Exchange System

The exchange system handles two modes of item transfer between inventories: loot (free taking) and trade (buying/selling with currency).

Two Modes

Opening an Exchange

Use actions to open exchanges:

Both actions are event delayed - they wait for the current scene to finish before opening.

The exchange UI shows two inventories side by side:

• Left: Party inventory (_party_inventory)
• Right: Exchange inventory (the one you specified)

Clicking items moves them between inventories. In trade mode, currency is automatically exchanged.

Currencies

Currencies are regular items with is_currency: true set in their template.

Example currency item:

Setting item prices:

Items can have prices in multiple currencies. The buyer must have all required currencies.

Modifying Trade Prices

The trade_init event fires for each item when a trade opens. Use it to set custom buy/sell prices.

Example - Merchants buy at 50% price:

game.on("trade_init", (traderInventory, item) => {
  for (const currency in item.price) {
    item.tradePrice.player[currency] = Math.round(item.price[currency] * 0.5);
  }
});

Example - Mage trader only accepts arcane items:

game.on("trade_init", (traderInventory, item) => {
  if (traderInventory.tags.includes("mage_trader") && !item.tags.includes("arcane")) {
    item.tradePrice.player = {};  // Can't sell to this merchant
    item.tradePrice.trader = {};  // Can't buy from this merchant
  }
});

Currency Methods

Currency only counts unequipped items - equipped currency items are not spendable.

Exchange Events

Canceling transfers:

Return false from inventory_transfer to prevent the transfer:

Trade Flow Example

If any step fails (can't afford, inventory full), the whole transaction is cancelled.

Creating a Shop

Quick Reference

Next Steps

• Overview - Item basics and templates
• Apply - Crafting and custom apply logic