Oct 14, 2026 | RUMCG Meeting

Agenda

• Interop 2027
• TPAC 2026

Admin

• Next meeting:

• November 11th - CANCELLED (due to RUM RUM)
• November 18th - RUM RUM in-person @ perf.now() Amsterdam
• December 9th - December meeting

General Summary

• Interop Initiative: Final 2027 feature scope will be published in Feb after TPAC; community encouraged to review 1,400+ open Web Platform Tests.
• TPAC Preparation: TPAC sets focused sessions consolidating biweekly talks; community feedback on real use cases is key to guide priorities.
• RUM RUM Event: Scheduled Nov 18 in Amsterdam; 74 signed up; replaces Nov meeting; shares TPAC outcomes and fosters collaboration.
• Agent Identity Issues: Browsers don't self-ID; challenge in distinguishing human vs agent-driven traffic; TPAC to address ecosystem incentives.
• Soft Navigation Metrics: Cloudflare’s CrUX soft nav data now public; growing demand from analytics vendors; RUM RUM to discuss metric integration.

Notes

Interop Initiative and Web Platform Tests

• The Interop project is progressing well toward improving cross-browser consistency on selected web features through coordinated testing.
• Ongoing refinement and feature selection for 2027 Interop are underway with champions assigned (15:00)

• The submission window closed in September; next step involves narrowing feature proposals and champion assignments.
• The final scope and chosen features will be published in February, following discussions at the upcoming TPAC meeting.
• Interop focuses on ensuring all selected features have existing Web Platform Tests (WPT) for verification.
• Browser vendors actively contribute and prioritize fixes to improve passing test rates, enhancing web interoperability.

• Test suite quality and review are critical, with over 1,400 open WPT pull requests needing attention (18:31)

• Many PRs date back several years and require triage to clear stale or flaky tests.
• Some tests already exist in Chromium but failed merging due to administrative issues, indicating a need for better review workflow.
• Community involvement is encouraged to review and improve tests, as small JavaScript tests are easy to contribute and can significantly impact Interop success.
• Assigned reviewers exist but may lack capacity; the community can help escalate important PRs to ensure timely reviews.

• Community feedback is vital at this stage to influence feature prioritization and test coverage (16:44)

• Michael Mocny urged contributors to review tests now, as this is the optimal time to make impactful changes before final feature selection.
• The process includes both focus areas with ready tests and investigation efforts to develop tests for features not yet mature.
• Nic Jansma highlighted a public Mozilla feedback tool where community members can rank and comment on Interop proposals, enabling influence on browser developer priorities.

• Some features require clarification and consensus before being accepted as focus areas (24:34)

• Preload and resource timing implementation inconsistencies illustrate the complexity of agreeing on specification clarity and test coverage.
• Discussions at TPAC aim to resolve such ambiguities, potentially relegating unclear items to exploratory investigation tracks.
• Participants noted that spec changes risk breaking implementations, so consensus-driven incremental improvements are preferred.

TPAC Meeting Preparation and Strategy

• TPAC is positioned as a key milestone to drive decisions, gather broad feedback, and accelerate web performance and interoperability efforts.
• TPAC will consolidate many biweekly discussions into focused sessions with 20-40 participants per meeting (29:21)

• The Web Performance Working Group’s agenda is nearly full, covering interoperability, container timing, declarative performance observer, and more.
• TPAC provides an opportunity for deep, multi-day focused discussion and more concrete decision-making than regular calls.
• Nic Jansma and Yoav Weiss emphasized TPAC’s role in setting direction and prioritizing next steps for features like navigation timing and speculative load measurement.

• Community input on use cases and ergonomics is highly valued to guide working group priorities (36:28)

• Yoav Weiss explained that concrete feedback on real-world problems with APIs helps working groups shape specs and implementations.
• Prioritization discussions are more relevant to browser teams’ internal resourcing, while the working group benefits from detailed community use cases.
• Barry Pollard encouraged contributors to add detailed comments and use cases on GitHub issues rather than just upvoting, as this drives more meaningful engagement.

• Pre-reads and distributed feedback ahead of TPAC can improve efficiency and focus during sessions (40:14)

• Yoav proposed distributing summary documents to avoid lengthy reviews during the meeting and focus on feedback and decisions.
• Nic Jansma agreed to coordinate sharing agenda links and explanatory material in Slack for the RUM CG and Web Performance groups.
• Cliff Crocker suggested simple polls or Slack discussions to gauge community priorities as complementary signals to GitHub issue feedback.

• RUM CG chairs will prepare and share TPAC session summaries with links and context within a week to support community review (43:49)

• Nic Jansma and Yoav Weiss committed to guiding community members to provide feedback on key topics before TPAC, roughly 12 days away.
• Barry Pollard is actively adding relevant links and resources to the agenda to facilitate this preparation.

