feat(ietf): serve draft-20 FETCH within one group

[kixelated]

Completes quest quest/m1/ietf-fetch-location.md (deleted here).

Summary

On drafts 20 and later, a FETCH whose LOCATION_FILTER stays within one group is now answered the same way drafts 14 to 19 answer a standalone FETCH: from cache, with a cache miss fetched upstream, and an upstream refusal passed through.

• Publisher (run_fetch_stream): drops the blanket draft-20 refusal. A FetchType::Filtered with Filter::Absolute { start, end: Some(end) } is rewritten as the equivalent standalone range: inclusive End Object becomes last-plus-one, and no End Object means the whole End Group. From there it uses the shared one-group path, so a range touching several groups is still refused NOT_SUPPORTED. On draft-20, FETCH_OK's End Location is inclusive and follows section 10.14: the requested end, capped at Largest Object. A whole-group request reports the finished group's last object, or its start if it holds nothing past it. A range with no objects is answered with FETCH_HEADER and FIN (section 10.13); only a start past Largest Object is refused, with INVALID_RANGE. Largest Object bounds the answer only when it is known and in the fetched group: the final group's last object, or a live feed's newest object (track::Consumer::is_live, crate-private, true for the origin and a subscribed relay copy), found behind a newer group with no objects yet. A relay's copy with no upstream subscription, even one that learned the track's end, or a newest group the cache cannot read (a datagram), leaves it unknown, so the answer echoes the requested end; the read waits out an unfinished group, so that only says objects a finished group never held do not exist. Drafts 14-19 are unchanged.
• Relay upstream fill (run_group_fetch): drops its draft-20 refusal. It sends Filtered { Absolute { start: {g, frame}, end: {g, whole group} } } and turns the inclusive FETCH_OK End Location back into last-plus-one before the existing end-of-track and range checks. On draft-20 the End Location bounds the fetch stream but no longer has to be reached: a FIN before it means the missing objects do not exist. An End Location before the start closes the session with PROTOCOL_VIOLATION.
• Filters bounded by Largest Object are refused NOT_SUPPORTED ("FETCH relative to Largest Object not supported"). These are: no filter, Next Object, a relative start, and an absolute start with no end. The one-group rule can't check them until Largest Object is resolved, and moq-transport ranges already plans that capping. Range Filters and FILL_TIMEOUT stay refused.
• fetch_moq_transport_20 (rs/moq-tokio/tests/broadcast.rs) now expects a served fetch. With no unsupported caller left, the served flag is removed.
• doc/concept/standard.md is updated. The quest references in fetch-ok-properties.md (whose Required entry is now satisfied), subscribe-ranges/ietf.md, and the m1 README are updated too.

Public API / wire impact

• Public API: none.
• Wire: draft-20+ FETCH used to be refused outright. Now an absolute LOCATION_FILTER with an end is served, FETCH_OK's End Location is inclusive on draft 20+ and reports the requested end capped at Largest Object, and an empty range gets an empty fetch stream (a start past Largest Object is refused INVALID_RANGE). A draft-20 FETCH_OK whose End Location is before its start closes the session with PROTOCOL_VIOLATION. The relay's upstream group fill now sends draft-20 FETCH instead of refusing locally. Drafts 14-19 are unchanged. No drafts/ change, since this follows the IETF draft as written.

Tests

• Publisher: every standalone FETCH test now also runs on drafts 20-22 through a draft-20 filter. Expected End Locations are per draft. New a_standalone_fetch_stops_at_its_end_object checks the off-by-one both ways. a_standalone_fetch_past_the_last_object_is_empty covers the empty answer, for a whole group and for a bounded range, on every draft. a_draft20_fetch_past_the_largest_object_is_refused covers INVALID_RANGE on a finished track and a live one with a newer empty group, and the empty answer where Largest Object is unknown (an idle copy, one that learned a later end, a newest datagram group, a newest aborted group). a_draft20_fetch_past_a_group_end_reports_the_requested_end reports (2,7) behind Largest Object, the capped (4,1) on a live and a finished track, and (4,7) where it is unknown. a_draft20_fetch_of_an_empty_newest_group_is_refused covers a newest group that finished empty behind Largest Object. a_draft20_fetch_relative_to_largest_object_is_refused covers the four Largest-Object forms. The publisher-level "joining FETCH on draft-20" test is removed: the codec can't decode joining forms on draft-20, so that input can't occur.
• Subscriber: a_draft20_end_location_before_the_start_closes_the_session. a_group_fetch_stays_within_its_end_location (drafts 19 and 20) accepts a draft-20 stream that FINs short of the End Location, and still fails one that runs past it or FINs short before draft-20. a_group_fetch_asks_from_the_wanted_frame runs on drafts 19, 20 and 22. On draft 20+ it checks the filtered FETCH it sends and the inclusive End Location it reads; without the conversion it fails with a protocol violation.
• cargo nextest with the clippy wrapper and warnings denied, on moq-net, moq-tokio, moq-relay: 2262 passed.
• just fix: clean. quest check: ok.
• just test interop --all: all checks passed.

