internal static class Create
{
    public record Command( ... ) : ICommand<int>;

    public class CommandHandler : ICommandHandler<Command, int>
    {
        ...
    }
}

    public async Task<TResult> SendAsync<TResult>(ICommand<TResult> command, CancellationToken token = default)
    {
        var handlerType = typeof(ICommandHandler<,>).MakeGenericType(command.GetType(), typeof(TResult));
        using var scope = _serviceFactory.CreateScope();
        var handler = scope.ServiceProvider.GetRequiredService(handlerType);

         ...
    }

        builder.Services.Scan(s => s.FromAssemblies(assemblies)
            .AddClasses(c =>
            {
                c.AssignableToAny(
                        typeof(ICommandHandler<,>),
                        typeof(ICommandHandler<>),
                        typeof(IQueryHandler<,>),
                        typeof(IEventHandler<>))
                    .WithoutAttribute<DecoratorAttribute>();
            }, false)
            .AsImplementedInterfaces()
            .WithScopedLifetime());