Interop Roadmap "Accelerates": Following the Fusaka upgrade, Ethereum interoperability may be poised for a crucial leap.

In previous articles in the Interop series, we discussed OIF (Intent Framework) and EIL (Interoperability Layer), which respectively solve the issues of cross-chain intent standardization (making the entire network understand what you want to do) and execution channel (making funds run in a standardized way).

However, achieving a perfect "single-chain experience" still requires a trade-off between speed and trust. After all, in the current interoperability experience, one either has to tolerate the slowness (such as Optimistic Rollup requiring a 7-day challenge period to confirm finality) or sacrifice decentralization (relying on the trust assumptions of multisignature bridges).

Breaking this "impossible triangle" requires a fundamental capability that spans the Ethereum interop roadmap's "Acceleration" and "Finalisation"—the "Proof-in-Time" capability brought by ZK technology (further reading: " Ethereum Interop Roadmap: How to Unlock the 'Last Mile' of Mass Adoption ").

In the newly activated Fusaka upgrade, the unassuming EIP-7825 has cleared the biggest engineering obstacle for this final outcome.

I. The Underrated EIP-7825 Behind the Fusaka Upgrade

On December 4th, the Ethereum Fusaka upgrade was officially activated on the mainnet. However, unlike the Dencun upgrade in the past, it was not a big deal. The market spotlight was mainly focused on Blob scaling and PeerDAS, with much discussion about the further reduction in L2 data costs.

But beyond this clamor, there is actually an inconspicuous proposal, EIP-7825, which has cleared the biggest obstacle for Ethereum to achieve L1 zkEVM and real-time proofs, and can even be said to be quietly paving the way for the end of Interop.

In this Fusaka upgrade, the focus of attention was almost entirely on capacity expansion: Blob capacity was increased by 8 times, and with PeerDAS random sampling verification, the cost narrative of the DA (data availability) track has become history.

Indeed, cheaper L2 is a good thing, but for Ethereum's long-term ZK roadmap, EIP-7825 is the real game-changer because it sets a gas cap (approximately 16.78 million gas) for a single Ethereum transaction.

As we all know, the Ethereum block gas limit has been increased to 60 million this year. But even with the ever-increasing limit, theoretically, if someone is willing to pay an extremely high gas price, they can still send a super complex "mega-transaction" that directly fills the entire block's 60 million gas capacity, thus clogging the entire block.

This was allowed before, but EIP-7825 introduced a new limit: regardless of the block size, the cost of a single transaction cannot exceed 16.78 million Gas.

So why limit the size of a single transaction? Actually, this change has no impact on ordinary users' transfers, but for ZK Prover (proof generator), it's a matter of life and death, which is also closely related to the way the ZK system generates proofs.

To give a simple example, before EIP-7825, if a block contained a "mega transaction" that consumed 60 million gas, ZK Prover had to run this extremely complex transaction sequentially. It could not be split or run in parallel. This was like a single-lane highway with a giant truck driving very slowly in front, and all the smaller cars (other transactions) behind it had to wait for it to pass.

This would undoubtedly spell the death penalty for "real-time proof"—because the time it takes to generate a proof is completely uncontrollable and could take tens of minutes or even longer.

After EIP-7825, even if the block capacity expands to 100 million Gas in the future, each transaction is forcibly limited to 16.78 million Gas. Each block is broken down into predictable, bounded, and parallelizable "small task units." This means that Ethereum's proof generation has changed from a tricky "logic puzzle" to a pure "money problem."

If we can invest enough parallel computing power, we can process these split small tasks simultaneously in a very short time, thereby generating ZK proofs for huge blocks.

As Michael, co-founder and CEO of Brevis, said, EIP-7825 is the most underestimated upgrade on the road to 100x scaling for ZK and Ethereum. It makes "real-time proof" go from "theoretically impossible" to "engineerably schedulable". As long as we can solve the computing power problem through parallel computing, even a block of 200 million gas can be expected to achieve proof in seconds. This is not only a breakthrough in ZK technology, but also the physical foundation for Ethereum Interoperability Layer (EIL) to achieve cross-chain settlement in seconds.

So this upgrade may not seem like a major event, but it is actually a huge breakthrough for the ZK roadmap and the future of Ethereum scaling in 2026.

II. L1 zkEVM: The "Trust Anchor" for Ethereum Interoperability

However, while EIP-7825 paves the physical path to real-time proofs by limiting the size of a single transaction (making it parallelizable), this is only one side of the coin. The other side is how the Ethereum mainnet itself utilizes this capability.

This involves the most hardcore narrative in the Ethereum roadmap—L1 zkEVM.

For a long time, zkEVM has been regarded as the "holy grail" for scaling Ethereum, not only because it can solve performance bottlenecks, but also because it redefines the trust mechanism of blockchain. Its core idea is to enable the Ethereum mainnet to generate and verify ZK proofs.

