hatch-pet

Hatch Pet creates, repairs, validates, previews, and packages Codex-compatible animated pet spritesheets from a concept, reference images, screenshots, or generated art. The end product is an 8x9 sprite atlas (192x208 per cell) with transparent unused cells, a pet.json manifest, QA contact sheets, and preview media, packaged so the sprite can be imported into the Codex floating pet companion via Settings, Pets, Import Codex sprite, which auto-detects the atlas and lets the user pick an animation row to play (idle, running-right, waving, and so on).

It owns the pet-specific work (prompt planning, animation rows, frame extraction, atlas geometry, QA, previews, and packaging) while delegating all normal visual generation to the installed $imagegen system skill rather than calling any image API directly. A normal run expects up to ten generation jobs: one base pet plus nine row strips, with running-left optionally derived by mirroring an already-approved running-right. A firm boundary forbids fabricating pet visuals with local Python/Pillow, SVG, canvas, or HTML/CSS; the bundled scripts are only for deterministic processing of already-generated outputs, recorded through record_imagegen_result.py (or generate_pet_images.py as a documented secondary fallback).

Use it when a user wants to hatch a Codex pet or build a custom animated pet asset. User inputs (pet name, description, reference images) are optional and inferred when omitted. The default art style deliberately matches Codex's built-in digital pets: compact chibi pixel-art-adjacent mascots with chunky silhouettes, thick outlines, limited palettes, and flat cel shading, simplifying more detailed references into that house style. Detailed transparency-and-effects rules keep every pixel either part of the sprite or cleanly chroma-keyable, allowing only small attached, hard-edged effects and disallowing motion lines, detached sparkles, shadows, glows, text, and backgrounds. This is the unmodified upstream Codex hatch-pet skill vendored for Open Design agents.