Layla Zulfa
Just over 100 dedicated Ethereum core contributors convened above the Arctic Circle this past week, gathering in the remote yet strategically significant town of Longyearbyen, Svalbard, for the Soldøgn Interop. This intensive, week-long working session was singularly focused on the "Glamsterdam" network upgrade, marking a critical juncture in Ethereum’s ongoing evolution towards enhanced scalability and efficiency. The highly concentrated environment fostered rapid iteration and problem-solving, culminating in key agreements and significant technical advancements that promise to substantially elevate the network’s capacity and resilience.
The Strategic Setting: Svalbard’s Unique Role in Global Innovation
The choice of Svalbard, a Norwegian archipelago nestled at 78° North latitude, for the Soldøgn Interop was far from arbitrary, carrying both practical and symbolic weight. Longyearbyen, the world’s northernmost permanent settlement, offers a unique regulatory environment where individuals of any nationality can reside and work without a visa, fostering an inclusive atmosphere conducive to international collaboration. Beyond its open borders, Svalbard is renowned as a bastion of digital and biological preservation. It hosts the Global Seed Vault, safeguarding the world’s agricultural biodiversity, and the Arctic World Archive, a digital repository tunneled deep into the permafrost, preserving invaluable data, cultural heritage, and critical source code – including a snapshot of Ethereum’s own foundational code – for millennia to come.
This symbolic alignment with long-term preservation and global accessibility resonated deeply with the Ethereum ethos of building a decentralized, enduring digital infrastructure. Furthermore, the timing of the interop leveraged Svalbard’s "midnight sun" phenomenon, where the sun remains visible 24 hours a day from late April through August. This perpetual daylight, mirroring Ethereum’s own commitment to 24/7 uptime, created an immersive work environment, allowing core developers to maximize productivity and often code into the "early hours" without the traditional constraints of day and night. The remote, distraction-free setting, coupled with its symbolic significance, underscored the gravity of the work undertaken.
A History of Intense Collaboration: The Interop Format
The Soldøgn Interop continued a tradition of highly focused, in-person development sprints that have proven indispensable for the Ethereum network’s progress. Following last year’s "Berlinterop," Soldøgn consciously returned to the "single-track" format successfully employed by previous landmark gatherings such as Amphora (2021), Edelweiss (2023), and Nyota (2024). This methodology eschews parallel tracks in favor of a unified effort, concentrating multi-client progress on a specific, critical network upgrade. For Soldøgn, the singular objective was to "harden" the Glamsterdam upgrade, ensuring its robustness and readiness for deployment.
These interop events are vital because they bring together diverse client teams – each responsible for developing and maintaining a different implementation of the Ethereum protocol (e.g., Geth, Erigon, Nethermind for the execution layer; Prysm, Lighthouse, Teku for the consensus layer). Direct, in-person collaboration allows for immediate identification and resolution of cross-client compatibility issues, real-time spec adjustments, and accelerated debugging cycles that would otherwise take weeks or months through asynchronous communication. The ability to converge on complex design decisions and test implementations concurrently significantly compresses the development timeline for major network upgrades.
Glamsterdam Upgrade: A Leap Towards Scalability and Efficiency
The Glamsterdam upgrade is designed to address several multi-dimensional problems critical to Ethereum’s long-term scalability, particularly concerning how blocks are constructed, validated, and processed, and how state-creation costs are managed. The overarching goal is to safely raise the network’s gas limit, thereby increasing transaction throughput without compromising decentralization or security. The interop aimed to harden Glamsterdam implementations across various client teams and establish a credible target for a post-upgrade gas limit floor.
By the end of the week, the concentrated efforts of the core contributors yielded three pivotal achievements:
- Alignment on a post-Glamsterdam gas limit floor of 200 million: A significant increase from the current limit, paving the way for substantially higher transaction capacity.
- Stable ePBS (enshrined Proposer-Builder Separation) implementations: Running successfully with external builders, enhancing block construction efficiency and mitigating Maximal Extractable Value (MEV) concerns.
- Final EIP-8037 repricing numbers locked in: A crucial step to balance increased transaction throughput with sustainable state growth.
