ClearSwap

On continuous AMMs, transaction ordering is everything. Bots sandwich trades, priority-gas auctions clog the mempool, and the fastest actor always wins. Moving to an on-chain order book fixes ordering but is far too expensive to compute on the EVM.

ClearSwap collects limit orders into discrete 45-second frequent batch auctions. Every order in a batch clears at one uniform price, so ordering stops mattering. The heavy computation (price sweeping, volume maximisation and pro-rata rationing) runs in a Rust engine compiled to WASM on Arbitrum Stylus, while Solidity contracts handle custody and settlement.

1. 01The clearing engine in Rust on Arbitrum Stylus: order sorting, candidate-price extraction, volume evaluation and pro-rata fills.
2. 02OrderBook, ClearingAdapter and Settlement contracts in Solidity, with non-prefunded orders (funds stay in traders' wallets until settlement).
3. 03A 4-stage invariant check on every engine result before any token moves.
4. 04Automatic zero-gas rollovers of unfilled orders into the next batch.
5. 0552 tests across the Rust engine and Foundry suites; all contracts verified on Arbiscan.

• Dual-VM split: Stylus does the maths, the EVM keeps custody. The adapter never trusts the engine's output blindly.
• Uniform-price clearing gives both sides price improvement and removes the incentive to pay for ordering.