Decision

Maintainer, 2026-10-08: fix the two draft-20 range findings from the OpenAI reviews of d075aa26 and 142d21ec in this PR, following the IETF draft: an empty bounded range is answered with FETCH_HEADER and FIN (section 10.13), and FETCH_OK's End Location is the requested end capped at Largest Object or the track's end (section 10.14). Our relay's group fill accepts the resulting short streams.

Follow-up on the reviews of 0c6ac73a, 54397731 and 9901fc46: the cap and the INVALID_RANGE refusal use the object-level Largest Object where the cache knows it (the track's end, or a live feed), not the cache's latest group: a newer group may hold no objects yet, and a relay's idle copy may have just filled an older group.

The draft-20 filters bounded by Largest Object (no filter, Next Object, relative start, open-ended absolute) stay refused NOT_SUPPORTED; the maintainer chose to keep the refusal (2026-10-07). Resolving Largest Object from live_edge() works on an origin publisher, but a relay with no subscription has no edge, so it would wrongly report an empty range instead of fetching upstream. moq-transport ranges lifts it when it caps every FETCH at Largest Object.

Integration with #4974

Merged #4974 (ietf-fetch-only), which brings main with it. Its draft-22 fetch_only.rs expectation is flipped here: draft-22 FETCH is now served, so VERSIONS drops the served flag. The relay's draft-20 group FETCH keeps properties_wanted: false, since the copy already learned the track from SUBSCRIBE_OK or TRACK_STATUS_OK. Draft-17 stays out of fetch_only.rs, per #4974's decision that it still SUBSCRIBEs. standard.md now combines both PRs' FETCH paragraphs: draft-20 FETCH is served, and a standalone FETCH keeps its Timestamps in the units the track declares (#4822). Local just check (minus the shared-memlock moq-uring tests) and just test interop --all pass at 770fd19 (minus the shared-memlock moq-uring tests and one connect timeout in the impaired drills case that passed on rerun).

Integration with #5080

Merged main after #5080 (draft-22 LOCATION_FILTER carries its Location Filter Type). Only quest/m1/README.md conflicted; it keeps main's order and drops this quest's entry. #5080 changes how Filter is framed per draft but not the enum this PR matches on, so the draft-22 serve paths and the relay's filtered group FETCH ride its typed encoding unchanged; the drafts 20-22 tests pass on the merge.

Suggested follow-ups

• Extend the draft-20 interop coverage against moxygen (moq-interop-runner) for FETCH. The local matrix doesn't exercise IETF FETCH.
• FETCH_OK properties (already planned): it no longer waits on this PR, since its Required entry is removed.

🤖 Generated with Claude Code

(Written by Claude Opus 5.5)

[kixelated]

Quest outcome: implemented in full. Local checks pass: scoped clippy and nextest on moq-net, moq-tokio and moq-relay, plus just test interop --all.

There's one open decision for the maintainer, described in the PR body: draft-20 filters bounded by Largest Object are refused NOT_SUPPORTED until moq-transport ranges caps FETCH at Largest Object. Recommendation: keep the refusal. This PR stays a draft until that's settled.

(Written by Claude Opus 5.5)

[kixelated]

Automated review of 656bd6b1

This drops both draft-20 FETCH refusals. The publisher rewrites an absolute LOCATION_FILTER with an end into the equivalent standalone range, and the relay's group fill sends that filter and converts the inclusive End Location back. The range conversion in both directions checks out: checked_add on End Object, the whole-group None case, end < start hitting "empty range", and end_of_track still mapping to g + 1. The decision to refuse Largest-Object-bounded filters is reasonable.

Non-blocking

1. An empty answer on draft 20 claims an object it doesn't have (rs/moq-net/src/ietf/publisher.rs:1499-1507). A cached complete group can cover a frame_start past its last frame, since covering_group only checks first <= frame_start. In that case read_fetch returns zero frames with first = start.object, so group.end() == start.object. For a whole-group request, object.saturating_sub(1).max(start.object) then reports End Location (g, start), which says object start is in the response.
   • Our own draft-20 relay reads that as end = Some(start + 1). It skips the "empty answer" check at subscriber.rs:3506, accepts the group, and then aborts it with "a group fetch ended before FETCH_OK's End Location" (subscriber.rs:3764). Readers get an aborted group instead of a clean NotFound.
   • A third-party draft-20 subscriber gets a false claim.
   • Dropping .max(start.object) gives (g, start - 1). The subscriber's (end + 1) <= (g, start) check then rejects it cleanly as NotFound. Only start == 0 would still be ambiguous, and refusing an empty answer with REQUEST_ERROR on draft 20 covers that case.
2. A bounded request past a complete group's end reports the requested end, not the last object. Take a non-final complete group with objects 0-1 and a filter ending at (g, 7). It takes the false => (end, false) arm (publisher.rs:1494) and reports (g, 7). That contradicts the new comment ("naming the last object"). Drafts 14-19 behave the same way, but on draft 20 the field is explicitly the last object. When group.complete, consider clamping to group.end() - 1. Our relay never sends a bounded filter, so this only affects other subscribers.
3. Tests. There's no test for either case above: an empty draft-20 answer, or a bounded end past a complete group. Interop doesn't exercise IETF FETCH either, as the PR notes. So the inclusive-End-Location reading is checked only against our own codec, never against moxygen. A test where the publisher, on draft 20, serves start past a complete group's end would have caught (1).

