# Impermanence: declares what should survive a wipe of "/".
{
  environment.persistence."/persist" = {
    hideMounts = true;

    directories = [
      "/etc/NetworkManager/system-connections" # Wifi connections, VPN
      "/var/lib/bluetooth" # Bluetooth connections
      "/var/lib/nixos" # keeps uid/gid stable across boots
      "/var/lib/systemd/coredump"
      "/var/lib/upower" # battery calibration state
      "/var/lib/systemd/backlight" # remembers screen brightness
      "/var/lib/systemd/timers" # last-run timestamps (e.g. nix gc weekly)
      "/var/log"
      "/var/cache/tuigreet"
      "/var/db/sudo/lectured" # remembers that the sudo lecture was already shown
    ];

    files = [
      "/etc/machine-id"
      "/etc/ssh/ssh_host_ed25519_key"
      "/etc/ssh/ssh_host_ed25519_key.pub"
      "/etc/ssh/ssh_host_rsa_key"
      "/etc/ssh/ssh_host_rsa_key.pub"
      "/var/lib/systemd/random-seed" # avoid a weak entropy pool on first boot
    ];
  };
}