MBD2 KubeJS

Current docs Minecraft 1.21.1 / MBD2 21.1.1Script runtime KubeJS 2101.7.2-build.226

MBD2 adds recipe schemas, registry events, targeted machine events, and a client renderer hook to KubeJS.

KubeJS supplies recipe data; the editor-authored Recipe Viewer UI controls how it is presented.

Script placement

Folder	MBD2 API	Use it for
startup_scripts	MBDRegistryEvents.machine, MBDRegistryEvents.recipeType	Registering recipe types and base machine definitions
server_scripts	ServerEvents.recipes, MBDMachineEvents.*, MBDRecipeTypeEvents.onTransferProxyRecipe	Recipes and machine behaviour
client_scripts	MBDMachineEvents.onClientTick / onCustomDataUpdate / onCustomKeyframe, MBDRecipeTypeEvents.onRecipeUI, MBDClientEvents.registerCustomRenderers	Visuals only

Every MBDMachineEvents and MBDRecipeTypeEvents subscription is targeted: the first argument is the machine-definition ID or recipe-type ID.

Registry changes need a full restart; /reload rebuilds recipes only.

Global bindings

Binding	Is
MBDRegistries	The MBD2 registries — RECIPE_CAPABILITIES, RECIPE_TYPES, MACHINE_DEFINITIONS, …
IO	IO.IN, IO.OUT, IO.BOTH, IO.NONE
CapabilityIO, ContentModifier, MachineState, ConfigBlockProperties	MBD2 config types
UIEvents, HoverTooltips, DataBindingBuilder, …	LDLib2 UI types; see its own documentation

Every com.lowdragmc.mbd2 and com.lowdragmc.lowdraglib2 class is also reachable through Java.loadClass(...).

Pages

Page	Covers
Registry events	Creating recipe types and base machine definitions at startup
Recipes	The full recipe builder
Traits	Reaching a machine's storage from an event
Events	Every machine and recipe-type event, and what each one can change
UI behaviour	Attaching server behaviour to an editor-authored machine UI
Script renderers	Drawing a machine from a client script
Dynamic recipe modification	Rewriting the selected recipe at runtime
Proxy recipe types	Filtering recipes imported from another recipe type
Example library	Copyable scripts

Machine authoring boundary

KubeJS registration creates only a bare single or multiblock definition. It does not expose the editor's states, traits, renderers, UI, recipe logic or multiblock patterns. Author those in an MBD2 editor project, then script recipes and behaviour against it.

Do not mix UI generations

MBDMachineEvents.onUI still exists, but wrapper.event.ui is an LDLib2 2.x UI, not the 1.20.1 WidgetGroup. Legacy getFirstWidgetById and setOnPressCallback examples do not run. See UI behaviour.

Blueprints do the same jobs

Everything on the events page is also available as a blueprint node graph, authored in the editor and shipped inside the machine. Use KubeJS when the pack owns the behaviour, a blueprint when the machine does.