Turn recursive entities into model [Answered]

public sealed class TodoListEntity {
  public Guid Id { get; set; }
  public ICollection<TodoItemEntity> Items { get; set; } = null!;
}

public sealed class TodoItemEntity {
  public Guid Id { get; set; }
  // Other data

  public Guid ListId { get; set; }
  public TodoListEntity List { get; set; } = null!;
}

public static TodoList ToModel(this TodoListEntity entity) =>
  new(entity.Id, entity.Items.Select(ToModel).ToArray());
public static TodoItem ToModel(this TodoItemEntity entity) =>
  new(entity.Id, /* Other data */, entity.List.ToModel());