{ ... }:

# Disk layout for nixos-anywhere + disko.
# Targets a single virtio disk (typical for Hetzner Cloud).
# GPT with a BIOS-boot partition so GRUB works without UEFI.
{
  disko.devices = {
    disk.main = {
      # Hetzner Cloud primary disk is /dev/sda on most instance types.
      # On NVMe instances it will be /dev/nvme0n1 - update accordingly.
      device = "/dev/sda";
      type = "disk";
      content = {
        type = "gpt";
        partitions = {
          # 1 MiB BIOS-boot partition required by GRUB on GPT disks
          boot = {
            size = "1M";
            type = "EF02"; # BIOS boot
            priority = 1;
          };

          # 512 MiB /boot - keeps kernels/initrds out of root for clarity.
          # Named ESP for historical reasons (matches the GPT partition label
          # already baked into the live disk from initial install) even
          # though it's not really an EFI System Partition (ext4, not
          # FAT32/type EF00) - this is a BIOS-boot setup, GRUB just needs a
          # plain filesystem here. Do NOT rename this attribute: disko
          # derives the actual GPT partition label from it, and renaming it
          # here does not relabel the already-installed physical partition -
          # fileSystems."/boot" would then point at a by-partlabel device
          # that doesn't exist, hanging boot.mount/local-fs.target on
          # activation (this exact mistake took the server down once).
          ESP = {
            size = "512M";
            type = "8300";
            content = {
              type = "filesystem";
              format = "ext4";
              mountpoint = "/boot";
            };
          };

          # Root partition - all remaining space
          root = {
            size = "100%";
            content = {
              type = "filesystem";
              format = "ext4";
              mountpoint = "/";
            };
          };
        };
      };
    };
  };
}