Layla Zulfa
This past week, more than 100 Ethereum core contributors convened in the remote, starkly beautiful landscape of Longyearbyen, Svalbard, above the Arctic Circle, for the Soldøgn Interop. This intensive, week-long gathering was dedicated to accelerating the development and hardening of the forthcoming Glamsterdam network upgrade, a critical milestone in Ethereum’s ongoing evolution towards enhanced scalability and efficiency. The choice of location, characterized by its perpetual daylight during this season—mirroring Ethereum’s intended 24/7 uptime—underscored the relentless dedication of the developers to the network’s continuous progress.
The Soldøgn Interop represents a pivotal moment in Ethereum’s development roadmap, following a lineage of focused, multi-client gatherings designed to streamline progress on major network upgrades. Unlike last year’s broader Berlinterop, Soldøgn returned to a more concentrated format, reminiscent of previous successful interops such as Amphora, Edelweiss, and Nyota. These events emphasize a "single-track" approach, uniting diverse client teams to collaboratively tackle specific challenges and ensure robust, multi-client compatibility for a targeted upgrade. For Soldøgn, the singular focus was unequivocally on hardening the Glamsterdam network.
By the close of the week, the concentrated efforts of the assembled experts yielded significant breakthroughs. Three primary objectives for the Glamsterdam upgrade were met: a consensus was reached on a post-Glamsterdam gas limit floor of 200 million, stable implementations of enshrined Proposer-Builder Separation (ePBS) were successfully demonstrated running with external builders, and the final repricing numbers for EIP-8037 were locked in. Beyond these immediate goals, substantial headway was also made on features earmarked for future upgrades, such as Hegotà, including FOCIL (Fork Choice in Consensus Layer) and native account abstraction, alongside a multitude of other vital topics.
The Arctic Crucible: A Unique Setting for Innovation
The decision to host such a critical technical summit in Longyearbyen, Svalbard, was both symbolic and practical. Svalbard is renowned as one of the few places globally where individuals, irrespective of their nationality, can live and work without a visa, fostering an environment of open collaboration much like the decentralized ethos of Ethereum itself. More profoundly, Svalbard is home to the Global Seed Vault and the Arctic World Archive—two ultra-secure, cold-storage facilities burrowed deep into the permafrost near Longyearbyen. These archives safeguard humanity’s most crucial data, from agricultural seeds to historical manuscripts and vital source code, including a snapshot of Ethereum’s own foundational code, ensuring its preservation for a millennium. This commitment to long-term resilience and security resonates deeply with Ethereum’s own architectural principles.
Furthermore, from late April through August, Svalbard experiences "Soldøgn" or "midnight sun," where the sun never sets. This unique phenomenon of 24/7 daylight served as a potent metaphor for Ethereum’s aspirational 24/7 uptime and availability. Core developers leveraged this continuous light, often working intensely into what would typically be the early hours, to maximize productivity and accelerate progress on the complex technical challenges at hand. This environment fostered an unparalleled sense of urgency and camaraderie among the contributors.
Glamsterdam: A Leap Towards Ethereum’s Scalability Future
The overarching objective of the Soldøgn Interop was to solidify the implementations for the Glamsterdam upgrade and establish a credible target for the network’s post-upgrade gas limit floor. Increasing the gas limit—a measure of computational work that can be included in a block—is a multi-faceted challenge. Glamsterdam addresses several dimensions of this problem: refining how blocks are constructed and proposed, optimizing client implementations for increased load, and managing the scaling of state-creation costs in conjunction with higher transaction throughput.
In practical terms, the week was designed to culminate in a stable, multi-client Glamsterdam development network (devnet) incorporating the latest ePBS, repricing, and block access list specifications. This devnet was crucial for generating comprehensive benchmarking data to inform and validate a robust gas limit proposal. The work involved countless hours of coding, intense debugging sessions, and frequent breakout discussions to align on critical design decisions and chart the course for longer-term roadmap items.
The Ethereum Foundation (EF) provided essential infrastructure to support the week’s demanding schedule. EthPandaOps delivered ethIQ for performance monitoring and a panda MCP server to facilitate agentic workflows among teams. The Protocol Support team established soldogn.xyz as the central hub for interop goals, schedules, and notes. Notably, the EF Digital Studio team was on-site, capturing the entire event on film, promising the release of the very first interop documentary, offering an unprecedented look into the collaborative spirit of Ethereum’s core development.
Key Achievements: Deep Dive into Glamsterdam’s Components
The interop’s success hinged on tangible progress across three core technical areas: ePBS, BAL Optimizations, and Gas Repricings.
