_:

{
  services.tailscale = {
    enable = true;

    # extraSetFlags (tailscale set, via the always-on tailscaled-set
    # service), not extraUpFlags -- extraUpFlags is only ever applied by
    # tailscaled-autoconnect, which itself only runs when
    # services.tailscale.authKeyFile is set (nothing in this repo sets one,
    # so tailscale up is a manual, one-time operator step on every host that
    # uses this service). extraSetFlags has no such gate, so
    # --advertise-exit-node self-reapplies on every boot once the operator
    # has authenticated the node once.
    extraSetFlags = [
      "--advertise-exit-node"
    ];
  };
}