func (s *GatewayService) Forward(ctx context.Context, c *gin.Context, account *A
 								if looksLikeToolSignatureError(msg2) && time.Since(retryStart) < maxRetryElapsed {
 									logger.LegacyPrintf("service.gateway", "Account %d: signature retry still failing and looks tool-related, retrying with tool blocks downgraded", account.ID)
 									filteredBody2 := FilterSignatureSensitiveBlocksForRetry(body)
-									retryReq2, buildErr2 := s.buildUpstreamRequest(ctx, c, account, filteredBody2, token, tokenType, reqModel, reqStream, shouldMimicClaudeCode)
+									retryCtx2, releaseRetryCtx2 := detachStreamUpstreamContext(ctx, reqStream)
+									retryReq2, buildErr2 := s.buildUpstreamRequest(retryCtx2, c, account, filteredBody2, token, tokenType, reqModel, reqStream, shouldMimicClaudeCode)
+									releaseRetryCtx2()
 									if buildErr2 == nil {
 										retryResp2, retryErr2 := s.httpUpstream.DoWithTLS(retryReq2, proxyURL, account.ID, account.Concurrency, account.IsTLSFingerprintEnabled())
 										if retryErr2 == nil {
@@ -4226,7 +4282,9 @@ func (s *GatewayService) Forward(ctx context.Context, c *gin.Context, account *A
 					rectifiedBody, applied := RectifyThinkingBudget(body)
 					if applied && time.Since(retryStart) < maxRetryElapsed {
 						logger.LegacyPrintf("service.gateway", "Account %d: detected budget_tokens constraint error, retrying with rectified budget (budget_tokens=%d, max_tokens=%d)", account.ID, BudgetRectifyBudgetTokens, BudgetRectifyMaxTokens)
-						budgetRetryReq, buildErr := s.buildUpstreamRequest(ctx, c, account, rectifiedBody, token, tokenType, reqModel, reqStream, shouldMimicClaudeCode)
+						budgetRetryCtx, releaseBudgetRetryCtx := detachStreamUpstreamContext(ctx, reqStream)
+						budgetRetryReq, buildErr := s.buildUpstreamRequest(budgetRetryCtx, c, account, rectifiedBody, token, tokenType, reqModel, reqStream, shouldMimicClaudeCode)
+						releaseBudgetRetryCtx()
 						if buildErr == nil {
 							budgetRetryResp, retryErr := s.httpUpstream.DoWithTLS(budgetRetryReq, proxyURL, account.ID, account.Concurrency, account.IsTLSFingerprintEnabled())
 							if retryErr == nil {
@@ -4498,7 +4556,9 @@ func (s *GatewayService) forwardAnthropicAPIKeyPassthrough(
 	var resp *http.Response
 	retryStart := time.Now()
 	for attempt := 1; attempt <= maxRetryAttempts; attempt++ {
-		upstreamReq, err := s.buildUpstreamRequestAnthropicAPIKeyPassthrough(ctx, c, account, body, token)
+		upstreamCtx, releaseUpstreamCtx := detachStreamUpstreamContext(ctx, reqStream)
+		upstreamReq, err := s.buildUpstreamRequestAnthropicAPIKeyPassthrough(upstreamCtx, c, account, body, token)
+		releaseUpstreamCtx()
 		if err != nil {
 			return nil, err
 		}
@@ -4774,6 +4834,7 @@ func (s *GatewayService) handleStreamingResponseAnthropicAPIKeyPassthrough(
 	usage := &ClaudeUsage{}
 	var firstTokenMs *int
 	clientDisconnected := false
+	sawTerminalEvent := false
 
 	scanner := bufio.NewScanner(resp.Body)
 	maxLineSize := defaultMaxLineSize
@@ -4836,17 +4897,20 @@ func (s *GatewayService) handleStreamingResponseAnthropicAPIKeyPassthrough(
 					// 兜底补刷，确保最后一个未以空行结尾的事件也能及时送达客户端。
 					flusher.Flush()
 				}
+				if !sawTerminalEvent {
+					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: clientDisconnected}, fmt.Errorf("stream usage incomplete: missing terminal event")
+				}
 				return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: clientDisconnected}, nil
 			}
 			if ev.err != nil {
+				if sawTerminalEvent {
+					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: clientDisconnected}, nil
+				}
 				if clientDisconnected {
-					logger.LegacyPrintf("service.gateway", "[Anthropic passthrough] Upstream read error after client disconnect: account=%d err=%v", account.ID, ev.err)
+					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, fmt.Errorf("stream usage incomplete after disconnect: %w", ev.err)
-					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, nil
 				}
 				if errors.Is(ev.err, context.Canceled) || errors.Is(ev.err, context.DeadlineExceeded) {
-					logger.LegacyPrintf("service.gateway", "[Anthropic passthrough] 流读取被取消: account=%d request_id=%s err=%v ctx_err=%v",
+					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, fmt.Errorf("stream usage incomplete: %w", ev.err)
-						account.ID, resp.Header.Get("x-request-id"), ev.err, ctx.Err())
-					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, nil
 				}
 				if errors.Is(ev.err, bufio.ErrTooLong) {
 					logger.LegacyPrintf("service.gateway", "[Anthropic passthrough] SSE line too long: account=%d max_size=%d error=%v", account.ID, maxLineSize, ev.err)
@@ -4858,11 +4922,19 @@ func (s *GatewayService) handleStreamingResponseAnthropicAPIKeyPassthrough(
 			line := ev.line
 			if data, ok := extractAnthropicSSEDataLine(line); ok {
 				trimmed := strings.TrimSpace(data)
+				if anthropicStreamEventIsTerminal("", trimmed) {
+					sawTerminalEvent = true
+				}
 				if firstTokenMs == nil && trimmed != "" && trimmed != "[DONE]" {
 					ms := int(time.Since(startTime).Milliseconds())
 					firstTokenMs = &ms
 				}
 				s.parseSSEUsagePassthrough(data, usage)
+			} else {
+				trimmed := strings.TrimSpace(line)
+				if strings.HasPrefix(trimmed, "event:") && anthropicStreamEventIsTerminal(strings.TrimSpace(strings.TrimPrefix(trimmed, "event:")), "") {
+					sawTerminalEvent = true
+				}
 			}
 
 			if !clientDisconnected {
@@ -4884,8 +4956,7 @@ func (s *GatewayService) handleStreamingResponseAnthropicAPIKeyPassthrough(
 				continue
 			}
 			if clientDisconnected {
-				logger.LegacyPrintf("service.gateway", "[Anthropic passthrough] Upstream timeout after client disconnect: account=%d model=%s", account.ID, model)
+				return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, fmt.Errorf("stream usage incomplete after timeout")
-				return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, nil
 			}
 			logger.LegacyPrintf("service.gateway", "[Anthropic passthrough] Stream data interval timeout: account=%d model=%s interval=%s", account.ID, model, streamInterval)
 			if s.rateLimitService != nil {
@@ -6011,6 +6082,7 @@ func (s *GatewayService) handleStreamingResponse(ctx context.Context, resp *http
 
 	needModelReplace := originalModel != mappedModel
 	clientDisconnected := false // 客户端断开标志，断开后继续读取上游以获取完整usage
+	sawTerminalEvent := false
 
 	pendingEventLines := make([]string, 0, 4)
 
@@ -6041,6 +6113,7 @@ func (s *GatewayService) handleStreamingResponse(ctx context.Context, resp *http
 		}
 
 		if dataLine == "[DONE]" {
+			sawTerminalEvent = true
 			block := ""
 			if eventName != "" {
 				block = "event: " + eventName + "\n"
@@ -6107,6 +6180,9 @@ func (s *GatewayService) handleStreamingResponse(ctx context.Context, resp *http
 		}
 
 		usagePatch := s.extractSSEUsagePatch(event)
+		if anthropicStreamEventIsTerminal(eventName, dataLine) {
+			sawTerminalEvent = true
+		}
 		if !eventChanged {
 			block := ""
 			if eventName != "" {
@@ -6140,18 +6216,22 @@ func (s *GatewayService) handleStreamingResponse(ctx context.Context, resp *http
 		case ev, ok := <-events:
 			if !ok {
 				// 上游完成，返回结果
+				if !sawTerminalEvent {
+					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: clientDisconnected}, fmt.Errorf("stream usage incomplete: missing terminal event")
+				}
 				return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: clientDisconnected}, nil
 			}
 			if ev.err != nil {
+				if sawTerminalEvent {
+					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: clientDisconnected}, nil
+				}
 				// 检测 context 取消（客户端断开会导致 context 取消，进而影响上游读取）
 				if errors.Is(ev.err, context.Canceled) || errors.Is(ev.err, context.DeadlineExceeded) {
-					logger.LegacyPrintf("service.gateway", "Context canceled during streaming, returning collected usage")
+					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, fmt.Errorf("stream usage incomplete: %w", ev.err)
-					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, nil
 				}
 				// 客户端已通过写入失败检测到断开，上游也出错了，返回已收集的 usage
 				if clientDisconnected {
-					logger.LegacyPrintf("service.gateway", "Upstream read error after client disconnect: %v, returning collected usage", ev.err)
+					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, fmt.Errorf("stream usage incomplete after disconnect: %w", ev.err)
-					return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, nil
 				}
 				// 客户端未断开，正常的错误处理
 				if errors.Is(ev.err, bufio.ErrTooLong) {
@@ -6209,9 +6289,7 @@ func (s *GatewayService) handleStreamingResponse(ctx context.Context, resp *http
 				continue
 			}
 			if clientDisconnected {
-				// 客户端已断开，上游也超时了，返回已收集的 usage
+				return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, fmt.Errorf("stream usage incomplete after timeout")
-				logger.LegacyPrintf("service.gateway", "Upstream timeout after client disconnect, returning collected usage")
-				return &streamingResult{usage: usage, firstTokenMs: firstTokenMs, clientDisconnect: true}, nil
 			}
 			logger.LegacyPrintf("service.gateway", "Stream data interval timeout: account=%d model=%s interval=%s", account.ID, originalModel, streamInterval)
 			// 处理流超时，可能标记账户为临时不可调度或错误状态
@@ -6557,15 +6635,16 @@ func (s *GatewayService) getUserGroupRateMultiplier(ctx context.Context, userID,
 
