Apply System

The apply system handles the "Apply" button in inventories. This powers crafting (combining items into new items) and custom interactions (puzzle mechanics, item insertion, etc.).

How It Works

When a player clicks the Apply button:

The Apply button appears when an inventory has either:

• Recipes assigned to it
• A custom interactive value set

The Apply Button

The interactive field on an inventory template names the interaction (craft, combine, enchant, …). You rarely set it by hand:

• An inventory with recipes auto-defaults interactive to craft — a crafting station needs nothing more than its recipes list.
• Set interactive explicitly only for a non-crafting custom interaction (a puzzle, an item slot, etc.).

Button label — from the locale. The label is resolved from the locale key apply_button.<interactive>, falling back to the generic apply_button. The game's own locale is checked first, then the engine's, so you can define or override any label without touching the engine:

To label a custom interaction, add its key to your game's locale (e.g. "apply_button.enchant": "Enchant"). No CSS or engine change needed.

Styling still uses the interactive value as a CSS class on the button (background, hover, etc.) — just not for the text:

.apply-button.enchant { background-color: #9b59b6; }
.apply-button.enchant:hover { background-color: #8244a5; }

Recipes

Recipes define how items transform into other items.

Recipe Template Fields

Input/Output Format

Learning Recipes

Recipes must be learned before they can be used.

Example - Learning from a book:

Recipe-scroll items (the easy way)

For a "recipe scroll" item — one whose only purpose is to teach a recipe — set the item template's learn_recipe field to the recipe id. The engine then adds a Learn choice to that item in the inventory automatically (no choices wiring), and:

• clicking Learn teaches the recipe, consumes the item, and shows the "recipe learned" notification;
• once the recipe is known the choice is greyed out;
• if the action runs while the recipe is already known (e.g. from a scene), it shows the "already known" notification instead.

The underlying action is learn_recipe_item (reads the active item's learn_recipe field). Its labels live in the engine locale (learn_recipe, recipe.learned, recipe.already_known) and are game-overridable.

Crafting Flow

When the player clicks Apply with a selected recipe:

If any check fails, an appropriate notification is shown.

Recipe Selection UI

When an inventory has recipes:

Clicking a recipe automatically moves the required ingredients from party inventory to the crafting inventory.

Stacking Rules

Crafting respects item stacking:

The system calculates available space by considering:

• Slots freed by consuming ingredients
• Existing partial stacks that can be filled
• Max stack values from item templates

Custom Apply Logic

Use the inventory_apply event for custom behavior:

game.on("inventory_apply", (inventory) => {
  if (inventory.id === "puzzle_altar") {
    // Check if correct items are placed
    const gem = inventory.getFirstItemById("red_gem");
    const key = inventory.getFirstItemById("ancient_key");

    if (gem && key) {
      // Consume items
      inventory.removeItem(gem);
      inventory.removeItem(key);

      // Store result and notify
      game.getStore("puzzle").set("altar_activated", true);
      game.showNotification("The altar glows with ancient power!");
    }

    // Prevent other calls, including default crafting(if the inventory has any recipes assigned to it)
    return false; 
  }
});

Assigning Recipes to Inventories

In the inventory template:

Example - Blacksmith inventory:

The Apply button defaults to "craft" when recipes are assigned.

Events

Methods

Quick Reference

Next Steps

• Overview - Item basics and templates
• Exchange - Trading and shops