miaoda-game-euchre-rules

Immutable, engine-neutral rules for fixed profile pagat-4p-partnership-no-loner-5points: a 24-card deck, two bidding rounds, dealer discard, bowers, follow-suit enforcement, trick scoring, and first team to 5. Lone hands and stick-the-dealer are excluded.

pnpm add miaoda-game-euchre-rules

Run a game

import {
  applyEuchreAction,
  createEuchreGame,
  createEuchrePlayerView,
} from 'miaoda-game-euchre-rules';

let state = createEuchreGame({
  playerIds: ['north', 'east', 'south', 'west'],
  seed: 2026,
});
const playerId = state.activePlayerId;
const view = createEuchrePlayerView(state, playerId);
if (view.legalActions.canOrderUp) {
  const result = applyEuchreAction(state, { type: 'order-up', playerId });
  if (result.ok) state = result.state;
}

Use the exhaustive canOrderUp, callSuits, discardCardIds, playCardIds, and canStartNextHand values. UI and bots should not duplicate left-bower effective suit or follow-suit logic.

Public events

import { projectEuchreEvents } from 'miaoda-game-euchre-rules';

if (result.ok) broadcast(projectEuchreEvents(result.events));

The projector rebuilds and detaches bidding, played-card, completed-trick, scoring, and hand-start events. Dealer discard produces no public event, so the discarded card id remains private. Unknown runtime event types throw instead of being forwarded.

Restore a snapshot

import { restoreEuchreState } from 'miaoda-game-euchre-rules';

state = restoreEuchreState(JSON.parse(savedJson));

Restore validation reconstructs the initial deal and replays accepted actions before trusting trump, tricks, scoring, or winner state. Use validateEuchreState for a non-throwing result.

Keep authoritative state on a trusted host. Send each player only createEuchrePlayerView(state, playerId) and projected events; these omit opponent hands, stock, and the dealer discard.