Just over 100 Ethereum core contributors braved the extreme northern latitude this past week, gathering high above the Arctic Circle in Longyearbyen, Svalbard, for the Soldólgn Interop. The intensive week-long collaborative working session was entirely dedicated to accelerating development, ironing out implementation friction, and hardening the upcoming Glamsterdam network upgrade.
The Soldólgn event followed the structural footsteps of last year’s Berlinterop while reverting to the tightly focused, single-track format pioneered during earlier landmark development sprints like Amphora, Edelweiss, and Nyota. Rather than spreading attention across disparate network layers, the core developers maintained a laser focus on multi-client progress specifically targeted at hardening Glamsterdam. By the time Friday arrived, the assembled teams had successfully delivered on all three of their primary core goals, achieving vital alignment on a post-Glamsterdam gas limit floor of 200 million, running stable Enshrined Proposer-Builder Separation (ePBS) implementations alongside external builders, and locking in final EIP-8037 repricing figures. Alongside these headline achievements, meaningful strides were also made on longer-term Hegotá features, including FOCIL and native account abstraction, alongside a broad array of auxiliary protocol topics.
Why Svalbard?
Choosing Svalbard as the backdrop for an Ethereum interop was not merely a novelty, but a symbolic and practical nod to the ethos of decentralization and resilience. Svalbard stands as one of the very few locations on Earth where individuals of any nationality can live and work entirely without the requirement of a visa. Furthermore, the remote Arctic archipelago houses critical global preservation repositories like the Global Seed Vault and the Arctic World Archive. Tunneled deep into the permafrost just outside Longyearbyen, these cold-storage facilities safeguard irreplaceable backups of global crops, literature, historic films, manuscripts, and core software source code that humanity might require thousands of years into the future—including a cryptographic snapshot of Ethereum’s source code.
Adding to the thematic resonance, from late April through August, the sun never sets in Svalbard, bathing the region in continuous daylight. This unique geographic phenomenon provides perpetual uptime, mirroring the uninterrupted, 24/7 reliability of the Ethereum network itself—a reality that the core developers fully embraced as they worked around the clock throughout the week.
Harden Glamsterdam, Scale Ethereum
The overarching mission of the Svalbard gathering was twofold: to thoroughly harden Glamsterdam client implementations and to derive a robust, mathematically sound target for a post-upgrade gas limit floor. Safely raising the network gas limit is a deeply multi-dimensional challenge. Glamsterdam directly addresses several of these interconnected constraints at once, examining how blocks are built and proposed, how much operational headroom client software maintains under heavy computational loads, and how the economic costs of state-creation scale alongside overall network throughput.
In practical terms, this meant concluding the week with a stable, multi-client Glamsterdam devnet successfully running the latest iterations of ePBS, along with repriced execution parameters, block access list specifications, and exhaustive benchmarking data required to anchor a credible gas limit proposal.
The vast majority of the week was spent heads-down writing production-grade code, frequently stretching into the early hours of the morning. These marathon coding sessions were punctuated by focused breakout gatherings designed to align the various client teams on complex architectural design decisions and discuss broader, long-term roadmap items. Three separate Ethereum Foundation teams provided the essential infrastructure that kept the event running smoothly. EthPandaOps shipped ethIQ alongside a dedicated panda Model Context Protocol (MCP) server to support the teams’ agentic workflows. Protocol Support established soldogn.xyz as the single source of truth for all interop goals, daily schedules, and technical notes. Meanwhile, the Ethereum Foundation Digital Studio team documented the entire gathering on film, setting the stage for what is expected to be the very first comprehensive interop documentary.
ePBS
Enshrined Proposer-Builder Separation goes far beyond simply cleaning up the relationship between block proposers and external builders. The architecture fundamentally restructures individual slots by introducing strict, formalized deadlines for block construction, payload reveals, and validator attestations. By making explicit allowances for how much time can be explicitly allocated for raw execution, ePBS significantly expands the operational headroom available to safely raise the network gas limit.
Client development teams kicked off the week with an ambitious goal: launching a 4 execution-layer by 4 consensus-layer Glamsterdam devnet by Monday evening. The inevitable early testing attempts surfaced enough cross-client edge cases and bugs to push that target to Tuesday, when a 4-by-3 configuration finally ran stably enough for formal stress testing to commence.
From that milestone onward, the remainder of the week transformed into an intensive ePBS hardening cycle characterized by continuous stress testing, the discovery of obscure edge cases, rapid bug fixing, and repeating the cycle. A Tuesday-morning Builder API breakout session substantially simplified the technical specification around validator registration, the bid-header-commitments flow, the trust model governing builder payments, and expected circuit-breaker behaviors.
Mid-week debugging zeroed in on complex cross-client edge cases, most notably surrounding execution-request invalidation of beacon requests, where a freshly minted test suite revealed a persistent gap across every single client implementation. By Thursday morning, consensus-layer teams were reporting stable ePBS performance, while execution-layer bid pathways continued to undergo rigorous debugging before being fully resolved toward the end of the week. Two nuanced questions remain genuinely contentious within AllCoreDevs discussions: whether an execution request signature should strictly commit to the receiving builder, and how to maintain resilience within a 1-ETH-staked-builder design against peer-to-peer, Sybil-based liveness attacks. By Friday, nearly all client implementations were successfully running together on glamsterdam-devnet-2, with the external builders pipeline tested thoroughly from end to end.