In other words, after each block of Ethereum is executed in the future, it can output a verifiable mathematical proof, so that other nodes (especially light nodes and L2) can confirm the correctness of the result without repeating the calculation. If the ability to generate ZK proofs is directly written into the Ethereum protocol layer (L1), the proposer will package a block and generate a ZK proof each time, and the verification node will no longer need to rerun the transaction, but only need to verify this tiny mathematical proof.

What does this mean for interoperability?

In the context of Interop, the significance of L1 zkEVM goes far beyond scaling itself. It can be considered the "trust anchor" for all L2 blockchains. After all, if Ethereum L1 can generate proofs in real time, it means that all L2 blockchains can read the final state of L1 in real time and without trust, which will bring about two qualitative changes:

• Eliminating the challenge period: The confirmation time between chains will be reduced from "7 days (OP mechanism)" to "seconds (ZK mechanism)";
• Decentralized interconnection: Cross-chain communication no longer requires trusting a multi-signature bridge from a third party, but rather trusting the mathematical truths of the Ethereum mainnet;

This is also the physical basis for the EIL (interoperability layer) that we mentioned in the previous article to truly function – without the real-time finality of L1, interoperability between L2s will never escape the shadow of "latency".

With the target (L1 zkEVM) and the physical limitations removed (EIP-7825), what about the specific implementation tools?

This leads to the subtle evolution that is taking place in the ZK technology stack: from zkEVM to zkVM.

III. Fusaka & EIP-7825: The Interoperability Roadmap is finally being liberated

If EIP-7825 provides ZK with a "parallelizable hardware environment" by limiting the size of a single transaction, then the evolution of the ZK technology stack is in search of a "more efficient software architecture." Although this sounds like a tongue twister, the difference is significant and represents two stages in ZK's development (further reading: " ZK Roadmap 'Dawn': Is the Roadmap to Ethereum's End Accelerating? ").

The first stage is naturally zkEVM, which can be regarded as the compatibility school or the improvement school.

The logic is to strive to mimic every instruction of the Ethereum EVM, so that developers can deploy Solidity code directly as much as possible, reducing the cost and barriers to migration.

In other words, zkEVM's biggest advantage is its compatibility with existing Ethereum applications, which greatly reduces the workload for Ethereum ecosystem developers. They can reuse most of the existing infrastructure and tools (including execution clients, block explorers, debugging tools, etc.).

However, precisely because of this, since EVM was not designed with ZK compatibility in mind, the proof efficiency of zkEVM often has a ceiling in order to ensure compatibility, the proof time is much slower, and it carries a heavy historical burden.

zkVM, on the other hand, belongs to the radical revolutionaries. It directly builds a virtual machine that is extremely friendly to ZK proofs (such as one based on RISC-V or WASM) to speed up proof time and achieve better execution speed and performance.

However, it also loses compatibility with many EVM features and the ability to use existing tools (such as low-level debuggers). But a clear trend is that more and more L2 projects are starting to shed their burdens, optimize for speed and cost, and explore zkVM-based architectures.

So why is the Fusaka upgrade considered an unlocker?

Before EIP-7825, both zkEVM and zkVM would experience a surge in proof generation time when faced with massive transactions on Ethereum because the task could not be split.

Now, EIP-7825 mandates that transactions be broken down into predictable small units. With a parallelizable environment, the efficient architecture of zkVM can unleash its full potential. Even complex Ethereum blocks can be put into zkVM and, with the help of parallel computing power, can achieve real-time proofs.

What does this mean for interoperability? The widespread adoption of zkVM, coupled with EIP-7825, means that the cost of generating proofs will drop significantly. When the cost of generating a cross-chain proof becomes negligible and the speed is as fast as sending an email, traditional "cross-chain bridges" will disappear completely, replaced by underlying general-purpose messaging protocols.

In conclusion

As mentioned repeatedly in previous Interop articles, Interop's ultimate goal is not just asset "cross-chain" communication, nor is it limited to the concept of "asset bridge." Rather, it is a collective term for a whole set of system-level capabilities, including cross-chain data communication, cross-chain logic execution, cross-chain user experience, cross-chain security, and consensus.

From this perspective, Interop can be understood as the universal language between future Ethereum ecosystem protocols. Its significance lies not only in the transmission of value, but also in the sharing of logic. ZK plays the role of ensuring the correctness of execution, supporting real-time state verification, and making cross-domain calls "dare to do and can do". It can even be said that without real-time ZK, it would be difficult to have a truly usable Interop UX.

So when EIP-7825 was quietly activated in the Fusaka upgrade, and when L1 zkEVM gradually became a reality, we are getting closer and closer to that final state: execution, settlement, and proof are completely abstracted in the background, and users are unaware of the existence of the chain throughout the entire process.

This is also the Interop finale that we all look forward to in the future.