Hatch Pet
Hatch a Codex-compatible animated pet from art or prompts with validated 8×9 spritesheets, QA contact sheets, previews, and pet.json packaging.
Overview
hatch-pet is an agent skill for the Build phase that creates, validates, and packages Codex-compatible animated pet spritesheets and pet.json from visual references.
Install
npx skills add https://github.com/nexu-io/open-design --skill hatch-petWhat is this skill?
- End-to-end hatch pipeline from character art, screenshots, or generated references
- Produces Codex-compatible 8×9 atlas spritesheets with transparent unused cells
- Row-by-row animation prompts plus bundled scripts for deterministic assembly
- QA contact sheets and preview videos before final packaging
- Ships final/spritesheet assets and pet.json; composes the installed $imagegen system skill
- Codex-compatible layout uses an 8×9 spritesheet atlas with transparent unused cells
- Primary outputs include final/spritesheet.png, final/spritesheet.webp, pet.json, and qa/contact-sheet.png
Adoption & trust: 1.1k installs on skills.sh; 61.4k GitHub stars; 3/3 security scanners passed (skills.sh audits).
What problem does it solve?
You want a custom Codex pet but lack a validated 8×9 animation atlas, QA checks, and pet.json packaging from raw art or prompts.
Who is it for?
Builders personalizing Codex with pixel or stylized pets who already have or can generate reference character art via imagegen.
Skip if: Non-Codex products that only need a single static logo, or environments where $imagegen is not installed and you cannot run bundled assembly scripts.
When should I use this skill?
Use when the user wants to hatch a Codex pet, build a custom animated pet, or create or repair a built-in pet asset with full spritesheet QA and packaging.
What do I get? / Deliverables
You get a validated spritesheet set, preview artifacts, and pet.json ready to drop into a Codex or Open Design agent surface.
- final/spritesheet.png and final/spritesheet.webp
- pet.json manifest for Codex-compatible pets
- qa/contact-sheet.png and preview media from the validation pass
Recommended Skills
Journey fit
Pet asset pipelines are created during Build when you personalize agent surfaces; they are not journey-wide methodology. Output is Codex pet packaging and spritesheet tooling—agent-tooling fits better than generic frontend pages or backend APIs.
How it compares
Use for full pet hatch packaging with atlas rules—not as a generic image generator or MCP image server by itself.
Common Questions / FAQ
Who is hatch-pet for?
Indie builders and designers customizing Codex or Open Design agents who need animated pet assets that meet Codex grid and manifest conventions.
When should I use hatch-pet?
During Build agent-tooling when a user says hatch a pet, wants a spritesheet pet, or needs to repair or validate an existing Codex pet atlas.
Is hatch-pet safe to install?
It drives image generation and filesystem outputs—review the Security Audits panel on this page and vet upstream Open Design and imagegen access before running on sensitive machines.
Workflow Chain
Requires first: imagegen
SKILL.md
READMESKILL.md - Hatch Pet
# Hatch Pet > **Open Design integration.** This is the unmodified Codex `hatch-pet` skill, > vendored under `skills/hatch-pet/` so any Open Design agent can run it. After > the skill finishes packaging, the resulting `spritesheet.webp` (under > `${CODEX_HOME:-$HOME/.codex}/pets/<pet-name>/`) can be imported into the > floating pet companion via **Settings → Pets → Import Codex sprite**. The > import flow auto-detects the 8×9 / `192×208` atlas and lets the user pick > which animation row to play (idle, running-right, waving, …). ## Overview Create a Codex-compatible animated pet from a concept, one or more reference images, or both. This skill owns pet-specific prompt planning, animation rows, frame extraction, atlas geometry, QA, previews, and packaging. It delegates visual generation to `$imagegen`. User-facing inputs are optional. If the user omits a pet name, infer one from the concept or reference filenames; if that is not possible, choose a short appropriate name. If the user omits a description, infer one from the concept or references. If the user omits reference images, generate the base pet from text first, then use that base as the canonical reference for every animation row. ## Generation Delegation Use `$imagegen` for all normal visual generation. Before generating base art, row strips, or repair rows, load and follow the installed image generation skill: ```text ${CODEX_HOME:-$HOME/.codex}/skills/.system/imagegen/SKILL.md ``` Do not call the Image API directly for the normal path. Let `$imagegen` choose its own built-in-first path and its own CLI fallback rules. If `$imagegen` says a fallback requires confirmation, ask the user before continuing. When invoking `$imagegen` from this skill, pass the generated pet prompt as the authoritative visual spec. Do not wrap it in the generic `$imagegen` shared prompt schema and do not add extra polish, hero-art, photo, product, or illustration-style augmentation. Pet prompts should stay terse, sprite-specific, and digital-pet oriented; only add role labels for input images and any essential user constraint. Use this skill's scripts for deterministic work only: preparing prompts and manifests, ingesting selected `$imagegen` outputs, extracting frames, validating rows, composing the final atlas, creating QA media, and packaging. Hard boundary: do not create, draw, tile, warp, mirror, or synthesize pet visuals with local Python/Pillow scripts, SVG, canvas, HTML/CSS, or other code-native art as a substitute for `$imagegen`. For a normal pet run, expect up to 10 visual generation jobs: 1 base pet plus 9 row-strip jobs. The only exception is `running-left`, which may be derived by mirroring `running-right` only after `running-right` has been generated, visuall