Proposal: Feynman Upgrade

General
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Proposal Title: Feynman Upgrade on Scroll Mainnet.

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.

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.

17 Likes
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Thanks @thegaram33 and @roylou for this protocol upgrade proposal. We appreciate the detailed overview of the Feynman Upgrade.

We have two quick questions:

  1. What is the expected net effect on user transaction costs from the new fee model? Are we anticipating average fees to generally go up or down?
  2. After L1 submission costs are paid, where does the remainder of the fee revenue go? Is any of it allocated to the Scroll DAO treasury?
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The fee model changes should not changes fees for most users, fees are expected to remain more-or-less the same. Very large, poorly compressible transactions will pay more.

In parallel we are working on other changes to further reduce fees: continously adjusting fee parameters, improving the gas price oracle, etc. But those changes do not require a protocol upgrade.

All fees are automatically sent to an L2 system contract, and then bridged back to Ethereum to cover operational expenses.

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While this is strictly speaking not part of the Feynman upgrade, I’d like to add that we are working on some access control changes to comply with L2BEAT’s updated standards and maintain Scroll’s stage-1 status.

The changes are:

  • We will introduce a new PauseController contract. This contract will authorize the Scroll multisig to pause contracts in case of a vulnerability. However, a cooldown period between consecutive pauses will apply, and a minority subgroup of the Security Council can unpause at any time.

  • We will transfer the authority to update some system parameters from the Scroll multisig to the Security Council multisig.

These changes will be reviewed and applied by the Scroll Security Council shortly before the Feynman upgrade. To learn about Scroll’s current access control setup, visit L2BEAT’s overview page.

9 Likes
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Thanks for the proposal and presentation in the community council, excited to see the next update!
Is there some more info on the conducted audit(s), and is this being reviewed by the security council as well?

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It’s good to know that robust fee model is being implemented while keeping costs stable for most users. Great proposal!

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The following reflects the views of L2BEAT’s governance team, composed of @kaereste, @Sinkas, and @Manugotsuka, and it’s based on their combined research, fact-checking, and ideation.

Given this proposal is a technical upgrade, we asked LB2EAT’s research team to help us review it. With their help, we also put together a simple breakdown of the proposed changes for delegates’ convenience in assessing the proposal.

In short, Feynman Upgrade does the following:

  1. It tweaks the transaction fee pricing

Fees for L2 transactions will be dynamically priced based on congestion, utilizing EIP-1559’s mechanism, and also based on the compression ratio. Since Scroll’s batcher pays L1 fees to posts compressed transaction data to Ethereum blobs, transactions that are less efficient to compress (usually larger transactions) will be made more expensive to match the batcher’s expense better

  1. Match Ethereum more closely

Adds support for recent EIPs (e.g., EIP-2935) and enhances EVM compatibility. This change will have a greater impact on developers than on users, but it’s still important to note.

  1. Introduce smart contract changes

After reviewing the changes, it’s worth pointing out that the most important one for us (L2BEAT) is the introduction of the PauseController. While it’s not separately mentioned in the proposal itself, as @thegaram33 pointed out, this will allow Scroll to satisfy our Stage 1 principle requirement — given that Scroll sets this contract as authorized pauser for core contracts and allows unpausing after a cooldown period.

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Thanks for the detailed list of features!

It seems reasonable to support this upgrade, given its features and the extensive work done to mitigate the associated risks.

Could you provide us with an update on how the Sepolia testnet went?

Thanks in advance!

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I edited the post to include the audit reports in Appendix C.

Please see above. The Security Council will review the access control changes, and will also review that the on-chain contract upgrades are consistent with this proposal.

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The Feynman upgrade has been successfully executed on the Scroll Sepolia testnet.

During the testnet upgrade, we identified two issues:

  • The Reth block executor component erroneously applied the Feynman special state transition multiple times.

  • The rollup-relayer component erroneously reset the message queue hash for the first Feynman chunk.

During previous end-to-end testing, these issues went undetected due to limitations of our current shadowfork testing methodology. The incident halted proving and finalization, but it had no impact on users apart from an increase in withdrawal latency.

The issues have been fixed, and the release candidate version has been updated. Since then, we have been running further tests on Scroll Sepolia, which now operates and finalizes normally.

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First of all, thanks to @thegaram33 for dropping this proposal and the presentation in the gov call as well as keeping everyone updated on the testnet results. We support the Feynman proposal since it’s another step forward to keep improving Scroll and clearing out some technical debt.

For context, EIP-1559 has been implemented in several chains, following its implementation on Ethereum, with great results. So, we are happy to see it implemented in Scroll to relate fee pricing with network usage and transaction compression ratios.

When it comes to EVM compatibility, getting the blockhash opcode to return actual block hashes instead of pseudo-random ones is one of those debts mentioned above. The same goes with making the ecPairing precompile fully compatible with Ethereum’s version. By implementing EIP-2935 and EIP-7623 from Ethereum’s Pectra upgrade, keeps Scroll close in the race to be the most EVM-compatible ZK-rollup. When discussing the features that make Scroll unique and we should use to differentiate it from other chains, being the most EVM-compatible chain was definitely one of them, and it’s nice to see the dev team in line with delegates’ ideas.

Lastly, when it comes to the smart contract changes, besides removing some limitations and old codec versions, having more predictable contract behaviour is of course welcome.

PD: Nice to see that the dev team is also addressing the implementation of a required requisite that not only serves to keep the Stage 1 badge within the L2Beat framework, but also to increase users’ trust in the protocol.

As verified delegates we believe this proposal is ready for a vote.

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The Foundation team endorses this proposal

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I fully support and endorse the Feynman upgrade: EIP-1559 fee tuning, real blockhash, full ecPairing parity, and leaner contracts push Scroll closer to Ethereum while clearing tech debt. No budget needed and rollout is clear; let’s ship it.

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Operational Expenses by whom please?

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The following reflects the views of L2BEAT’s governance team, composed of @kaereste, @Sinkas, and @Manugotsuka, and it’s based on their combined research, fact-checking, and ideation.

The L2BEAT Governance team endorses this proposal.

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This is a necessary and good upgrade, and I hereby endorse it.

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I also endorse this proposal to move forward to a vote, as a necessary upgrade. Thank you to @thegaram33 for bringing this proposal to the DAO.

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Congratulations on the clear and well-structured proposal. We endorse this proposal to vote.
The Feynman upgrade represents an important step in Scroll’s evolution, especially in terms of network security and performance.

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As a verified delegate, I endorse this proposal. As a builder, the closer we can get Scroll to EVM equivalent the easier it will be to attract new builders and support the existing builders.

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The funds go to the Foundation and are used to cover the costs of running the network, at this point in time.