{ ... }:
{
  # UEFI/GPT single-disk layout on the Samsung 990 EVO Plus NVMe.
  # ESP for systemd-boot + a small swap + ext4 root spanning the rest.
  disko.devices.disk.main = {
    type = "disk";
    device = "/dev/disk/by-id/nvme-Samsung_SSD_990_EVO_Plus_1TB_S7U4NU1YB01420B";
    content = {
      type = "gpt";
      partitions = {
        ESP = {
          size = "1G";
          type = "EF00";
          content = {
            type = "filesystem";
            format = "vfat";
            mountpoint = "/boot";
            mountOptions = [ "umask=0077" ];
          };
        };
        swap = {
          size = "8G";
          content = {
            type = "swap";
            discardPolicy = "both";
          };
        };
        root = {
          size = "100%";
          content = {
            type = "filesystem";
            format = "ext4";
            mountpoint = "/";
          };
        };
      };
    };
  };
}