This is the modified Fairy-Stockfish source used by john.fun/chess.
Every engine source file matches build-manifest.json.

Install Python 3, GNU Make and Emscripten (original build: 5.0.6-git).
Run from this directory:
  python3 tools/build_browser.py --output ../browser-assets
The build creates the matching threaded search engine and ffish rules module.
NNUE is disabled; no network weights are required.

Modifications include hero abilities, Monster +2/+3, Scottish Progressive,
state serialization, same-player search, and the browser command interface.
Copyright and license notices are preserved in the source and Copying.txt.