 // RecordUsageInput 记录使用量的输入参数
 type RecordUsageInput struct {
-	Result            *ForwardResult
+	Result             *ForwardResult
-	APIKey            *APIKey
+	APIKey             *APIKey
-	User              *User
+	User               *User
-	Account           *Account
+	Account            *Account
-	Subscription      *UserSubscription  // 可选：订阅信息
+	Subscription       *UserSubscription  // 可选：订阅信息
-	UserAgent         string             // 请求的 User-Agent
+	UserAgent          string             // 请求的 User-Agent
-	IPAddress         string             // 请求的客户端 IP 地址
+	IPAddress          string             // 请求的客户端 IP 地址
-	ForceCacheBilling bool               // 强制缓存计费：将 input_tokens 转为 cache_read 计费（用于粘性会话切换）
+	RequestPayloadHash string             // 请求体语义哈希，用于降低 request_id 误复用时的静默误去重风险
-	APIKeyService     APIKeyQuotaUpdater // 可选：用于更新API Key配额
+	ForceCacheBilling  bool               // 强制缓存计费：将 input_tokens 转为 cache_read 计费（用于粘性会话切换）
+	APIKeyService      APIKeyQuotaUpdater // 可选：用于更新API Key配额
 }
 
 // APIKeyQuotaUpdater defines the interface for updating API Key quota and rate limit usage
@@ -6574,6 +6653,14 @@ type APIKeyQuotaUpdater interface {
 	UpdateRateLimitUsage(ctx context.Context, apiKeyID int64, cost float64) error
 }
 
+type apiKeyAuthCacheInvalidator interface {
+	InvalidateAuthCacheByKey(ctx context.Context, key string)
+}
+
+type usageLogBestEffortWriter interface {
+	CreateBestEffort(ctx context.Context, log *UsageLog) error
+}
+
 // postUsageBillingParams 统一扣费所需的参数
 type postUsageBillingParams struct {
 	Cost                  *CostBreakdown
@@ -6581,6 +6668,7 @@ type postUsageBillingParams struct {
 	APIKey                *APIKey
 	Account               *Account
 	Subscription          *UserSubscription
+	RequestPayloadHash    string
 	IsSubscriptionBill    bool
 	AccountRateMultiplier float64
 	APIKeyService         APIKeyQuotaUpdater
@@ -6592,19 +6680,22 @@ type postUsageBillingParams struct {
 //   - API Key 限速用量更新
 //   - 账号配额用量更新（账号口径：TotalCost × 账号计费倍率）
 func postUsageBilling(ctx context.Context, p *postUsageBillingParams, deps *billingDeps) {
+	billingCtx, cancel := detachedBillingContext(ctx)
+	defer cancel()
+
 	cost := p.Cost
 
 	// 1. 订阅 / 余额扣费
 	if p.IsSubscriptionBill {
 		if cost.TotalCost > 0 {
-			if err := deps.userSubRepo.IncrementUsage(ctx, p.Subscription.ID, cost.TotalCost); err != nil {
+			if err := deps.userSubRepo.IncrementUsage(billingCtx, p.Subscription.ID, cost.TotalCost); err != nil {
 				slog.Error("increment subscription usage failed", "subscription_id", p.Subscription.ID, "error", err)
 			}
 			deps.billingCacheService.QueueUpdateSubscriptionUsage(p.User.ID, *p.APIKey.GroupID, cost.TotalCost)
 		}
 	} else {
 		if cost.ActualCost > 0 {
-			if err := deps.userRepo.DeductBalance(ctx, p.User.ID, cost.ActualCost); err != nil {
+			if err := deps.userRepo.DeductBalance(billingCtx, p.User.ID, cost.ActualCost); err != nil {
 				slog.Error("deduct balance failed", "user_id", p.User.ID, "error", err)
 			}
 			deps.billingCacheService.QueueDeductBalance(p.User.ID, cost.ActualCost)
@@ -6613,31 +6704,187 @@ func postUsageBilling(ctx context.Context, p *postUsageBillingParams, deps *bill
 
 	// 2. API Key 配额
 	if cost.ActualCost > 0 && p.APIKey.Quota > 0 && p.APIKeyService != nil {
-		if err := p.APIKeyService.UpdateQuotaUsed(ctx, p.APIKey.ID, cost.ActualCost); err != nil {
+		if err := p.APIKeyService.UpdateQuotaUsed(billingCtx, p.APIKey.ID, cost.ActualCost); err != nil {
 			slog.Error("update api key quota failed", "api_key_id", p.APIKey.ID, "error", err)
 		}
 	}
 
 	// 3. API Key 限速用量
 	if cost.ActualCost > 0 && p.APIKey.HasRateLimits() && p.APIKeyService != nil {
-		if err := p.APIKeyService.UpdateRateLimitUsage(ctx, p.APIKey.ID, cost.ActualCost); err != nil {
+		if err := p.APIKeyService.UpdateRateLimitUsage(billingCtx, p.APIKey.ID, cost.ActualCost); err != nil {
 			slog.Error("update api key rate limit usage failed", "api_key_id", p.APIKey.ID, "error", err)
 		}
-		deps.billingCacheService.QueueUpdateAPIKeyRateLimitUsage(p.APIKey.ID, cost.ActualCost)
 	}
 
 	// 4. 账号配额用量（账号口径：TotalCost × 账号计费倍率）
 	if cost.TotalCost > 0 && p.Account.Type == AccountTypeAPIKey && p.Account.HasAnyQuotaLimit() {
 		accountCost := cost.TotalCost * p.AccountRateMultiplier
-		if err := deps.accountRepo.IncrementQuotaUsed(ctx, p.Account.ID, accountCost); err != nil {
+		if err := deps.accountRepo.IncrementQuotaUsed(billingCtx, p.Account.ID, accountCost); err != nil {
 			slog.Error("increment account quota used failed", "account_id", p.Account.ID, "cost", accountCost, "error", err)
 		}
 	}
 
-	// 5. 更新账号最近使用时间
+	finalizePostUsageBilling(p, deps)
+}
+
+func resolveUsageBillingRequestID(ctx context.Context, upstreamRequestID string) string {
+	if requestID := strings.TrimSpace(upstreamRequestID); requestID != "" {
+		return requestID
+	}
+	if ctx != nil {
+		if clientRequestID, _ := ctx.Value(ctxkey.ClientRequestID).(string); strings.TrimSpace(clientRequestID) != "" {
+			return "client:" + strings.TrimSpace(clientRequestID)
+		}
+		if requestID, _ := ctx.Value(ctxkey.RequestID).(string); strings.TrimSpace(requestID) != "" {
+			return "local:" + strings.TrimSpace(requestID)
+		}
+	}
+	return ""
+}
+
+func resolveUsageBillingPayloadFingerprint(ctx context.Context, requestPayloadHash string) string {
+	if payloadHash := strings.TrimSpace(requestPayloadHash); payloadHash != "" {
+		return payloadHash
+	}
+	if ctx != nil {
+		if clientRequestID, _ := ctx.Value(ctxkey.ClientRequestID).(string); strings.TrimSpace(clientRequestID) != "" {
+			return "client:" + strings.TrimSpace(clientRequestID)
+		}
+		if requestID, _ := ctx.Value(ctxkey.RequestID).(string); strings.TrimSpace(requestID) != "" {
+			return "local:" + strings.TrimSpace(requestID)
+		}
+	}
+	return ""
+}
+
+func buildUsageBillingCommand(requestID string, usageLog *UsageLog, p *postUsageBillingParams) *UsageBillingCommand {
+	if p == nil || p.Cost == nil || p.APIKey == nil || p.User == nil || p.Account == nil {
+		return nil
+	}
+
+	cmd := &UsageBillingCommand{
+		RequestID:          requestID,
+		APIKeyID:           p.APIKey.ID,
+		UserID:             p.User.ID,
+		AccountID:          p.Account.ID,
+		AccountType:        p.Account.Type,
+		RequestPayloadHash: strings.TrimSpace(p.RequestPayloadHash),
+	}
+	if usageLog != nil {
+		cmd.Model = usageLog.Model
+		cmd.BillingType = usageLog.BillingType
+		cmd.InputTokens = usageLog.InputTokens
+		cmd.OutputTokens = usageLog.OutputTokens
+		cmd.CacheCreationTokens = usageLog.CacheCreationTokens
+		cmd.CacheReadTokens = usageLog.CacheReadTokens
+		cmd.ImageCount = usageLog.ImageCount
+		if usageLog.MediaType != nil {
+			cmd.MediaType = *usageLog.MediaType
+		}
+		if usageLog.ServiceTier != nil {
+			cmd.ServiceTier = *usageLog.ServiceTier
+		}
+		if usageLog.ReasoningEffort != nil {
+			cmd.ReasoningEffort = *usageLog.ReasoningEffort
+		}
+		if usageLog.SubscriptionID != nil {
+			cmd.SubscriptionID = usageLog.SubscriptionID
+		}
+	}
+
+	if p.IsSubscriptionBill && p.Subscription != nil && p.Cost.TotalCost > 0 {
+		cmd.SubscriptionID = &p.Subscription.ID
+		cmd.SubscriptionCost = p.Cost.TotalCost
+	} else if p.Cost.ActualCost > 0 {
+		cmd.BalanceCost = p.Cost.ActualCost
+	}
+
+	if p.Cost.ActualCost > 0 && p.APIKey.Quota > 0 && p.APIKeyService != nil {
+		cmd.APIKeyQuotaCost = p.Cost.ActualCost
+	}
+	if p.Cost.ActualCost > 0 && p.APIKey.HasRateLimits() && p.APIKeyService != nil {
+		cmd.APIKeyRateLimitCost = p.Cost.ActualCost
+	}
+	if p.Cost.TotalCost > 0 && p.Account.Type == AccountTypeAPIKey && p.Account.HasAnyQuotaLimit() {
+		cmd.AccountQuotaCost = p.Cost.TotalCost * p.AccountRateMultiplier
+	}
+
+	cmd.Normalize()
+	return cmd
+}
+
+func applyUsageBilling(ctx context.Context, requestID string, usageLog *UsageLog, p *postUsageBillingParams, deps *billingDeps, repo UsageBillingRepository) (bool, error) {
+	if p == nil || deps == nil {
+		return false, nil
+	}
+
+	cmd := buildUsageBillingCommand(requestID, usageLog, p)
+	if cmd == nil || cmd.RequestID == "" || repo == nil {
+		postUsageBilling(ctx, p, deps)
+		return true, nil
+	}
+
+	billingCtx, cancel := detachedBillingContext(ctx)
+	defer cancel()
+
+	result, err := repo.Apply(billingCtx, cmd)
+	if err != nil {
+		return false, err
+	}
+
+	if result == nil || !result.Applied {
+		deps.deferredService.ScheduleLastUsedUpdate(p.Account.ID)
+		return false, nil
+	}
+
+	if result.APIKeyQuotaExhausted {
+		if invalidator, ok := p.APIKeyService.(apiKeyAuthCacheInvalidator); ok && p.APIKey != nil && p.APIKey.Key != "" {
+			invalidator.InvalidateAuthCacheByKey(billingCtx, p.APIKey.Key)
+		}
+	}
+
+	finalizePostUsageBilling(p, deps)
+	return true, nil
+}
+
+func finalizePostUsageBilling(p *postUsageBillingParams, deps *billingDeps) {
+	if p == nil || p.Cost == nil || deps == nil {
+		return
+	}
+
+	if p.IsSubscriptionBill {
+		if p.Cost.TotalCost > 0 && p.User != nil && p.APIKey != nil && p.APIKey.GroupID != nil {
+			deps.billingCacheService.QueueUpdateSubscriptionUsage(p.User.ID, *p.APIKey.GroupID, p.Cost.TotalCost)
+		}
+	} else if p.Cost.ActualCost > 0 && p.User != nil {
+		deps.billingCacheService.QueueDeductBalance(p.User.ID, p.Cost.ActualCost)
+	}
+
+	if p.Cost.ActualCost > 0 && p.APIKey != nil && p.APIKey.HasRateLimits() {
+		deps.billingCacheService.QueueUpdateAPIKeyRateLimitUsage(p.APIKey.ID, p.Cost.ActualCost)
+	}
+
 	deps.deferredService.ScheduleLastUsedUpdate(p.Account.ID)
 }
 
