Technical reference

Codex Pet package format

A Codex custom pet package is a local folder that contains pet.json and spritesheet.webp.

Quick facts

Package folder	`~/.codex/pets/<pet-name>/`
Required manifest	`pet.json`
Required spritesheet	`spritesheet.webp`
Atlas size	`1536x1872`
Grid	`8 columns x 9 rows`
Cell size	`192x208`
Format	`transparent WebP / RGBA`

Manifest shape

{
  "id": "codie",
  "displayName": "Codie",
  "description": "A tiny pixel robot companion for Codex Pet.",
  "spritesheetPath": "spritesheet.webp"
}

Animation rows

Row	State	Used frames
0	`idle`	6
1	`running-right`	8
2	`running-left`	8
3	`waving`	4
4	`jumping`	5
5	`failed`	8
6	`waiting`	6
7	`running`	6
8	`review`	6

Validation checklist

Atlas is exactly 1536x1872.
Each cell is 192x208.
Used cells are non-empty and unused cells are transparent.
No grid lines, labels, or frame numbers are present.
The pet identity stays consistent across rows.