# Crownroom starter opening books

Separate opening books for Russian and Brazilian draughts, generated from the
standard start by Crownroom's adapted MIT-licensed Damka engine. No third-party
game collections, published opening annotations, or commercial books were used.

## Commercial reuse

This directory's generated data and generator are offered under the MIT license
in LICENSE.txt: commercial use and modification are permitted without royalties.
Retain that license and copyright notice when distributing copies. The Damka
engine retains its separate MIT notice in ../vendor/damka/LICENSE.txt.

## Scope and generation

Run `node scripts/build-opening-books.mjs` from the project root. The generator
explores every legal move for the first two plies, then the engine's preferred
continuation, recording positions through ply 9 (ten half-moves / five moves
per player). Transpositions are merged. Search targets depth 14 with a 300 ms
budget per position. Completed depths and position counts are in data.js.
Time-limited searches can produce different recommendations on different runs.

These are compact engine-generated starter repertoires, not independently
verified tournament theory. Their strength has not been benchmarked. They
provide instant early replies and may leave book as soon as a player chooses
an unrecorded continuation. They do not establish an Elo rating.

Medium and Hard computer opponents use the books automatically. Beginner and
Easy retain their existing behavior. Analysis always performs a fresh search,
so book evaluations do not become move-rating verdicts. The exact variant,
side and complete board must match; every book move is checked against the
current legal-move rules. Missing or invalid entries fall back to search.
American play is unchanged. No opening book or endgame data is fetched remotely.