Each room owns a ChessEngine wrapped in a GameSession; only the server
calls insert/retract/fireRules and all EntityIds are minted server-side.
GameSessionRegistry keys sessions by room code so two rooms cannot
observe or collide with each other's working-memory state.
GameSession.applyMove validates algebraic inputs, finds the matching
legal move via ChessEngine.findMove, applies it, and returns a fact-
level diff (inserted/retracted) plus the new turn and terminal state.
Terminal states are sticky: further moves after checkmate/draw return
GAME_OVER rather than silently mutating a dead session.
Exposes @paratype/chess's headless surface (ChessEngine, coord helpers,
schema types) via a new package entry point; the React app continues to
import concrete modules directly.
Introduces PresetRegistry + three pawn-focused preset rules from
RULES.md (pawns-move-backward, double-pawn-sprint,
pawn-diagonal-no-capture). Presets register themselves via
side-effect imports and expose getExtraMoves/filterMoves hooks for
the ChessEngine to invoke during move generation (engine wiring is
P3.11). Registry enforces incompatibility and requires invariants.
- packages/chess/src/engine.ts — ChessEngine integrates all rule modules
(pawn, knight, sliding, king, castling, en-passant, promotion, check,
checkmate, stalemate, draws) into a playable game without the Rete
production network
- packages/chess/src/pgn.ts — minimal SAN/PGN parser with full
disambiguation support (file/rank hints, full from-square)
- packages/chess/tests/fide-games/classic-games.test.ts — 5 game tests:
Fool's Mate, Scholar's Mate, Ruy López, Sicilian Defence, Italian Game
All 5 tests green; typecheck clean.
