post_install() {
  echo ">>> Initializing Nix for this system..."

  # Create /nix if missing
  if [ ! -d /nix ]; then
    sudo mkdir -m 0755 /nix
    sudo chown root:root /nix
  fi

  # Enable Nix daemon
  if systemctl list-unit-files | grep -q nix-daemon.service; then
    sudo systemctl enable --now nix-daemon.service
  fi

  # Add user to nix-users
  if id -u kevinveenbirkenbach >/dev/null 2>&1; then
    sudo usermod -aG nix-users kevinveenbirkenbach
  fi
}