BAL Optimizations
If ePBS represents the consensus-layer side of the Glamsterdam scaling narrative, the execution-layer counterpart relies heavily on two dominant pillars: gas repricings and Block-Level Access Lists. By providing client software with precise, upfront information regarding a block’s read and write sets, Block-Level Access Lists enable advanced techniques such as parallel execution, batched input-output operations, and parallel state-root computations. Together, these optimizations dictate how large a block client nodes can comfortably handle without degrading network health.
The Soldólgn Block-Level Access List track operated on its own dedicated devnets, completely separated from the Glamsterdam ePBS chains, ensuring that performance optimization benchmarks did not become entangled with consensus-layer stabilization efforts. Each optimization was engineered to sit behind its own feature flag, allowing the week’s measurement workflows to compare performance metrics in complete isolation rather than evaluating them as an entangled bundle.
The Block-Level Access List benchmark dashboard and public leaderboard successfully surfaced each client software’s worst-case performance scenarios across the comprehensive test suite. By focusing their efforts on lifting the slowest execution paths first, the development teams were able to elevate the gas limit floor universally across the board, ensuring improvements benefited every implementation rather than just the fastest ones.
Gas Repricings
The Glamsterdam upgrade incorporates a series of execution-layer gas repricings designed to recalibrate operational costs so they more accurately reflect actual resource consumption at substantially higher throughput levels. EIP-8037, which implements a state-creation gas cost increase, sits directly at the heart of this effort. It raises the economic price of writing brand-new state data into the system, ensuring that a higher block gas limit does not inadvertently translate into unbounded, runaway state growth.
Heading into the Svalbard gathering, the EIP-8037 specification carried dynamic per-state-byte pricing tied directly to the block gas limit. This dynamic approach made combinatorial testing exceptionally painful—requiring separate fuzz matrices for every individual gas limit band—and made benchmarking nearly intractable. Early in the week, development teams reached a consensus to drop dynamic pricing entirely in favor of a fixed cost-per-state-byte model, leaving future repricing adjustments to be handled cleanly at fork boundaries rather than mid-fork.
The underlying accounting model itself followed a more iterative developmental path. A Monday breakout session successfully moved state-gas accounting from mid-execution to the end of individual call frames. A Tuesday follow-up session closed out lingering questions regarding account creation costs, code deposit fees, and CREATE-transaction reverts. However, Wednesday testing surfaced unexpected reservoir refund and refill edge cases that forced developers to completely rethink the mechanism.
A Thursday breakout ultimately reverted the accounting logic back to the opcode level, after concluding that the true structural complexity resided within the reservoir model rather than the core accounting calculations. By Friday, the specification had stabilized on bal-devnet-6, with the Block-Level Access List track successfully delivering its final repricing figures.
This entire iterative arc highlights one of the most valuable aspects of in-person interop gatherings: the exceptional ability to resolve complex specification, implementation, testing, debugging, and design hurdles in a matter of hours rather than weeks. At their absolute best, interop weeks compress a full month of asynchronous progress into a single working day. By Friday, all three major development threads converged on the defining headline metric of the week: a credible 200 million post-Glamsterdam gas limit floor. This significant capability increase is made possible because ePBS structures slots to grant execution environments more breathing room, Block-Level Access List optimizations provide clients with necessary throughput headroom under that structural framework, and EIP-8037 guarantees that the elevated gas limit will not trigger runaway state bloat.
Other Glamsterdam Threads
Beyond ePBS, Block-Level Access Lists, and gas repricings, the majority of the remaining Glamsterdam upgrade scope was rigorously debated and finalized across numerous focused breakout sessions. Consensus-layer teams finalized decisions regarding several smaller Glamsterdam Ethereum Improvement Proposals. EIP-8061, which increases the exit and consolidation churn limit, was successfully included in glamsterdam-devnet-1. Conversely, EIP-8080, which proposed handling exits via the consolidation queue, was formally declined for inclusion. EIP-8045, targeting the removal of slashed-validator duties, was significantly scoped down to apply exclusively to proposer duties within the defined look-ahead window. Meanwhile, EIP-7688, which introduces SSZ stable containers, remains within the official Glamsterdam scope but is temporarily held out of glamsterdam-devnet-1 while development teams work through bounded gossip-message sizing requirements for attestations under progressive lists.
During a Wednesday-morning execution-layer and consensus-layer sync architecture breakout, developers decided to defer EIP-8237 out of the Glamsterdam upgrade to preserve strategic optionality for a more comprehensive, long-term top-up sync architecture in a future network fork. In its place, the assembled experts agreed to draft a new Ethereum Improvement Proposal that standardizes forkchoiceUpdated, newPayload, and getPayload sequencing, specifies a clean snap-sync initiation handshake, and tightens valid-and-invalid consistency across engine API surfaces.
