PQ Interop #26 | Feb 11, 2026

[will-corcoran]

Resources

• Zoom link: https://ethereumfoundation.zoom.us/j/4840114962?pwd=S8FArsXkTutjZDmVohZ7b0VOCaY4An.1
• Facilitator email: will@ethereum.org
• Facilitator Telegram: @corcoranwill
• Telegram: PQ Interop — threads: #general, #devnet-1, #devnet-2, #devnet-3, #tooling, #leanVM, #onboarding

High-Level Documents

• Devnet-0 : lean consensus client interop
• Devnet-1 : PQ signature signing & verification
• Devnet-2 : single-layer PQ signature aggregation ✅ LAUNCHED
• Devnet-3 : aggregator role separation + subnet aggregation

Overview

A. Devnet-2: Implementation Status (Devnet N)
B. Devnet-3: Specification Status (Devnet N+1)
C. New Client Onboarding
D. Tooling & Infrastructure
E. Schedule / Next Steps

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Meeting Minutes — Call 25 (Feb 04, 2026)

A. Devnet-2: Implementation Status

Long-running stability remains the focus. Reached ~1,000 finalized slots (new record) before losing finality again. Daily restart cycles continue.

Client Readiness

Client	Devnet-2 Status	Stability	Notes
Zeam	✅ Complete	🔶 Sync issues on restart	Improving performance and stability. Syncing issues still occurring on devnet restarts, causing network finality problems. leanPoint checkpoint sync tool working with Zeam nodes; Partha testing with other clients. Zeam confirmed able to sync via checkpoint sync, but further improvements needed. Devnet-3 aggregation PR implemented, under review — hoping to merge this week.
Ream	✅ Complete	✅ Stable	Fairly stable on long devnet runs. Excessive memory use identified (likely data not being saved to disk) — not yet causing problems, fix in progress. Syncing works well. Retired all Devnet-1 code, kept Devnet-2 feature flags, added Devnet-3 feature flags. Started implementing committee aggregation PR.
Qlean	✅ Complete	✅ Stable	Quiet week. Improving metrics and P2P identify protocol (reading peer agent versions — not yet working, may need spec PR to clarify). Getting started on Devnet-3 implementation. Kamil continuing work on committee aggregation spec.
Lantern	✅ Complete	🔶 Debugging	Investigating spec divergence: Lantern rejected a block at slot ~951 that other peers accepted. Likely a spec compliance issue. Will release updated image once root cause is found.
Lighthouse	❓ Unknown	—	No representative on call.
Grandine	🔶 In progress	🔶 Issues remain	Fixed a few issues, added metrics. Some things still not working. Limited dedicated resources — will continue next week.
Ethlambda	🔶 Catching up	🔶 Improving	Significant stability work: fixed memory issue via chain/attestation pruning post-finalization. Added P2P stability: incoming block request support, recurrent redialing for disconnected peers. Added support for Zeam's blocks-by-root container message format. Improved log messages for debugging. Working on: fetching unknown blocks referenced by gossip attestations (currently discarding as invalid), multiple response chunks in blocks-by-root requests, checkpoint sync. Starting Devnet-3 next week.
Nimbus	❓ Unknown	—	No representative on call.

Spec/Implementation Issues Raised

• Sync-on-restart causing finality loss (Zeam): After devnet restarts, Zeam nodes have issues syncing up to head, which cascades into network finality problems. Focus area for this week.
• Block rejection divergence (Lantern): Lantern rejecting blocks accepted by other peers at slot ~951. Under investigation — likely spec compliance issue.
• P2P identify protocol (Qlean): Agent version not properly readable from connected peers. May require spec clarification PR if other clients aren't updating their agent version fields correctly.

B. Devnet-3: Specification Status

Committee Aggregation PR — Priority Merge

The committee aggregation PR (Kamil) is the critical-path spec item for Devnet-3. Key changes:

• Removed latest_attestations and latest_known_attestations — replaced by aggregations for fork choice safe target updates
• Removed some tests that became less relevant (follow-up PR planned for replacements)
• PR is large but intentionally scoped to avoid further growth

Merge plan: Thomas will stop pushing other PRs to leanSpec to avoid rebase conflicts. Kamil to rebase on latest master and get tests passing (target: by Feb 5). Thomas will merge immediately once ready, then iterate with follow-up PRs.

Devnet-3 PM Document Updates

• Mihir (Lantern) flagged that the PM repo Devnet-3 doc needs updating (e.g., 5-interval model not yet reflected).
• Unnawut: Use the leanSpec Devnet-3 PR filter as the most current source — PM repo will lag by ~1 week.
• Mercy's readiness checklist (PR #68) open for review — can start filling out for Devnet-3.

Research Updates

leanMultisig / Proof Size (Emile):

• Merkle pruning optimization complete.
• Seriously considering removing LookUp[star] — currently requires two separate WHIR commitments, adding conceptual/implementation complexity and increasing proof size. Branch in progress.
• Proof size now below 256 KB. With aggressive WHIR rates, could reach ~150 KB. Theoretically below 100 KB if capacity gap / proximity conjectures are proven.

