Synchronous Composability with Real-Time Proving

The Ethereum Economic Zone (EEZ) is a set of contracts on Ethereum and rules for connecting chains to them, letting a connected chain run one transaction that uses Ethereum and other connected chains synchronously within the same block. The design relies on real-time proving, where a chain's proof is ready within one 12-second Ethereum slot, along with a composer that precomputes crosschain call answers and a proxy that stands in for contracts on other chains. The article's example is a rollup transaction that borrows USDC on Aave, swaps it on Uniswap, bridges the ETH back and posts it as margin on an exchange in one step. The article also lists limits, including that a chain cannot have fast blocks, synchronous Ethereum calls and a decentralized sequencer at once.