+func detachedBillingContext(ctx context.Context) (context.Context, context.CancelFunc) {
+	base := context.Background()
+	if ctx != nil {
+		base = context.WithoutCancel(ctx)
+	}
+	return context.WithTimeout(base, postUsageBillingTimeout)
+}
+
+func detachStreamUpstreamContext(ctx context.Context, stream bool) (context.Context, context.CancelFunc) {
+	if !stream {
+		return ctx, func() {}
+	}
+	if ctx == nil {
+		return context.Background(), func() {}
+	}
+	return context.WithoutCancel(ctx), func() {}
+}
+
 // billingDeps 扣费逻辑依赖的服务（由各 gateway service 提供）
 type billingDeps struct {
 	accountRepo         AccountRepository
@@ -6657,6 +6904,28 @@ func (s *GatewayService) billingDeps() *billingDeps {
 	}
 }
 
+func writeUsageLogBestEffort(ctx context.Context, repo UsageLogRepository, usageLog *UsageLog, logKey string) {
+	if repo == nil || usageLog == nil {
+		return
+	}
+	usageCtx, cancel := detachedBillingContext(ctx)
+	defer cancel()
+
+	if writer, ok := repo.(usageLogBestEffortWriter); ok {
+		if err := writer.CreateBestEffort(usageCtx, usageLog); err != nil {
+			logger.LegacyPrintf(logKey, "Create usage log failed: %v", err)
+			if _, syncErr := repo.Create(usageCtx, usageLog); syncErr != nil {
+				logger.LegacyPrintf(logKey, "Create usage log sync fallback failed: %v", syncErr)
+			}
+		}
+		return
+	}
+
+	if _, err := repo.Create(usageCtx, usageLog); err != nil {
+		logger.LegacyPrintf(logKey, "Create usage log failed: %v", err)
+	}
+}
+
 // RecordUsage 记录使用量并扣费（或更新订阅用量）
 func (s *GatewayService) RecordUsage(ctx context.Context, input *RecordUsageInput) error {
 	result := input.Result
@@ -6758,11 +7027,12 @@ func (s *GatewayService) RecordUsage(ctx context.Context, input *RecordUsageInpu
 		mediaType = &result.MediaType
 	}
 	accountRateMultiplier := account.BillingRateMultiplier()
+	requestID := resolveUsageBillingRequestID(ctx, result.RequestID)
 	usageLog := &UsageLog{
 		UserID:                user.ID,
 		APIKeyID:              apiKey.ID,
 		AccountID:             account.ID,
-		RequestID:             result.RequestID,
+		RequestID:             requestID,
 		Model:                 result.Model,
 		InputTokens:           result.Usage.InputTokens,
 		OutputTokens:          result.Usage.OutputTokens,
@@ -6807,33 +7077,32 @@ func (s *GatewayService) RecordUsage(ctx context.Context, input *RecordUsageInpu
 		usageLog.SubscriptionID = &subscription.ID
 	}
 
-	inserted, err := s.usageLogRepo.Create(ctx, usageLog)
-	if err != nil {
-		logger.LegacyPrintf("service.gateway", "Create usage log failed: %v", err)
-	}
-
 	if s.cfg != nil && s.cfg.RunMode == config.RunModeSimple {
+		writeUsageLogBestEffort(ctx, s.usageLogRepo, usageLog, "service.gateway")
 		logger.LegacyPrintf("service.gateway", "[SIMPLE MODE] Usage recorded (not billed): user=%d, tokens=%d", usageLog.UserID, usageLog.TotalTokens())
 		s.deferredService.ScheduleLastUsedUpdate(account.ID)
 		return nil
 	}
 
-	shouldBill := inserted || err != nil
+	billingErr := func() error {
-
+		_, err := applyUsageBilling(ctx, requestID, usageLog, &postUsageBillingParams{
-	if shouldBill {
-		postUsageBilling(ctx, &postUsageBillingParams{
 			Cost:                  cost,
 			User:                  user,
 			APIKey:                apiKey,
 			Account:               account,
 			Subscription:          subscription,
+			RequestPayloadHash:    resolveUsageBillingPayloadFingerprint(ctx, input.RequestPayloadHash),
 			IsSubscriptionBill:    isSubscriptionBilling,
 			AccountRateMultiplier: accountRateMultiplier,
 			APIKeyService:         input.APIKeyService,
-		}, s.billingDeps())
+		}, s.billingDeps(), s.usageBillingRepo)
-	} else {
+		return err
-		s.deferredService.ScheduleLastUsedUpdate(account.ID)
+	}()
+
+	if billingErr != nil {
+		return billingErr
 	}
+	writeUsageLogBestEffort(ctx, s.usageLogRepo, usageLog, "service.gateway")
 
 	return nil
 }
@@ -6844,13 +7113,14 @@ type RecordUsageLongContextInput struct {
 	APIKey                *APIKey
 	User                  *User
 	Account               *Account
-	Subscription          *UserSubscription // 可选：订阅信息
+	Subscription          *UserSubscription  // 可选：订阅信息
-	UserAgent             string            // 请求的 User-Agent
+	UserAgent             string             // 请求的 User-Agent
-	IPAddress             string            // 请求的客户端 IP 地址
+	IPAddress             string             // 请求的客户端 IP 地址
-	LongContextThreshold  int               // 长上下文阈值（如 200000）
+	RequestPayloadHash    string             // 请求体语义哈希，用于降低 request_id 误复用时的静默误去重风险
-	LongContextMultiplier float64           // 超出阈值部分的倍率（如 2.0）
+	LongContextThreshold  int                // 长上下文阈值（如 200000）
-	ForceCacheBilling     bool              // 强制缓存计费：将 input_tokens 转为 cache_read 计费（用于粘性会话切换）
+	LongContextMultiplier float64            // 超出阈值部分的倍率（如 2.0）
-	APIKeyService         *APIKeyService    // API Key 配额服务（可选）
+	ForceCacheBilling     bool               // 强制缓存计费：将 input_tokens 转为 cache_read 计费（用于粘性会话切换）
+	APIKeyService         APIKeyQuotaUpdater // API Key 配额服务（可选）
 }
 
 // RecordUsageWithLongContext 记录使用量并扣费，支持长上下文双倍计费（用于 Gemini）
@@ -6933,11 +7203,12 @@ func (s *GatewayService) RecordUsageWithLongContext(ctx context.Context, input *
 		imageSize = &result.ImageSize
 	}
 	accountRateMultiplier := account.BillingRateMultiplier()
+	requestID := resolveUsageBillingRequestID(ctx, result.RequestID)
 	usageLog := &UsageLog{
 		UserID:                user.ID,
 		APIKeyID:              apiKey.ID,
 		AccountID:             account.ID,
-		RequestID:             result.RequestID,
+		RequestID:             requestID,
 		Model:                 result.Model,
 		InputTokens:           result.Usage.InputTokens,
 		OutputTokens:          result.Usage.OutputTokens,
@@ -6981,33 +7252,32 @@ func (s *GatewayService) RecordUsageWithLongContext(ctx context.Context, input *
 		usageLog.SubscriptionID = &subscription.ID
 	}
 
-	inserted, err := s.usageLogRepo.Create(ctx, usageLog)
-	if err != nil {
-		logger.LegacyPrintf("service.gateway", "Create usage log failed: %v", err)
-	}
-
 	if s.cfg != nil && s.cfg.RunMode == config.RunModeSimple {
+		writeUsageLogBestEffort(ctx, s.usageLogRepo, usageLog, "service.gateway")
 		logger.LegacyPrintf("service.gateway", "[SIMPLE MODE] Usage recorded (not billed): user=%d, tokens=%d", usageLog.UserID, usageLog.TotalTokens())
 		s.deferredService.ScheduleLastUsedUpdate(account.ID)
 		return nil
 	}
 
