AZIP-28: Update L1 Gas Constants for Glamsterdam

[spalladino]

AZIP: AZIP-28

Aztec's fee model uses fixed estimates for the L1 gas required to propose a checkpoint and verify an epoch. Ethereum's Glamsterdam fork changes the gas schedule for these operations, so retaining the current constants would cause users to underpay relative to the costs borne by sequencers and provers after the fork.

Proposal

Update the initial estimates in v6 from:

• L1_GAS_PER_CHECKPOINT_PROPOSED: 300,000 → 500,000
• L1_GAS_PER_EPOCH_VERIFIED: 3,600,000 → 4,000,000

These values come from local benchmarks and are estimates, not final production measurements. In early October 2026, we expect to run v6 under the Amsterdam gas schedule on Sepolia. We will take representative measurements there and adjust the constants before the v6 mainnet deployment if needed.

Rationale

The proposal is to deploy the final values directly with v6. Users may pay somewhat more during the period between the v6 deployment and Glamsterdam activation, but this keeps the implementation simple and avoids a second governance action timed to the Ethereum fork.

Alternatives considered include retaining the existing values, making them governance-controlled with delayed activation, and adding a permissionless update triggered by fork-specific execution behavior. The fixed-value approach avoids the added contract and coordination complexity of those options.

Feedback is welcome on the proposed estimates, the Sepolia validation plan, and the tradeoff between temporary pre-fork overpayment and additional activation machinery.