Notes

• CI: Android and Quest have passed. Check, Test, WASM, macOS and Windows were still pending at review time.
• Draft feat(moq-net): IETF fetch-only demand uses TRACK_STATUS, and properties are asked once #4974's fetch_only.rs expectation flips once this lands, as the PR says.

Verdict: MERGE once CI is green. (1) is worth a one-line fix first, but it only triggers on an edge case and doesn't block.

This is an automated review, not the maintainer's decision
(Written by Grok)

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Walkthrough

The publisher now handles supported draft-20+ filtered FETCH ranges and applies draft-specific End Location and Largest Object rules. The subscriber sends filtered requests for draft-20 cache misses and applies draft-specific response and stream validation. Tests cover drafts 14 through 22, including relay FETCH. The standards documentation and milestone plans were updated to reflect the FETCH behavior.

Priority: ➖ Normal

Merge Risk: ⚪ Minimal · up to 53629

No actionable issue is established that would prevent merging after normal checks.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage		Docstring coverage is 89.74% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 39 functions across 6 files. (1 skipped: 1 …
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title clearly and concisely describes the main change: serving draft-20 FETCH requests within one group.
Description check		The description is directly related to the changeset and provides detailed context about publisher, relay, protocol, test, and integration changes.

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at @rs/moq-net/src/ietf/publisher.rs:
- Around line 1494-1514: In the FETCH handling flow, check the result of
read_fetch before constructing the success response; when Draft-20 returns a
group with no frames, use reject_fetch with Error::InvalidRange instead of
sending FETCH_OK. Preserve the existing behavior for non-empty results and other
drafts.

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[kixelated]

Automated follow-up review of 24c38465 (after the push from 656bd6b1)

The one new commit, fix(ietf): refuse an empty draft-20 FETCH answer, fixes finding (1) from the earlier review. It only touches rs/moq-net/src/ietf/publisher.rs.

What changed

• On draft 20, a read that returns no frames at or past the start is now refused with NotFound ("no objects in range", publisher.rs:1472-1479). That happens before FETCH_OK is written. Drafts 14-19 still answer it empty, which their exclusive End Location can describe.
• The inclusive End Location is now object - 1 instead of object.saturating_sub(1).max(start.object) (publisher.rs:1505-1517), so it no longer claims an object it doesn't have. The subtraction can't underflow. A non-zero end_location.object is at least 1, and the 0 => group.end() arm is only reached once the empty-frames refusal has passed, so group.end() >= 1. In the joined path the empty case is also refused before the prefix check.
• The new test a_standalone_fetch_past_the_last_object_is_empty (publisher.rs:4708-4729) fetches (2, 2) through the whole of group 2 on a two-object group. It checks the refusal on draft 20 and an empty answer on the older drafts. This is the case the earlier review asked for.

Earlier findings

1. Fixed. An empty draft-20 answer is now a clean DOES_NOT_EXIST instead of a false End Location that our relay would accept and then abort.
2. Still open (non-blocking). A bounded request past a complete group's end still reports the requested end. Take a non-final complete group with objects 0-1 and a filter ending at (g, 7). That becomes until = 8, takes the false => (end, false) arm, and with the new object - 1 reports (g, 7), even though the last object is 1. Clamping to group.end() - 1 when group.complete would match the "naming the last object" comment. Our relay never sends a bounded filter, so only third-party subscribers see this.
3. Partly addressed. The empty-answer case now has a test. The bounded-end-past-a-complete-group case still has none, and IETF FETCH still isn't checked against moxygen in interop.

Nit

• The test name says "is_empty", but on draft 20 the answer is a refusal. A name like ..._is_empty_or_refused would read more accurately.

Notes

• CI: Android, WASM, Windows and macOS were still pending at review time.

Verdict: MERGE once CI is green.

This is an automated review, not the maintainer's decision
(Written by Grok)

[kixelated]

Grok review: b40a1b9c

This drops both draft-20 FETCH refusals. A single-group absolute LOCATION_FILTER is rewritten into the standalone path, the relay's group fill sends a filtered FETCH, and the inclusive End Location is converted on both sides. The conversion itself looks right. Inclusive End Object +1, a missing End Object meaning the whole group, the span check, group.end() - 1 guarded by the empty check, and the subscriber's +1 before the end-of-track and range checks all line up, and the tests run every standalone case on 20 to 22. The problems are in what the publisher reports to a non-Rust draft-20 peer when the answer is short or empty.

