As the designated account abstraction standard for Ethereum, ERC-4337 has had limited adoption since its launch. EF has now proposed the Ethereum Interop Layer (EIL), which aims to use a unified solution to smooth out the liquidity and experience fragmentation between L2 chains. EIL (Ethereum Interactive Layer) was proposed by Ethereum's "Account and Chain Abstraction Team" and is a complete set of technical solutions that can achieve a unified experience across multiple L2 networks without any modifications to the underlying blockchain. ERC-4337 is a necessary prerequisite for EIL. This scheme was proposed by Vitalik as the first author, and its biggest advantage is that it does not require modification of the Ethereum protocol layer, and only requires the deployment of smart contracts to achieve account abstraction functionality. However, since its launch, the adoption rate of ERC-4337 has not shown significant growth, and most users are still using traditional accounts (EOA). The lack of ecological compatibility and relatively higher gas costs have become the main factors hindering its popularization. As an upgraded version of ERC-4337, EIL naturally inherits all the functions of ERC-4337, that is, the entire set of smart contracts deployed on the chain. Understanding EIL is not complicated, essentially it extends the capabilities of ERC-4337 to multi chain scenarios. Firstly, EIL allows users to sign at once, driving multiple operations on multiple chains. For example, if a user buys assets from Chain A and Chain B, they can first complete the signatures of these two parts. Then a new role is introduced in EIL, called Cross chain Liquidity Provider, or XLP. It is similar to an intermediary, but its responsibility is not to send all business transactions for users, but to provide "advance payment" and atomic exchange of funds and gas between different L2. The choice of which XLP to serve a cross chain operation is determined by the bidding mechanism on the chain. The user provides a fee range in the request, and multiple XLPs compete for the same order. Whoever submits a valid voucher on the chain first earns the cross chain fee. Therefore, the core capabilities of EIL do not require any modifications to the L1 or L2 network, and can be achieved by deploying contracts and relying on the existing ERC-4337 infrastructure. Its core innovation is reflected in two aspects: "multi chain batch authorization" and "on chain bidding financing". The cost is that the pressure is transferred to the wallet and off chain infrastructure. The wallet side should support multi chain UserOp, one-time signature multi chain verification, interaction with XLP, and a new cross chain UX. Off chain infrastructure should be responsible for discovering and monitoring XLP, supporting XLP bidding and matching, as well as multi chain balance and risk management. If the above functions are effectively implemented, multiple L2 networks will gradually converge in user experience, truly achieving a seamless experience similar to single chain operation. https://substack.chainfeeds.xyz/p/ethereum-interop-layer-erc-4337-l2