Hutchling is an unofficial Codex pet inspired by the Fred Hutchinson Cancer Center. It is packaged as a standard Codex custom pet directory with a pet.json manifest and a spritesheet.webp atlas.

Clone this repository, then copy the hutchling pet directory into your Codex pets folder:

git clone https://github.com/fredhutch/hutchling.git
cd hutchling

CODEX_PETS_DIR="${CODEX_HOME:-$HOME/.codex}/pets"
mkdir -p "$CODEX_PETS_DIR"
cp -R hutchling "$CODEX_PETS_DIR/"

If Codex is already running, restart it or open a new Codex window so it can load the new custom pet. Hutchling should appear by its display name, Hutchling, from the installed manifest.

Open Codex Settings from the app menu, or press Cmd+, on macOS. Go to the Appearance tab, open Pets, and select Hutchling. If it does not appear immediately, use the custom-pets refresh control in Appearance > Pets, then select it.

To show or hide the floating pet overlay, type /pet in the prompt composer. You can also use Wake Pet or Tuck Away Pet from Settings > Appearance, or open the command menu with Cmd+K on macOS or Ctrl+K on Windows/Linux and run the same commands.

After installation, these files should exist:

${CODEX_HOME:-$HOME/.codex}/pets/hutchling/
  pet.json
  spritesheet.webp

You can inspect the manifest with:

cat "${CODEX_HOME:-$HOME/.codex}/pets/hutchling/pet.json"

Expected manifest:

{
  "id": "hutchling",
  "displayName": "Hutchling",
  "description": "A cute Fred Hutch Cancer Research Center inspired research pet.",
  "spritesheetPath": "spritesheet.webp"
}

hutchling/
  pet.json
  spritesheet.webp
preview/
  contact-sheet.png
  previews/
    failed.gif
    idle.gif
    jumping.gif
    review.gif
    running.gif
    running-left.gif
    running-right.gif
    waiting.gif
    waving.gif

The hutchling/ directory is the installable pet source. The preview/ directory is only for GitHub documentation and is not required for installation.

Hutchling uses the Codex hatch-pet atlas format:

The rows are:

This is an unofficial Codex pet package. It is not officially endorsed by Fred Hutch.