High-level Flow Overview

• Special actors stake to become an L2 preconfirmer and provide the service of preconfirmation to users.
• A permissionless set of L1 Proposers can opt-in to additional slashing conditions and be Enforcers . Their job will be to enforce the inclusion of a preconfirmed transaction. For the sake of this flow EigenLayer-like opt-in scheme is assumed.

1. Users submit preconfirmation requests (PR) - containing PR tip - to one or multiple Preconfirmers. Preconfirmers simulate and validate the user transaction and PR.
2. Preconfirmers through a p2p messaging channel broadcast preconfirmation enforcement requests (PER) containing enforcement bids they are willing to spend. Enforcers notice these PERs and the bids.
3. Enforcers commit to valid PERs - ones signed by a valid staked Preconfirmer . The commitment is known as PERCom. Sane Enforcers commit to the highest bid. Enforcers can replace commitment for a certain PER via nonce. Enforcers cannot cancel PER once committed to one.
4. Enforcers request/enforce inclusion from L1 builders through a slightly modified MEV-boost pipeline. L1 builders include the preconfirmed transactions.
5. As part of the newly sequenced L2 transaction list (therefore block) an Includer submits the PERCom and disburses the various fees. The preconfirmation of the earliest slot is considered valid. In other words the earliest Enforcer wins the PER tip. If the commitment is not honoured the Enforcer is slashed.
6. The fees are disbursed as:
   • The PR tip goes to the Preconfirmer staked balance.
   • The preconfirmer PER bid goes from their staked balance to the Includer . The Includer is likely the L1 builder or vertically aligned with them.
   • Note: Outside of this flow L1 Builder would be able to offer higher MEV bid to the L1 Proposer (the Enforcer) that is the actual payment to the L1 Proposer.

Outcomes

With the flow above the following was achieved:

• The user got the earliest possible preconfirmation for their L2 transactions
• The L1 Proposers were not asked to run L2 nodes
• The L1 Proposers were made safe to commit to preconfirmations by Preconfirmers
• The L1 Block builders and Searchers profited from honouring the preconfirmation.
• The L2 Preconfirmers were paid through users preconfirmation tips.
• Despite the addition of a new actor no new payment relationship is created within the GMEV-Boost. Proposers get paid via the PBS auction bid via the builders, while the builders (and the other downstream actors) continue extracting value by means outside of the PBS pipeline.