FOCIL Breakout #33, April 21, 2026

Protocol Calls & happenings
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Agenda

  • Development updates
  • Spec updates
  • Testing updates
  • and more

Meeting Time: Tuesday, April 21, 2026 at 14:00 UTC (60 minutes)

GitHub Issue

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Meeting Summary:

The FOCIL Breakout 33 meeting focused on specification updates and development progress, with Jihoon presenting PR updates to the CL spec that included deadline changes and Felix’s framework modifications for EL testing. The team discussed integration testing challenges between clients, particularly regarding which fork and AIPs to base the code on, with Fabio from Basel reporting readiness to integrate once specifications are determined. The group acknowledged that while GLAMsterdam DevNet is in progress, a full FOCIL DevNet setup during the interop period is unlikely due to resource constraints, though they agreed to discuss integration details further if client teams are present at the interop. The team decided to hold the next breakout meeting in two weeks, with the possibility of skipping it if no significant updates arise from the interop progress.

Click to expand detailed summary

Jihoon led the FOCIL Breakout meeting and provided updates on specification changes, including a PR to the CL spec that simplifies the protocol and a PR by Felix from Steel that introduces framework changes and test cases for the EL. The team discussed these updates and shared links to the relevant GitHub pull requests for review. No specific decisions or action items were mentioned, and the meeting appeared to be in the early stages with more updates expected on integration testing on clients.

Justin Traglia asked about the BPS suffix meaning, which was explained as basis points (1 out of 10,000). The team discussed reviewing a PR, with Thomas being unavailable due to vacation, and Nico offering to review it after the call. Jihoon mentioned this PR would be the final change to the SE spec before moving forward with development.

Fabio reported that he is working on unit tests and integration with CL, but is facing challenges with determining the correct fork to base the code on. Jihoon explained that previously, multi-client local dev nets were managed by sharing Kurtosis config, but now the client team should own their implementation. Jihoon indicated that there are currently no plans for DevNet due to resource constraints and focus on Glamsterdam, though local dev nets could potentially be run at the end of interop if CL is ready.

The team discussed the implementation of Glamsterdam DevNet, with Nico indicating it should be straightforward once stable. They agreed to discuss during the interop which base image and EIPs to use for integration, with Fabio suggesting they define the artwork and AIPs to include. Jihoon proposed gathering developers at the interop to discuss resources and next steps, and mentioned preparing specs and updating the router explorer. The team also considered whether to hold the next breakout session on the 5th, but left this decision open.

The team discussed the status of net zero stabilization, noting that it remains in flux despite gas cost changes. They agreed to schedule their next breakout meeting in two weeks, with the option to skip it if there is nothing new to discuss. The group emphasized the importance of making progress on interop work in the meantime.

Next Steps:

  • Jihoon: Ask Mikhail to review the CL spec PR regarding included list deadlines
  • Nico: Review the CL spec PR after the call
  • Fabio: Start integrating execution spec tests with Basel and run Basel against them
  • Jihoon: Take a look into Engine API spec for FOCIL to check if anything has changed
  • Fabio and Jihoon: During the interop, define which base (fork and EIPs) to use for integration, including deciding on engine new payload version (V05 or V06) and which EIPs to include
  • Jihoon: Prepare spec-side items including which API versions to use and ensure Kurtosis is ready to support FOCIL
  • Jihoon: Update the router explorer as it is outdated
  • Fabio and other attendees: If attending the interop, gather with developers from different client teams to discuss integration plans and resource availability

Recording Access:

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YouTube recording available: https://youtu.be/Uj18ob_u-so

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FOCIL moves closer to its first devnet.

Spec Updates

  • Jihoon opened a CL spec PR that revises inclusion list deadlines, making the protocol simpler and easier to reason about while preserving its behavior.

  • Felix from STEEL opened and merged an EL spec PR that introduces the framework changes required for FOCIL testing and adds a set of EL test cases. Client teams can now run these tests against their implementations.

Development Updates

  • Besu has all the FOCIL code in place and is currently writing unit tests, with plans to integrate the EEST test cases next.

  • Lodestar has no new updates.

FOCIL Devnet Planning

  • Fabio proposed using the Interop to align on the fork base and the set of EIPs to include.

  • The group agreed that FOCIL devnets will be based on glamsterdam-devnet-0 specs.

Links

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