Enshrined Proposer-Builder Separation (ePBS): Reinforcing Consensus
ePBS is a critical upgrade designed to refine the proposer-builder relationship within Ethereum’s block production mechanism. It aims to reduce the impact of Maximal Extractable Value (MEV) by separating the roles of block proposal and block building. More fundamentally, ePBS restructures transaction slots by introducing explicit deadlines for block construction, payload revelation, and attestations. This restructuring creates more predictable time allocation for execution, which is vital for safely increasing the gas limit.
The week began with an ambitious goal: to achieve a stable 4 Execution Layer (EL) x 4 Consensus Layer (CL) Glamsterdam devnet by Monday evening. Initial attempts quickly exposed several issues, pushing the target to Tuesday, when a 4×3 configuration demonstrated sufficient stability for stress testing to commence. The remainder of the week was a continuous ePBS hardening cycle: stress testing, identifying and fixing edge cases, and iterating.
A significant breakthrough occurred during a Tuesday-morning Builder API breakout session, which substantially simplified the specification around validator registration, the bid/header/commitments flow, the trust model for builder payments, and circuit-breaker behavior. Mid-week debugging efforts pinpointed cross-client edge cases, particularly concerning the invalidation of beacon requests by execution requests. A new test suite revealed a surprising gap across all client implementations, which was swiftly addressed. By Thursday morning, CL teams reported stable ePBS functionality, with EL-side bid pathways resolving through Thursday and Friday. Two critical, yet contentious, questions remained for the All Core Devs (ACD) to address: 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 open points, by Friday, nearly all clients were running cohesively on glamsterdam-devnet-2, with the external builders pipeline thoroughly tested end-to-end.
Block-Level Access Lists (BAL) Optimizations: Enhancing Execution Layer Throughput
While ePBS strengthens the consensus layer’s scaling capabilities, the execution layer’s complementary efforts focus on gas repricings and Block-Level Access Lists (EIP-7928). BALs provide clients with upfront information about a block’s read/write set, enabling parallel execution, batching of I/O operations, and parallel state-root computation. These optimizations are crucial for determining the maximum block size clients can efficiently process.
The Soldøgn BAL track operated on its own dedicated devnets, distinct from the Glamsterdam ePBS chains, preventing entanglement between optimization benchmarks and consensus-layer stabilization work. Each optimization was placed behind its own feature flag, allowing for isolated measurement and comparison. The BAL benchmark dashboard and leaderboard were instrumental in identifying each client’s worst-case scenarios across the test suite. By prioritizing the slowest paths, teams could collectively elevate the gas limit floor across all implementations, rather than merely boosting the fastest ones. This collaborative approach ensures a more uniformly robust network.
Gas Repricings: Calibrating Costs for Higher Throughput
Glamsterdam introduces several Execution Layer (EL) gas repricings, recalibrating operational costs to more accurately reflect resource usage at higher transaction throughputs. EIP-8037, specifically designed to increase state-creation gas costs, is central to this effort. Its purpose is to raise the price of writing new state, thereby preventing an increased gas limit from leading to unbounded state growth and potential network bloat.
Prior to Soldøgn, the EIP-8037 specification included dynamic per-state-byte pricing tied to the block gas limit, which presented significant testing and benchmarking complexities. Early in the week, teams collectively agreed to abandon dynamic pricing in favor of a fixed cost_per_state_byte, with future repricings to be handled at subsequent fork boundaries rather than within a single fork.
The accounting model itself underwent an iterative refinement process throughout the week. A Monday breakout session shifted state-gas accounting from mid-execution to the end of the call-frame. A Tuesday follow-up addressed account creation costs, code deposit costs, and CREATE-transaction reverts. Wednesday’s discussions unearthed reservoir refund/refill edge cases, necessitating a complete re-evaluation. The Thursday breakout ultimately reverted accounting to the opcode level, concluding that the primary complexity resided 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 iterative process vividly illustrates the profound benefit of interop weeks: the ability to resolve intricate specification, implementation, testing, debugging, and design issues in a matter of hours, a feat that would typically span weeks of asynchronous communication. Interop weeks effectively compress months of distributed progress into highly productive daily increments.
By Friday, these three critical threads—ePBS, BAL optimizations, and gas repricings—converged, culminating in the headline achievement of the week: a credible 200 million post-Glamsterdam gas limit floor. This substantial increase in network capacity is rendered feasible by ePBS, which structurally grants execution more time within each slot; by BAL optimizations, which provide client implementations with the necessary throughput headroom under this new structure; and by EIP-8037, which ensures that a higher gas limit does not result in unsustainable state growth.
