Feynman Upgrade on Scroll Mainnet

Relevant forum post can be found here.

Proposal Type: Governance.

Authors: Péter Garamvölgyi (@thegaram33) and Roy Lou (@roylou).

Summary

The purpose of this proposal is to inform the Scroll DAO of a proposed protocol upgrade, and to allow projects, users, and developers to prepare in advance. There will be a call on 16th August to discuss this, which you can find in the governance calendar.

As this is a core protocol upgrade governance proposal, there is no associated funding request.

Executive Summary

I am Peter, a Protocol Engineer at Up Labs. We work with the Scroll Foundation to implement upgrades to the Scroll protocol.

We propose the Feynman upgrade to be considered for inclusion and execution during the August 2025 governance cycle. This is the latest upgrade since Euclid.

Feynman contains the following changes:

• More robust fee model.
• Improved EVM compatibility.
• Simplified smart contracts.

These changes will improve protocol security and developer experience.

Motivation

The motivation for this protocol upgrade is the continued evolution of Scroll’s technology. The proposed changes will make Scroll more robust and easier to understand, remove technical debt, and further increase compatibility with Ethereum.

Execution

Operational

The upgrade will be developed and rolled out via the same process that we used for Euclid: Development done by Up Labs, review and approval by the Scroll DAO, execution by the Scroll Security Council. As before, all code is open-sourced on GitHub.

Personnel & Resources

The changes are being developed and tested by Up Labs. Audits are conducted by external parties and internal engineering teams. The upgrade will be executed by engineers from Up Labs, with the review and approval from the Scroll Security Council.

Financial

This proposal does not require funding.

Upgrade Timeline

If the proposal passes, the upgrade will be rolled out with the following timeline:

1. July 29th July 22th (Tue): Upgrade Scroll Sepolia.
2. August 1st (Fri): Submit upgrade to governance proposal.
3. August 4th (Mon): Governance voting begins.
4. August 11th (Mon): Governance voting ends.
5. August 12th (Tue): Security council signs the upgrade transaction according to the voting result.
6. August 19th (Tue) at 08:00:00 UTC: Feynman transition occurs.

The above network upgrade times are tentative; node operators should keep an eye on the node release page.

Evaluation

Execution of this proposal will be concluded by upgrading Scroll’s core smart contracts, followed by a hard fork upgrade in the L2 network. At that point, Feynman will be live on Scroll mainnet, and the features described in Appendix A will be activated on Scroll.

Conclusion

In this proposal, we presented the Feynman protocol upgrade. This upgrade will improve the fee model, improve EVM compatibility, and simplify Scroll’s smart contracts. The result is improved protocol security and developer experience.

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Appendix A: Detailed List of Features

The Feynman network upgrade activates the following features.

More Robust Fee Model

Scroll uses a two-dimensional fee model: Users are charged execution gas (similar to Ethereum), and an additional rollup fee (aka L1 data fee). The rollup fee aims to cover rollup-specific costs: the costs incurred by Scroll for posting compressed data on Ethereum (Data Availability), as well as proving and finalizing transactions.

In Feynman, we update both fee dimensions:

• Execution gas (L2 base fee): Adopt EIP-1559 congestion pricing to dynamically increase the base fee during periods of congestion.
• Rollup fee: Consider the transaction’s compressibility and make commit cost proportional to transaction size. Large transactions with bad compression ratio will pay more, but most transactions will not be affected.

These two changes will make Scroll more resilient against certain adversarial scenarios.

Improved EVM Compatibility

In Feynman, we address some of the technical debt stemming from our old halo2-based proving system, and add some recent EIPs from Ethereum’s Pectra upgrade.

• The blockhash opcode will now return the actual block hash, instead of a pseudo-random hash derived from the chain ID and block number.
• The ecPairing precompile will now be fully compatible with Ethereum’s version, we remove the previous input limits.
• Adopt EIP-2935: Serve historical block hashes from state from Pectra. This system contract will allow smart contract devs to access to most recent 8191 block hashes. This EIP also plays a key role in restoring the blockhash opcode’s original behavior.
• Adopt EIP-7623: Increase calldata cost from Pectra.

Please note that EIP-7702 from Pectra has been supported since the Euclid upgrade.

Simplified Smart Contracts

Migrating from halo2 to OpenVM allowed us to remove some previous limitations of the protocol, including transaction skipping. In Feynman, we remove skipping, as well as old codec versions from our deployed smart contracts.

Appendix B: Impact on Stakeholders

Impact on Node Operators

As usual, l2geth node operators will need to upgrade their nodes to follow the Feynman upgrade on Scroll Sepolia and Scroll mainnet. Please keep an eye on the node releases, and contact the Scroll team if you have any questions.

Impact on Dapps and Indexers

While Feynman introduces several contract changes, most of them are internal. Projects that decode batches can continue using the current EuclidV2 codec, however the batch version will become v8.

Maintainers of smart contracts that rely on the blockhash opcode must carefully consider the impact of the change in this opcode’s behavior on their dapp.

Finally, any projects that do off-chain fee computation (instead of relying on RPC queries) should review the new fee formula [1] [2] and update their system accordingly.

Appendix C: Audit Reports

This section was added on 2025-07-23.

The smart contract diff audit was conducted by Trail of Bits, see the report here.

The circuit guest program audit was conducted by security and zk engineers from Scroll, see the report here.