// Give items only the FIRST time a player joins this world

PlayerEvents.loggedIn(event => {
  const p = event.player;
  const data = p.persistentData;

  if (!data.gotStarters) {
    data.gotStarters = true;

    // Examples — change these to your pack’s needs:
    p.give('ftbquests:book');
    p.give(Item.of('supplementaries:bubble_blower', '{Damage:0}'));
  }
});
