moq-streaming-format: declare WAI as a MoQ streaming format #85

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dcharlot merged 1 commit from wai/moq-streaming-format into main 2026-09-10 12:21:10 -04:00

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2026-09-10

Transaction Science

moq-streaming-format: declare WAI as a MoQ streaming format ...

WAI already references MoQ for confidentiality (MLS + SFrame), and that binding
treats MoQ as a pipe. MoQ is not a pipe — it is a two-layer design, and the upper
layer has an open slot exactly where a container of capability-dispatched objects
belongs.

MOQT moves objects in groups on tracks and does not know what an object means.
MSF (draft-ietf-moq-msf) says what objects mean: it fragments a stream into
objects, declares what a publisher emits in a catalog, and sets prioritisation.
The alignment with WAI is structural rather than aspirational — MSF's unit is an
object in a group, WAI envelopes are already objects, and jwp-receipts already
commits per object and signs per group. Neither layer has to change to agree.

THE SLOT IS OPEN, AND CHEAPLY. MSF's `packaging` field has a fixed value set and
no central registry, which reads closed. draft-ietf-moq-cmsf shows it is not: a
sibling I-D that declares packaging value `cmaf`, says it extends the allowed
values defined in MSF, inherits MSF wholesale, adds two track-level catalog
fields, and registers nothing — "this document has no IANA actions". LOCMAF is a
second instance. A sibling draft, no registry action, no permission sought.

What CMSF did NOT take is the per-object slot. MSF §12 defines properties at
Track AND Object scope with an IANA type registry holding essentially one entry
(MSF_COMPRESSION); CMSF defines no per-object property. §5 takes that slot with
WAI_RECEIPT — content hash, joules, acquisition class, group-receipt hash — which
is the shape jwp-receipts already has. `acquisition` MUST accompany
`joules_micro`, because a joule figure without its acquisition class is what
energy-measurement §2 forbids, and putting it on a wire does not make it
acceptable.

The load-bearing rule is §3: the object boundary MUST be the envelope boundary.
That is what makes MOQT's object identity and the receipt's per-object commitment
the same unit. If they diverge, every guarantee that composes them is void.

§4 makes the catalog do work rather than decorate: `wai_capabilities` MUST be
exhaustive, a sink MUST NOT subscribe assuming an undeclared capability will not
appear, and `wai_determinism` is the WEAKEST tier on the track — declaring the
strongest would let a track advertise a guarantee most of its objects do not
meet.

§6 states what this does not do, so it is not re-argued: no MOQT wire encoding,
no replacement for CMSF or LOC, no making MoQ WAI's transport, and no pinning of
a draft revision. MOQT is pre-Last-Call; where it and this text disagree, MOQT
wins and this text is what changes.

Ingest queue item 13b from the landscape survey (#80 §4.4). Sourced from direct
reads of draft-ietf-moq-msf and draft-ietf-moq-cmsf-00.

Co-Authored-By: Claude Opus 5 <[email protected]>

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