What kind of future are we heading towards from aggregation bridges to atomic interoperability?

If you are an on-chain Degen, you are probably familiar with the following scenarios:

Transfer ETH from the mainnet to Arbitrum to interact with DeFi at lower Gas fees; exchange USDT on Polygon for USDC on Base; or, for optimal strategy, distribute assets across different chains to connect with specific applications.

Behind these operations lies one of the core propositions of the blockchain world - cross-chain interoperability. This article also plans to outline the evolutionary path of cross-chain technology and reveal how Web3 transitions from a singular “cross-chain bridge” to the ultimate goal of “seamless interoperability.”

Rollup and Fragmentation of Multi-Chain Ecosystem

If you are an old player in the Ethereum ecosystem, how many L2s have you used at most? 5, 10, or 20 or more?

In fact, compared to the total amount, the vast majority of players may have only explored a small part of the L2 panorama. According to incomplete statistics from L2BEAT, there are nearly a hundred L2s in the Ethereum ecosystem today, not including other independent L1 public chains. We are currently in an unprecedentedly prosperous multi-chain era.

However, this has also led to a new dilemma where liquidity and yield opportunities are increasingly fragmented — the traffic originally concentrated on Ethereum is gradually being divided, forming isolated value islands, while it is destined that with the increase in the number of public chains and L2s, the degree of liquidity fragmentation will further intensify.

So what does this mean for the average user? When you need to perform a cross-chain operation from chain A to chain B, it's like planning a complicated international trip, full of challenges.

After all, from Chain A to Chain B, each route has different travel times (bridge time), tolls (cross-chain costs), and fuel consumption (Gas), and the travel time, tolls, and fuel consumed may vary each time, making it difficult to find the optimal route:

• Some routes may only support specific tokens;
• The tolls for certain routes may vary based on the amount of tokens, so it may not be ideal for large transactions;
• Or the contract interaction costs for certain routes may be high, leading to increased travel time and fuel consumption;

This process is not only cumbersome, but each step may also incur additional slippage and fees. Therefore, just as DEX aggregators like 1inch became a necessity after the flourishing of DEXs like Uniswap and SushiSwap, cross-chain bridge aggregators have also become the first wave of evolutionary direction against the backdrop of an increasing number of bridges in the market.

The idea of cross-chain (layer) aggregation not only achieves direct aggregation and transfer of assets between different blockchain networks but also includes the aggregation of DEXs and DEX aggregators, such as Uniswap, 1inch, etc. This means that users can directly complete exchanges between different assets while their assets are cross-chain (layer).

This means that you only need to enter the starting point (DAI on Arbitrum) and the endpoint (ETH on Optimism), and the system will instantly calculate the optimal solution based on the current market conditions. Users only need to confirm once, and the backend will complete the entire process of cross-chain + exchange operations.

This marks the evolution of the cross-chain experience from “manual” to “automatic”, significantly lowering the user threshold.

Evolution from “Cross-Chain” to “Aggregation”

In short, the core value of a cross-chain aggregator lies in becoming a smart navigation system for users, simplifying complex multi-step operations into a one-click process.

This is also the focus of development for cross-chain aggregators and similar concepts over the past few years. In this process, the system will automatically find all available routes and rank them according to the following three criteria—maximum asset output on the target chain, lowest Gas fees, and shortest time. Users only need to select from the paths provided by the aggregator to complete the optimal cross-chain exchange operation.

We can intuitively feel the advantages of this cross-chain (layer) aggregation exchange by comparing it with traditional cross-chain exchange paths. Suppose a user has DAI on Arbitrum and wants to exchange it for ETH on Optimism. Under traditional cross-chain (layer) projects, various paths can be used to achieve this:

• First, use 1inch on Arbitrum to exchange DAI for ETH, and then use the cross-chain bridge to transfer ETH from Arbitrum to Optimism;
• Or first use a cross-chain bridge to swap DAI from Arbitrum to Optimism, and then use Uniswap on Optimism to swap DAI for ETH;

Different paths, although they have their own advantages in terms of cost and experience, share a similar underlying logic. They all involve the two fundamental operations of cutting into the same asset for cross-chain (layer) transfer and exchanging different assets, followed by optimal selection for each. This requires a comprehensive evaluation based on factors such as the size of the exchange funds, the magnitude of the slippage, the adequacy of network liquidity, and the speed of transactions.

However, in the idea of cross-chain (layer) aggregation, the aforementioned trade-offs and considerations do not need to be made by the user. They automatically find all available routes and help users move funds between different blockchains in the optimal way based on factors such as maximum output on the destination chain, minimum Gas fees for transactions and transfers, and minimum bridging time.

