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The Merge Mainnet Readiness Checklist

This document outlines various tasks to work through to make the Merge ready for Mainnet release.

Note: The set of items is not final and will be aligned with ongoing R&D and implementation work.

Table of contents


Meta Specs

Consensus layer

  • Specs feature complete
  • Transition process specified #2462
  • Ensure structural conformance with existing specs #2472
  • Rebase with Altair #2530
  • Rebase with London (update ExecutionPayload) #2533
  • P2P spec (primarily just version bumping topics for new types) #2531
  • Optimistic sync spec
  • Upgrade beacon-APIs to handle new types
  • [BONUS] Annotated specs link

Execution layer

  • High level design doc
  • EIPs
    • EVM BLOCKHASH [unchanged but weaker randomness documented in PoW -> PoS transition EIP] EIP-3675
    • Transition process EIP-3675
  • Network -- devp2p
    • Block gossip deprecation EIP-3675
    • State sync post-merge
    • Block sync post-merge
    • Discovery
  • Upgrade JSON-RPC (execution-apis) with new methods and deprecations #200
  • [BONUS] Executable execution-specs and testing through the Merge

Engine API

  • Basic JSON-RPC extension, link (used in rayonism)
  • Production refinements Engine API. Previous docs: WIP doc, Interop Edition
    • Support execution-layer state sync
    • Support async block insert
    • Consider support for Consensus <-> Execution consistency (e.g. recover from crash or bad insert on execution layer)
    • Consider bi-directional communication
    • ...
  • Discuss JSON-RPC vs websockets vs restful http
  • Migrate to execution-APIs or other permanent home, link
  • Remove unauthenticated port from specification #219

Public facing documents


Unit tests

  • Consensus
    • Inherit all prior unit tests and generators
    • Merge specific tests with mocked execution-layer
    • Fork and fork-choice tests across merge boundary
  • Execution

Integration tests



  • Short-lived devnets without transition process
  • Short-lived devnets with transition process
  • Long-lived devnets
  • Fork public testnets
    • Ropsten (deprecated after merge)
    • Sepolia
    • Goerli


Most research related to the merge has been completed. This section lists topics which are either tangentially related, or nice-to-haves, and still require R&D work.

  • Transition process analysis
  • Execution-layer sync
    • Historic block sync (reverse header then forward body)
    • Historic state sync (optimistic beacon block transition provides head data for EL sync)
    • Sync during transition period (forward sync to PoW TTD, reverse sync past TTD)
  • Discovery [is there actually anything to do here?]
  • [In research, not to be included merge] Execution-layer proof of custody
  • Consider weak subjectivity period implications
    • Generate accurate weak subjectivity period calculations
    • [IN PROGRESS] Specify standard data format & methods for weak subjectivity checkpoint distribution
  • Disaster recovery if invalid chain finalized
    • EL will perform re-orgs beyond finality but at a potential high sync cost
    • [WIP] Client multiplexers (link, note: doesn't help with DR, but can potentially prevent invalid chains being finalized)
  • Stress tests
    • Single client load/metrics
    • Network load testing
      • Larger blocks
      • Shorter slot times
      • Large execution state (shadow-forking mainnet)
  • Further threat analysis
    • Miner attacks
    • Resource exhaustion post-merge
  • Fee Market behavior changes (missed slots impact)