Longyearbyen, Svalbard – In a remarkable display of decentralized collaboration, over 100 Ethereum core contributors recently converged above the Arctic Circle in Longyearbyen, Svalbard, for the "Soldøgn Interop." This intensive, week-long gathering was dedicated to accelerating the development and hardening of the upcoming "Glamsterdam" network upgrade, a pivotal step in Ethereum’s ongoing evolution towards enhanced scalability and efficiency. Against a backdrop of perpetual daylight, mirroring Ethereum’s 24/7 uptime, developers tackled complex technical challenges, laying critical groundwork for the network’s future.
Main Facts: A Landmark Week for Ethereum’s Glamsterdam Upgrade
The Soldøgn Interop, named after the Norwegian term for "midnight sun," proved to be a profoundly productive week for the Ethereum ecosystem. Core developers successfully delivered on three primary objectives, setting crucial parameters for the Glamsterdam upgrade:
- Alignment on a post-Glamsterdam gas limit floor of 200 million: This significant increase in transaction capacity is designed to alleviate network congestion and enable more complex operations on the blockchain.
- Stable ePBS (enshrined Proposer-Builder Separation) implementations running with external builders: This architectural shift is vital for improving network censorship resistance, decentralization, and overall efficiency in block production.
- Final EIP-8037 repricing numbers locked in: This Ethereum Improvement Proposal (EIP) addresses state-creation costs, ensuring that the network’s state growth remains manageable even with increased transaction throughput.
Beyond these immediate Glamsterdam goals, the interop also saw meaningful progress on features earmarked for future upgrades, such as "Hegotå," including advancements in FOCIL (Forward-Compatible Indexing Language) and native account abstraction. The success of Soldøgn underscores the power of focused, in-person collaboration in driving forward one of the world’s most complex and critical decentralized networks. The achievements of this week directly contribute to Ethereum’s ambitious roadmap, promising a more robust, scalable, and user-friendly blockchain experience.
Chronology: From Arctic Sun to Code Milestones
The Soldøgn Interop wasn’t an isolated event but a continuation of a vital tradition within the Ethereum development community. These interops serve as crucial junctures for core contributors from various client teams to synchronize efforts, resolve cross-client compatibility issues, and collectively push forward major network upgrades.
The Interop Tradition: Focused Progress
Soldøgn followed in the footsteps of last year’s Berlinterop but consciously returned to a more concentrated, single-track format reminiscent of earlier successful gatherings like Amphora (2021), Edelweiss (2023), and Nyota (2024). This single-track approach, focusing intensely on a specific upgrade – in this case, "hardening Glamsterdam" – allows for unparalleled progress, compressing weeks of asynchronous online communication into days of direct, iterative problem-solving. These multi-client interops are instrumental in ensuring that all diverse client implementations (such as Geth, Erigon, Nethermind, Lighthouse, Teku, Nimbus, Prysm, Lodestar, etc.) remain compatible and robust throughout the upgrade process.
Glamsterdam’s Path: Hardening and Scaling
The overarching objective for the week was clear: to harden Glamsterdam implementations and establish a credible target for a post-upgrade gas limit floor. Raising the gas limit safely is a multi-dimensional challenge, impacting how blocks are constructed and proposed (ePBS), the processing headroom available to client implementations under increased load (BALs), and how state-creation costs scale alongside higher throughput (EIP-8037). In essence, the goal was to achieve a stable, multi-client Glamsterdam development network that integrated the latest specifications for ePBS, repricing, and block access lists, alongside gathering comprehensive benchmarking data to support the proposed gas limit increase.
A Week of Intense Collaboration
The atmosphere throughout the week was one of intense, focused collaboration. Most of the time was spent "heads down" writing code, often extending into the early hours of the morning, a testament to the dedication of the contributors. These coding sprints were punctuated by frequent breakout sessions, where small groups aligned on critical design decisions and debated longer-term roadmap items. This iterative process of coding, testing, debugging, and aligning in real-time is the hallmark of successful interops, dramatically accelerating development cycles.
