Maintanance Upgrade Proposal 18a: Arena-Z Chain Servicer Migration

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Proposal Title: Arena-Z Chain Servicer Migration

Proposal Type: Maintenance Upgrade

Voting Cycle Type: Off-cycle

Executive Summary

This Maintenance Upgrade Proposal requests the Optimism Security Council to execute two administrative changes on behalf of Arena-Z (the Chain Governor, as defined by the Law of Chains), in accordance with the Technical Configurability provisions. These changes apply to both Arena-Z Mainnet (Chain ID: 7897) and Arena-Z Testnet (Chain ID: 9899):

  • Proposer Migration — Update the proposer address in the DisputeGameFactory to a new Chain Servicer-operated address.
  • Fee Vault Recipient Update — Predeploy batched fee vault implementations to update the fee recipient to new Arena-Z-operated addresses.

Impacted Stakeholders: Arena-Z, Node Operators

Expected Outcomes: These changes are purely administrative and do not alter the protocol’s behavior for end users, infrastructure providers, or other chains. Arena-Z, as the Chain Governor under the Law of Chains, is exercising its right to migrate Chain Servicers.

Motivation

Arena-Z’s ProxyAdmin owner roles are managed by the Optimism Security Council. As such, the Security Council can only act by direction of Optimism Governance. The Law of Chains ensures that Arena-Z, as the Chain Governor, can migrate its Chain Servicers under Technical Configurability:

“Chain Governors may make basic technical configurations permitted to them by the OP Stack. This should include the ability for the Chain Governor to change the Sequencer on its OP Chain between those which have been approved by Optimism Governance, and to appoint a new Chain Governor to take its place in the event it elects to make such a transition.”

Arena-Z wishes to migrate its Chain Servicer operations, requiring updates to the proposer role, fee vault recipients, and withdrawal network configuration. Since these operations require the ProxyAdminOwner (Security Council) to execute, this proposal is submitted for governance approval.

No conflicts of interest are anticipated. This is a routine administrative migration of operational roles.

Specifications

Blockspace Charter

  • Arena-Z Mainnet
  • No changes to the Blockspace Charter are proposed; this is an administrative address migration.

Technical Details

Action 1: Proposer Migration in DisputeGameFactory

Function: setImplementation(uint32 _gameType, IDisputeGame _impl, bytes _args)

The proposer and challenger addresses are encoded as CWIA (Clone-With-Immutable-Args) data in the gameArgs of the DisputeGameFactory. The implementation contract does not change — the existing PermissionedDisputeGame implementation is reused. Only the _args parameter is updated with the new proposer address.

Mainnet (Ethereum L1)

DisputeGameFactory at 0x658656A14AFdf9c507096aC406564497d13EC754

Parameter Current New
Proposer 0x5f16E66D8736B689a430564a31c8d887ca357CD8 0xDA89371d5C940233B200f9a235bF0Ea8AB9fAe96

Other immutables (unchanged):

  • Game Type: 1 (PermissionedDisputeGame)
  • Implementation: 0x58bf355C5d4EdFc723eF89d99582ECCfd143266A
  • Absolute Prestate: 0x033c000916b4a88cfffeceddd6cf0f4be3897a89195941e5a7c3f8209b4dbb6e
  • VM: 0x6463dEE3828677F6270d83d45408044fc5eDB908
  • Anchor State Registry: 0x0C9fF654bCd0769142Fe70951B0634C5AE19BA3C
  • WETH: 0x1D21c2535154d5D0337eda61df9c07f306AA17f7
  • L2 Chain ID: 7897
  • Challenger: 0x9BA6e03D8B90dE867373Db8cF1A58d2F7F006b3A (Security Council Safe, unchanged)

Execution: ProxyAdminOwner 0x5a0Aae59D09fccBdDb6C6CcEB07B7279367C3d2A (2-of-2: Security Council + Foundation) calls setImplementation with updated args.