Beyond these primary goals, meaningful progress was also reported on features slated for future upgrades, such as "Hegotà," including FOCIL (Future of Consensus Layer) and native account abstraction.
Core Achievements: Unpacking the 200M Gas Limit
The journey to establishing a credible 200M gas limit involved intricate work across three major technical pillars:
1. Enhanced Proposer-Builder Separation (ePBS)
ePBS represents a fundamental restructuring of block production within Ethereum’s consensus layer. It aims to formalize and enshrine the separation between block proposers (validators chosen to propose new blocks) and block builders (specialized entities that construct block contents). This separation is crucial for mitigating the negative externalities of MEV, which can lead to centralization risks and suboptimal network performance. By introducing explicit deadlines for block construction, payload revelation, and attestations, ePBS effectively reallocates time within a slot, creating more "headroom" for execution and thus enabling a higher gas limit.
The week began with an ambitious target: a stable 4 Execution Layer (EL) x 4 Consensus Layer (CL) Glamsterdam devnet by Monday evening. Initial attempts surfaced compatibility issues, pushing the target to Tuesday, where a 4×3 configuration achieved sufficient stability for stress testing. The remainder of the week was a rigorous ePBS hardening cycle: stress testing, exposing edge cases, fixing, and repeating. A critical Builder API breakout session streamlined the specification around validator registration, the bid/header/commitments flow, and the trust model for builder payments. Mid-week debugging revealed a cross-client gap in execution-request invalidation of beacon requests, prompting the development of a new test suite that exposed vulnerabilities across all client implementations. By Thursday, CL teams reported stable ePBS, with EL-side bid pathways resolving into Friday.
Two key questions remain for the All Core Developers (ACD) to genuinely contend with: whether a request signature should commit to the receiving builder, and how to maintain the resilience of a 1 ETH-staked-builder design against P2P Sybil-based liveness attacks. Despite these remaining points, by Friday, nearly all clients were successfully running together on glamsterdam-devnet-2, with the external builders pipeline tested end-to-end – a monumental step forward for the network’s architectural integrity.
2. Block-Level Access List (BAL) Optimizations
While ePBS strengthens the consensus layer, the execution layer’s counterpart in the Glamsterdam scaling story involves gas repricings and Block-Level Access Lists (BALs), specifically EIP-7928. BALs provide clients with upfront information about a block’s read/write set, enabling crucial optimizations such as parallel execution, batched I/O operations, and parallel state-root computation. These optimizations directly dictate how large a block clients can efficiently process without performance degradation, thereby supporting a higher gas limit.
The Soldøgn BAL track operated on its own dedicated devnets, ensuring that optimization benchmarks were not conflated with consensus-layer stabilization efforts. Each optimization was placed behind its own feature flag, allowing for isolated measurement and comparison. The "BAL benchmark dashboard" and leaderboard proved invaluable, highlighting each client’s worst-case scenarios across the test suite. This data-driven approach allowed teams to strategically focus on improving the slowest paths first, ensuring that the gas limit floor could be raised uniformly across the board, not just for the fastest implementations. This collaborative benchmarking effort ensures that the benefits of BAL optimizations are broadly distributed across the diverse client ecosystem.
3. Strategic Gas Repricings (EIP-8037)
Glamsterdam incorporates several Execution Layer gas repricings designed to better align transaction costs with actual resource usage, especially at higher throughput levels. At the heart of these changes is EIP-8037, which proposes an increase in the gas cost of creating new state. This is a critical measure to prevent unbounded state growth if the gas limit were simply raised without corresponding adjustments to state-creation costs. Without such repricing, a higher gas limit could inadvertently incentivize excessive state accumulation, leading to increased hardware requirements for nodes and potential centralization.
Initially, EIP-8037 featured dynamic per-state-byte pricing tied to the block gas limit, which presented significant testing and benchmarking challenges. Recognizing this complexity, teams at Soldøgn swiftly agreed to simplify the spec by adopting a fixed cost_per_state_byte, with future repricing to be handled at subsequent hard fork boundaries.