Infrastructure Powering Progress
The seamless operation of Soldøgn was significantly bolstered by the dedicated infrastructure provided by three key Ethereum Foundation (EF) teams:
- EthPandaOps delivered essential tools like
ethIQ, a performance monitoring dashboard, and apanda MCP serverto facilitate efficient agentic workflows for the development teams. - Protocol Support meticulously set up
soldogn.xyz, serving as the single, authoritative source for all interop goals, the detailed schedule, and comprehensive notes, ensuring transparency and accessibility. - The EF Digital Studio team was on-site, meticulously documenting the entire week on film. The community can eagerly anticipate the very first interop documentary, offering a unique behind-the-scenes look at the collaborative efforts shaping Ethereum’s future.
ePBS: Reshaping Block Construction for Efficiency
Ensuring the stability and efficiency of Ethereum’s consensus mechanism is paramount, and ePBS (enshrined Proposer-Builder Separation) sits at the heart of Glamsterdam’s scaling strategy. Beyond merely cleaning up the existing proposer/builder relationship, ePBS fundamentally restructures the network’s slots by introducing explicit deadlines for block construction, payload reveal, and attestations. This restructuring clearly delineates the time allocated for execution, thereby significantly increasing the headroom available for raising the gas limit without compromising network stability.
The week’s ePBS track kicked off with an ambitious goal: to establish a functional 4 Execution Layer (EL) x 4 Consensus Layer (CL) Glamsterdam development network by Monday evening. Initial attempts revealed several compatibility and implementation issues, pushing the target to Tuesday, where a 4×3 configuration achieved sufficient stability to commence stress testing.
From that point onward, the rest of the week evolved into an intensive ePBS hardening cycle. This involved a continuous loop of stress testing the devnet, exposing edge cases, implementing fixes, and then repeating the process. A crucial Tuesday-morning Builder API breakout session 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 meticulously pinpointed cross-client edge cases, particularly around the invalidation of beacon requests by execution requests. A newly developed test suite revealed a critical gap across every client implementation, highlighting the necessity of these in-person interops. By Thursday morning, CL teams reported stable ePBS operations, while EL-side bid pathways continued to be debugged, with these issues largely resolved by Friday.
Despite the significant progress, two questions remained genuinely contentious for the All Core Devs (ACD) community:
- Whether a request signature should commit to the receiving builder.
- How to maintain resilience against P2P Sybil-based liveness attacks with a 1 ETH-staked-builder design.
By the end of the week, nearly all clients were successfully running together on glamsterdam-devnet-2, with the external builders pipeline thoroughly tested end-to-end, marking a monumental achievement for the ePBS implementation.
BAL Optimizations and Gas Repricings: The Execution Layer’s Evolution
While ePBS addresses the consensus layer’s role in scaling, the execution layer’s counterpart for Glamsterdam’s scaling narrative centers around two dominant components: gas repricings and Block-Level Access Lists (BALs), as outlined in EIP-7928.
Block-Level Access Lists (BALs): Enhancing Throughput
BALs are designed to provide clients with sufficient upfront information about a block’s read/write set. This crucial data enables several performance optimizations, including parallel execution, batched I/O operations, and parallel state-root computation. Collectively, these enhancements directly dictate how large and complex a block clients can comfortably process, thereby increasing the network’s overall throughput capacity.
The Soldøgn BAL track operated on its own dedicated development networks, separate from the Glamsterdam ePBS chains. This isolation was strategic, preventing optimization benchmarks from becoming entangled with the ongoing consensus-layer stabilization work. Each optimization was implemented behind its own feature flag, allowing for the week’s measurement work to compare their performance in isolation rather than as a single, undifferentiated bundle. The BAL benchmark dashboard and leaderboard proved invaluable, highlighting each client’s worst-case scenarios across the comprehensive test suite. By focusing on improving the slowest paths first, teams could effectively lift the gas limit floor across the board, rather than merely optimizing for the fastest implementation.