-	shouldBill := inserted || err != nil
+	billingErr := func() error {
-
+		_, err := applyUsageBilling(ctx, requestID, usageLog, &postUsageBillingParams{
-	if shouldBill {
-		postUsageBilling(ctx, &postUsageBillingParams{
 			Cost:                  cost,
 			User:                  user,
 			APIKey:                apiKey,
 			Account:               account,
 			Subscription:          subscription,
+			RequestPayloadHash:    resolveUsageBillingPayloadFingerprint(ctx, input.RequestPayloadHash),
 			IsSubscriptionBill:    isSubscriptionBilling,
 			AccountRateMultiplier: accountRateMultiplier,
 			APIKeyService:         input.APIKeyService,
-		}, s.billingDeps())
+		}, s.billingDeps(), s.usageBillingRepo)
-	} else {
+		return err
-		s.deferredService.ScheduleLastUsedUpdate(account.ID)
+	}()
+
+	if billingErr != nil {
+		return billingErr
 	}
+	writeUsageLogBestEffort(ctx, s.usageLogRepo, usageLog, "service.gateway")
 
 	return nil
 }

backend/internal/service/gateway_streaming_test.go

@@ -181,7 +181,8 @@ func TestHandleStreamingResponse_EmptyStream(t *testing.T) {
 
 	result, err := svc.handleStreamingResponse(context.Background(), resp, c, &Account{ID: 1}, time.Now(), "model", "model", false)
 	_ = pr.Close()
-	require.NoError(t, err)
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "missing terminal event")
 	require.NotNil(t, result)
 }
 

backend/internal/service/openai_gateway_record_usage_test.go

@@ -7,35 +7,63 @@ import (
 	"time"
 
 	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/ctxkey"
 	"github.com/stretchr/testify/require"
 )
 
 type openAIRecordUsageLogRepoStub struct {
 	UsageLogRepository
 
-	inserted bool
+	inserted   bool
-	err      error
+	err        error
-	calls    int
+	calls      int
-	lastLog  *UsageLog
+	lastLog    *UsageLog
+	lastCtxErr error
 }
 
 func (s *openAIRecordUsageLogRepoStub) Create(ctx context.Context, log *UsageLog) (bool, error) {
 	s.calls++
 	s.lastLog = log
+	s.lastCtxErr = ctx.Err()
 	return s.inserted, s.err
 }
 
+type openAIRecordUsageBillingRepoStub struct {
+	UsageBillingRepository
+
+	result     *UsageBillingApplyResult
+	err        error
+	calls      int
+	lastCmd    *UsageBillingCommand
+	lastCtxErr error
+}
+
+func (s *openAIRecordUsageBillingRepoStub) Apply(ctx context.Context, cmd *UsageBillingCommand) (*UsageBillingApplyResult, error) {
+	s.calls++
+	s.lastCmd = cmd
+	s.lastCtxErr = ctx.Err()
+	if s.err != nil {
+		return nil, s.err
+	}
+	if s.result != nil {
+		return s.result, nil
+	}
+	return &UsageBillingApplyResult{Applied: true}, nil
+}
+
 type openAIRecordUsageUserRepoStub struct {
 	UserRepository
 
 	deductCalls int
 	deductErr   error
 	lastAmount  float64
+	lastCtxErr  error
 }
 
 func (s *openAIRecordUsageUserRepoStub) DeductBalance(ctx context.Context, id int64, amount float64) error {
 	s.deductCalls++
 	s.lastAmount = amount
+	s.lastCtxErr = ctx.Err()
 	return s.deductErr
 }
 
@@ -44,29 +72,35 @@ type openAIRecordUsageSubRepoStub struct {
 
 	incrementCalls int
 	incrementErr   error
+	lastCtxErr     error
 }
 
 func (s *openAIRecordUsageSubRepoStub) IncrementUsage(ctx context.Context, id int64, costUSD float64) error {
 	s.incrementCalls++
+	s.lastCtxErr = ctx.Err()
 	return s.incrementErr
 }
 
 type openAIRecordUsageAPIKeyQuotaStub struct {
-	quotaCalls     int
+	quotaCalls          int
-	rateLimitCalls int
+	rateLimitCalls      int
-	err            error
+	err                 error
-	lastAmount     float64
+	lastAmount          float64
+	lastQuotaCtxErr     error
+	lastRateLimitCtxErr error
 }
 
 func (s *openAIRecordUsageAPIKeyQuotaStub) UpdateQuotaUsed(ctx context.Context, apiKeyID int64, cost float64) error {
 	s.quotaCalls++
 	s.lastAmount = cost
+	s.lastQuotaCtxErr = ctx.Err()
 	return s.err
 }
 
 func (s *openAIRecordUsageAPIKeyQuotaStub) UpdateRateLimitUsage(ctx context.Context, apiKeyID int64, cost float64) error {
 	s.rateLimitCalls++
 	s.lastAmount = cost
+	s.lastRateLimitCtxErr = ctx.Err()
 	return s.err
 }
 
@@ -93,23 +127,38 @@ func i64p(v int64) *int64 {
 func newOpenAIRecordUsageServiceForTest(usageRepo UsageLogRepository, userRepo UserRepository, subRepo UserSubscriptionRepository, rateRepo UserGroupRateRepository) *OpenAIGatewayService {
 	cfg := &config.Config{}
 	cfg.Default.RateMultiplier = 1.1
+	svc := NewOpenAIGatewayService(
+		nil,
+		usageRepo,
+		nil,
+		userRepo,
+		subRepo,
+		rateRepo,
+		nil,
+		cfg,
+		nil,
+		nil,
+		NewBillingService(cfg, nil),
+		nil,
+		&BillingCacheService{},
+		nil,
+		&DeferredService{},
+		nil,
+	)
+	svc.userGroupRateResolver = newUserGroupRateResolver(
+		rateRepo,
+		nil,
+		resolveUserGroupRateCacheTTL(cfg),
+		nil,
+		"service.openai_gateway.test",
+	)
+	return svc
+}
 
-	return &OpenAIGatewayService{
+func newOpenAIRecordUsageServiceWithBillingRepoForTest(usageRepo UsageLogRepository, billingRepo UsageBillingRepository, userRepo UserRepository, subRepo UserSubscriptionRepository, rateRepo UserGroupRateRepository) *OpenAIGatewayService {
-		usageLogRepo:        usageRepo,
+	svc := newOpenAIRecordUsageServiceForTest(usageRepo, userRepo, subRepo, rateRepo)
-		userRepo:            userRepo,
+	svc.usageBillingRepo = billingRepo
-		userSubRepo:         subRepo,
+	return svc
-		cfg:                 cfg,
-		billingService:      NewBillingService(cfg, nil),
-		billingCacheService: &BillingCacheService{},
-		deferredService:     &DeferredService{},
-		userGroupRateResolver: newUserGroupRateResolver(
-			rateRepo,
-			nil,
-			resolveUserGroupRateCacheTTL(cfg),
-			nil,
-			"service.openai_gateway.test",
-		),
-	}
 }
 
 func expectedOpenAICost(t *testing.T, svc *OpenAIGatewayService, model string, usage OpenAIUsage, multiplier float64) *CostBreakdown {
@@ -252,9 +301,10 @@ func TestOpenAIGatewayServiceRecordUsage_FallsBackToGroupDefaultRateWhenResolver
 
 func TestOpenAIGatewayServiceRecordUsage_DuplicateUsageLogSkipsBilling(t *testing.T) {
 	usageRepo := &openAIRecordUsageLogRepoStub{inserted: false}
+	billingRepo := &openAIRecordUsageBillingRepoStub{result: &UsageBillingApplyResult{Applied: false}}
 	userRepo := &openAIRecordUsageUserRepoStub{}
 	subRepo := &openAIRecordUsageSubRepoStub{}
-	svc := newOpenAIRecordUsageServiceForTest(usageRepo, userRepo, subRepo, nil)
+	svc := newOpenAIRecordUsageServiceWithBillingRepoForTest(usageRepo, billingRepo, userRepo, subRepo, nil)
 
 	err := svc.RecordUsage(context.Background(), &OpenAIRecordUsageInput{
 		Result: &OpenAIForwardResult{
@@ -272,11 +322,254 @@ func TestOpenAIGatewayServiceRecordUsage_DuplicateUsageLogSkipsBilling(t *testin
 	})
 
 	require.NoError(t, err)
+	require.Equal(t, 1, billingRepo.calls)
 	require.Equal(t, 1, usageRepo.calls)
 	require.Equal(t, 0, userRepo.deductCalls)
 	require.Equal(t, 0, subRepo.incrementCalls)
 }
 
