{ ... }:

# Declarative OS-disk layout (disko). UEFI: GPT with an ESP + btrfs root.
# disko both PARTITIONS/FORMATS this disk and generates the NixOS
# `fileSystems.*` entries, so hardware-configuration.nix must NOT define
# fileSystems for "/" or "/boot".
#
# ⚠️  Root is btrfs (was ext4): the disk previously held a CachyOS btrfs root,
#     and disko's `mkfs` create step SKIPS formatting when `blkid` still
#     detects a filesystem signature on the freshly-cut partition. A stale
#     btrfs superblock survives `wipefs`+repartition inside the new root
#     partition's range, so an ext4 root got skipped and `mount -t ext4`
#     then failed on the leftover btrfs bytes ("bad superblock"). btrfs's
#     create runs `mkfs.btrfs -f`, which reformats past any stale signature.
#
# ⚠️  This disk is WIPED on install. This is the Kingston SA400 SSD that
#     currently holds CachyOS (btrfs root+subvols on sdb2, ESP on sdb1).
#     The dev-data disks (sdc ext4 /mnt/hdd_01, LVM vg_ssd /mnt/ssd_01) and the
#     leftover ntfs disks (sda, sdf, nvme0n1) are NOT listed here — they are
#     mounted as plain fileSystems in configuration.nix (or, for the ntfs
#     disks, ignored entirely) so they are never touched.
{
  disko.devices.disk.os = {
    type = "disk";
    device = "/dev/disk/by-id/ata-KINGSTON_SA400S37480G_50026B738072F6C6";
    content = {
      type = "gpt";
      partitions = {
        ESP = {
          size = "512M";
          type = "EF00";
          content = {
            type = "filesystem";
            format = "vfat";
            mountpoint = "/boot";
            mountOptions = [ "umask=0077" ];
          };
        };
        root = {
          size = "100%";
          content = {
            type = "btrfs";
            extraArgs = [ "-f" ];
            mountpoint = "/";
          };
        };
      };
    };
  };
}