The bell & settlement

At the top of every minute the round that just ended settles, and a new one opens.

#One price, two jobs

The close of round N is the open of Hyperliquid's 1-minute candle that starts at the bell. That same price is the strike of round N+1. One read serves both, so the two can never disagree, and neither can be sampled late.

#Winner

• close > strike: UP wins.
• close < strike: DOWN wins.
• close == strike: nobody beat the line. The round voids and everyone is refunded. See Voids & refunds.

#Same-transaction scoreboard

settle() calls ArenaRegistry.onRoundSettled() inside the same transaction. The public scoreboard can't land on a different price, or in a different block, from the result that caused it.

The hook gets a fixed gas budget (HOOK_GAS = 1,500,000). If a caller tries to settle with less gas than that, settle reverts (HookGas). Gas estimation therefore can't find a limit where the money settles and the scoreboard silently doesn't. A hook that fails with its full budget can never block the money.

#Redeem

After settlement, winning shares redeem for 1 tUSDC each (redeem(round)). Surviving runs roll their stack into the next round.