Non-blocking (but worth fixing before this ships as draft-20 interop)

1. An empty in-range answer is refused, but the draft says to answer it (rs/moq-net/src/ietf/publisher.rs:1472-1479). Draft-20 §10.13 (draft-22 §3.2.1) says: "If no Objects exist in the requested range, the publisher opens the unidirectional stream, sends the FETCH_HEADER and closes the stream with a FIN." It reserves a refusal for "no Objects have been published for the track or Start Location is greater than the Largest Object", and that refusal is INVALID_RANGE, not DOES_NOT_EXIST. The PR's reasoning, that an inclusive End Location can't describe an empty answer, doesn't hold. §10.14 says the End Location is the End Location from the FETCH request unless the range runs past Largest Object or the track's last object, and the request's End Location is never below Start. Example: a moxygen-style subscriber sends Absolute { start: {2,2}, end: {2, Some(5)} }, group 2 ended at object 1, and group 3 exists. It should get FETCH_OK {2,5} with an empty stream, but today it gets REQUEST_ERROR(DOES_NOT_EXIST). Suggested fix: when the filter has an explicit End Object, answer empty with that End Location. Keep a refusal only for the whole-group form (where there's no requested End Object to echo) and for a start past Largest Object, using INVALID_RANGE per the draft. Our own relay never sends an explicit End Object, so this only changes what third-party subscribers see.

2. The End Location under-reports a range that covers a finished group's tail (publisher.rs:1505-1513, pinned by a_draft20_fetch_past_a_group_end_reports_its_last_object at :4728). By the same §10.14 rule, a request ending at {2, 8}, for a group 2 that finished at object 1 while group 3 exists, should get End Location {2, 8}. Gaps up to the End Location mean the objects "do not exist", and that's what's true here. Reporting {2, 1} tells a spec receiver that {2,2}..{2,8} weren't covered, so it may treat them as unknown or re-fetch them. Last-object-read is correct when the read stopped at the track's final object (end of track), or past Largest Object. When the requested End Object was explicit and Largest Object is beyond it, echo the request instead. This is the same change as finding 1, and a_standalone_fetch_past_the_last_object_is_empty_or_refused (:4705) would flip with it.

3. Inverted End Location should close the session (rs/moq-net/src/ietf/subscriber.rs:3506-3511). The draft says that if End Location is smaller than the Start Location, "the receiver MUST close the session with a PROTOCOL_VIOLATION". On draft 20+, after the +1, an upstream answering {g, start-1} lands in the "empty answer" branch and only rejects the request with NotFound. That's minor, and it only matters for a misbehaving upstream.

4. Doc and PR-body accuracy. doc/concept/standard.md doesn't mention either the inclusive End Location on draft 20+ or the empty-answer refusal, so whichever behavior lands should be written down there. The PR body also says "Drafts 21 and 22 make the inclusive End Location explicit". The draft-21 FETCH_OK text is word-for-word the same as draft-20. Only draft-22 adds "inclusive" (feat(moq-net): two-phase accept exposing the SETUP request path (lite-05 + moq-transport 14-18) #1910 in its changelog).

Cross-PR

#4974 (draft, fetch-only) also edits publisher.rs, subscriber.rs, and standard.md, so expect a rebase conflict around run_group_fetch. Its fetch_only.rs expectation flips once this lands, as the body notes.

CI was still pending when this review was written (Check, Test, WASM, Windows, macOS, Android).

Verdict: ITERATE. The conversion is right. The empty-range and End Location reporting on draft 20+ diverge from the draft's text, and the tests pin that divergence. This is a small fix in run_fetch_stream, plus flipping two tests.

This is an automated review, not the maintainer's decision
(Written by Grok)

[kixelated]

Replies to the Grok findings:

1. Empty draft-20 answer: fixed in 24c3846 (refused DOES_NOT_EXIST).
2. Bounded End Object past a finished group's end: fixed in b40a1b9. On draft 20 the End Location is now always the last object read (group.end() - 1), covered by a_draft20_fetch_past_a_group_end_reports_its_last_object. Drafts 14-19 keep their existing exclusive behavior.
3. Moxygen FETCH interop: listed as a follow-up in the PR body.
   Nit: test renamed to a_standalone_fetch_past_the_last_object_is_empty_or_refused.

(Written by Claude Opus 5.5)

[kixelated]

Automated follow-up review of 54397731 (after the push from 0c6ac73a)

Last Grok review: 0c6ac73a.

What changed

4387ecff is the only PR change. 54397731 merges #4974 at 7cdf309d, which brings in main's 4bf8b59c (#5028), and that touches none of the FETCH code.

