How do you use IServiceScopeFactory to manually create and manage a DI scope outside the normal request pipeline?

IServiceScopeFactory.CreateScope() returns an IServiceScope (implementing IDisposable) whose ServiceProvider can resolve scoped services within that isolated scope's lifetime -- essential for singleton or background contexts (like a BackgroundService or a Console app's Main method) that have no natural per-request scope but still need to consume scoped services like a DbContext, ensuring proper disposal via a using block once the unit of work completes.

public class ReportGenerator : BackgroundService {
    private readonly IServiceScopeFactory _scopeFactory;
    protected override async Task ExecuteAsync(CancellationToken ct) {
        using var scope = _scopeFactory.CreateScope();
        var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
        await GenerateReportAsync(db);
    }  // scope disposed here, DbContext and other scoped services cleaned up
}