Beyond the intuitive “aggregation” evolution path that can be felt on the user experience side, on the technical level, in order to break down barriers, the cross-chain track has been exploring various more diverse technological solutions for many years:

• Message layer interoperability: For example, LayerZero, IBC (Cosmos), achieve data interoperability through cross-chain message verification.
• State layer synchronization: Allows different chains to directly share state without the need for intermediaries.
• Zero-Knowledge (ZK) Cross-Chain: Utilizing zero-knowledge proofs to make cross-chain verification more efficient and secure.

These solutions point to a common goal, making the blockchain world truly “seamlessly interconnected”, allowing users to feel no boundaries of the chain.

On August 29, the Ethereum Foundation also released “Protocol Update 003 — Improve UX,” focusing on improving user experience (Improve UX), as one of the three major strategies after restructuring the research and development team (Scale L1, Scale Blobs, Improve UX).

The article from EF emphasizes that interoperability (interop) is at its core, aiming for a seamless, secure, and permissionless Ethereum ecosystem experience.

Latest Cross-Chain Thoughts on Ethereum

Against this backdrop, there are two new paths worth noting in the academic and developer communities, which may determine the future shape of cross-chain in the Ethereum ecosystem.

1. SCOPE: Rebuilding Ethereum's “synchronous composability”

First of all, there is the idea of SCOPE (Synchronous Composability Protocol) recently proposed by Ethereum researcher jvranek, which aims to achieve synchronous composability between Ethereum L1 and L2, as well as L2 and L2, supporting atomic execution of cross-domain contracts.

In simple terms, it means enabling interactions between different Rollups and between Rollups and the Ethereum mainnet to be executed “atomically” as if they were on the same chain—all operations within a single transaction must either succeed completely or fail completely, with no intermediate states. However, this has previously been constrained by the barriers of cross-chain interoperability, making it difficult to achieve once cross-chain operations are involved.

For example, with SCOPE, you will be able to simultaneously call the Aave protocol on Arbitrum and the Uniswap protocol on Optimism in a comprehensive strategic trade involving Swap and Lend. Either both succeed or both fail, and there will be no getting stuck halfway, wasting Gas and opportunity costs.

The potential value is also evident, as it will unlock complex DeFi strategy combinations such as cross-L2 flash loans and one-click liquidations. Although SCOPE is still in the PoC stage, it is widely regarded as a key piece in solving the fragmentation of L2 composability.

Once mature, the aggregation experience at the application layer will complement the atomic interoperability at the underlying layer: the former lowers the barrier to entry, while the latter ensures security and consistency.

2. ZK Accelerated Interoperability: Replacing 'Trust' with Mathematics

Another direction is to leverage zero-knowledge proofs (ZK Proof) to make cross-chain verification no longer rely on a set of trusted intermediaries (verification nodes), but purely depend on mathematics.

The state changes on the source chain can generate a concise ZK proof. The target chain verifies the source chain events through mathematical proof, thereby confirming them as true within the security model. The representative solutions include the native Interop mechanism proposed by ZKsync, among others.

There are also some engineering-oriented routes that attempt to achieve a dynamic balance between “speed” and “security cost.” Taking the concept of the t1 Protocol as an example, the positioning is to find a middle ground between “pure ZK trust minimization” and “highly trusted intermediaries,” aiming for asynchrony, speed, and guarantees provided by cryptoeconomics.

It uses TEE + AVS to prove events/states on other chains, and when the risk amount exceeds the crypto-economic budget, ZK proofs are introduced on demand (saving daily costs); in terms of specific security architecture, it separates sorting and execution, allowing TEE outputs to be reproducible for fraud detection and punishment, achieving accountability in the crypto economy through deterministic outputs.

In short, this type of approach emphasizes “enhancing the experience of 80% of user needs by ten times first,” and then leveraging a proof system with cost elasticity at critical moments. From the perspective of engineering implementation, if it can be combined with the wallet's intent routing, risk control, and limit mechanisms, it would be a very pragmatic direction for implementation.

Overall, whether it is cross-chain aggregation at the application layer or atomic interoperability / ZK acceleration at the protocol layer, the common trend is to gradually diminish the sense of 'chain' and the perception of 'cross':

For ordinary users, you may not need to remember names like SCOPE or ZK Interop; what really matters is that cross-chain operations are becoming faster (in seconds), more secure (mathematical guarantees), and more seamless (completed in one go).

This is also the form that cross-chain finality should achieve: allowing users to focus on the flow of value itself, rather than the barriers between chains.