public record CreateTodoListCommand : IRequest<int>
{
    public string? Title { get; init; }
    public string? Colour { get; init; }
}

public class CreateTodoListCommandHandler : IRequestHandler<CreateTodoListCommand, int>
{
    private readonly IApplicationDbContext _context;

    public CreateTodoListCommandHandler(IApplicationDbContext context) => _context = context;

    public async Task<int> Handle(CreateTodoListCommand request, CancellationToken cancellationToken)
    {
        var entity = new TodoList
        {
            Title = request.Title,
            Colour = Colour.From(request.Colour ?? Colour.Grey)
        };

        _context.TodoLists.Add(entity);
        await _context.SaveChangesAsync(cancellationToken);
        return entity.Id;
    }
}