+func TestOpenAIGatewayServiceRecordUsage_DuplicateBillingKeySkipsBillingWithRepo(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{inserted: false}
+	billingRepo := &openAIRecordUsageBillingRepoStub{result: &UsageBillingApplyResult{Applied: false}}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	quotaSvc := &openAIRecordUsageAPIKeyQuotaStub{}
+	svc := newOpenAIRecordUsageServiceWithBillingRepoForTest(usageRepo, billingRepo, userRepo, subRepo, nil)
+
+	err := svc.RecordUsage(context.Background(), &OpenAIRecordUsageInput{
+		Result: &OpenAIForwardResult{
+			RequestID: "resp_duplicate_billing_key",
+			Usage: OpenAIUsage{
+				InputTokens:  8,
+				OutputTokens: 4,
+			},
+			Model:    "gpt-5.1",
+			Duration: time.Second,
+		},
+		APIKey: &APIKey{
+			ID:    10045,
+			Quota: 100,
+		},
+		User:          &User{ID: 20045},
+		Account:       &Account{ID: 30045},
+		APIKeyService: quotaSvc,
+	})
+
+	require.NoError(t, err)
+	require.Equal(t, 1, billingRepo.calls)
+	require.Equal(t, 1, usageRepo.calls)
+	require.Equal(t, 0, userRepo.deductCalls)
+	require.Equal(t, 0, subRepo.incrementCalls)
+	require.Equal(t, 0, quotaSvc.quotaCalls)
+}
+
+func TestOpenAIGatewayServiceRecordUsage_BillsWhenUsageLogCreateReturnsError(t *testing.T) {
+	usage := OpenAIUsage{InputTokens: 8, OutputTokens: 4}
+	usageRepo := &openAIRecordUsageLogRepoStub{inserted: false, err: errors.New("usage log batch state uncertain")}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	svc := newOpenAIRecordUsageServiceForTest(usageRepo, userRepo, subRepo, nil)
+
+	err := svc.RecordUsage(context.Background(), &OpenAIRecordUsageInput{
+		Result: &OpenAIForwardResult{
+			RequestID: "resp_usage_log_error",
+			Usage:     usage,
+			Model:     "gpt-5.1",
+			Duration:  time.Second,
+		},
+		APIKey:  &APIKey{ID: 10041},
+		User:    &User{ID: 20041},
+		Account: &Account{ID: 30041},
+	})
+
+	require.NoError(t, err)
+	require.Equal(t, 1, usageRepo.calls)
+	require.Equal(t, 1, userRepo.deductCalls)
+	require.Equal(t, 0, subRepo.incrementCalls)
+}
+
+func TestOpenAIGatewayServiceRecordUsage_UsageLogWriteErrorDoesNotSkipBilling(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{inserted: false, err: MarkUsageLogCreateNotPersisted(context.Canceled)}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	quotaSvc := &openAIRecordUsageAPIKeyQuotaStub{}
+	svc := newOpenAIRecordUsageServiceForTest(usageRepo, userRepo, subRepo, nil)
+
+	err := svc.RecordUsage(context.Background(), &OpenAIRecordUsageInput{
+		Result: &OpenAIForwardResult{
+			RequestID: "resp_not_persisted",
+			Usage: OpenAIUsage{
+				InputTokens:  8,
+				OutputTokens: 4,
+			},
+			Model:    "gpt-5.1",
+			Duration: time.Second,
+		},
+		APIKey: &APIKey{
+			ID:    10043,
+			Quota: 100,
+		},
+		User:          &User{ID: 20043},
+		Account:       &Account{ID: 30043},
+		APIKeyService: quotaSvc,
+	})
+
+	require.NoError(t, err)
+	require.Equal(t, 1, usageRepo.calls)
+	require.Equal(t, 1, userRepo.deductCalls)
+	require.Equal(t, 0, subRepo.incrementCalls)
+	require.Equal(t, 1, quotaSvc.quotaCalls)
+}
+
+func TestOpenAIGatewayServiceRecordUsage_BillingUsesDetachedContext(t *testing.T) {
+	usage := OpenAIUsage{InputTokens: 10, OutputTokens: 6, CacheReadInputTokens: 2}
+	usageRepo := &openAIRecordUsageLogRepoStub{inserted: false, err: context.DeadlineExceeded}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	quotaSvc := &openAIRecordUsageAPIKeyQuotaStub{}
+	svc := newOpenAIRecordUsageServiceForTest(usageRepo, userRepo, subRepo, nil)
+
+	reqCtx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	err := svc.RecordUsage(reqCtx, &OpenAIRecordUsageInput{
+		Result: &OpenAIForwardResult{
+			RequestID: "resp_detached_billing_ctx",
+			Usage:     usage,
+			Model:     "gpt-5.1",
+			Duration:  time.Second,
+		},
+		APIKey: &APIKey{
+			ID:    10042,
+			Quota: 100,
+		},
+		User:          &User{ID: 20042},
+		Account:       &Account{ID: 30042},
+		APIKeyService: quotaSvc,
+	})
+
+	require.NoError(t, err)
+	require.Equal(t, 1, userRepo.deductCalls)
+	require.NoError(t, userRepo.lastCtxErr)
+	require.Equal(t, 1, quotaSvc.quotaCalls)
+	require.NoError(t, quotaSvc.lastQuotaCtxErr)
+}
+
+func TestOpenAIGatewayServiceRecordUsage_BillingRepoUsesDetachedContext(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{}
+	billingRepo := &openAIRecordUsageBillingRepoStub{result: &UsageBillingApplyResult{Applied: true}}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	svc := newOpenAIRecordUsageServiceWithBillingRepoForTest(usageRepo, billingRepo, userRepo, subRepo, nil)
+
+	reqCtx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	err := svc.RecordUsage(reqCtx, &OpenAIRecordUsageInput{
+		Result: &OpenAIForwardResult{
+			RequestID: "resp_detached_billing_repo_ctx",
+			Usage: OpenAIUsage{
+				InputTokens:  8,
+				OutputTokens: 4,
+			},
+			Model:    "gpt-5.1",
+			Duration: time.Second,
+		},
+		APIKey:  &APIKey{ID: 10046},
+		User:    &User{ID: 20046},
+		Account: &Account{ID: 30046},
+	})
+
+	require.NoError(t, err)
+	require.Equal(t, 1, billingRepo.calls)
+	require.NoError(t, billingRepo.lastCtxErr)
+	require.Equal(t, 1, usageRepo.calls)
+	require.NoError(t, usageRepo.lastCtxErr)
+}
+
+func TestOpenAIGatewayServiceRecordUsage_BillingFingerprintIncludesRequestPayloadHash(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{}
+	billingRepo := &openAIRecordUsageBillingRepoStub{result: &UsageBillingApplyResult{Applied: true}}
+	svc := newOpenAIRecordUsageServiceWithBillingRepoForTest(usageRepo, billingRepo, &openAIRecordUsageUserRepoStub{}, &openAIRecordUsageSubRepoStub{}, nil)
+
+	payloadHash := HashUsageRequestPayload([]byte(`{"model":"gpt-5","input":"hello"}`))
+	err := svc.RecordUsage(context.Background(), &OpenAIRecordUsageInput{
+		Result: &OpenAIForwardResult{
+			RequestID: "openai_payload_hash",
+			Usage: OpenAIUsage{
+				InputTokens:  10,
+				OutputTokens: 6,
+			},
+			Model:    "gpt-5",
+			Duration: time.Second,
+		},
+		APIKey:             &APIKey{ID: 501, Quota: 100},
+		User:               &User{ID: 601},
+		Account:            &Account{ID: 701},
+		RequestPayloadHash: payloadHash,
+	})
+	require.NoError(t, err)
+	require.NotNil(t, billingRepo.lastCmd)
+	require.Equal(t, payloadHash, billingRepo.lastCmd.RequestPayloadHash)
+}
+
+func TestOpenAIGatewayServiceRecordUsage_UsesFallbackRequestIDForBillingAndUsageLog(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{}
+	billingRepo := &openAIRecordUsageBillingRepoStub{result: &UsageBillingApplyResult{Applied: true}}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	svc := newOpenAIRecordUsageServiceWithBillingRepoForTest(usageRepo, billingRepo, userRepo, subRepo, nil)
+
+	ctx := context.WithValue(context.Background(), ctxkey.RequestID, "req-local-fallback")
+	err := svc.RecordUsage(ctx, &OpenAIRecordUsageInput{
+		Result: &OpenAIForwardResult{
+			RequestID: "",
+			Usage: OpenAIUsage{
+				InputTokens:  8,
+				OutputTokens: 4,
+			},
+			Model:    "gpt-5.1",
+			Duration: time.Second,
+		},
+		APIKey:  &APIKey{ID: 10047},
+		User:    &User{ID: 20047},
+		Account: &Account{ID: 30047},
+	})
+
+	require.NoError(t, err)
+	require.NotNil(t, billingRepo.lastCmd)
+	require.Equal(t, "local:req-local-fallback", billingRepo.lastCmd.RequestID)
+	require.NotNil(t, usageRepo.lastLog)
+	require.Equal(t, "local:req-local-fallback", usageRepo.lastLog.RequestID)
+}
+
+func TestOpenAIGatewayServiceRecordUsage_BillingErrorSkipsUsageLogWrite(t *testing.T) {
+	usageRepo := &openAIRecordUsageLogRepoStub{}
+	billingRepo := &openAIRecordUsageBillingRepoStub{err: errors.New("billing tx failed")}
+	userRepo := &openAIRecordUsageUserRepoStub{}
+	subRepo := &openAIRecordUsageSubRepoStub{}
+	svc := newOpenAIRecordUsageServiceWithBillingRepoForTest(usageRepo, billingRepo, userRepo, subRepo, nil)
+
+	err := svc.RecordUsage(context.Background(), &OpenAIRecordUsageInput{
+		Result: &OpenAIForwardResult{
+			RequestID: "resp_billing_fail",
+			Usage: OpenAIUsage{
+				InputTokens:  8,
+				OutputTokens: 4,
+			},
+			Model:    "gpt-5.1",
+			Duration: time.Second,
+		},
+		APIKey:  &APIKey{ID: 10048},
+		User:    &User{ID: 20048},
+		Account: &Account{ID: 30048},
+	})
+
+	require.Error(t, err)
+	require.Equal(t, 1, billingRepo.calls)
+	require.Equal(t, 0, usageRepo.calls)
+}
+
 func TestOpenAIGatewayServiceRecordUsage_UpdatesAPIKeyQuotaWhenConfigured(t *testing.T) {
 	usage := OpenAIUsage{InputTokens: 10, OutputTokens: 6, CacheReadInputTokens: 2}
 	usageRepo := &openAIRecordUsageLogRepoStub{inserted: true}

backend/internal/service/openai_gateway_service.go

@@ -259,6 +259,7 @@ type openAIWSRetryMetrics struct {
 type OpenAIGatewayService struct {
 	accountRepo           AccountRepository
 	usageLogRepo          UsageLogRepository
+	usageBillingRepo      UsageBillingRepository
 	userRepo              UserRepository
 	userSubRepo           UserSubscriptionRepository
 	cache                 GatewayCache
@@ -295,6 +296,7 @@ type OpenAIGatewayService struct {
 func NewOpenAIGatewayService(
 	accountRepo AccountRepository,
 	usageLogRepo UsageLogRepository,
+	usageBillingRepo UsageBillingRepository,
 	userRepo UserRepository,
 	userSubRepo UserSubscriptionRepository,
 	userGroupRateRepo UserGroupRateRepository,
@@ -312,6 +314,7 @@ func NewOpenAIGatewayService(
 	svc := &OpenAIGatewayService{
 		accountRepo:         accountRepo,
 		usageLogRepo:        usageLogRepo,
+		usageBillingRepo:    usageBillingRepo,
 		userRepo:            userRepo,
 		userSubRepo:         userSubRepo,
 		cache:               cache,
@@ -2014,7 +2017,9 @@ func (s *OpenAIGatewayService) Forward(ctx context.Context, c *gin.Context, acco
 	}
 