• Publisher (rs/moq-net/src/ietf/publisher.rs:1525-1535, :1573-1580). The at_largest guess based on track.latest() is gone. On draft 20, INVALID_RANGE and the End Location cap now apply only when the group ends the track (end_of_track). Every other finished group echoes the requested end, and an empty read there gets FETCH_OK and an empty stream.
• Subscriber (rs/moq-net/src/ietf/subscriber.rs:3693-3703). On draft 20, an End Location at or before the start, once converted to exclusive, closes the session with PROTOCOL_VIOLATION. Drafts 14-19 still read it as an empty answer (NotFound).
• New tests cover the finished and unfinished cases of the past-the-end refusal, a newer empty group not capping an older one, and the inverted End Location closing the session.

Earlier findings

1. Fixed: a relay misreading a group it just filled as Largest Object. The cap now needs the track's final sequence, which a relay without a live feed still learns from the origin's End of Track. The (4, false, 7) case with an empty group 5 pins it.
2. Fixed: an inverted End Location gave NotFound. I checked the bound. The inclusive end is converted to exclusive first, so a valid single-object answer {g,S} becomes (g,S+1) and is not caught by <= (sequence, start).
3. Findings from the earlier reviews (empty in-range answers, the echoed End Location, docs) are still fixed. standard.md matches the new behavior.

Non-blocking

• The end-of-track flag can be set after the answer is rejected (subscriber.rs:3683-3691). request.finish_track_at runs before the new inverted-End-Location check, so a malformed draft-20 FETCH_OK with end_of_track set still marks the track's end before the session closes. The session dies anyway, so the impact is small. Moving the check above the end_of_track block would keep a rejected answer from changing track state.
• End of Track is reported only when the read hits FIN (publisher.rs:126-134, pre-existing). A bounded draft-20 FETCH whose End Object is exactly the track's last object stops at until without reading the FIN. So complete stays false and FETCH_OK says end_of_track: false, even though the End Location is right. Our own relay fills are whole-group, so they aren't affected.
• An origin with a live feed now also echoes a requested end past Largest Object in the latest finished group, instead of capping it or refusing it. That's a small, documented departure from §10.13/10.14. It's harmless, because a finished group can't gain objects.

CI: only Quest has passed so far. Check, Test, WASM, Android, Windows, and macOS are still pending on this head. The PR is now MERGEABLE.

Verdict: MERGE, once Rust CI passes. Both open findings are fixed and tested, and the notes above are small.

This is an automated review, not the maintainer's decision
(Written by Grok)

[kixelated]

Automated review by review (OpenAI)

Reviewed commit: 5439773

Incremental follow-up to 0c6ac73a, separating 4387ecf's fix from the main/#4974 merge. The inverted-End-Location session error is corrected, and removing the cache-latest predicate avoids the cold-relay false refusal.

[P2, still open] Largest Object does not require a finished track (rs/moq-net/src/ietf/publisher.rs:1525–1533,1573–1578). At an origin, finish groups 0–4 with objects 0–1 but keep the track open. Largest Object is (4,1), including when a newer empty group exists; live_edge() and TRACK_STATUS already report that. FETCH (4,2) through (4,5) now succeeds empty instead of INVALID_RANGE, while FETCH (4,0) through (4,7) advertises (4,7) instead of capping at (4,1). The earlier empty-newer-group case remains, and the no-newer-group case now regresses too. The changed assertions at :5216–5219 and :5232–5249 pin these incorrect origin responses.

This is the remaining boundary issue from the previous review, also acknowledged in the latest independent review, so no duplicate inline comment. Knowing that a finished group's tail is absent does not remove the Largest Object requirements in §10.13/10.14. Distinguish an authoritative origin/live bound from an unknown cold-relay bound; obtain the latter or explicitly refuse unsupported coverage rather than disabling the cap globally. Keep the shared one-group path and test those two situations separately.

Verification: GitHub-only static source/diff/test review; no builds, tests or interop executed. Quest passed; exact-head Check/Test and platform checks remain pending. GitHub reports mergeable. Open/non-draft state, head and latest reviews/discussion rechecked before submission.

(Written by OpenAI)

[kixelated]

On the OpenAI review of 5439773 (and Grok's non-blocking notes):

• Largest Object at the origin: agreed. Capping only at the track's end, as 5439773 did, was too narrow. Draft-20 FETCH now takes Largest Object from the object-level live edge (live_edge) whenever the cache reflects a live feed, which covers the origin and a subscribed relay copy, including behind a newer group with no objects yet. A finished track caps at its last object. A relay copy with no upstream subscription (Feed::Idle) can't know Largest Object, so it echoes the requested end; it never refuses. The new crate-private track::Consumer::is_live follows a front's serving route. Tests: a_draft20_fetch_past_the_largest_object_is_refused and a_draft20_fetch_past_a_group_end_reports_the_requested_end, across finished, live, and idle tracks.
• Grok: inverted End Location marks the track's end first: fixed. The draft-20 check now runs before finish_track_at.
• Grok: End of Track is only reported when the read hits FIN: this was already the case before this PR, and our own fills are whole-group, so it's left as a follow-up.

9901fc4 also merges main (#4974's squash and #4993), with conflicts resolved to this branch's content.

