Mons TypeScript engine

The Mons rules engine is implemented in strict TypeScript and distributed as two dependency-free npm packages:

• mons-web is an ES module for browsers and bundlers.
• mons-rust is the existing CommonJS package for Node.js. Its historical package name is unchanged for compatibility.

Both packages expose the same 23 named game APIs and the same TypeScript declarations.

import { GameVariant, MonsGameModel } from "mons-web";

const game = MonsGameModel.new(GameVariant.Classic);
const output = game.process_input_fen("l10,5;l9,4");

const { GameVariant, MonsGameModel } = require("mons-rust");

const game = MonsGameModel.new(GameVariant.Classic);

Migrating mons-web initialization

mons-web no longer has a default initializer or an initSync export. Remove the default import and initialization call; named imports are ready to use immediately. The generated InitInput, SyncInitInput, and InitOutput TypeScript types are removed with those loaders.

-import initMonsWeb, { MonsGameModel } from "mons-web";
-await initMonsWeb();
+import { MonsGameModel } from "mons-web";

The named API is otherwise preserved, including enum values, FEN formats, model classes, event ordering, random automoves, and smart-automove preferences.

Incoming strings retain the previous runtime normalization: unpaired UTF-16 surrogates become U+FFFD before parsing or echoing. One intentional error-policy change applies to malformed data: native RuntimeError("unreachable") traps from invalid UTF-8 slice boundaries or genuine board/location bounds failures are deterministic TypeScript RangeErrors. Wrapped location indices that resolve inside the board remain compatible aliases.

Published JavaScript targets ES2020. The Node package uses Node's built-in performance and cryptographic-random services directly; the browser package uses the corresponding globalThis APIs. Node.js 22.13 through 22.x, or Node.js 24 or newer, is required only for repository development and release tooling.

Validation

Install the workspace with Node.js 22.13 through 22.x, or Node.js 24 or newer, and run the standard checks:

npm ci --engine-strict
npm run format:check
npm run lint
npm run typecheck
npm run build
npm test
npm run test:automove-parity

Run ./scripts/run-rules-tests.sh with no options to replay the deterministic compressed stream of 699,994 canonical unique rules transitions recovered from 699,999 historical raw fixtures. The command validates and streams the corpus without unpacking or rewriting it.

Run node ./scripts/check-complete-games.cjs to validate the immutable public corpus of 1,527 complete real-player games. Run npm run test:complete-games to replay all 25,185 turns and 169,480 inputs through the TypeScript engine across all 12 variants.

Release

Run ./publish.sh --check-only to execute the complete Node-only validation, build both package tarballs, and perform npm dry runs without publishing. Publishing is an explicit release operation: run ./publish.sh from a clean worktree only when both packages should be released to the latest tag.

A real publish acquires the transient mons-npm-publish-lock tag on origin, or on the shared remote named by MONS_PUBLISH_LOCK_REMOTE. All publishers must use this script and the same remote for the lock to serialize releases across hosts. If a process terminates without releasing the tag, the script prints inspection and lease-protected stale-lock recovery commands.