feat: implement and deploy blind_chess MVP

- pnpm workspace: shared/server/client packages
- Server: Fastify+ws, chess.js, FSM (touch-move + hierarchy),
  per-player view filter, zod validation, rate limiting, grace-window
  disconnect handling
- Client: Svelte 5 + Vite, click-to-move board, moderator panel,
  promotion/draw dialogs
- Shared: protocol types, ModeratorText enum, geometricMoves helper
  (provably zero opponent-info leak)
- 43 tests pass (21 shared, 22 server incl. 4 real-WS integration)
- Deploy: CT 690 on node-241 (192.168.0.245), systemd-managed,
  Caddy block for chess.sethpc.xyz
- Live at https://chess.sethpc.xyz

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/server/src/games.ts

@@ -0,0 +1,122 @@
+import { Chess } from 'chess.js';
+import { randomBytes } from 'node:crypto';
+import type {
+  Color, GameId, Mode, PlayerToken,
+} from '@blind-chess/shared';
+import { type Game, PRUNE_AFTER_FINISHED_MS, RATE_LIMIT } from './state.js';
+
+const games = new Map<GameId, Game>();
+
+export function newGameId(): GameId {
+  const alphabet = 'abcdefghijklmnopqrstuvwxyz0123456789';
+  let id = '';
+  while (true) {
+    const buf = randomBytes(8);
+    id = '';
+    for (let i = 0; i < 8; i++) id += alphabet[buf[i]! % alphabet.length];
+    if (!games.has(id)) return id;
+  }
+}
+
+export function newPlayerToken(): PlayerToken {
+  return randomBytes(18).toString('base64url').slice(0, 24).toLowerCase().replace(/[^a-z0-9]/g, 'a');
+}
+
+export function chooseSide(side: Color | 'random'): Color {
+  if (side === 'random') return Math.random() < 0.5 ? 'w' : 'b';
+  return side;
+}
+
+export function createGame(opts: {
+  mode: Mode;
+  creatorSide: Color;
+  highlightingEnabled: boolean;
+}): { game: Game; creatorToken: PlayerToken } {
+  const id = newGameId();
+  const creatorToken = newPlayerToken();
+  const now = Date.now();
+
+  const game: Game = {
+    id,
+    mode: opts.mode,
+    highlightingEnabled: opts.highlightingEnabled,
+    status: 'waiting',
+    createdAt: now,
+    chess: new Chess(),
+    moveHistory: [],
+    announcements: [],
+    players: {
+      w: opts.creatorSide === 'w' ? makeSlot(creatorToken, now) : null,
+      b: opts.creatorSide === 'b' ? makeSlot(creatorToken, now) : null,
+    },
+    armed: null,
+    drawOffer: null,
+    disconnectAt: {},
+  };
+
+  games.set(id, game);
+  return { game, creatorToken };
+}
+
+function makeSlot(token: PlayerToken, now: number) {
+  return {
+    token,
+    socket: null,
+    joinedAt: now,
+    rateBucket: { tokens: RATE_LIMIT.capacity, last: now },
+  };
+}
+
+export function getGame(id: GameId): Game | undefined {
+  return games.get(id);
+}
+
+export function deleteGame(id: GameId): void {
+  games.delete(id);
+}
+
+export function allGames(): IterableIterator<Game> {
+  return games.values();
+}
+
+export function activeGameCount(): number {
+  let n = 0;
+  for (const g of games.values()) if (g.status !== 'finished') n++;
+  return n;
+}
+
+/** Find game where this token is bound to a player slot; returns the slot color. */
+export function findTokenInGame(game: Game, token: PlayerToken): Color | null {
+  if (game.players.w?.token === token) return 'w';
+  if (game.players.b?.token === token) return 'b';
+  return null;
+}
+
+/** Claim the open slot in a game. Returns the color claimed or null if both filled. */
+export function claimSlot(
+  game: Game,
+  joinAs: Color | 'auto',
+): { color: Color; token: PlayerToken } | null {
+  const tryClaim = (c: Color): { color: Color; token: PlayerToken } | null => {
+    if (game.players[c]) return null;
+    const token = newPlayerToken();
+    game.players[c] = makeSlot(token, Date.now());
+    return { color: c, token };
+  };
+
+  if (joinAs === 'w') return tryClaim('w');
+  if (joinAs === 'b') return tryClaim('b');
+  return tryClaim('w') ?? tryClaim('b');
+}
+
+export function pruneFinished(): number {
+  const now = Date.now();
+  let removed = 0;
+  for (const [id, g] of games) {
+    if (g.status === 'finished' && g.finishedAt && now - g.finishedAt > PRUNE_AFTER_FINISHED_MS) {
+      games.delete(id);
+      removed++;
+    }
+  }
+  return removed;
+}