 	// Build upstream request
-	upstreamReq, err := s.buildUpstreamRequest(ctx, c, account, body, token, reqStream, promptCacheKey, isCodexCLI)
+	upstreamCtx, releaseUpstreamCtx := detachStreamUpstreamContext(ctx, reqStream)
+	upstreamReq, err := s.buildUpstreamRequest(upstreamCtx, c, account, body, token, reqStream, promptCacheKey, isCodexCLI)
+	releaseUpstreamCtx()
 	if err != nil {
 		return nil, err
 	}
@@ -2206,7 +2211,9 @@ func (s *OpenAIGatewayService) forwardOpenAIPassthrough(
 		return nil, err
 	}
 
-	upstreamReq, err := s.buildUpstreamRequestOpenAIPassthrough(ctx, c, account, body, token)
+	upstreamCtx, releaseUpstreamCtx := detachStreamUpstreamContext(ctx, reqStream)
+	upstreamReq, err := s.buildUpstreamRequestOpenAIPassthrough(upstreamCtx, c, account, body, token)
+	releaseUpstreamCtx()
 	if err != nil {
 		return nil, err
 	}
@@ -2543,6 +2550,7 @@ func (s *OpenAIGatewayService) handleStreamingResponsePassthrough(
 	var firstTokenMs *int
 	clientDisconnected := false
 	sawDone := false
+	sawTerminalEvent := false
 	upstreamRequestID := strings.TrimSpace(resp.Header.Get("x-request-id"))
 
 	scanner := bufio.NewScanner(resp.Body)
@@ -2562,6 +2570,9 @@ func (s *OpenAIGatewayService) handleStreamingResponsePassthrough(
 			if trimmedData == "[DONE]" {
 				sawDone = true
 			}
+			if openAIStreamEventIsTerminal(trimmedData) {
+				sawTerminalEvent = true
+			}
 			if firstTokenMs == nil && trimmedData != "" && trimmedData != "[DONE]" {
 				ms := int(time.Since(startTime).Milliseconds())
 				firstTokenMs = &ms
@@ -2579,19 +2590,14 @@ func (s *OpenAIGatewayService) handleStreamingResponsePassthrough(
 		}
 	}
 	if err := scanner.Err(); err != nil {
-		if clientDisconnected {
+		if sawTerminalEvent {
-			logger.LegacyPrintf("service.openai_gateway", "[OpenAI passthrough] Upstream read error after client disconnect: account=%d err=%v", account.ID, err)
 			return &openaiStreamingResultPassthrough{usage: usage, firstTokenMs: firstTokenMs}, nil
 		}
+		if clientDisconnected {
+			return &openaiStreamingResultPassthrough{usage: usage, firstTokenMs: firstTokenMs}, fmt.Errorf("stream usage incomplete after disconnect: %w", err)
+		}
 		if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
-			logger.LegacyPrintf("service.openai_gateway",
+			return &openaiStreamingResultPassthrough{usage: usage, firstTokenMs: firstTokenMs}, fmt.Errorf("stream usage incomplete: %w", err)
-				"[OpenAI passthrough] 流读取被取消，可能发生断流: account=%d request_id=%s err=%v ctx_err=%v",
-				account.ID,
-				upstreamRequestID,
-				err,
-				ctx.Err(),
-			)
-			return &openaiStreamingResultPassthrough{usage: usage, firstTokenMs: firstTokenMs}, nil
 		}
 		if errors.Is(err, bufio.ErrTooLong) {
 			logger.LegacyPrintf("service.openai_gateway", "[OpenAI passthrough] SSE line too long: account=%d max_size=%d error=%v", account.ID, maxLineSize, err)
@@ -2605,12 +2611,13 @@ func (s *OpenAIGatewayService) handleStreamingResponsePassthrough(
 		)
 		return &openaiStreamingResultPassthrough{usage: usage, firstTokenMs: firstTokenMs}, fmt.Errorf("stream read error: %w", err)
 	}
-	if !clientDisconnected && !sawDone && ctx.Err() == nil {
+	if !clientDisconnected && !sawDone && !sawTerminalEvent && ctx.Err() == nil {
 		logger.FromContext(ctx).With(
 			zap.String("component", "service.openai_gateway"),
 			zap.Int64("account_id", account.ID),
 			zap.String("upstream_request_id", upstreamRequestID),
 		).Info("OpenAI passthrough 上游流在未收到 [DONE] 时结束，疑似断流")
+		return &openaiStreamingResultPassthrough{usage: usage, firstTokenMs: firstTokenMs}, errors.New("stream usage incomplete: missing terminal event")
 	}
 
 	return &openaiStreamingResultPassthrough{usage: usage, firstTokenMs: firstTokenMs}, nil
@@ -3030,6 +3037,7 @@ func (s *OpenAIGatewayService) handleStreamingResponse(ctx context.Context, resp
 	// 否则下游 SDK（例如 OpenCode）会因为类型校验失败而报错。
 	errorEventSent := false
 	clientDisconnected := false // 客户端断开后继续 drain 上游以收集 usage
+	sawTerminalEvent := false
 	sendErrorEvent := func(reason string) {
 		if errorEventSent || clientDisconnected {
 			return
@@ -3060,22 +3068,27 @@ func (s *OpenAIGatewayService) handleStreamingResponse(ctx context.Context, resp
 				logger.LegacyPrintf("service.openai_gateway", "Client disconnected during final flush, returning collected usage")
 			}
 		}
+		if !sawTerminalEvent {
+			return resultWithUsage(), fmt.Errorf("stream usage incomplete: missing terminal event")
+		}
 		return resultWithUsage(), nil
 	}
 	handleScanErr := func(scanErr error) (*openaiStreamingResult, error, bool) {
 		if scanErr == nil {
 			return nil, nil, false
 		}
+		if sawTerminalEvent {
+			logger.LegacyPrintf("service.openai_gateway", "Upstream scan ended after terminal event: %v", scanErr)
+			return resultWithUsage(), nil, true
+		}
 		// 客户端断开/取消请求时，上游读取往往会返回 context canceled。
 		// /v1/responses 的 SSE 事件必须符合 OpenAI 协议；这里不注入自定义 error event，避免下游 SDK 解析失败。
 		if errors.Is(scanErr, context.Canceled) || errors.Is(scanErr, context.DeadlineExceeded) {
-			logger.LegacyPrintf("service.openai_gateway", "Context canceled during streaming, returning collected usage")
+			return resultWithUsage(), fmt.Errorf("stream usage incomplete: %w", scanErr), true
-			return resultWithUsage(), nil, true
 		}
 		// 客户端已断开时，上游出错仅影响体验，不影响计费；返回已收集 usage
 		if clientDisconnected {
-			logger.LegacyPrintf("service.openai_gateway", "Upstream read error after client disconnect: %v, returning collected usage", scanErr)
+			return resultWithUsage(), fmt.Errorf("stream usage incomplete after disconnect: %w", scanErr), true
-			return resultWithUsage(), nil, true
 		}
 		if errors.Is(scanErr, bufio.ErrTooLong) {
 			logger.LegacyPrintf("service.openai_gateway", "SSE line too long: account=%d max_size=%d error=%v", account.ID, maxLineSize, scanErr)
@@ -3098,6 +3111,9 @@ func (s *OpenAIGatewayService) handleStreamingResponse(ctx context.Context, resp
 			}
 
 			dataBytes := []byte(data)
+			if openAIStreamEventIsTerminal(data) {
+				sawTerminalEvent = true
+			}
 
 			// Correct Codex tool calls if needed (apply_patch -> edit, etc.)
 			if correctedData, corrected := s.toolCorrector.CorrectToolCallsInSSEBytes(dataBytes); corrected {
@@ -3214,8 +3230,7 @@ func (s *OpenAIGatewayService) handleStreamingResponse(ctx context.Context, resp
 				continue
 			}
 			if clientDisconnected {
-				logger.LegacyPrintf("service.openai_gateway", "Upstream timeout after client disconnect, returning collected usage")
+				return resultWithUsage(), fmt.Errorf("stream usage incomplete after timeout")
-				return resultWithUsage(), nil
 			}
 			logger.LegacyPrintf("service.openai_gateway", "Stream data interval timeout: account=%d model=%s interval=%s", account.ID, originalModel, streamInterval)
 			// 处理流超时，可能标记账户为临时不可调度或错误状态
@@ -3313,11 +3328,12 @@ func (s *OpenAIGatewayService) parseSSEUsageBytes(data []byte, usage *OpenAIUsag
 	if usage == nil || len(data) == 0 || bytes.Equal(data, []byte("[DONE]")) {
 		return
 	}
-	// 选择性解析：仅在数据中包含 completed 事件标识时才进入字段提取。
+	// 选择性解析：仅在数据中包含终止事件标识时才进入字段提取。
-	if len(data) < 80 || !bytes.Contains(data, []byte(`"response.completed"`)) {
+	if len(data) < 72 {
 		return
 	}
-	if gjson.GetBytes(data, "type").String() != "response.completed" {
+	eventType := gjson.GetBytes(data, "type").String()
+	if eventType != "response.completed" && eventType != "response.done" {
 		return
 	}
 
@@ -3670,14 +3686,15 @@ func (s *OpenAIGatewayService) replaceModelInResponseBody(body []byte, fromModel
 
 // OpenAIRecordUsageInput input for recording usage
 type OpenAIRecordUsageInput struct {
-	Result        *OpenAIForwardResult
+	Result             *OpenAIForwardResult
-	APIKey        *APIKey
+	APIKey             *APIKey
-	User          *User
+	User               *User
-	Account       *Account
+	Account            *Account
-	Subscription  *UserSubscription
+	Subscription       *UserSubscription
-	UserAgent     string // 请求的 User-Agent
+	UserAgent          string // 请求的 User-Agent
-	IPAddress     string // 请求的客户端 IP 地址
+	IPAddress          string // 请求的客户端 IP 地址
-	APIKeyService APIKeyQuotaUpdater
+	RequestPayloadHash string
+	APIKeyService      APIKeyQuotaUpdater
 }
 
