UtilityCraft Registries

Registries let an extension add data to systems that UtilityCraft already runs. Your addon owns the new items, blocks, entities, textures, and scripts; UtilityCraft only receives the JSON-serializable definitions that connect them to its machines.

import * as DoriosLib from "DoriosLib/index.js";

DoriosLib.registry.registerFuel({
  "utilitycraft:example_biomass": 12000,
});

Where registrations belong

Keep registrations in BP/scripts/config/ and import them once from its index:

BP/scripts/
├── config/
│   ├── index.js
│   ├── integrations.js
│   ├── resources.js
│   └── recipes/
│       └── index.js
└── main.js

BP/scripts/config/index.js

import "./resources.js";
import "./integrations.js";
import "./recipes/index.js";

The template's main.js imports config/index.js once. Call registry methods while modules load—not inside onTick, an interval, or an event that can run repeatedly. DoriosLib queues each payload and dispatches it after the world is ready.

Shared rules

Rule	Meaning
JSON-serializable payload	Use plain objects, arrays, strings, numbers, and booleans. Functions and class instances do not belong in registry data.
Exact identifiers	Item and block IDs normally include their namespace. Resource types such as example_coolant are unnamespaced storage keys.
Add or replace	A new key adds an entry. Registering a key that already exists replaces or extends it according to that registry's page. Pack and registration order matter when two addons use the same key.
Addon-owned content	Prefer your own namespace and inputs so another pack cannot unexpectedly replace the same definition.
Assets remain yours	Registering data never creates the referenced item, block, entity, texture, or localization entry.

Choose a registry

Goal	Guide	Main methods
Process an item in an existing machine	Add recipes to existing machines	registerCrusherRecipe(), registerPressRecipe(), registerInfuserRecipe(), registerMelterRecipe(), registerFurnaceRecipe(), registerCrafterRecipe()
Burn a custom item or improve coolant	Fuels and coolants	registerFuel(), registerCoolant()
Move custom liquids or gases in containers	Fluids and gases	registerFluidItem(), registerFluidHolder(), registerGasItem(), registerGasHolder()
Integrate a seed with plant machines and Bonsai	Plants and bonsais	registerPlant()
Add probabilistic machine loot	Fishing and sieve drops	registerAutoFisherDrop(), registerSieveDrop()

For the method-level API, see the DoriosLib registry reference.

Continue with Add recipes to existing machines.