Beyond Glamsterdam: Glimpses into Ethereum’s Future
While Glamsterdam dominated the immediate focus, several breakout sessions also cast a forward glance toward Hegotà and subsequent network upgrades.
A proposal-agnostic session on native Account Abstraction initiated discussions, meticulously outlining the requirements and constraints that any future design must satisfy. Feature-set goals included alternative signature schemes, transaction aggregation and batching, account recovery mechanisms, gas sponsorship, flexible nonces, and keystore wallets. These were balanced against stringent hard constraints such as public-mempool compatibility, statelessness, and robust Layer 2 (L2) Denial-of-Service (DoS) resistance.
A Thursday FOCIL (Fork Choice in Consensus Layer) breakout provided updates on implementation progress, with early prototypes already functional. Multi-client interop and a dedicated FOCIL devnet were identified as the immediate next steps. Two key design decisions emerged: disabling FOCIL during periods of 2-epoch non-finality (mirroring proposer-boost circuit-breaker behavior) and adopting an index-based bookmark approach to ensure compatibility with frame transactions and EIP-7702.
Looking further ahead, a long-running ETH P2P track sketched out a QUIC-based replacement for libp2p, envisioning a protocol with privacy-by-default and slot-aware integration. An erasure-coded broadcast prototype demonstrated simulated propagation approximately six times faster than GossipSub for 2.4 MB payloads, promising significant network efficiency gains. The CL track also revealed strong sentiment towards eventually deprecating validator consolidations entirely, suggesting a final fork to support them, followed by a future requirement for exit-then-redeposit for validator management, as a cleaner long-term solution to address validator-set state growth.
The Development Process: Collaboration and Evolution
On Wednesday afternoon, Nixo and Ansgar, the co-leads of the All Core Developers Execution (ACDE) calls, facilitated a session to gather feedback from core contributors regarding the ACD process itself. The session revisited the "headliner construct," a framework for organizing hard fork content, and debated the merits of maintaining a "strawmap" for future development. Critically, the session formalized the criteria for EIP SFI (Signaling for Inclusion).
The consensus was to retain headliners but introduce more flexibility, allowing for a "theme + candidate EIP" pattern. The per-fork year assignments in the strawmap beyond 2026 were deemed overly canonicalized and likely to be softened. A new four-point SFI definition was proposed, granting All Core Developers Testing (ACDT) the ability to signal readiness, with ACDE/ACDC (All Core Developers Consensus) retaining the final decision. A new prioritization-ordering process, to be produced after Call For Inclusion (CFI) decisions and reflected in the meta-EIP, will replace SFI’s traditional role in driving devnet inclusion, starting with Hegotà.
In terms of call coordination, Alex Stokes announced a three-month sabbatical, with Pari stepping in as interim ACDC moderator and Barnabas filling in for ACDT. This ensures continuity in the crucial coordination of core development efforts. The current leadership structure now sees Nixo and Ansgar chairing ACDE, Pari as interim ACDC, and Mario, Barnabas, and Danceratopz rotating ACDT moderation. This robust and distributed leadership model underscores the decentralized nature of Ethereum’s governance.
Broader Impact and Next Steps
Beyond the headline items, the in-person gathering facilitated significant progress on a wide array of other crucial topics. Teams worked on improving test harnesses, compressing Hive feedback loops from hours to minutes, and enhancing engine-API plumbing with gossip deduplication, batched calls, and light-client-driven head discovery. Discussions also touched upon hard tradeoffs related to client diversity, a cornerstone of network resilience. A comprehensive list of session notes is publicly available at soldogn.xyz.
The successful Soldøgn Interop now transitions into the next phase: taking the prototypes and agreements forged in Svalbard and transforming them into production-ready code. The coming weeks will see developers focused on hardening client implementations against the new specifications, finalizing comprehensive test coverage, and merging the draft Pull Requests generated during the interop into the main codebases.
The final decisions regarding critical parameters such as the 200M gas limit target and the definitive repricing numbers will be publicly deliberated and confirmed on upcoming AllCoreDevs calls, which are expected to heavily feature these topics in the immediate future.
The Soldøgn Interop stands as a testament to the power of focused, collaborative development within the Ethereum ecosystem. The tireless efforts of over 100 contributors, working under the unique conditions of the Arctic midnight sun, have not only pushed the Glamsterdam upgrade significantly forward but have also laid crucial groundwork for subsequent advancements, ensuring Ethereum’s continued evolution as a scalable, efficient, and robust global computing platform. The Ethereum community eagerly anticipates the release of the interop documentary, which will capture the spirit and intensity of this remarkable week.
