Per moq-lite Lite-03 (kixelated/moq `rs/moq-lite/src/lite/priority.rs`),
`Publisher::serve_group` calls `priority.insert(track.priority,
sequence)` and feeds the resulting position into `stream.set_priority`.
Priority sorts first by `track.priority u8` (higher track = drains
ahead under congestion), then by group `sequence` within a track
(newer = drains ahead).
Pre-fix we passed raw `sequence.toInt()` directly to setPriority,
ignoring the per-track byte. For our single-Opus-track production case
this was unobservable — newer-first ordering held by sequence
monotonicity — but a future multi-track broadcast (audio + companion
catalog / status track) would have starved the lower-rate track the
moment audio's outbound queue got congested.
Fix: add `trackPriority: Int = DEFAULT_TRACK_PRIORITY` parameter to
`MoqLiteSession.publish()`, store on PublisherStateImpl, and bit-pack
in `openGroupStream`:
bits 31..24 trackPriority u8 (0..255)
bits 23..0 sequence low 24 bits
The 24-bit sequence window is ample (≈ 6 days at 1 group/sec, beyond
which all newer groups within a single track tie — but they still
beat older groups of any LOWER-priority track via the top byte).
Production sessions cycle on JWT refresh every 9 min, so the wrap is
defensive only.
`DEFAULT_TRACK_PRIORITY = 0x80` matches the existing subscriber-side
DEFAULT_PRIORITY midpoint, so all existing call sites keep their
prior behavior.
Test seam: `FakeWebTransport.openUniStream` now records the most-
recent `setPriority` value via a shared `AtomicInteger` cell that the
peer-side `FakeReadStream` exposes as `lastSetPriority`. Lets the new
regression test verify the bit-pack formula on the actual peer-side
read stream rather than peeking into private state.
Regression test:
`MoqLiteSessionTest.publisher_packs_trackPriority_and_sequence_into_setPriority_value`.
Audit doc: nestsClient/plans/2026-05-09-moq-lite-rfc-compliance.md (M1).
https://claude.ai/code/session_012TGfo99Ugz7fcCPv85a8Tq
Claude
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