moq-lite-05: make Timescale/Timestamp mandatory; drop one-sided field prefixes

[kixelated]

What changed

moq-lite: Timescale & Timestamp are now mandatory

Every Track has a media timeline. Timescale MUST be non-zero, and the per-frame Timestamp Delta (FRAME) and per-datagram Timestamp (datagram body) are now unconditional on the wire.

• Removed the Timescale == 0 case that omitted the timestamp fields — endpoints no longer have to handle both present/absent variants.
• A Timescale of 0 is now a protocol violation (subscriber resets the Subscribe/Fetch stream).
• Expiration is always timestamp-based. The only remaining wall-clock fallback is the empty-group case (a group with zero frames structurally carries no timestamp).

moq-lite: dropped Publisher/Subscriber prefix on one-sided fields

The prefix now appears only where the same base name exists on both sides.

• Publisher Timescale → Timescale
• Publisher Compression → Compression
• Subscriber Max Latency → Max Latency
• Priority and Ordered keep the prefix (both Publisher/Subscriber variants exist and the prioritization rules/example rely on the distinction).
• Wire format unchanged by the rename. Released-version (-03/-04) changelog entries keep their original field names; a -05 bullet documents the rename.

moq-timestamp extension: graceful degradation instead of mandatory

moq-transport objects are independently droppable, so the extension keeps the optional/fallback posture (the inverse of moq-lite).

• Removed SETUP negotiation entirely — the properties are self-describing KVPs, and the IANA Setup Option registration is dropped.
• A missing Timescale defaults to 1000 (milliseconds); an object with no Timestamp falls back to wall-clock arrival time.
• Documented that the object Timestamp is absolute, not delta-encoded, because moqt provides no reliable per-object delivery within a group/subgroup — a delta would be corrupted by any lost predecessor.

Reviewer notes

• The two drafts are intentionally asymmetric: moq-lite mandates timestamps on the wire (reliable in-group frame ordering), while the moqt extension degrades gracefully (independently droppable objects). Flagging in case you'd prefer them to read more alike.
• IANA in moq-timestamp now has a gap (0x915C0 TIMESCALE, 0x915C2 TIMESTAMP) where the setup option 0x915C1 used to sit. Harmless given the deliberately sparse values; can renumber to close it if preferred.
• Both drafts build clean via make (kramdown-rfc + xml2rfc OK).

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[coderabbitai]

Caution

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Walkthrough

Two IETF draft documents are updated. In draft-lcurley-moq-lite.md, every Track's Timescale is now required to be non-zero; receiving a zero value triggers a protocol-violation reset. The expiration model is rewritten to derive group age from per-frame timestamps and Timescale, with a wall-clock fallback only for groups containing zero frames. Several field names are renamed: Subscriber Max Latency → Max Latency in SUBSCRIBE/SUBSCRIBE_UPDATE; Publisher Timescale/Publisher Compression → Timescale/Compression in TRACK_INFO and FRAME. Wire-format diagrams for DATAGRAM Body and FRAME are adjusted to reflect these changes. In draft-lcurley-moq-timestamp.md, the extension is made self-describing without SETUP negotiation: absent TIMESCALE defaults to 1000 ms, a zero value is invalid and treated as 1000 ms, and absent TIMESTAMP uses wall-clock arrival time as effective time. The MOQT Setup Options IANA registration table is removed.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the moq-lite changes: mandatory Timescale/Timestamp fields and removal of one-sided prefixes.
Description check	✅ Passed	The description clearly matches the PR changes and objectives, including moq-lite mandatory timestamps and the moq-timestamp fallback behavior.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch claude/admiring-black-116af1

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