[barnabemonnot]

Description

Implements the execution-layer side of EIP-8198: Quick Slots (12s → 10s slots) in the Bogota fork. The EL never consumes the slot duration; its diff is two fork-activated parameter changes:

• Base fee: the maximum per-block change becomes BASE_FEE_MAX_CHANGE_NUMERATOR / BASE_FEE_MAX_CHANGE_DENOMINATOR = 5/48, multiplying before dividing (target_fee_gas_delta * 5 // 48). This matches the per-second reaction rate of 1/8 at 12s to first order; at the extremes the base fee rises ~1.0% faster and falls ~1.1% slower per second.
• Blob schedule (provisional): target 12, maximum 18, BLOB_BASE_FEE_UPDATE_FRACTION 12018519. These keep the fastest rise and fall of the blob base fee per second and the 1.5 max/target ratio; blob throughput per second is +2.9% at both target and maximum. Final values are pending a joint decision with the CL (the CL BLOB_SCHEDULE needs a matching entry).
• Gas limit: unchanged. The ordinary ±1/1024 rule applies across the fork; tests guard this.

Test framework:

• Adds base_fee_max_change_numerator() (1 from London) and uses it in the EIP-1559 calculators, plus an EIP8198 mixin for Bogota.
• Fixes the state-test → blockchain-test conversion, which backed out the genesis base fee assuming a 1/8 max change (* 8 // 7); it now uses the genesis fork's fraction. Output is unchanged for 1/8 forks.

Tests in tests/bogota/eip8198_quick_slots/ cover base fee updates at max, target and small values (including the 1-wei increase floor), the base fee rule and gas limit rule on each side of the fork, and blob limits, excess blob gas and blob base fee before, at and after the fork. The ref-spec pin is the blob of the EIP text with the proposed EL values filled in (to be proposed on ethereum/EIPs#12217).

Depends on #3665 (Bogota fork module). Until it lands and this is rebased, the diff includes that module; please review only the last four commits.

Related Issues or PRs

Depends on #3665. EIP: ethereum/EIPs#12217. CL: ethereum/consensus-specs#5592. Tracker: #3664.

Checklist

• Ran fast static checks to avoid CI fails, see Code Standards & Verifying Changes: just static
• PR title has the form <type>(<area>): <title>, where <type> and <area> come from an appropriate C-<type>, respectively A-<area>, label. The title should match the target squash commit message.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.93%. Comparing base (53ec7a8) to head (de5b55c).

Additional details and impacted files

@@                   Coverage Diff                    @@
##           eips/bogota/eip-8198    #3703      +/-   ##
========================================================
+ Coverage                 94.91%   94.93%   +0.02%     
========================================================
  Files                       672      672              
  Lines                     40846    40849       +3     
  Branches                   3775     3775              
========================================================
+ Hits                      38767    38779      +12     
+ Misses                     1445     1440       -5     
+ Partials                    634      630       -4     

Flag	Coverage Δ
unittests	94.93% <100.00%> (+0.02%)	⬆️

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[spencer-tb]

Added some commits, rebased on forks/bogota, and changed the base branch to eips/bogota/eip-8198 == forks/bogota :)

Happy to merge to eips/bogota/eip-8198 when you see fit.. once the EIPs repo PR is merged. If this gets included in focil-devnet-1 we can later PR to devnets/focil/1 and get a wider review from the team!

[barnabemonnot]

Thank you for the review and edits @spencer-tb ! I'm happy to merge anytime, not sure if we should block on the EIP PR itself getting merged.