Gas Repricings: Calibrating Costs with EIP-8037
Glamsterdam incorporates several Execution Layer gas repricings, meticulously calibrating transaction costs to better reflect actual resource usage at higher throughput levels. At the core of these changes lies EIP-8037, the state-creation gas cost increase. This EIP is critical because it raises the price of writing new state, a necessary measure to ensure that a higher gas limit does not inadvertently lead to unbounded and unsustainable state growth.
Heading into Soldøgn, the EIP-8037 specification included dynamic per-state-byte pricing tied to the block gas limit. This dynamic approach presented significant testing and benchmarking challenges, requiring an unmanageably large number of fuzz matrices and making performance measurement nearly intractable. Recognizing this bottleneck, teams agreed early in the week to abandon dynamic pricing in favor of a fixed cost_per_state_byte. Future repricing adjustments would then be handled at subsequent hard fork boundaries, simplifying implementation and testing significantly.
The development of the accounting model itself followed a more iterative and collaborative path. A Monday breakout session shifted state-gas accounting from mid-execution to the end-of-call-frame. A Tuesday follow-up addressed account creation costs, code deposit costs, and CREATE-transaction reverts. By Wednesday, reservoir refund/refill edge cases emerged, necessitating a fundamental rethinking of the model. A Thursday breakout reverted the accounting to the opcode level, concluding that the primary complexity resided within 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 iteration and resolution of complex specification, implementation, testing, debugging, and design issues within hours, rather than weeks, exemplifies the immense value of interop weeks. At their most effective, these gatherings can compress months of asynchronous progress into each day of face-to-face collaboration.
By the end of the Soldøgn Interop, these three critical development threads – ePBS, BAL optimizations, and gas repricings – converged to yield the week’s headline achievement: a credible 200 million post-Glamsterdam gas limit floor. This substantial increase in transaction capacity is made possible by the synergistic effects of these changes: ePBS structures the slot to afford execution more time, BAL optimizations grant clients the necessary throughput headroom within that structure, and EIP-8037 ensures that the higher gas limit does not translate into runaway state growth, maintaining the long-term health and sustainability of the Ethereum network.
Supporting Data: The Strategic Choice of Svalbard
The selection of Longyearbyen, Svalbard, as the venue for the Soldøgn Interop was far from arbitrary; it was a deliberate and symbolically rich choice that resonated deeply with the principles and aspirations of the Ethereum project.
A Nexus for Global Collaboration
Svalbard holds a unique geopolitical status. It is one of the few places on Earth where individuals, regardless of their nationality, can live and work without requiring a visa. This open-border policy, enshrined in the Svalbard Treaty, fosters an environment of global collaboration and inclusivity – values that are fundamental to the decentralized and international nature of Ethereum’s development. By choosing a location that inherently embraces diversity and accessibility, the interop subtly reinforced Ethereum’s commitment to being a global public good.
Guardians of Humanity’s Data
Beyond its inclusive policies, Svalbard is renowned as a sanctuary for humanity’s most precious data. It is home to the Global Seed Vault and the Arctic World Archive, two state-of-the-art cold-storage facilities tunneled deep into the permafrost outside Longyearbyen. These "doomsday vaults" serve as secure repositories for critical information, including backups of agricultural crops, invaluable books, historical films, ancient manuscripts, and essential source code. Notably, the Arctic World Archive holds a snapshot of Ethereum’s own source code, preserving its foundational blueprint for potentially thousands of years. This connection created a powerful metaphor for the Ethereum developers: working to secure and advance a digital infrastructure that, much like the physical archives, is designed for enduring resilience and long-term societal benefit. The environment itself became a living symbol of permanence and foresight.
Eternal Daylight, Eternal Uptime
Perhaps the most striking feature of Svalbard during the interop was the phenomenon of the midnight sun. From late April through August, the sun never sets, bathing the landscape in continuous daylight. This "24/7 uptime" served as a perfect, poignant metaphor for the Ethereum network itself, which is designed to operate continuously, without interruption, globally. Core developers, working under the perpetual Arctic sun, mirrored the relentless, always-on nature of the blockchain they are building, drawing inspiration from their unique surroundings to power through intense coding and collaborative sessions. The unbroken light symbolized the unyielding commitment to Ethereum’s continuous operation and evolution.
