Momo Ayase for Codex with PetEase

An unofficial, hand-QA'd Momo Ayase fan pet for Codex, plus PetEase: an accessibility-focused toolkit that audits real Codex v2 sprite atlases, detects motion hazards, compiles deterministic reduced-motion editions, installs with backup and rollback, and builds reproducible release archives.

This is not a reskin around an empty page. The repository ships one complete 1536×2288, 8×11 Codex v2 atlas with nine animated states, sixteen look directions, a tested Python CLI, machine-readable reports, CI, sample policy, and reproducible packages.

Unofficial fan project. Momo Ayase and DANDADAN belong to their respective rights holders. The software is MIT-licensed; artwork has separate terms in ASSET_LICENSE.md.

简体中文 · Acceptance · Repair guide · Architecture

What ships

• pet/: installable Momo Ayase Codex v2 pet, with transparent lossless WebP.
• petease audit: validates manifest safety, atlas dimensions, required/unused cells, transparent RGB residue, cell-edge clipping, motion jumps, luminance changes, centroid shifts, and scale changes.
• petease compile-reduced: replaces each animated state with a deterministic representative still while preserving all sixteen look-direction cells.
• petease install: refuses structurally broken pets, performs a staged copy, verifies the sprite checksum, backs up an existing install, and rolls back on failure.
• petease package / verify-archive: creates and verifies deterministic .codex-pet transport archives.
• JSON, HTML, and SARIF output for people, CI, and GitHub code scanning.
• Tests with synthetic valid and malicious packages; no copyrighted fixture images are needed to exercise the tool.
• Committed visual QA evidence, including contact sheets, direction semantics, continuity metrics, and three-reviewer blind validation.

Install the pet

Download momo-ayase-codex-pet-v0.1.2.zip and petease-0.1.2-py3-none-any.whl from the same Release, extract the pet bundle, then:

py -m pip install .\petease-0.1.2-py3-none-any.whl
petease install .\pet --dry-run
petease install .\pet

Restart Codex, open Settings → Pets, and select Momo Ayase. PetEase installs into the selected CODEX_HOME (or ~/.codex) and preserves an existing pet as a timestamped sibling backup.

To install into an isolated directory first:

petease install .\pet --codex-home .\.acceptance-codex --dry-run
petease install .\pet --codex-home .\.acceptance-codex

Audit any Codex v2 pet

PetEase is character-agnostic. Point it at any directory containing pet.json and its v2 atlas:

petease audit pet \
  --json-out build/audit.json \
  --html-out build/audit.html \
  --sarif-out build/audit.sarif \
  --strict

Exit codes are stable:

• 0: structurally valid; in strict mode, no motion warnings.
• 1: invalid package or structural error.
• 2: structurally valid, but strict motion policy reported warnings.

Tune warning thresholds without weakening structural checks:

petease audit pet --policy examples/policy.json --strict

Compile a reduced-motion edition

petease compile-reduced pet build/momo-reduced \
  --json-out build/reduced-audit.json
petease audit build/momo-reduced --strict

The compiler chooses a deterministic medoid pose for each animated state (idle intentionally uses frame zero), repeats it across that state's used cells, preserves look-direction cells, records source/output SHA-256 values, and writes petease-provenance.json.

It will not overwrite an arbitrary non-empty directory, even with --force.

Build a reproducible transport archive

petease package pet dist/momo-ayase.codex-pet
petease verify-archive dist/momo-ayase.codex-pet

Entries are lexically sorted, timestamps and permissions are normalized, unsafe paths and symlinks are rejected, and the command prints the archive SHA-256.

Develop and verify

Python 3.10+ is supported.

To reproduce the locked CI environment:

uv sync --locked --extra dev
uv run python scripts/release_gate.py --json build/release-gate.json

The equivalent standard-library/pip workflow is:

python -m venv .venv
python -m pip install -e ".[dev]"
python -m unittest discover -v
python -m coverage run -m unittest discover
python -m coverage report
python -m ruff check .
python scripts/release_gate.py --json build/release-gate.json

The exact public-release acceptance sequence and expected artifacts are in docs/ACCEPTANCE.md. If anything fails, use the code-indexed procedures in docs/REPAIR.md.

Why Momo, and why this tool?

The character is not invented for this repository. Momo is a lead character in DANDADAN's official character roster. Before implementation, repository and code searches across the main Codex pet lists found no existing Momo Ayase pet, while several other popular candidates already had implementations.

The tool addresses a separate gap: existing pet repositories mostly validate layout or preview animation, while PetEase treats motion comfort and safe, reproducible transformation as first-class build outputs. The research record, search queries, date, and limits are preserved in docs/RESEARCH.md.

Popularity and careful execution can improve discoverability, but no project can honestly guarantee stars or views.

Privacy and security

PetEase is offline by default. It does not send telemetry, inspect Codex conversations, or need network access. Installation is restricted to a single validated pet ID under the selected Codex home. Package sprite paths cannot be absolute or escape their directory. See SECURITY.md.

Credits and rights

PetEase code and original documentation: © 2026 KanadeK, MIT.

Momo Ayase and DANDADAN are owned by their respective rights holders. Generated fan art is not covered by the MIT license. No official reference image is committed, packaged, or published. See NOTICE.md and ASSET_LICENSE.md.