How do I install the Sheet Definition skill?

Run npx skillmds@latest add liberatedpixelcup/sheet-definition in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Sheet Definition safe to use?

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Which AI agents work with Sheet Definition?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Sheet Definition free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Sheet Definition?

liberatedpixelcup (@liberatedpixelcup) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Sheet Definition by liberatedpixelcup

Name: Sheet Definition
Author: liberatedpixelcup

Sheet Definition

Add or edit sheet_definitions JSON for items, categories, variants, credits, layers, or z-positions. Use when adding art, a new category, a credits entry, or renaming an asset. Copy a neighboring definition; do not invent keys.

File contents

Sheet definitions

Copy a neighboring JSON under sheet_definitions/. Do not invent a schema. Accepted fields: SheetDefinition in scripts/generateSources/items.ts. Human walkthrough and the credits example: CONTRIBUTING.md. Multi-layer example: tail_lizard.json.

Typical required keys: name, type_name, layer_1 (zPos plus body-type paths into spritesheets/), and credits[] (file, authors, licenses, urls; notes is optional).

type_name is the hash key and name supplies the Item half of the Item_variant hash value, so both are part of the URL contract — see catalog.

credits[].file must name the spritesheet file or one of its path-segment ancestors, not an arbitrary string prefix. searchCredit in credits.ts matches credit.file against the path exactly, against path + ".png", or against credit.file + "/", then retries after trimming at the last /. So arms/hands/ring covers arms/hands/ring/stud, but arms/hands/ri covers nothing. Failing to match logs missing credit after searching recursively and then throws missing credit inside ….

Existing category: add PNGs under spritesheets/ and the variant name on the matching definition (variants). Palette-backed items use recolors and do not add a PNG per color — follow Adding Palette Support, do not invent recolors keys.

New category: new JSON next to similar items.

Optional: animations restricts the animations filter; omit it for the default list. Asset renames need aliases on the destination definition and an issue first. Other keys (tags, replace_in_path, match_body_color, …) — copy a neighbor that already uses them.

Then npm run validate-site-sources and commit any dirty CREDITS.csv / z_positions.csv. CREDITS.csv is generate-only. z_positions.csv may be edited as a bulk aid; JSON is the source of truth (npm run z-positions:update writes the CSV back to JSON). The app reads generated dist/*-metadata.js, not the JSON directly; if a new item is invisible after npm run dev, see generated-metadata.

---name: sheet-definitiondescription: Add or edit sheet_definitions JSON for items, categories, variants, credits, layers, or z-positions. Use when adding art, a new category, a credits entry, or renaming an asset. Copy a neighboring definition; do not invent keys.---# Sheet definitionsCopy a neighboring JSON under `sheet_definitions/`. Do not invent a schema.Accepted fields: `SheetDefinition` in[`scripts/generateSources/items.ts`](../../../scripts/generateSources/items.ts).Human walkthrough and the `credits` example:[CONTRIBUTING.md](../../../CONTRIBUTING.md#adding-a-new-category).Multi-layer example: [tail_lizard.json](../../../sheet_definitions/body/lizard/tail_lizard.json).Typical required keys: `name`, `type_name`, `layer_1` (`zPos` plus body-typepaths into `spritesheets/`), and `credits[]` (`file`, `authors`, `licenses`,`urls`; `notes` is optional).`type_name` is the hash key and `name` supplies the `Item` half of the`Item_variant` hash value, so both are part of the URL contract — see[catalog](../catalog/SKILL.md).`credits[].file` must name the spritesheet file or one of its **path-segmentancestors**, not an arbitrary string prefix. `searchCredit` in[`credits.ts`](../../../scripts/generateSources/credits.ts) matches`credit.file` against the path exactly, against `path + ".png"`, or against`credit.file + "/"`, then retries after trimming at the last `/`. So`arms/hands/ring` covers `arms/hands/ring/stud`, but `arms/hands/ri` coversnothing. Failing to match logs `missing credit after searching recursively`and then throws `missing credit inside …`.**Existing category:** add PNGs under `spritesheets/` and the variant name onthe matching definition (`variants`). Palette-backed items use `recolors` anddo **not** add a PNG per color — follow[Adding Palette Support](../../../PALETTE_RECOLOR_GUIDE.md#adding-palette-support-to-items),do not invent `recolors` keys.**New category:** new JSON next to similar items.**Optional:** `animations` restricts the animations filter; omit it for thedefault list. Asset renames need `aliases` on the **destination** definitionand an issue first. Other keys (`tags`, `replace_in_path`, `match_body_color`,…) — copy a neighbor that already uses them.Then `npm run validate-site-sources` and commit any dirty `CREDITS.csv` /`z_positions.csv`. `CREDITS.csv` is generate-only. `z_positions.csv` may beedited as a bulk aid; JSON is the source of truth(`npm run z-positions:update` writes the CSV back to JSON). The app readsgenerated `dist/*-metadata.js`, not the JSON directly; if a new item isinvisible after `npm run dev`, see[generated-metadata](../generated-metadata/SKILL.md).

Frequently asked questions