Codex Pets: pet format and CLI session checks
Checked November 5, 2026 by Codex Pets Team

Scope
These are dated observations, not a guarantee for every Codex release or
platform. File checks, animation quality, artwork permission and installation
are separate questions. Original pet package files were not modified.

Pet format
The public OpenAI Hatch Pet reference described the older v1 contract:
8 columns, 9 rows, 1536 x 1872 pixels, 192 x 208 pixel cells.
https://github.com/openai/skills/blob/main/skills/.curated/hatch-pet/references/codex-pet-contract.md

The Hatch Pet contract bundled with Windows desktop build 26.1029.7803.0
required v2 for newly hatched pets: 8 columns, 11 rows, 1536 x 2288 pixels.
The first nine rows remain the standard actions. Rows 9 and 10 contain sixteen
clockwise look poses, starting at 0 degrees (up), in 22.5-degree increments.
The pointer deadzone uses idle. An intermediate 8 x 9 image is not the final
new v2 package. Follow the contract installed with the workflow being used.

SHA-256 of the inspected bundled contract:
8c6d1557900c44f267003b9097ad1cfb4e4d29e574ae325c0dd0943b71510d72
SHA-256 of the inspected bundled animation-row reference:
62643046b18de139c9147bebe79a0912c9cb1b629c535ed4189a07c41b10a3e3

The installed codex-pets-react 0.2.0 renderer agreed on standard state rows and
active frame counts: idle 6, right 8, left 8, wave 4, jump 5, failed 8,
waiting 6, working 6, review 6. Extra canvas columns are not active frames.
https://github.com/backnotprop/codex-pets-react

The real Boxcat v1 and Beanie v2 packages passed this site's local ZIP checker:
root manifest/image, ZIP integrity, matching version and decoded image size.
A Beanie image deliberately declared as v1 was rejected for its size mismatch.
The bundled validate_atlas.py with Pillow accepted Beanie without warnings.
Legacy Boxcat and Mosaic Invader failed its newer authoring check for nonzero
RGB in fully transparent pixels. That does not demonstrate installation failure;
these are legacy geometry examples, not clean new-artwork templates.

The browser preview plays nine standard action states. It does not validate
the pointer-driven v2 look sequence or establish support in every desktop app.
https://codexpets.org/tools/sprite-preview

CLI session recovery
The controlled native test used Windows Codex CLI 0.163.0 in an interactive
terminal. An owned test conversation was exited and resumed by its exact ID.
It recovered an earlier marker that was not repeated in the recovery question.
The picker loaded its saved messages. The original directory's picker found
the conversation; an empty different directory did not under the Cwd filter.
Adding --all made the title findable across directories. --last selected the
controlled conversation in its original directory.

Root --continue and --resume flags were rejected. A nonexistent session ID
returned exit 1 and 'No saved session found', directing the reader to the picker.
Later attachments showed open-in-another-app protection. Closing test clients
and retrying did not establish immediate writable lock recovery. No locks,
history or configuration were deleted and no second writer was forced.

Global --last --all was not executed because it could select an unrelated
active conversation. Its semantics and directory-choice preference are based
on help/documentation. Non-interactive recovery, macOS, WSL and deleted-file
restoration were not established by this interactive Windows test.
https://learn.chatgpt.com/docs/developer-commands?surface=cli

Public references
https://codexpets.org/guides/codex-pet-spritesheet-format
https://codexpets.org/guides/resume-codex-session
https://codexpets.org/contact