Cratis Arc tenant context access

Inject ITenantIdAccessor to read the tenant selected for an operation in Cratis Arc. In a request, Arc checks that candidate against any registered ITenantMembership hooks. Without those hooks, reading the ID supplies context but no proof that the caller may use it. Configure tenant membership before using the context to access customer data.

Accessing the Current Tenant

using Cratis.Arc.Tenancy;

public class CustomerService(ITenantIdAccessor tenantIdAccessor)
{
    public async Task HandleAsync()
    {
        var tenantId = tenantIdAccessor.Current;

        if (tenantId == TenantId.NotSet)
        {
            return;
        }

        await LoadTenantDataAsync(tenantId);
    }

    private static Task LoadTenantDataAsync(TenantId tenantId) => Task.CompletedTask;
}

The NotSet branch skips work when no tenant is selected. LoadTenantDataAsync is a placeholder that returns a completed task; it neither loads data nor authorizes access. A production implementation needs membership enforcement before storage access, not just the presence check shown here.

Use a tenant in background work

Background work without an HTTP request does not invoke request membership hooks. Make the required authorization decision, then begin an explicit tenant scope. Create the dependency-injection scope for tenant-scoped services inside it, so those services resolve against the selected tenant. Do not capture a request-scoped storage service in a singleton and reuse it for later work.

Explicit scopes require Arc’s TenantIdAccessor to be the effective ITenantIdAccessor. A custom accessor registered before or after Arc remains effective, but resolving ITenantScope then throws ExplicitTenantScopeRequiresArcAccessor. This prevents a scope from appearing to select a tenant that the custom accessor would not honor.

TenantId.NotSet

TenantId.NotSet means no tenant could be resolved from the current context. Decide whether your application permits that case rather than silently treating it as a named customer.

TenantId.Default is the named default, and IsDefault includes both NotSet and Default. Arc’s default MongoDB resolver maps both to the same unsuffixed database. The example’s NotSet check therefore allows the named default; it does not reject every request that would use default storage. Use IsDefault when the decision concerns both aliases, and see database isolation for the storage mappings.