 // RecordUsage records usage and deducts balance
@@ -3743,11 +3760,12 @@ func (s *OpenAIGatewayService) RecordUsage(ctx context.Context, input *OpenAIRec
 	// Create usage log
 	durationMs := int(result.Duration.Milliseconds())
 	accountRateMultiplier := account.BillingRateMultiplier()
+	requestID := resolveUsageBillingRequestID(ctx, result.RequestID)
 	usageLog := &UsageLog{
 		UserID:                user.ID,
 		APIKeyID:              apiKey.ID,
 		AccountID:             account.ID,
-		RequestID:             result.RequestID,
+		RequestID:             requestID,
 		Model:                 billingModel,
 		ServiceTier:           result.ServiceTier,
 		ReasoningEffort:       result.ReasoningEffort,
@@ -3788,29 +3806,32 @@ func (s *OpenAIGatewayService) RecordUsage(ctx context.Context, input *OpenAIRec
 		usageLog.SubscriptionID = &subscription.ID
 	}
 
-	inserted, err := s.usageLogRepo.Create(ctx, usageLog)
 	if s.cfg != nil && s.cfg.RunMode == config.RunModeSimple {
+		writeUsageLogBestEffort(ctx, s.usageLogRepo, usageLog, "service.openai_gateway")
 		logger.LegacyPrintf("service.openai_gateway", "[SIMPLE MODE] Usage recorded (not billed): user=%d, tokens=%d", usageLog.UserID, usageLog.TotalTokens())
 		s.deferredService.ScheduleLastUsedUpdate(account.ID)
 		return nil
 	}
 
-	shouldBill := inserted || err != nil
+	billingErr := func() error {
-
+		_, err := applyUsageBilling(ctx, requestID, usageLog, &postUsageBillingParams{
-	if shouldBill {
-		postUsageBilling(ctx, &postUsageBillingParams{
 			Cost:                  cost,
 			User:                  user,
 			APIKey:                apiKey,
 			Account:               account,
 			Subscription:          subscription,
+			RequestPayloadHash:    resolveUsageBillingPayloadFingerprint(ctx, input.RequestPayloadHash),
 			IsSubscriptionBill:    isSubscriptionBilling,
 			AccountRateMultiplier: accountRateMultiplier,
 			APIKeyService:         input.APIKeyService,
-		}, s.billingDeps())
+		}, s.billingDeps(), s.usageBillingRepo)
-	} else {
+		return err
-		s.deferredService.ScheduleLastUsedUpdate(account.ID)
+	}()
+
+	if billingErr != nil {
+		return billingErr
 	}
+	writeUsageLogBestEffort(ctx, s.usageLogRepo, usageLog, "service.openai_gateway")
 
 	return nil
 }

backend/internal/service/openai_gateway_service_test.go

@@ -916,7 +916,7 @@ func TestOpenAIStreamingTimeout(t *testing.T) {
 	}
 }
 
-func TestOpenAIStreamingContextCanceledDoesNotInjectErrorEvent(t *testing.T) {
+func TestOpenAIStreamingContextCanceledReturnsIncompleteErrorWithoutInjectingErrorEvent(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	cfg := &config.Config{
 		Gateway: config.GatewayConfig{
@@ -940,8 +940,8 @@ func TestOpenAIStreamingContextCanceledDoesNotInjectErrorEvent(t *testing.T) {
 	}
 
 	_, err := svc.handleStreamingResponse(c.Request.Context(), resp, c, &Account{ID: 1}, time.Now(), "model", "model")
-	if err != nil {
+	if err == nil || !strings.Contains(err.Error(), "stream usage incomplete") {
-		t.Fatalf("expected nil error, got %v", err)
+		t.Fatalf("expected incomplete stream error, got %v", err)
 	}
 	if strings.Contains(rec.Body.String(), "event: error") || strings.Contains(rec.Body.String(), "stream_read_error") {
 		t.Fatalf("expected no injected SSE error event, got %q", rec.Body.String())
@@ -993,6 +993,107 @@ func TestOpenAIStreamingClientDisconnectDrainsUpstreamUsage(t *testing.T) {
 	}
 }
 
+func TestOpenAIStreamingMissingTerminalEventReturnsIncompleteError(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	cfg := &config.Config{
+		Gateway: config.GatewayConfig{
+			StreamDataIntervalTimeout: 0,
+			StreamKeepaliveInterval:   0,
+			MaxLineSize:               defaultMaxLineSize,
+		},
+	}
+	svc := &OpenAIGatewayService{cfg: cfg}
+
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+	c.Request = httptest.NewRequest(http.MethodPost, "/", nil)
+
+	pr, pw := io.Pipe()
+	resp := &http.Response{
+		StatusCode: http.StatusOK,
+		Body:       pr,
+		Header:     http.Header{},
+	}
+
+	go func() {
+		defer func() { _ = pw.Close() }()
+		_, _ = pw.Write([]byte("data: {\"type\":\"response.in_progress\",\"response\":{}}\n\n"))
+	}()
+
+	_, err := svc.handleStreamingResponse(c.Request.Context(), resp, c, &Account{ID: 1}, time.Now(), "model", "model")
+	_ = pr.Close()
+	if err == nil || !strings.Contains(err.Error(), "missing terminal event") {
+		t.Fatalf("expected missing terminal event error, got %v", err)
+	}
+}
+
+func TestOpenAIStreamingPassthroughMissingTerminalEventReturnsIncompleteError(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	cfg := &config.Config{
+		Gateway: config.GatewayConfig{
+			MaxLineSize: defaultMaxLineSize,
+		},
+	}
+	svc := &OpenAIGatewayService{cfg: cfg}
+
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+	c.Request = httptest.NewRequest(http.MethodPost, "/", nil)
+
+	pr, pw := io.Pipe()
+	resp := &http.Response{
+		StatusCode: http.StatusOK,
+		Body:       pr,
+		Header:     http.Header{},
+	}
+
+	go func() {
+		defer func() { _ = pw.Close() }()
+		_, _ = pw.Write([]byte("data: {\"type\":\"response.in_progress\",\"response\":{}}\n\n"))
+	}()
+
+	_, err := svc.handleStreamingResponsePassthrough(c.Request.Context(), resp, c, &Account{ID: 1}, time.Now())
+	_ = pr.Close()
+	if err == nil || !strings.Contains(err.Error(), "missing terminal event") {
+		t.Fatalf("expected missing terminal event error, got %v", err)
+	}
+}
+
+func TestOpenAIStreamingPassthroughResponseDoneWithoutDoneMarkerStillSucceeds(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	cfg := &config.Config{
+		Gateway: config.GatewayConfig{
+			MaxLineSize: defaultMaxLineSize,
+		},
+	}
+	svc := &OpenAIGatewayService{cfg: cfg}
+
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+	c.Request = httptest.NewRequest(http.MethodPost, "/", nil)
+
+	pr, pw := io.Pipe()
+	resp := &http.Response{
+		StatusCode: http.StatusOK,
+		Body:       pr,
+		Header:     http.Header{},
+	}
+
+	go func() {
+		defer func() { _ = pw.Close() }()
+		_, _ = pw.Write([]byte("data: {\"type\":\"response.done\",\"response\":{\"usage\":{\"input_tokens\":2,\"output_tokens\":3,\"input_tokens_details\":{\"cached_tokens\":1}}}}\n\n"))
+	}()
+
+	result, err := svc.handleStreamingResponsePassthrough(c.Request.Context(), resp, c, &Account{ID: 1}, time.Now())
+	_ = pr.Close()
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.NotNil(t, result.usage)
+	require.Equal(t, 2, result.usage.InputTokens)
+	require.Equal(t, 3, result.usage.OutputTokens)
+	require.Equal(t, 1, result.usage.CacheReadInputTokens)
+}
+
 func TestOpenAIStreamingTooLong(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	cfg := &config.Config{
@@ -1124,7 +1225,7 @@ func TestOpenAIStreamingHeadersOverride(t *testing.T) {
 
 	go func() {
 		defer func() { _ = pw.Close() }()
-		_, _ = pw.Write([]byte("data: {}\n\n"))
+		_, _ = pw.Write([]byte("data: {\"type\":\"response.completed\",\"response\":{}}\n\n"))
 	}()
 
 	_, err := svc.handleStreamingResponse(c.Request.Context(), resp, c, &Account{ID: 1}, time.Now(), "model", "model")
@@ -1674,6 +1775,12 @@ func TestParseSSEUsage_SelectiveParsing(t *testing.T) {
 	require.Equal(t, 3, usage.InputTokens)
 	require.Equal(t, 5, usage.OutputTokens)
 	require.Equal(t, 2, usage.CacheReadInputTokens)
+
+	// done 事件同样可能携带最终 usage
+	svc.parseSSEUsage(`{"type":"response.done","response":{"usage":{"input_tokens":13,"output_tokens":15,"input_tokens_details":{"cached_tokens":4}}}}`, usage)
+	require.Equal(t, 13, usage.InputTokens)
+	require.Equal(t, 15, usage.OutputTokens)
+	require.Equal(t, 4, usage.CacheReadInputTokens)
 }
 
 func TestExtractCodexFinalResponse_SampleReplay(t *testing.T) {

backend/internal/service/openai_ws_protocol_forward_test.go

@@ -392,6 +392,7 @@ func TestNewOpenAIGatewayService_InitializesOpenAIWSResolver(t *testing.T) {
 		nil,
 		nil,
 		nil,
+		nil,
 		cfg,
 		nil,
 		nil,