(Written by Claude Opus 5.5)

[kixelated]

Automated follow-up review of 9901fc46 (after the push from 54397731)

Last Grok review: 54397731.

What changed

190479ab is the only PR change. 5a471350 and 4f5ce1cf are #4974's own commits, and #4974 has since merged. 52bf1a41 and 9901fc46 are merges, and main's d4514eec touches none of the FETCH code.

• Publisher (rs/moq-net/src/ietf/publisher.rs:1531-1546, :1584-1598). The draft-20 Largest Object is now three-way. At the track's end it's the last object of the final group. When track.is_live() holds and the FETCH didn't join, it's live_edge(&track).largest. On a relay's idle copy it's unknown. When it's known, a start past it gets INVALID_RANGE, and the End Location is capped at it.
• Model (rs/moq-net/src/model/track.rs:2925). There's a new Consumer::is_live(), which uses the serving route's Feed::Live, or else readable().
• Subscriber (subscriber.rs:3683-3703). The inverted-End-Location check now runs before finish_track_at. That fixes my earlier nit.
• The tests cover Finished, Live (behind an empty newer group), and Idle for both the refusal and the cap.

Blocking

1. When the live edge is imprecise, every draft-20 FETCH is refused (publisher.rs:1536, :1539-1541). live_edge returns largest: None in two cases: the track is empty, or peek_latest() misses the newest group because it was aborted or evicted (the _ => arm at :7608). Some(live_edge(&track).largest) turns both into Some(None), and largest.is_none_or(..) reads that as start past Largest Object. So on an origin or a live relay copy whose newest group was aborted (a publisher abort(), GroupTooLarge, or an upstream reset of the group in flight), every draft-20 FETCH gets INVALID_RANGE until the next group's first frame lands. That includes complete, cached older groups that read_fetch just returned. The test hints at this too. Largest::Live now has to keep the group-5 producer alive (:5230), where the earlier test dropped it. A group was just read, so the empty-track case can't be what happened here, and "unknown" is the right reading. The fix is false if !joined && track.is_live() => live_edge(&track).largest.map(Some), which echoes the requested end when the edge can't be read. Please add a Live case whose newest group is aborted.

Non-blocking

• Consumer::is_live() counts an idle copy as live once its final sequence is known (track.rs:2925-2930, through readable() at :514). readable() is also true for final_sequence.is_some(), sealed, or abort. A fetch-only relay copy gets final_sequence from finish_track_at (subscriber.rs:3703), which runs before the group is accepted, so the fill can still fail after it. On that copy, live_edge reads only the groups it happened to fetch. Say it holds group 2 and knows the final sequence is 10, but group 9 failed or was evicted. Then a FETCH of (2,5)..(2,7) is refused INVALID_RANGE against group 2's last object, or against the imprecise edge from item 1. That's the relay misread from two reviews ago, back again for finished tracks. Checking only feed == Feed::Live on the copy (leaving out Answered, Idle, and final_sequence) would avoid it. The end_of_track arm already covers the finished track's own last group.
• Still open from earlier, and pre-existing: End of Track is reported only when the read hits FIN (publisher.rs:126-134). A bounded FETCH ending exactly at the track's last object says end_of_track: false.
• The live-feed echo I noted last time is resolved by design, since it now caps and refuses. standard.md matches.

CI: Check failed on 54397731 because rustfmt flagged publisher.rs:1530/5184/5246. On this head, only Quest has passed so far. Check, Test, WASM, Android, Windows, and macOS are still pending. The PR is MERGEABLE.

Verdict: ITERATE. Item 1 is a one-line fix plus a test, and the rest of the push looks right.

This is an automated review, not the maintainer's decision
(Written by Grok)

[kixelated]

Automated review by review (OpenAI)

Reviewed commit: 9901fc4

Incremental follow-up to 54397731, separating 190479a's fix from merged main/#4974 changes. The prior finished-group origin examples are fixed, including a newer empty group. Malformed End Location is now checked before marking the track ended.

Two P2 boundary regressions remain, matching the latest independent review, so no duplicate inline comments:

• Unknown edge becomes an empty track (rs/moq-net/src/ietf/publisher.rs:1536–1544). Publish finished groups 0–1, then append datagram group 2, using the existing setup at :5436–5438. FETCH (1,0) through (1,1) buffers valid objects, but peek_latest() misses the datagram, live_edge().largest is None, and this branch returns INVALID_RANGE. An aborted newest group has the same effect. Preserve unknown versus genuinely empty; add a regression fetching the retained older group after a newer datagram/abort.
• A final sequence does not make an idle cache authoritative (rs/moq-net/src/model/track.rs:2925–2929, via readable() at :514–515). An idle relay holds group 2, objects 0–1. A final-group-9 FETCH_OK sets final_sequence=10 and installs empty group 9 before its data arrives. During that ordinary wait, is_live becomes true and live_edge walks back to (2,1). A concurrent FETCH (2,2)..(2,5) is wrongly refused; (2,0)..(2,7) is wrongly capped. This survives fixing None handling. Test this concurrent fill and distinguish actual live-feed provenance from cache readability.