The accounting model for gas repricings underwent an iterative refinement process throughout the week. Monday’s breakout shifted state-gas accounting from mid-execution to end-of-call-frame. A Tuesday follow-up addressed account creation costs, code deposit costs, and CREATE-transaction reverts. Wednesday revealed reservoir refund/refill edge cases, necessitating a complete re-evaluation. By Thursday, the accounting reverted to opcode level, as it was determined that the primary complexity lay in the reservoir model itself, not the accounting computation. By Friday, the specification had stabilized on bal-devnet-6, with the BAL track delivering the final repricing numbers. This rapid resolution of complex specification, implementation, and debugging issues in a matter of days exemplifies the unique value proposition of interop weeks, compressing months of asynchronous progress into intensive daily sprints.
The convergence of these three threads—ePBS providing more execution time, BAL optimizations enhancing client throughput, and EIP-8037 ensuring sustainable state growth—culminated in the headline achievement: a credible 200M post-Glamsterdam gas limit floor, marking a significant milestone for Ethereum’s scaling roadmap.
Beyond the Core: Other Glamsterdam EIPs and Discussions
While ePBS, BALs, and gas repricings dominated the core work, other Glamsterdam-scoped Ethereum Improvement Proposals (EIPs) were also extensively discussed and decided upon:
- EIP-8061 (Exit/Consolidation Churn Increase): Included in
glamsterdam-devnet-1, aimed at improving validator exit processes. - EIP-8080 (Exits via Consolidation Queue): Declined for inclusion, indicating a strategic decision to streamline exit mechanisms differently.
- EIP-8045 (Slashed-Validator Duty Removal): Scoped down to proposer duties within the look-ahead window only, reflecting a cautious approach to penalizing slashed validators.
- EIP-7688 (SSZ Stable Containers): Remains in Glamsterdam scope but was held out of
glamsterdam-devnet-1as the team addresses bounded gossip-message size for attestations under progressive lists, emphasizing the importance of network health.
A Wednesday-morning EL/CL sync architecture breakout deferred EIP-8237 out of Glamsterdam, opting to preserve optionality for a longer-term "top-up sync" architecture in a future fork. In its place, attendees agreed to draft a new EIP that standardizes forkchoiceUpdated, newPayload, and getPayload sequencing, specifies a snap-sync initiation handshake, and tightens valid/invalid consistency between engine API surfaces. These refinements are crucial for improving client synchronization and network stability.
Hardening was a constant theme, with a Thursday session dedicated to fork-choice compliance testing frameworks, the Diamond repository for reproducible CL edge-case scenarios, and buildoor, EthPandaOps’ external-builder testing tool. The buildoor demo, showcasing attack scenarios suggested by attendees, highlighted the community’s proactive approach to security and resilience.
Gazing into the Future: Hegotà and Beyond
Several breakout sessions extended beyond Glamsterdam, looking towards the "Hegotà" upgrade and subsequent forks, signaling Ethereum’s continuous innovation pipeline.
- Native Account Abstraction: A proposal-agnostic session explored the requirements and constraints for future designs. Goals included alternative signature schemes, aggregation, batching, recovery, gas sponsorship, and flexible nonces, alongside critical constraints like public-mempool compatibility, statelessness, and Layer 2 (L2) Denial-of-Service (DoS) resistance. This foundational discussion lays the groundwork for a more flexible and user-friendly account model.
- FOCIL (Future of Consensus Layer): A Thursday breakout focused on implementation updates, with early prototypes already functional. Multi-client interop and a dedicated FOCIL devnet are the immediate next steps. Key design decisions included disabling FOCIL during two-epoch non-finality (mirroring proposer-boost circuit-breaker behavior) and adopting an index-based bookmark approach for compatibility with frame transactions and EIP-7702. FOCIL aims to improve the efficiency and security of the consensus layer.
- ETH P2P Track: A long-running track sketched a QUIC-based replacement for libp2p, promising privacy-by-default and slot-aware integration. An erasure-coded broadcast prototype demonstrated approximately six times faster propagation than GossipSub on 2.4 MB payloads, indicating significant potential for network throughput and latency improvements. The CL track also expressed strong sentiment towards eventually deprecating validator consolidations entirely, suggesting a final fork supporting them, followed by a forced exit-then-redeposit mechanism. This aims to provide a cleaner, long-term solution to managing validator-set state growth, which is crucial for network health.