RUM RUM Community Event and Meeting Cadence

• RUM RUM is planned as a key in-person event to foster collaboration and share insights, with adjustments to the regular meeting schedule.
• RUM RUM 2026 will be held November 18th at Google offices in Amsterdam, one day before Perf Now (04:50)

• Barry Pollard is assisting with event logistics, aiming to replicate or improve on last year’s successful gathering.
• Registration is free, and as of the meeting, 74 attendees have signed up, signaling strong community interest.
• The agenda is still tentative but will include browser team updates and discussions on web performance topics.

• The November RUM CG meeting will be skipped in favor of the RUM RUM event, with the next regular meeting planned for December (07:22)

• December’s meeting remains tentative due to holiday schedules and participant availability.
• RUM RUM offers a unique chance for face-to-face interaction, enhancing community bonding and progress on shared goals.

• RUM RUM will also serve as a forum to share TPAC outcomes and continue ongoing discussions on interoperability and agent identity (48:59)

• Nic Jansma and Barry Pollard plan to bring back insights from TPAC to the community at RUM RUM.
• The event will allow direct feedback exchange and potentially influence working group priorities.

Agent Identity Challenges and Discussions

• Agent identity remains a complex issue with many unknowns, requiring further exploration and clearer use cases.
• Current browsers largely do not self-identify, making it hard to distinguish human users from automated or agent-driven browsing (49:59)

• Yoav Weiss highlighted the difficulty in measuring what portion of traffic is agentic, complicating user experience analysis.
• The community expressed a need for declarative signals indicating whether traffic is human or AI/agent-driven to improve measurement accuracy.

• Use cases and definitions remain fuzzy, especially regarding the agency and representation of user experience (51:12)

• Sergey Chernyshev noted the challenge of interpreting browser activity that may not reflect real user interaction.
• Differentiation between co-browsing, headless scenarios, and hybrid models adds complexity to identity solutions.

• There is tension between transparency and risk, as agents fear being blocked if they reveal themselves (51:25)

• Yoav pointed out the paradox where non-identifying agents risk being blocked unfairly, while identifying may lead to deliberate blocking.
• Discussions at TPAC may help clarify approaches and ecosystem incentives around agent identity.

• RUM CG sees potential value in identifying agent-driven browsers due to their possibly higher conversion or goal completion rates (53:11)

• Nic Jansma suggested that agentic traffic might be more focused and valuable, offering a rationale for prioritizing such signals in measurement.
• This perspective could influence how RUM data is interpreted and how agents are treated in analytics.

• There is interest in broadening the discussion to include mobile apps and other non-browser agents as part of the identity conversation (54:16)

• Sergey raised the point that mobile apps are often excluded from RUM discussions but share similar measurement challenges.
• Generalizing identity and measurement frameworks could improve coverage and relevance across platforms.

Soft Navigation Data and Emerging Metrics

• New data releases and metrics continue to expand the scope and depth of web performance insights.
• Cloudflare’s recent release of soft navigation data in CrUX marks the first public availability of this metric (55:56)

• Barry Pollard announced the availability and encouraged community members to explore and provide feedback.
• This data offers new dimensions for understanding navigation experiences beyond hard load events.

• Soft navigation support is becoming increasingly important, with requests for broader adoption by analytics vendors and platforms (55:56)

• Barry suggested that more customers request soft nav data support, indicating growing market demand.
• RUM RUM is expected to include presentations or discussions on soft nav insights and their implications.

• RUM CG plans to integrate these new metrics into ongoing performance discussions and tooling (56:24)

• Barry indicated potential RUM RUM sessions focusing on soft navigation and related performance topics.
• This reflects the group’s commitment to staying current with evolving measurement capabilities.

Action items

Nic Jansma

• Prepare and post TPAC session summaries and pre-read links to the RUM Community Group Slack and mailing list to encourage community feedback ahead of TPAC (44:04)
• Ensure participation or observation in TPAC agent identity breakout sessions and related discussions to represent RUM CG interests (46:45)

Nic Jansma and Yoav Weiss

• Collaborate to guide RUM Community Group members towards relevant TPAC materials and GitHub issues for pre-event review (43:48)

RUM Community Group members

• Review and provide concrete feedback and use cases on key Interop and Web Performance Working Group proposals, especially those listed on Mozilla feedback tool, before TPAC sessions (21:40)
• Encourage community to provide detailed comments and use cases on GitHub issues related to Interop features and web performance enhancements discussed (38:22)

Web Perf group and RUM Community Group

• Consider triaging open Web Platform Tests pull requests to clear backlog and assist with test maintenance, potentially involving the Web Perf group (20:17)

Barry Pollard

• Share link to slides and related materials about speculation rules and agenda with the group (26:42)
• Present insights and data on soft navigation at the RUM RUM event in Amsterdam (56:35)

Nic Jansma and co-chairs

• Facilitate Slack polls or other simple feedback mechanisms for RUM Community Group prioritization of TPAC topics (42:12)