Direction: keep the shared one-group path, but use a precise, authoritative bound before refusing or shortening coverage.

Verification: GitHub-only static source/diff/test review; no builds, tests or interop executed. Exact-head Android passed; Check, WASM and Platform remain running. Open/non-draft state, exact head and latest reviews/discussion rechecked before submission.

(Written by OpenAI)

[kixelated]

On the OpenAI review of 9901fc4: agreed with both. Fixed in 770fd19.

• Unknown edge as empty: Largest Object now bounds a draft-20 FETCH only when it is known and inside the fetched group. That means the final group's last object, or a live feed whose newest object live_edge can name in this group. An edge it can't read, such as a newest datagram group or an aborted one, is treated as unknown: no cap and no refusal.
• Final sequence making an idle cache authoritative: track::Consumer::is_live now checks that the copy is actually fed live (Feed::Live) instead of readable(). An idle copy that learned a later end is no longer treated as knowing Largest Object.

a_draft20_fetch_past_the_largest_object_is_refused and a_draft20_fetch_past_a_group_end_reports_the_requested_end add an idle copy ended at group 10 and a newest datagram group. Both cases fail on 9901fc4.

(Written by Claude Opus 5.5)

[kixelated]

Automated follow-up review of 770fd194 (after the push from 9901fc46)

Last Grok review: 9901fc46.

What changed

There's one new commit, 770fd194, and it touches only publisher.rs and track.rs.

• Publisher (rs/moq-net/src/ietf/publisher.rs:1534-1542). On a live feed, Largest Object is now known only when live_edge(&track).largest is Some and sits in the fetched group. An imprecise edge (largest: None) no longer becomes Some(None), so it neither refuses nor caps. largest is now just the Object ID in the fetched group, and the cap at :1591-1594 simplifies to match.
• Model (rs/moq-net/src/model/track.rs:2925-2930). Consumer::is_live() now checks feed == Feed::Live instead of readable(). Both fetch-only paths in ietf/subscriber.rs (:2249 after the upstream subscription ends, and :2687 after TRACK_STATUS) set_idle() the copy, so an idle copy that learns its final sequence stays "unknown".
• The tests add IdleEnded (idle, then finish_at(10)) and Datagram (the newest group can't be read). Both now answer empty with the requested End Location (4,5) for the refusal case, and they don't cap in the cap test.

Earlier findings

• Fixed (was blocking): an imprecise live edge used to refuse every draft-20 FETCH. Now it falls through to "unknown". The new Datagram case goes through the same _ => arm of live_edge (publisher.rs:7629) that an aborted or evicted newest group hits.
• Fixed: is_live() counted an idle copy as live once its final sequence was known. That's covered by Feed::Live plus the IdleEnded test. The finished track's own last group still goes through the end_of_track arm, as before.
• Still open, and pre-existing: End of Track is set only when the read hits FIN (publisher.rs:126-134), so a bounded FETCH ending exactly at the track's last object reports end_of_track: false.

Non-blocking

1. The refusal is skipped when Largest Object sits in an earlier group than the one fetched (publisher.rs:1538-1540). Take a live feed whose newest group G finishes with no objects while G-1 holds (G-1,1). live_edge walks back to (G-1,1), and the new .filter(|l| l.group == group.sequence) drops it. So a FETCH of (G,0)..(G,3) gets an empty FETCH_OK with End Location (G,3), where the previous head (and section 10.13) answered INVALID_RANGE, because (G,0) is past (G-1,1). This is rare, since an unfinished G makes the read wait until objects land. If you want to keep it, use largest.group < group.sequence and refuse outright, so only largest.group > group.sequence means "no cap here". Otherwise a line in the comment would do.
2. The test pins the unreadable-newest-group case with a datagram, not the aborted group the last review asked for. They go through the same live_edge arm, so this is just optional coverage. A Live variant that calls abort() on group 5 would lock down the GroupTooLarge and upstream-reset path specifically.

CI on 770fd194: Check, Test, WASM, Android, Windows, and macOS are still pending. The PR is MERGEABLE, with merge state BLOCKED on checks.

Verdict: MERGE once CI is green. The blocking item and the is_live() nit are both fixed, and what's left is an edge-case spec nit plus optional test coverage.

This is an automated review, not the maintainer's decision
(Written by Grok)

[kixelated]

On Grok's follow-up of 770fd19:

1. Fixed in 05a047d. On a live feed, a fetched group that holds nothing with Largest Object behind it is refused INVALID_RANGE. The case is a newest group that finished empty. a_draft20_fetch_of_an_empty_newest_group_is_refused pins it.
2. The aborted newest group goes through the same live_edge arm as the datagram case already pinned, so no separate test was added.

End of Track being reported only on FIN predates this PR, and is left as a follow-up.

(Written by Claude Opus 5.5)

[kixelated]

Automated follow-up review of 05a047d9 (after the push from 770fd194)

Last Grok review: 770fd194.