Official Responses: Governance, Process, and Future Roadmaps
The Soldøgn Interop was not solely about coding and technical implementation; it also served as a crucial forum for refining the internal governance and strategic direction of the Ethereum core development process.
Refining the All Core Devs (ACD) Process
On Wednesday afternoon, Nixo and Ansgar, the two All Core Devs Execution (ACDE) co-leads, facilitated a session to gather vital input from core contributors regarding the ACD process itself. The discussions revisited several key aspects:
- The Headliner Construct: The concept of "headliners" (major themes or EIPs guiding a hard fork) was broadly supported, but participants advocated for loosening the rigidity between EIPs and themes, suggesting that "theme + candidate EIP" should be a viable pattern. This offers greater flexibility in shaping future hard forks.
- The Straw Map: The community debated the utility and potential pitfalls of the "strawmap," a high-level, multi-year roadmap. There was a consensus that year assignments for forks beyond 2026 were becoming "overcanonicalized" and should be softened, allowing for more organic adaptation to emerging technical priorities and challenges.
- EIP SFI Criteria: New, formalized criteria for "Sign-off for Inclusion" (SFI) for EIPs were put forward (EIP-11475). This new four-point definition clarifies the readiness signal from ACD Testnet (ACDT) teams, with ACDE and ACD Consensus (ACDC) retaining the final call for inclusion. A new prioritization-ordering process, to be produced after Call for Inclusion (CFI) decisions and reflected in the meta-EIP, will replace SFI’s previous role in driving devnet inclusion, starting with the Hegotå upgrade. These adjustments aim to streamline decision-making and ensure a more responsive development pipeline.
Leadership Transitions
The session also brought news of upcoming leadership transitions within the core development calls. Alex Stokes announced he would be taking a three-month sabbatical, with Pari stepping in to cover ACDC moderation in the interim, and Barnabas filling in for ACDT. The overall coordination of the All Core Devs calls will continue under the leadership of Nixo and Ansgar for ACDE, with Pari as interim for ACDC, and Mario, Barnabas, and Danceratopz rotating ACDT moderation. These changes highlight the distributed and collaborative nature of Ethereum’s leadership, ensuring continuity and fresh perspectives.
Glamsterdam’s Ancillary Decisions
Beyond the major ePBS, BAL, and repricing work, the interop also saw final decisions on several smaller, yet important, Glamsterdam EIPs:
- EIP-8061 (exit/consolidation churn increase) was confirmed for inclusion in
glamsterdam-devnet-1. - EIP-8080 (exits via the consolidation queue) was declined for inclusion in Glamsterdam.
- EIP-8045 (slashed-validator duty removal) was scoped down to proposer duties within the look-ahead window only.
- EIP-7688 (SSZ stable containers) remains within Glamsterdam scope but will be held out of
glamsterdam-devnet-1as the team works through issues related to bounded gossip-message size for attestations under progressive lists.
A Wednesday-morning Execution Layer/Consensus Layer (EL/CL) sync architecture breakout led to the deferral of EIP-8237 out of Glamsterdam. This decision was made to preserve optionality for a longer-term "top-up sync" architecture in a future fork. In its place, the group agreed to draft a new EIP that standardizes forkchoiceUpdated / newPayload / getPayload sequencing, specifies a snap-sync initiation handshake, and tightens valid/invalid consistency between the engine API surfaces.
Hardening Frameworks
A consistent theme of the week was "hardening" the network against potential vulnerabilities. A Thursday session focused on advanced fork-choice compliance testing frameworks, the Diamond repository (a collection of reproducible CL edge-case scenarios), and buildoor, PandaOps’s external-builder testing tool. buildoor was impressively demoed mid-session, allowing attendees to suggest various attack scenarios on the spot, which the tool then simulated, proving its robustness in identifying and mitigating potential threats.
Implications: Beyond Glamsterdam – Ethereum’s Horizon
While Glamsterdam was the immediate focus, the Soldøgn Interop also provided a crucial platform for strategic discussions and foundational work on future Ethereum upgrades, collectively shaping the network’s long-term trajectory. Several breakout sessions looked ahead to "Hegotå" and subsequent forks, signaling Ethereum’s continuous innovation.
