Minecraft Builder Skill

Minecraft Builder Skill

Overview

Create Minecraft builds by writing small JavaScript recipes that use Lodestone-backed helper functions. Export vanilla .nbt structure files, then open the included viewer so the user can inspect and iterate on the build.

Workflow

1. Work from the installed skill directory. Do not rerun the Skills CLI after installation; use this skill's local scripts/ and assets/.
2. Before running any build or preview scripts, ensure dependencies are installed. If node_modules/@mattzh72/lodestone is missing, run this from the installed skill directory:

npm install --omit=dev

3. Write an ESM recipe file. Use assets/examples/celestial-forge.mjs as the canonical example for ambitious floating megastructures.
4. Generate NBT:

node scripts/run-build.mjs path/to/recipe.mjs --out-dir minecraft-builds/my-build

5. Open the preview:

node scripts/preview.mjs --nbt minecraft-builds/my-build/my-build.nbt

6. Iterate by editing the recipe, regenerating the .nbt, and reopening or refreshing the preview.

Dependencies

Skills CLI installs copy the skill files but may not install Node packages. This skill intentionally keeps dependencies in package.json and npm-shrinkwrap.json instead of vendoring node_modules.

Before using scripts/run-build.mjs or scripts/preview.mjs, check for node_modules/@mattzh72/lodestone. If it is absent, run npm install --omit=dev from the installed skill directory. Do not install dependencies globally, and do not guess alternate Lodestone versions.

Recipe Contract

Export a default function that receives api and returns either a Lodestone Structure or an object with { structure, metadata }.

export default function build(api) {
  const structure = api.createStructure([16, 12, 16])
  api.fill(structure, [0, 0, 0], [15, 0, 15], 'minecraft:stone_bricks')
  api.hollowBox(structure, [4, 1, 4], [11, 7, 11], 'minecraft:spruce_planks')
  return { structure, metadata: { name: 'example-build' } }
}

Available helpers include createStructure, setBlock, fill, hollowBox, line, sphere, cylinder, normalizeBlock, createBlockNbt, and Lodestone classes under api.lodestone.

References

• For exact recipe helper signatures, supported option fields, defaults, and unsupported behavior, search references/recipe-api.md.
• For Lodestone classes, structure NBT, block states, renderer APIs, resource pack APIs, supported fields, and unsupported behavior, search references/lodestone/.
• For exact default-pack block ids, rendered block-state value enums, special renderer state values, and generic renderer properties like waterlogged, search references/lodestone/default-pack-block-states.md.
• Prefer these local references over guessing. Use rg for class names, method names, block-state properties, NBT tag names, and option fields before using advanced APIs.

Reference Lookup

• Before choosing nontrivial block-state values, search references/lodestone/default-pack-block-states.md.
• For one block, print its exact section, for example rg -n -A 80 '### `minecraft:oak_stairs`' references/lodestone/default-pack-block-states.md.
• For global property enums, search property-index lines, for example rg -n '^- `shape`|^- `waterlogged`' references/lodestone/default-pack-block-states.md.
• Before relying on automatic connection behavior, search references/lodestone/structure.md for updateBlockStates() and check the supported and unsupported coverage.
• When writing block entities or custom NBT, search references/lodestone/nbt.md and references/recipe-api.md before constructing tags.

Build Guidance

• Keep all coordinates inside the structure size. The runner validates bounds and fails fast.
• Use vanilla block IDs with the minecraft: namespace. Block-state strings like minecraft:oak_stairs[facing=east,half=bottom,shape=straight] are supported.
• The runner enables Lodestone's Minecraft-like block state updates by default. Panes, iron bars, and fences get north/east/south/west states from neighboring compatible or solid blocks. Use --no-block-state-updates only when a recipe intentionally sets those states by hand.
• Prefer clear block palettes and readable geometry. The viewer uses Lodestone's bundled default resource pack, so highly unusual or custom blocks may not preview well.
• Include metadata.name to control the output filename. Names are slugified.
• Default output is gzip-compressed vanilla structure NBT with DataVersion set by the runner unless overridden.
• For block entities, pass a Lodestone NbtCompound as the last argument to setBlock or use api.createBlockNbt({ id: 'minecraft:chest' }).

Preview

The preview script starts a minimal Vite server and opens the build automatically. It serves the target .nbt and Lodestone's default resource pack through local middleware, so recipes do not need to copy assets.

Use --no-open when running in a non-interactive environment:

node scripts/preview.mjs --nbt path/to/build.nbt --no-open

Open directly in night lighting when helpful for review:

node scripts/preview.mjs --nbt path/to/build.nbt --lighting night