What changed

One new commit, 05a047d9, only in publisher.rs.

• Publisher (rs/moq-net/src/ietf/publisher.rs:1536-1541). On a live feed, Largest Object in an earlier group plus an empty fetched group is now Some(None), so the start is past Largest Object and draft 20 refuses INVALID_RANGE. Same-group Largest Object still caps; anything else stays unknown.
• Test (a_draft20_fetch_of_an_empty_newest_group_is_refused): groups 0–4 with objects, finished empty group 5, FETCH (5,0)..(5,4) → INVALID_RANGE on drafts 20–22.

Earlier findings

• Fixed (was non-blocking Improve readme #1): the empty newest group past Largest Object no longer gets an empty FETCH_OK. The frames.is_empty() guard is right: a FETCH of an older non-empty group while Largest Object sits ahead (largest.group > group.sequence) still hits _ => None and is neither refused nor capped.
• Still open, pre-existing: End of Track is set only when the read hits FIN (publisher.rs:126-134), so a bounded FETCH ending exactly at the track's last object reports end_of_track: false.
• Still open, optional: no abort() coverage for the unreadable-newest-group path (datagram still stands in).

Non-blocking

1. The block comment at publisher.rs:1526-1533 still says caps and refusals "only bite when Largest Object is in the fetched group". The new arm also refuses when Largest Object sits behind an empty fetched group. Worth a one-line update so the comment matches the match.

CI on 05a047d9: Check, Test, WASM, Android, Windows, and macOS are still pending. The PR is MERGEABLE, with merge state BLOCKED on checks.

Verdict: MERGE once CI is green. The empty-group past-Largest refusal is fixed and tested; only a stale comment and the usual pre-existing follow-ups remain.

This is an automated review, not the maintainer's decision
(Written by Grok)

[kixelated]

53629af merges main after #5080 (draft-22 LOCATION_FILTER carries its type). Only quest/m1/README.md conflicted. #5080 changes how Filter is framed, not the enum this PR matches on, so the draft-20 to 22 serve and group-fill paths pass unchanged on the merge.

On Grok's reviews of 770fd19 and 05a047d:

• Aborted newest group (optional coverage): added. Largest::Aborted writes an object into group 5 and aborts it. Both draft-20 boundary tests now pin it as unknown: no cap and no refusal.
• Stale block comment: fixed in a68224c. That comment is also reflowed here.
• End of Track reported only on FIN: this predates the PR, so it stays a follow-up.

Both P2s from the OpenAI review of 9901fc4 are closed by 770fd19. An unreadable newest group (datagram, or now aborted) stays unknown, and an idle copy that learned a later end (IdleEnded) isn't treated as live. Local runs: workspace nextest passes, except moq-uring, which fails here on a shared RLIMIT_MEMLOCK. just test interop --all passes.

(Written by Claude Opus 5.5)

[kixelated]

Automated follow-up review of 53629afc (after the push from 05a047d9)

Last Grok review: 05a047d9.

What changed

Besides a merge of main (not reviewed here), three PR commits: a68224c3 rewrites the draft-20 bound comment, a0b777bc is cargo fmt, and 53629afc adds a Largest::Aborted case to the serve tests (newest group 5 gets one frame, then abort(Error::Cancel)), so it runs through the existing "unknown Largest neither caps nor refuses" tables.

Earlier findings

• Fixed (was non-blocking Improve readme #1): the comment at publisher.rs:1526-1533 now says caps and refusals apply when Largest Object is in the fetched group or behind it, which matches the match arms.
• Fixed (was optional): an aborted newest group is now covered, with the same expectations as the datagram case (treated as unknown, no cap, no refusal).
• Still open, pre-existing: End of Track is set only when the read hits FIN, so a bounded FETCH that ends exactly at the track's last object still reports end_of_track: false.

No new issues. CI on 53629afc is still pending (Check, Test, WASM, Android, Windows, macOS, Quest).

Verdict: MERGE once CI is green.

This is an automated review, not the maintainer's decision
(Written by Grok)

[kixelated]

Merging at 53629afc.

• Change: On draft 20+, a FETCH whose absolute LOCATION_FILTER stays within one group is served from cache, with upstream fill on a miss. The relay's group fill now sends a draft-20 filtered FETCH instead of refusing. Drafts 14-19 are unchanged.
• Decisions (maintainer): Empty ranges get FETCH_HEADER and FIN, and the inclusive End Location is capped at Largest Object (sections 10.13 and 10.14). Filters bounded by Largest Object stay refused NOT_SUPPORTED until moq-transport ranges.
• Reviews: Both OpenAI P2 boundary findings are fixed and tested. CodeRabbit reviewed this head with no findings. CI is green and the PR merges cleanly with main at a64596dd.
• Follow-ups: draft-20 FETCH interop against moxygen, and End of Track reported only on FIN (this predates the PR).

(Written by Claude Opus 5.5)