acnab

acnab renders chess positions from standard chess notation in the terminal and in the browser.

Play it free right now: wsams.github.io/acnab/web — no install, no account. Type SAN/PGN moves and watch the board update live. Optional CPU player (Stockfish in the browser) can be toggled on for a real game after a coin toss for White.

The browser UI shows the live board beside a Moves panel: type SAN/PGN, hit Render, and the position updates with FEN, material, and move history. Dual clocks, theme/piece-color presets, and browser-local saves sit alongside the board for over-the-board notation tracking. Turn on CPU player to face Stockfish at a chosen strength — input stays chess notation.

CLI usage

Render a game directly:

python3 chess.py --moves '1. e4 e5 2. Nf3 Nc6 3. Bb5 a6'

Use stdin when quoting is inconvenient in bash or fish:

printf '1. d4 d5 2. c4' | python3 chess.py --moves-file -

Print shell completion helpers:

python3 chess.py --print-completion bash
python3 chess.py --print-completion fish

Save and reload games locally:

python3 chess.py --moves '1. e4 e5 2. Nf3 Nc6' --save demo
python3 chess.py --load demo
python3 chess.py --list-games

Supported notation

• Standard SAN/PGN style moves such as e4, Nf3, Qxd5+, O-O, and c8=Q#
• Legacy coordinate-style moves such as Pf2f4 and Nb8c6

Web usage

Free on GitHub Pages

Open https://wsams.github.io/acnab/web/ to play in the browser for free.

GitHub Pages publishes the static UI from web/ (the site root redirects there). The build is fully static and client-side:

• live board updates while typing
• localStorage drafts and named saves
• theme, SVG piece-set, and piece-color switching plus FEN/status summaries
• flip board for couch co-op
• shareable board links (notation encoded in the URL hash; opening a link resets to the start and autoplays)
• play controls to step through or autoplay a game with sliding piece animation
• optional CPU opponent (Stockfish.js 18 WASM, skill/Elo presets) — off by default; coin toss for who plays White
• no CDN runtime dependency for the chess engine (Stockfish is vendored under web/vendor/stockfish/, GPLv3)

Example shared game (opens at move 1 and plays through to mate): Open the demo board

Local static preview

python3 -m http.server 8080 --directory web

Then open http://localhost:8080/.

Optional PHP + Python API

Serve web/ with PHP if you want the optional POST render endpoint that shells out to chess.py. Opening web/index.php still serves the same client-side UI.

Development notes

Install Python dependencies and run the lightweight checks:

python3 -m pip install -r requirements.txt
python3 -m unittest discover -s tests
python3 -m py_compile chess.py web/chess.py acnab_core.py
php -l web/index.php

Install Node release tooling (used by CI):

npm clean-install

Build the GitHub Pages artifact locally:

npm run build:pages

Releases

Pushes to master run semantic-release via .github/workflows/release.yml (direct npx semantic-release, no third-party release action). GitHub Pages publishes from the master branch (legacy); .github/workflows/pages.yml verifies npm run build:pages still produces a clean _site/ artifact.