backend/internal/service/usage_billing.go

@@ -0,0 +1,110 @@
+package service
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"strings"
+)
+
+var ErrUsageBillingRequestIDRequired = errors.New("usage billing request_id is required")
+var ErrUsageBillingRequestConflict = errors.New("usage billing request fingerprint conflict")
+
+// UsageBillingCommand describes one billable request that must be applied at most once.
+type UsageBillingCommand struct {
+	RequestID          string
+	APIKeyID           int64
+	RequestFingerprint string
+	RequestPayloadHash string
+
+	UserID              int64
+	AccountID           int64
+	SubscriptionID      *int64
+	AccountType         string
+	Model               string
+	ServiceTier         string
+	ReasoningEffort     string
+	BillingType         int8
+	InputTokens         int
+	OutputTokens        int
+	CacheCreationTokens int
+	CacheReadTokens     int
+	ImageCount          int
+	MediaType           string
+
+	BalanceCost         float64
+	SubscriptionCost    float64
+	APIKeyQuotaCost     float64
+	APIKeyRateLimitCost float64
+	AccountQuotaCost    float64
+}
+
+func (c *UsageBillingCommand) Normalize() {
+	if c == nil {
+		return
+	}
+	c.RequestID = strings.TrimSpace(c.RequestID)
+	if strings.TrimSpace(c.RequestFingerprint) == "" {
+		c.RequestFingerprint = buildUsageBillingFingerprint(c)
+	}
+}
+
+func buildUsageBillingFingerprint(c *UsageBillingCommand) string {
+	if c == nil {
+		return ""
+	}
+	raw := fmt.Sprintf(
+		"%d|%d|%d|%s|%s|%s|%s|%d|%d|%d|%d|%d|%d|%s|%d|%0.10f|%0.10f|%0.10f|%0.10f|%0.10f",
+		c.UserID,
+		c.AccountID,
+		c.APIKeyID,
+		strings.TrimSpace(c.AccountType),
+		strings.TrimSpace(c.Model),
+		strings.TrimSpace(c.ServiceTier),
+		strings.TrimSpace(c.ReasoningEffort),
+		c.BillingType,
+		c.InputTokens,
+		c.OutputTokens,
+		c.CacheCreationTokens,
+		c.CacheReadTokens,
+		c.ImageCount,
+		strings.TrimSpace(c.MediaType),
+		valueOrZero(c.SubscriptionID),
+		c.BalanceCost,
+		c.SubscriptionCost,
+		c.APIKeyQuotaCost,
+		c.APIKeyRateLimitCost,
+		c.AccountQuotaCost,
+	)
+	if payloadHash := strings.TrimSpace(c.RequestPayloadHash); payloadHash != "" {
+		raw += "|" + payloadHash
+	}
+	sum := sha256.Sum256([]byte(raw))
+	return hex.EncodeToString(sum[:])
+}
+
+func HashUsageRequestPayload(payload []byte) string {
+	if len(payload) == 0 {
+		return ""
+	}
+	sum := sha256.Sum256(payload)
+	return hex.EncodeToString(sum[:])
+}
+
+func valueOrZero(v *int64) int64 {
+	if v == nil {
+		return 0
+	}
+	return *v
+}
+
+type UsageBillingApplyResult struct {
+	Applied              bool
+	APIKeyQuotaExhausted bool
+}
+
+type UsageBillingRepository interface {
+	Apply(ctx context.Context, cmd *UsageBillingCommand) (*UsageBillingApplyResult, error)
+}

backend/internal/service/usage_cleanup_service_test.go

@@ -56,7 +56,8 @@ type cleanupRepoStub struct {
 }
 
 type dashboardRepoStub struct {
-	recomputeErr error
+	recomputeErr   error
+	recomputeCalls int
 }
 
 func (s *dashboardRepoStub) AggregateRange(ctx context.Context, start, end time.Time) error {
@@ -64,6 +65,7 @@ func (s *dashboardRepoStub) AggregateRange(ctx context.Context, start, end time.
 }
 
 func (s *dashboardRepoStub) RecomputeRange(ctx context.Context, start, end time.Time) error {
+	s.recomputeCalls++
 	return s.recomputeErr
 }
 
@@ -83,6 +85,10 @@ func (s *dashboardRepoStub) CleanupUsageLogs(ctx context.Context, cutoff time.Ti
 	return nil
 }
 
+func (s *dashboardRepoStub) CleanupUsageBillingDedup(ctx context.Context, cutoff time.Time) error {
+	return nil
+}
+
 func (s *dashboardRepoStub) EnsureUsageLogsPartitions(ctx context.Context, now time.Time) error {
 	return nil
 }
@@ -550,13 +556,14 @@ func TestUsageCleanupServiceExecuteTaskMarkFailedUpdateError(t *testing.T) {
 }
 
 func TestUsageCleanupServiceExecuteTaskDashboardRecomputeError(t *testing.T) {
+	dashboardRepo := &dashboardRepoStub{recomputeErr: errors.New("recompute failed")}
 	repo := &cleanupRepoStub{
 		deleteQueue: []cleanupDeleteResponse{
 			{deleted: 0},
 		},
 	}
-	dashboard := NewDashboardAggregationService(&dashboardRepoStub{}, nil, &config.Config{
+	dashboard := NewDashboardAggregationService(dashboardRepo, nil, &config.Config{
-		DashboardAgg: config.DashboardAggregationConfig{Enabled: false},
+		DashboardAgg: config.DashboardAggregationConfig{Enabled: true},
 	})
 	cfg := &config.Config{UsageCleanup: config.UsageCleanupConfig{Enabled: true, BatchSize: 2}}
 	svc := NewUsageCleanupService(repo, nil, dashboard, cfg)
@@ -573,15 +580,17 @@ func TestUsageCleanupServiceExecuteTaskDashboardRecomputeError(t *testing.T) {
 	repo.mu.Lock()
 	defer repo.mu.Unlock()
 	require.Len(t, repo.markSucceeded, 1)
+	require.Eventually(t, func() bool { return dashboardRepo.recomputeCalls == 1 }, time.Second, 10*time.Millisecond)
 }
 
 func TestUsageCleanupServiceExecuteTaskDashboardRecomputeSuccess(t *testing.T) {
+	dashboardRepo := &dashboardRepoStub{}
 	repo := &cleanupRepoStub{
 		deleteQueue: []cleanupDeleteResponse{
 			{deleted: 0},
 		},
 	}
-	dashboard := NewDashboardAggregationService(&dashboardRepoStub{}, nil, &config.Config{
+	dashboard := NewDashboardAggregationService(dashboardRepo, nil, &config.Config{
 		DashboardAgg: config.DashboardAggregationConfig{Enabled: true},
 	})
 	cfg := &config.Config{UsageCleanup: config.UsageCleanupConfig{Enabled: true, BatchSize: 2}}
@@ -599,6 +608,7 @@ func TestUsageCleanupServiceExecuteTaskDashboardRecomputeSuccess(t *testing.T) {
 	repo.mu.Lock()
 	defer repo.mu.Unlock()
 	require.Len(t, repo.markSucceeded, 1)
+	require.Eventually(t, func() bool { return dashboardRepo.recomputeCalls == 1 }, time.Second, 10*time.Millisecond)
 }
 
 func TestUsageCleanupServiceExecuteTaskCanceled(t *testing.T) {

backend/internal/service/usage_log_create_result.go

@@ -0,0 +1,60 @@
+package service
+
+import "errors"
+
+type usageLogCreateDisposition int
+
+const (
+	usageLogCreateDispositionUnknown usageLogCreateDisposition = iota
+	usageLogCreateDispositionNotPersisted
+)
+
+type UsageLogCreateError struct {
+	err         error
+	disposition usageLogCreateDisposition
+}
+
+func (e *UsageLogCreateError) Error() string {
+	if e == nil || e.err == nil {
+		return "usage log create error"
+	}
+	return e.err.Error()
+}
+
+func (e *UsageLogCreateError) Unwrap() error {
+	if e == nil {
+		return nil
+	}
+	return e.err
+}
+
+func MarkUsageLogCreateNotPersisted(err error) error {
+	if err == nil {
+		return nil
+	}
+	return &UsageLogCreateError{
+		err:         err,
+		disposition: usageLogCreateDispositionNotPersisted,
+	}
+}
+
+func IsUsageLogCreateNotPersisted(err error) bool {
+	if err == nil {
+		return false
+	}
+	var target *UsageLogCreateError
+	if !errors.As(err, &target) {
+		return false
+	}
+	return target.disposition == usageLogCreateDispositionNotPersisted
+}
+
+func ShouldBillAfterUsageLogCreate(inserted bool, err error) bool {
+	if inserted {
+		return true
+	}
+	if err == nil {
+		return false
+	}
+	return !IsUsageLogCreateNotPersisted(err)
+}

backend/migrations/071_add_usage_billing_dedup.sql

@@ -0,0 +1,13 @@
+-- 窄表账务幂等键：将“是否已扣费”从 usage_logs 解耦出来
+-- 幂等执行：可重复运行
+
+CREATE TABLE IF NOT EXISTS usage_billing_dedup (
+    id BIGSERIAL PRIMARY KEY,
+    request_id VARCHAR(255) NOT NULL,
+    api_key_id BIGINT NOT NULL,
+    request_fingerprint VARCHAR(64) NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS idx_usage_billing_dedup_request_api_key
+    ON usage_billing_dedup (request_id, api_key_id);

backend/migrations/072_add_usage_billing_dedup_created_at_brin_notx.sql

@@ -0,0 +1,7 @@
+-- usage_billing_dedup 是按时间追加写入的幂等窄表。
+-- 使用 BRIN 支撑按 created_at 的批量保留期清理，尽量降低写放大。
+-- 使用 CONCURRENTLY 避免在热表上长时间阻塞写入。
+
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_usage_billing_dedup_created_at_brin
+    ON usage_billing_dedup
+    USING BRIN (created_at);

backend/migrations/073_add_usage_billing_dedup_archive.sql

@@ -0,0 +1,10 @@
+-- 冷归档旧账务幂等键，缩小热表索引与清理范围，同时不丢失长期去重能力。
+
+CREATE TABLE IF NOT EXISTS usage_billing_dedup_archive (
+    request_id VARCHAR(255) NOT NULL,
+    api_key_id BIGINT NOT NULL,
+    request_fingerprint VARCHAR(64) NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL,
+    archived_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    PRIMARY KEY (request_id, api_key_id)
+);