Proof of ownership of new proposer address

Action 2: Fee Vault Recipient Update

The three L2 fee vault predeploys (same addresses on both networks):

  • L1FeeVault: 0x420000000000000000000000000000000000001A
  • SequencerFeeVault: 0x4200000000000000000000000000000000000011
  • BaseFeeVault: 0x4200000000000000000000000000000000000019

Mainnet (Arena-Z, Chain ID: 7897)

Current implementation version: v1.5.0-beta.2

Parameter Current New
Recipient (all 3 vaults) 0xBeA2Bc852a160B8547273660E22F4F08C2fa9Bbb (Gelato 4-of-9 Safe) 0x6f6B5c7bdf4A7Ba9Fd39A4869285e2ebEd1C6a49
Withdrawal Network L1 (0) L1 (0) — unchanged
Min Withdrawal Amount 2 ETH 2 ETH — unchanged

Required Steps (mainnet only, 4 Security Council transactions):

Since current implementations use immutable recipients baked into constructor bytecode (no setRecipient() function), new implementation contracts must be predeployed and proxies upgraded via the L2 ProxyAdmin (0x4200000000000000000000000000000000000018). The L1 ProxyAdminOwner (Security Council) sends L1→L2 transactions to execute. Implementation deployments are predeployed offchain prior to SC execution and are not part of the SC batch.

Note: L1FeeVault and BaseFeeVault share identical bytecode and constructor args, so a single predeployed implementation is reused for both. SequencerFeeVault requires its own implementation. The three proxy upgrades are batched into a single SC transaction.

  1. (Pre-execution) Predeploy shared FeeVault implementation (for L1FeeVault + BaseFeeVault) on Arena-Z Mainnet
  2. (Pre-execution) Predeploy SequencerFeeVault implementation on Arena-Z Mainnet
  3. Batched SC transaction: Upgrade L1FeeVault, BaseFeeVault, and SequencerFeeVault proxies → new implementations via L2 ProxyAdmin

Security Considerations

  • No protocol behavior changes: both actions are administrative role/configuration changes. The dispute game mechanics, fault proof system, and bridge security are unaffected.
  • No new code deployed for Action 1: the existing PermissionedDisputeGame implementation is reused; only CWIA args are updated.
  • Existing games unaffected: games already created continue with their original proposer/challenger. Only new games will use the updated proposer.
  • Fee vault upgrade (Action 2): deploys new implementations with updated recipient as a constructor immutable. Contract code is identical to current deployment — only the immutable recipient value changes.
  • Challenger unchanged: challenger roles remain unchanged on both networks, preserving the existing security model.

Impact Summary

  • No downtime required — changes are transparent to end users
  • No chain reorg or restart needed
  • Existing in-progress dispute games are unaffected
  • No impact on other Superchain members

Key Dates:

Milestone Target Date
Proposal posted & on-chain veto period begins 2026/03/12
Veto period ends (7 days, optimistic approval) 2026/03/19
Security Council executes transactions 2026/03/19+

Precommitment Impact Review

Precommitment Impact
Collective Fee Take No change. Fee vault mechanisms remain the same; only the recipient address changes.
Governor/Servicer Role Separation No change. Arena-Z is exercising its existing right as Chain Governor to migrate Chain Servicers. The Security Council and Foundation roles remain unchanged.
Ossified GasLimits No change. Gas limits are not modified.
Direct Fee Margin Controls No change. Fee margins and scalars are not modified.

Action Plan

  1. Arena-Z confirms all new addresses for both mainnet and testnet.
  2. Proposal is posted to the Optimism Governance Forum for a 1-week veto period (target: 2026/03/12).
  3. Prior to SC execution, OP Labs predeploys the two fee vault implementation contracts on Arena-Z Mainnet.
  4. Upon approval, the Security Council prepares and simulates the following 2 transactions on Ethereum Mainnet:
  • Tx 1: DisputeGameFactory.setImplementation(1, 0x58bf..., newArgs) on Ethereum — updates proposer
  • Tx 2: Batched upgrade — L1FeeVault, BaseFeeVault, and SequencerFeeVault proxies upgraded to predeployed implementations via L2 ProxyAdmin
  1. Security Council verifies all addresses match expected values and executes.

Contingency: If last-minute bugs or issues are found during simulation, execution will be delayed until the issue is resolved. No on-chain changes take effect until all transactions are verified.

Conclusion

This proposal enables Arena-Z to exercise its Technical Configurability rights as Chain Governor under the Law of Chains by migrating its Chain Servicer operations. The changes are limited to administrative address updates — updating the proposer role in the DisputeGameFactory and updating fee vault recipient addresses on both mainnet and testnet — and do not alter the protocol’s security model or behavior.

The Security Council is requested to verify and execute these 2 transactions upon governance approval following the 7-day veto period ending 2026/03/19.

By submitting a proposal, you represent and warrant to the Optimism Collective that all the information it contains is true and complete to the best of your knowledge.

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