System hardening remained a consistent, overriding theme throughout the entire week. A dedicated Thursday session explored fork-choice compliance testing frameworks, examined the Diamond repository containing reproducible consensus-layer edge-case scenarios, and reviewed buildoor, EthPandaOps’s specialized external-builder testing tool, which was demonstrated live while attendees fired off an endless stream of real-time attack scenarios.
Beyond Glamsterdam
Looking past the immediate horizon of the Glamsterdam upgrade, several breakout groups turned their attention toward Hegotá and the subsequent network upgrades that will follow.
A deliberately proposal-agnostic session focused on native Account Abstraction kicked off discussions by systematically working through the core requirements and constraints that any future design must satisfy. Broader feature-set goals—such as alternative signature schemes, signature aggregation, transaction batching, account recovery, gas sponsorship, flexible nonces, and keystore-based wallets—were weighed alongside strict system constraints, including public-mempool compatibility, statelessness preservation, and resilience against Layer 2 denial-of-service attacks.
A Thursday FOCIL breakout concentrated heavily on recent implementation updates. Early prototypes were already reported as fully functional, with multi-client interoperability testing and a dedicated FOCIL devnet established as the immediate next steps. Two notable design choices were finalized during the session: disabling FOCIL during two-epoch periods of non-finality, mirroring existing proposer-boost circuit-breaker behaviors, and adopting an index-based bookmark approach to ensure complete compatibility with frame transactions and EIP-7702.
Looking even further down the road, a long-running peer-to-peer networking track sketched out a QUIC-based replacement for libp2p featuring privacy-by-default capabilities and slot-aware integration. They also reviewed an erasure-coded broadcast prototype that successfully simulated roughly six times faster data propagation compared to GossipSub when handling large 2.4-megabyte payloads. The consensus-layer track also revealed strong collective sentiment favoring the eventual, complete deprecation of validator consolidations—proposing a final network fork that supports them before forcing an exit-and-redeposit workflow as a cleaner, more sustainable long-term solution to mounting validator-set state growth.
ACD Process
On Wednesday afternoon, AllCoreDevs Execution co-leads Nixo and Ansgar hosted a collaborative session designed to gather direct feedback from core contributors regarding the broader AllCoreDevs governance process. The session revisited the established headliner construct, debated the operational pros and cons of utilizing a visual strawmap, and formalized the criteria for EIP Readiness for Inclusion (SFI).
Participants expressed a strong collective desire to retain the headliner framework while loosening rigid boundaries between EIPs and broader themes, ultimately accepting a hybrid "theme plus candidate EIP" pattern as a viable organizational approach. The per-fork year assignments outlined in the straw map past 2026 were widely criticized as overly canonicalized and likely to be softened over time. A revised, four-point SFI definition was introduced, establishing that AllCoreDevs Testing will signal technical readiness while AllCoreDevs Execution and AllCoreDevs Consensus retain final decision-making authority. A new prioritization-ordering process—produced following Core-Feature Inclusion decisions and reflected directly in the overarching meta-EIP—will formally replace SFI’s historical role in driving devnet inclusion, beginning with the Hegotá upgrade cycle.
On the coordination front, Alex Stokes announced he will be taking a scheduled three-month sabbatical starting the following week. Pari will step in to cover AllCoreDevs Consensus moderation during his absence, while Barnabas Busa will fill in for AllCoreDevs Testing. With these temporary rotations, Nixo and Ansgar continue to chair AllCoreDevs Execution, Pari holds the interim position for Consensus, and Mario, Barnabas, and Danceratopz rotate duties for Testing moderation.
Everything Else
Beyond these major focal points, development teams utilized their rare in-person time to advance progress across a multitude of secondary initiatives. These ranged from improving test harnesses—significantly compressing Hive feedback loops from hours down to minutes—to implementing engine-API plumbing enhancements, such as gossip deduplication, batched RPC calls, and light-client-driven head discovery. Developers also tackled difficult, nuanced trade-offs surrounding client diversity and network resilience. A complete, itemized archive of all session notes remains publicly accessible via the event’s dedicated portal.
Next Steps
With the Svalbard gathering concluded, core contributors return to their home bases to transition the concepts and prototypes developed during the week into production-ready code. The coming weeks will see teams working heads-down on hardening individual client implementations against newly minted specifications, finalizing comprehensive test coverage, and turning Soldólgn’s draft pull requests into merged code contributions.
As is standard protocol within the Ethereum ecosystem, definitive decisions regarding key network parameters—such as the final 200 million gas limit target and exact repricing figures—will be officially made and shared with the broader community during upcoming AllCoreDevs calls. These discussions are expected to dominate community technical channels in the week ahead.
Organizers extended their gratitude to everyone who made the long journey up to 78 degrees north latitude to ensure the event’s success, offering a special shout-out to EthPandaOps for keeping the working groups organized and focused, and to all the developers who labored beneath the persistent midnight sun. Among the attendees was the Ethrex crew, participating in their first-ever interop gathering. The event concluded as a uniquely productive milestone for the network, documented in its entirety by a forthcoming short film capturing the spirit of the Arctic development sprint.
Ethereum & Smart Contracts
Ethereum & Smart Contracts
Ethereum & Smart Contracts
