feat(scene)!: pin moq-mux's decoupled playout clock (moq-dev/moq#8272)

README.md

@@ -303,15 +303,15 @@ best video and audio its catalog lists, switches when the catalog changes, and
 comes back on its own when the publisher restarts.
 
 A broadcast source, a guest's included, plays on its publisher's timestamps,
-so its sound and picture stay in sync through network jitter and stalls. Its
-audio plays as far behind what arrives as the network's jitter needs, measured
-as it goes, the same delay `moq play --delay auto` holds, up to 2 s. Each
-picture waits for the sound stamped with it, and the canvas shows the last one
-meanwhile. A sound stall longer than that delay pauses the picture too and
-starts both again together; a picture stall leaves the sound playing. A burst
-after a stall skips ahead to the delay. Without audio, the
-picture plays 100 ms behind. Sources shows how far behind each broadcast
-plays.
+so its sound and picture stay in sync through network jitter. It plays as far
+behind what arrives as the network's jitter needs, measured as it goes as
+`moq play --delay auto` does, plus 50 ms to hand its sound to the mix, up to
+2 s in all. Sound and picture each
+keep that schedule on their own: a sound stall leaves the picture playing,
+and the sound comes back on the clock, skipping what it missed; a picture
+stall leaves the sound playing, with the canvas showing the last picture
+meanwhile. Without audio, the picture plays 100 ms behind. Sources shows how
+far behind each broadcast plays.
 
 ### Audio scenes
 

quest/m0/pin-main.md

@@ -3,8 +3,9 @@
 ## Goal
 
 The `moq` submodule is at moq's `main` as of the day this quest starts, and
-`just ci` passes on it. Every breaking change between `644d48996` (where
-[pin-sync](/quest/m0/pin-sync.md) leaves it) and that commit is fixed in one
+`just ci` passes on it. Every breaking change between `644d48996`
+([moq-dev/moq#8272](https://github.com/moq-dev/moq/pull/8272), where the
+studio's pin sits) and that commit is fixed in one
 PR, so each later wait-gated pin moves past only its own upstream change.
 
 ## Plan
@@ -36,7 +37,3 @@ On 2026-11-09, moq's `main` (`103052ed0`) was 117 first-parent commits past
 Each change's PR has an Impact section with the migration. If an upstream
 change a pin waits for is already on `main` when this starts, this PR also
 does that pin's work and deletes the pin quest.
-
-## Required
-
-- [moq-mux's decoupled playout clock is pinned](/quest/m0/pin-sync.md) - the playout rewrite onto `moq_mux::sync`, which this builds on