WHIR Cryptography (Thomas):

• Onur (EF grantee) making major progress on WHIR (polynomial commitment scheme inside leanVM).
• Large PR merged on WHIR repo: low-level sum check optimization with significant performance impact on leanVM.
• PRs incoming for Plonky3 integration — goal is to use Plonky3 main branch inside leanVM to benefit from open-source community contributions.

leanSpec Minimal Client (Thomas):

• Removed TCP transport — now QUIC-only using Python standard library. Significant simplification.
• Can add TCP back later if needed, but not required for current devnet scope.

leanSpec Book / PDF Companion (Thomas):

• Chapters written: consensus intro, SSZ (with LaTeX diagrams), time model (slots, clock, genesis), state transition (started), P2P layer (ENR, QUIC transport — started).
• Written for broad audience: developers, researchers, students, newcomers.
• Currently in separate repo, updated as PDF. Plan to move LaTeX source into leanSpec repo for community PRs.

leanSpec Testing (Thomas):

• Added interop test folder with multi-node mesh finalization tests (inspired by Ream's approach). 70-second test runs checking finalization.
• Found and fixed test vector performance issue: state root calculations were redundantly computed. 6x speedup in CI test vector execution time.

Devnet-4 Forward Planning Discussion

Gajinder proposed recursive aggregation for Devnet-4.

Recursive aggregation readiness (Emile):

• "Close to okay" — a few details remaining.
• Single-layer recursion functional. Multi-layer (infinite) recursion is possible but has remaining work: bytecode evaluation proving and bitfield management for mixed raw signatures + aggregated proofs.
• Main blocker is leanVM implementation, then Python bindings update, then leanSpec integration.

API-first approach agreed:

• Gajinder requested Emile spec the recursive aggregation API first, so clients and spec work can proceed in parallel with implementation.
• Emile agreed to try to define the API.

Devnet-3 interop timeline:

• Gajinder pushing for Devnet-3 interop by end of next week (Zeam, Ream, Qlean).
• Shariq (Ream): "Possible goal — let's see."
• Kamil (Qlean): Willing to try, noted it's ambitious.

Stabilization vs. new features debate (Kamil):

• Suggested that if leanVM recursion isn't ready, a devnet cycle could be used for optimization/stabilization instead (e.g., reducing block sizes by not including all proofs, network stability improvements).
• Also suggested running multiple parallel networks — stable Devnet-2 alongside new Devnet-3 — if infrastructure allows.
• Gajinder: Stabilization is part of development; Devnet-3 runs will be longer with multiple runs focused on scaling validators and aggregator subnets. Can move toward Devnet-4 in parallel.
• Consensus: Discuss further next week. Not premature but needs more clarity on leanVM timeline.

C. New Client Onboarding

Client	Status	Current Focus
Ethlambda	On Devnet-2	Stability fixes, fetching unknown blocks, multiple response chunks, checkpoint sync. Starting Devnet-3 next week.
Gean	Devnet-0 complete	Moved to Devnet-1. Integrating LeanSig (signing + verification), lean metrics, lean-quickstart. Writing Go bindings to Rust code (following Zeam/Lantern approach).
Nimbus	Starting	No representative on call.

D. Tooling & Infrastructure

Devnet-2 Long-Running Operations

• Record reached: ~1,000 finalized slots (highest yet) before finality was lost again. Clients need to investigate and update images.
• Daily restarts: Katya continuing for 4 initial clients. Teams must respond to pinned restart planning message in #tooling when images are ready.
• Action: All teams to follow #tooling channel with notifications enabled.

Core Dump Collection (New Request)

• Kamil (Qlean): Requested core dump collection when nodes crash — log analysis alone is sometimes insufficient for debugging.
• Katya: Can provide this on request. System journal extraction also possible.
• Next step: Kamil to ensure Qlean Docker images include debug symbols; Katya and Kamil to coordinate on collection setup.

Infrastructure Constraint

• Hetzner server limits: New account cannot scale servers until late February (first invoice). One aggregator per committee (one committee for now) — scaling is config-only but hardware-constrained. (Partha, via chat)

E. Schedule / Next Steps

• Devnet-3 interop target: End of next week (aspirational — Zeam, Ream, Qlean)

Action Items

Owner	Action	Deadline
Kamil	Rebase committee aggregation PR on latest master, get tests passing	Feb 5
Thomas	Merge committee aggregation PR once ready; stop other leanSpec PRs until then	Immediately after Kamil
Emile	Spec recursive aggregation API for Devnet-4 (so clients/spec work can parallelize)	TBD
Zeam	Fix sync-on-restart issues causing finality loss	This week
Zeam	Review and merge Devnet-3 aggregation PR	This week
Zeam (Partha)	Test leanPoint with non-Zeam clients	Ongoing
Ream	Fix excessive memory use (data not saved to disk)	ASAP
Ream	Continue Devnet-3 committee aggregation implementation	Ongoing
Qlean	Investigate P2P identify protocol agent version issue; open spec PR if needed	Ongoing
Qlean (Kamil)	Prepare Qlean Docker images with debug symbols for core dump collection	Ongoing
Lantern	Investigate block rejection divergence at slot ~951, release updated image	This week
Ethlambda	Implement unknown block fetching, multi-chunk blocks-by-root, checkpoint sync; start Devnet-3	Next week
Gean	Continue Devnet-1: LeanSig integration, lean metrics, lean-quickstart	Ongoing
Katya	Continue daily restarts; coordinate core dump collection with Qlean	Ongoing
Mercy	Readiness checklist PR #68 — team leads review, start filling for Devnet-3	Next call
All clients	Update PM Devnet-3 doc to reflect 5-interval model	Ongoing
All clients	Follow #tooling channel with notifications enabled; respond to restart planning	Ongoing

[ch4r10t33r]

I would like to demo the leanpoint tool in tomorrow's call.