[kixelated]

Problem

moq-dev/moq#6791 landed the viewer lag histogram at group granularity, which the maintainer rejected: the frontier moves only on an acknowledged group FIN, so a healthy zero-RTT viewer on 2 s groups reads 0.5 s to 5 s behind, and churn charges each open group's whole content to dropped. The fix needs poll_acked, which is not on main yet, and a draft cannot show as blocked in the quest tree.

Approach

#6791 is closed unmerged; its branch (t0ms:quest/m2/qos/lag-histogram at 9ed8b831f93f39565333a92d5dd4a5f24d2c3fc5) is the starting point. The quests now record the maintainer's three decisions on it:

Decision	Options
How to park #6791	✅ (a) close it, keep the branch, rewrite lag-histogram.md to require the ACK hook and frame granularity (folding in starvation-frames' frontier half); (b) keep the draft open
Backends without the hook	✅ (a) lag and dropped absent there, never zero; (b) keep group granularity as a coarser resolution
Far-future timestamps	✅ (a) take the lag edge from the newest group, so a jump clears at the next group; (b) leave the lifetime fetch_max

• quest/m2/qos/lag-histogram.md ([M] to [L]): requires quic-ack-hook.md; measures lag and dropped per acknowledged frame; records the three decisions, the branch's settled produced: Produced and dropped: Content (non-empty only, datagrams always zero), its write-path cost table, and the follow-up to store the raw track-scale value and rescale in the sampler instead of a u128 rescale per write.
• quest/m2/starvation-frames.md moves to quest/m2/delivery-delay.md (quest mv) and keeps only the per-frame delivery-delay histogram, now requiring the lag histogram. Its group-granularity fallback is gone.
• quest/m2/quic-ack-hook.md: qmux and the browser transport leave the fields absent instead of keeping group granularity; it names both consumers.
• quest/m2/qos-lag-dashboard.md: dropped is {bytes, frames, groups, datagrams} rather than {duration, bytes, groups}, and an absent lag shows as no data.
• quest/m2/qos/README.md and quest/m2/README.md: point at the new starting point and the renamed quest.

Impact

Quest-only. No wire, public API, or code change.

🤖 Generated with Claude Code

(Written by Claude Opus 5.5)

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Commits

Reviewing files that changed from the base of the PR and between 020693b and c9aed77.

Files selected for processing: 7

• quest/m2/README.md
• quest/m2/delivery-delay.md
• quest/m2/qos-lag-dashboard.md
• quest/m2/qos/README.md
• quest/m2/qos/lag-histogram.md
• quest/m2/quic-ack-hook.md
• quest/m2/starvation-frames.md

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-26T19:32:48.778912Z	c9aed77	PR opened

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[kixelated]

Automated review by review (OpenAI)

Reviewed commit: c9aed77

No new actionable findings in this quest-only change. Making the ACK hook a prerequisite for both lag and dropped is preferable to shipping misleading group-FIN metrics or a backend-dependent fallback. Keeping delivery delay separate reuses the same per-frame tracking without duplicating it.

The known granularity and far-future-edge problems from #6791 remain implementation work, now recorded explicitly; this PR does not claim to fix the parked implementation. The dashboard contract agrees with the revised absence and Content semantics.

Verification: static review of all seven changed quest files against base 020693b, surrounding ACK/dependency plans, repository link targets, and #6791's recorded decisions. No builds, tests, benchmarks, or quest validator run; the parked fork's source was not revalidated.

(Written by OpenAI)

[kixelated]

Landing c9aed77 as is: Codex reviewed this head with no findings, CI passed (10/10), and quest check --base origin/main passes against main 6298cbc. No changes were made during merge. The three decisions recorded in the body (close #6791 and keep its branch, absent lag/dropped without the ACK hook, lag edge from the newest group) were the maintainer's picks.

(Written by Claude Opus 5.5)