Billing module

PlatformBillingService
       │
       ├── IPlatformBillingRepository → SqlSugarPlatformBillingRepository
       ├── QuotaService → EntitlementResolver
       └── IPlatformBillingEventPublisher → NullPlatformBillingEventPublisher

CatalogService
       │
       ├── ICatalogRepository → SqlSugarCatalogRepository
       ├── ICatalogEntitlementMappingStore
       └── ICatalogEventPublisher

                Start
                  │
                  ▼
           Active (trial)
                  │
                  ▼
           Active (paid)
              │       │
              ▼       ▼
          Paused    Cancelled
              │       │
              ▼       ▼
          Resumed    Expired

public class QuotaCheckResult
{
    public bool IsAllowed { get; }
    public long Remaining { get; }
    public long Used { get; }
    public long Limit { get; }
    public OverQuotaBehavior Behavior { get; }
}

Tenant → Active Subscription → Plan → Catalog Offerings → Entitlements

await billingService.RecordUsageAsync(
    tenantId: "100",
    entitlementKey: "storage.files",
    delta: 1);