commander/FileSystemService.cs

namespace CommanderApp
{
    public class FileSystemService : IFileSystemService
    {
        public string GetRootPath()
        {
#if ANDROID || IOS || MACCATALYST
            return FileSystem.Current.AppDataDirectory;
#else
        return Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
#endif
        }

        public IEnumerable<FileSystemItem> GetDirectoryContents(string path)
        {
            if (!Directory.Exists(path))
                return Enumerable.Empty<FileSystemItem>();

            var items = new List<FileSystemItem>();

            // Добавляем ".." если не корень
            var parent = Directory.GetParent(path);
            if (parent != null)
            {
                items.Add(new FileSystemItem
                {
                    Name = "..",
                    FullName = parent.FullName,
                    IsDirectory = true
                });
            }

            var dirs = Directory.GetDirectories(path)
                .Select(d => new FileSystemItem
                {
                    Name = Path.GetFileName(d),
                    FullName = d,
                    IsDirectory = true
                });

            var files = Directory.GetFiles(path)
                .Select(f => new FileSystemItem
                {
                    Name = Path.GetFileName(f),
                    FullName = f,
                    IsDirectory = false
                });

            items.AddRange(dirs.OrderBy(d => d.Name));
            items.AddRange(files.OrderBy(f => f.Name));

            return items;
        }
    }
}