Strengthening the Governance Structure: ACD Process Refinements
On Wednesday afternoon, Nixo and Ansgar, the two All Core Developers Execution (ACDE) co-leads, facilitated a crucial session to gather input on the ACD process itself. Discussions revisited the "headliner construct," debated the utility of a "strawmap," and formalized the EIP SFI (Sign-off for Inclusion) criteria. The consensus favored retaining headliners but loosening the rigid EIP-vs-theme structure, accepting "theme + candidate EIP" as a viable pattern. The "straw map’s" per-fork year assignments beyond 2026 were deemed overly canonical and likely to be softened, reflecting a desire for greater flexibility in future planning.
A new four-point SFI definition was put forth, empowering All Core Developers Testing (ACDT) to signal readiness, with ACDE/All Core Developers Consensus (ACDC) retaining the final call. A new prioritization-ordering process, to be produced after Call For Inclusion (CFI) decisions and reflected in the meta-EIP, will replace SFI’s old role of driving devnet inclusion, starting with the Hegotà upgrade.
Significant leadership changes were also announced: Alex Stokes will take a three-month sabbatical, with Pari covering ACDC moderation and Barnabas filling in for ACDT. The updated moderation team now comprises Nixo and Ansgar chairing ACDE, Pari as interim for ACDC, and Mario, Barnabas, and Danceratopz rotating ACDT moderation. These structural adjustments aim to enhance the efficiency and resilience of Ethereum’s core development governance.
The Unseen Work: Broader Technical Improvements
Beyond the headline items, the in-person interop facilitated progress on numerous other technical fronts. Teams collaborated on developing better test harnesses, compressing Hive feedback loops from hours to minutes, significantly accelerating the debugging process. Improvements to engine-API plumbing, including gossip deduplication, batched calls, and light-client-driven head discovery, enhance the efficiency of communication between execution and consensus clients. Discussions also delved into hard tradeoffs around client diversity, acknowledging its importance for network resilience while navigating the complexities of multi-client development. The full breadth of these collaborative efforts is meticulously documented in the session notes available at soldogn.xyz.
Implications for the Ethereum Ecosystem
The outcomes of the Soldøgn Interop have profound implications for the entire Ethereum ecosystem. The successful hardening of Glamsterdam and the agreement on a 200M gas limit floor represent a significant step towards a more scalable and efficient network. For users, this translates to potentially lower transaction fees and faster transaction processing, especially during periods of high network demand. For decentralized application (dApp) developers, a higher gas limit provides more block space, enabling more complex smart contract interactions and potentially fostering new use cases previously constrained by throughput limitations.
The advancements in ePBS are critical for decentralization and mitigating MEV, promoting a healthier and fairer block production environment. The EIP-8037 repricing ensures that this increased capacity does not come at the cost of unsustainable state growth, maintaining the long-term viability and accessibility of running an Ethereum node. Furthermore, the progress on future features like Account Abstraction and FOCIL signals a clear roadmap for continued innovation, promising a more user-friendly and robust platform. The refined ACD process reflects a maturing governance structure, ensuring that future upgrades are developed and implemented with transparency and broad community consensus.
Next Steps and Outlook
With the Soldøgn Interop concluded, core development teams will now return home to transition the prototypes and agreements made during the week into production-ready code. The coming weeks are anticipated to involve intensive work on hardening client implementations against the new specifications, finalizing comprehensive test coverage, and merging the draft Pull Requests (PRs) from Soldøgn into the main codebase.
As is standard practice, the final decisions for critical values such as the 200M gas limit target and the definitive repricing numbers will be publicly announced and discussed during the upcoming AllCoreDevs calls, ensuring transparency and community involvement. These will be major topics for discussion in the immediate future.
The Soldøgn Interop in Svalbard stands as a testament to the Ethereum community’s unwavering commitment to innovation, collaboration, and the continuous improvement of the world’s leading decentralized platform. The productivity achieved under the midnight sun, with contributions from veterans and newcomers alike, including the Ethrex crew at their first interop, has laid a robust foundation for Glamsterdam and beyond. The Ethereum community eagerly anticipates the release of the interop documentary, which will capture the spirit and intensity of this pivotal week.