Native Account Abstraction: User Experience Revolution
A deliberately proposal-agnostic session on native Account Abstraction kicked off discussions, meticulously working through the requirements and constraints any future design must satisfy. This crucial feature aims to revolutionize the user experience on Ethereum by making accounts more flexible and programmable. Feature-set goals included support for alternative signature schemes, transaction aggregation, batching, easier account recovery, gas sponsorship, flexible nonces, and integrated keystore wallets. These user-centric enhancements were balanced against hard technical constraints, such as public-mempool compatibility, statelessness, and robust resistance to Layer 2 (L2) Denial-of-Service (DoS) attacks, ensuring that enhanced user experience doesn’t compromise network security or efficiency.
FOCIL’s Promise: Improved Indexing
A Thursday FOCIL (Forward-Compatible Indexing Language) breakout focused on implementation updates, with early prototypes already demonstrating functionality. The immediate next steps include multi-client interop and the establishment of a dedicated FOCIL devnet. Two notable design decisions were also made: disabling FOCIL during 2-epoch non-finality (mirroring existing proposer-boost circuit-breaker behavior) and adopting an index-based bookmark approach for compatibility with frame transactions and EIP-7702. FOCIL promises to make querying and interacting with Ethereum’s state more efficient and future-proof.
P2P Network Evolution: Speed and Privacy
A long-running ETH P2P track sketched out ambitious plans for the network’s peer-to-peer layer. This included a QUIC-based replacement for libp2p, aiming for privacy-by-default and slot-aware integration, which would significantly enhance network communication. Additionally, an erasure-coded broadcast prototype was demonstrated, simulating approximately six times faster propagation than the current GossipSub protocol for 2.4 MB payloads. These advancements are critical for improving block propagation times and overall network robustness, especially as block sizes potentially increase with higher gas limits. The CL track also surfaced strong sentiment toward eventually deprecating consolidations entirely – declaring a final fork that supports them, then forcing exit-then-redeposit afterwards – as the cleaner long-term answer to validator-set state growth, streamlining network management.
Immediate Next Steps: From Prototype to Production
The conclusion of Soldøgn marks a transition from intensive prototyping to the crucial phase of production readiness. Teams are now returning home, tasked with taking the innovations and agreements forged in Svalbard and transforming them into robust, shippable code. The next several weeks will be characterized by "heads-down" work, focusing on hardening client implementations against the newly finalized specifications, ensuring comprehensive test coverage, and merging Soldøgn’s draft Pull Requests into the main codebases.
Transparency and Public Engagement
As always, the Ethereum core development process maintains a commitment to transparency. The final decisions for critical values, such as the 200 million gas limit target and the definitive repricing numbers, will be formally made and publicly shared during upcoming AllCoreDevs calls. These calls serve as the official channels for communicating major protocol decisions to the broader Ethereum community and are expected to be the central topics of discussion in the immediate weeks following the interop.
Conclusion: A United Front for Decentralization
The Soldøgn Interop in Svalbard stands as a testament to the unwavering dedication and collaborative spirit of the Ethereum core development community. In a remote Arctic outpost, under the perpetual light of the midnight sun, over a hundred brilliant minds united to push the boundaries of decentralized technology. The week’s achievements, particularly the foundational work on the Glamsterdam upgrade and its implications for scalability, efficiency, and decentralization, represent a significant leap forward for Ethereum.
A heartfelt thank you extends to everyone who traveled to 78°N and contributed to the success of this monumental week. Special recognition goes to EthPandaOps for their exceptional organizational prowess, keeping the group focused and productive each day, and to all who worked tirelessly under the unique conditions of the midnight sun to meet daily goals – including the Ethrex crew, who made their impactful debut at this interop. It was an incredibly productive and memorable week, and the forthcoming full-length documentary by the EF Digital Studio team will ensure its legacy is beautifully preserved for the entire Ethereum community. The future of Ethereum, shaped by such collaborative efforts, continues to shine ever brighter.
