Network
Blackjack.

The server implements the full WebSocket handshake and frame parser in pure Python stdlib — no external packages. asyncio.start_server handles concurrent connections; _ws_decode_frames manually parses the length-prefixed binary frame format including masking, while _ws_encode handles server→client framing.

Each GameRoom instance manages a state machine across five phases: waiting → betting → playing → dealer_turn → finished. Turn sequencing uses await _advance_turn() with cooperative yielding — the dealer draw loop uses await asyncio.sleep() between cards to pace reveals without blocking other connections.

Player identities are tied to a UUID generated in the browser and stored in a cookie, then sent with every create/join message. The server maps this UUID to a players table in leaderboard.db, tracking total_wins, total_losses, and best_balance using MAX(best_balance, ?) so high scores are preserved across sessions.

Each player starts with $1,000 in chips and sets a bet before cards are dealt. Payouts follow standard rules: win returns 1:1, blackjack pays 3:2 via math.floor(bet * 1.5), push returns the stake, bust/lose deducts the bet. For split hands, the bet is divided equally between both sub-hands. Balances persist to the DB at game end.