diff --git a/backend/internal/repository/usage_billing_repo.go b/backend/internal/repository/usage_billing_repo.go
index 2b6edad3..62f48b58 100644
--- a/backend/internal/repository/usage_billing_repo.go
+++ b/backend/internal/repository/usage_billing_repo.go
@@ -290,7 +290,6 @@ func incrementUsageBillingAccountQuota(ctx context.Context, tx *sql.Tx, accountI
 	if err != nil {
 		return nil, err
 	}
-	defer func() { _ = rows.Close() }()
 
 	var state service.AccountQuotaState
 	if rows.Next() {
@@ -299,18 +298,36 @@ func incrementUsageBillingAccountQuota(ctx context.Context, tx *sql.Tx, accountI
 			&state.DailyUsed, &state.DailyLimit,
 			&state.WeeklyUsed, &state.WeeklyLimit,
 		); err != nil {
+			_ = rows.Close()
 			return nil, err
 		}
 	} else {
 		if err := rows.Err(); err != nil {
+			_ = rows.Close()
 			return nil, err
 		}
+		_ = rows.Close()
 		return nil, service.ErrAccountNotFound
 	}
 	if err := rows.Err(); err != nil {
+		_ = rows.Close()
 		return nil, err
 	}
-	if state.TotalLimit > 0 && state.TotalUsed >= state.TotalLimit && (state.TotalUsed-amount) < state.TotalLimit {
+	// 必须在执行下一条 SQL 前显式关闭 rows：pq 驱动在同一连接上
+	// 不允许前一条查询的结果集未耗尽时启动新查询，否则会返回
+	// "unexpected Parse response" 错误。
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	// 任意维度额度在本次递增中从"未超"跨越到"已超"时，必须刷新调度快照，
+	// 否则 Redis 中缓存的 Account 仍显示旧的 used 值，后续请求会继续选中本账号，
+	// 最终观察到 daily_used / weekly_used 大幅超过配置的 limit。
+	// 对于日/周额度，即使本次触发了周期重置（pre=0、post=amount），
+	// 判定式 (post-amount) < limit 同样成立，逻辑与总额度保持一致。
+	crossedTotal := state.TotalLimit > 0 && state.TotalUsed >= state.TotalLimit && (state.TotalUsed-amount) < state.TotalLimit
+	crossedDaily := state.DailyLimit > 0 && state.DailyUsed >= state.DailyLimit && (state.DailyUsed-amount) < state.DailyLimit
+	crossedWeekly := state.WeeklyLimit > 0 && state.WeeklyUsed >= state.WeeklyLimit && (state.WeeklyUsed-amount) < state.WeeklyLimit
+	if crossedTotal || crossedDaily || crossedWeekly {
 		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 nil, err
diff --git a/backend/internal/repository/usage_billing_repo_integration_test.go b/backend/internal/repository/usage_billing_repo_integration_test.go
index eda34cc9..e8d4d327 100644
--- a/backend/internal/repository/usage_billing_repo_integration_test.go
+++ b/backend/internal/repository/usage_billing_repo_integration_test.go
@@ -199,6 +199,94 @@ func TestUsageBillingRepositoryApply_UpdatesAccountQuota(t *testing.T) {
 	require.InDelta(t, 3.5, quotaUsed, 0.000001)
 }
 
+func TestUsageBillingRepositoryApply_EnqueuesSchedulerOutboxOnQuotaCrossing(t *testing.T) {
+	ctx := context.Background()
+	client := testEntClient(t)
+	repo := NewUsageBillingRepository(client, integrationDB)
+
+	newFixture := func(t *testing.T, extra map[string]any) (int64, int64) {
+		t.Helper()
+		user := mustCreateUser(t, client, &service.User{
+			Email:        fmt.Sprintf("usage-billing-outbox-user-%d-%s@example.com", time.Now().UnixNano(), uuid.NewString()),
+			PasswordHash: "hash",
+		})
+		apiKey := mustCreateApiKey(t, client, &service.APIKey{
+			UserID: user.ID,
+			Key:    "sk-usage-billing-outbox-" + uuid.NewString(),
+			Name:   "billing-outbox",
+		})
+		account := mustCreateAccount(t, client, &service.Account{
+			Name:  "usage-billing-outbox-" + uuid.NewString(),
+			Type:  service.AccountTypeAPIKey,
+			Extra: extra,
+		})
+		return apiKey.ID, account.ID
+	}
+
+	outboxCountFor := func(t *testing.T, accountID int64) int {
+		t.Helper()
+		var count int
+		require.NoError(t, integrationDB.QueryRowContext(ctx,
+			"SELECT COUNT(*) FROM scheduler_outbox WHERE event_type = $1 AND account_id = $2",
+			service.SchedulerOutboxEventAccountChanged, accountID,
+		).Scan(&count))
+		return count
+	}
+
+	t.Run("daily_first_crossing_enqueues", func(t *testing.T) {
+		apiKeyID, accountID := newFixture(t, map[string]any{
+			"quota_daily_limit": 10.0,
+		})
+		// 第一次低于日限额：不应入队 outbox
+		_, err := repo.Apply(ctx, &service.UsageBillingCommand{
+			RequestID:        uuid.NewString(),
+			APIKeyID:         apiKeyID,
+			AccountID:        accountID,
+			AccountType:      service.AccountTypeAPIKey,
+			AccountQuotaCost: 4,
+		})
+		require.NoError(t, err)
+		require.Equal(t, 0, outboxCountFor(t, accountID), "below limit should not enqueue")
+
+		// 第二次跨越日限额：应入队一次 outbox
+		_, err = repo.Apply(ctx, &service.UsageBillingCommand{
+			RequestID:        uuid.NewString(),
+			APIKeyID:         apiKeyID,
+			AccountID:        accountID,
+			AccountType:      service.AccountTypeAPIKey,
+			AccountQuotaCost: 8,
+		})
+		require.NoError(t, err)
+		require.Equal(t, 1, outboxCountFor(t, accountID), "crossing daily limit should enqueue once")
+
+		// 再次递增（已超）：不应重复入队
+		_, err = repo.Apply(ctx, &service.UsageBillingCommand{
+			RequestID:        uuid.NewString(),
+			APIKeyID:         apiKeyID,
+			AccountID:        accountID,
+			AccountType:      service.AccountTypeAPIKey,
+			AccountQuotaCost: 2,
+		})
+		require.NoError(t, err)
+		require.Equal(t, 1, outboxCountFor(t, accountID), "subsequent increments beyond limit should not re-enqueue")
+	})
+
+	t.Run("weekly_first_crossing_enqueues", func(t *testing.T) {
+		apiKeyID, accountID := newFixture(t, map[string]any{
+			"quota_weekly_limit": 10.0,
+		})
+		_, err := repo.Apply(ctx, &service.UsageBillingCommand{
+			RequestID:        uuid.NewString(),
+			APIKeyID:         apiKeyID,
+			AccountID:        accountID,
+			AccountType:      service.AccountTypeAPIKey,
+			AccountQuotaCost: 15, // 单次即跨越
+		})
+		require.NoError(t, err)
+		require.Equal(t, 1, outboxCountFor(t, accountID), "single-shot crossing weekly limit should enqueue once")
+	})
+}
+
 func TestDashboardAggregationRepositoryCleanupUsageBillingDedup_BatchDeletesOldRows(t *testing.T) {
 	ctx := context.Background()
 	repo := newDashboardAggregationRepositoryWithSQL(integrationDB)