Milestone Design

[frisitano]

Overview

This issue will define the milestones that will be leveraged to implement the rollup node. The intention of these milestones will be to provide a functional solution that provides incremental value as quickly as possible.

Milestone 1 - L2 P2P Sync

In milestone 1 we will build a rollup node that will exclusively use the L2 p2p network to sync to the chain tip. A potential design for this milestone is that when the rollup node is launched it will leverage an initial trust anchor to fetch the latest (safe?) L2 block. This will be used to invoke a fork-choice update (FCU) using the engine API on the execution node. When the execution client has synced to the latest safe block the rollup node will then use the blocks gossiped over the L2 p2p network to follow the chain tip.

There are several trust assumptions associated with this milestone:

1. The trust anchor used to fetch the latest safe L2 head is honest.
2. There is no equivocation on blocks gossiped over the L2 p2p network.

Tasks:

• Design Watcher Component #4
• Design Scroll wire protocol #1
• Design and Implement CI #3
• Implement Milestone 1 Gossip Source #7
• Design and Implement Engine Driver #5
• Network Discovery Exploration #10

Milestone 2 - Unsafe Block Consolidation

In milestone 2 we will implement logic that allows us to consolidate the unsafe chain that has been built using blocks gossiped over the L2 p2p network with data derived from L1. This will be achieved by deriving the latest payload attributes from data posted on L1 and asserting consistency with the chain derived on L2.

Tasks:

• Implement Block Consolidation #8

Milestone 3 - Provable Derivation Pipeline

The provable derivation pipeline is used to incrementally read batches posted on L1, extract the payload attributes associated with the blocks, and execute blocks to construct the chain tip. This process should be compatible with a no_std environment such that it can be used to generate a proof attesting to the chain.

Tasks:

• Design Provable Derivation Pipeline #2

[frisitano]

The initial sync of the chain can source the block hash from the singed block gossiped over P2P.