feat(studio)!: audio scenes replace mixes

quest/m0/README.md

@@ -94,6 +94,7 @@ repository.
 - [Wayland display and window sources](/quest/m0/wayland-sources.md) - portal-picked sources that reopen without the picker
 - [Destinations](/quest/m0/destinations.md) - RTMP, RTMPS, and WHIP push with per-destination codecs and shared encoders, on a UI-free egress library a hosted service can reuse
 - [Composable scenes](/quest/m0/scenes/README.md) - scenes nest scenes and the program, any scene publishes at its own size, and mixes become audio scenes
+- [Pan each sound](/quest/m0/audio-pan.md) - the Audio panel and `[audio.<source>]` pan each sound wherever it plays
 - [Clap-to-measure sync delay](/quest/m0/sync-clap.md) - a clap sets a microphone's delay against its camera
 - [Audio filters](/quest/m0/audio-filters.md) - per-source noise suppression, gate, compressor, limiter, and plugins, configured from the studio
 - [Browser sources on macOS and Windows](/quest/m0/browser-source.md) - the out-of-process CEF pages Linux has, with shared GPU textures on the other desktops
@@ -111,6 +112,7 @@ repository.
 - [moq-video's browser backends are pinned](/quest/m0/pin-browser-video.md) - the web studio's video slice and browser composition
 - [moq-audio's browser backends are pinned](/quest/m0/pin-browser-audio.md) - the web studio's audio slice
 - [moq-audio's source tap is pinned](/quest/m0/pin-audio-tap.md) - the samples clap-to-measure sync times a clap from
+- [moq-audio's strip pan is pinned](/quest/m0/pin-audio-pan.md) - the bus strip pan the studio's pan sets
 
 ## Related
 

quest/m0/audio-pan.md

@@ -0,0 +1,29 @@
+# [S] Pan each sound
+
+## Goal
+
+Each sound's strip in the Audio panel has a pan beside its fader, saved as
+`pan` in `[audio.<source>]` and applied wherever the sound plays, in every
+audio scene holding it, as gain, mute, and delay are. `README.md` documents
+it.
+
+## Plan
+
+Decided 2026-11-07 with the maintainer, on
+[moq-dev/studio#77](https://github.com/moq-dev/studio/pull/77), which landed
+the rest of audio scenes:
+
+- ✅ Pan is a property of the source's bus strip, like its gain, set in
+  moq-audio; the studio only sets it and saves it. Rejected: a pan per audio
+  scene a sound is sent to.
+- ✅ Settled moq-side in
+  [Pan a bus source](https://github.com/moq-dev/moq/blob/main/quest/m3/audio-strip-pan.md):
+  a constant-power law, -3 dB at center; a stereo source is balanced, the
+  far side attenuated and each channel kept where it is; a bus that is not
+  stereo refuses a pan other than center.
+- Changing pan never drops or repeats audio, ramped across a block as gain
+  is.
+
+## Required
+
+- [moq-audio's strip pan is pinned](/quest/m0/pin-audio-pan.md) - the `Strip` pan the studio sets

quest/m0/pin-audio-pan.md

@@ -0,0 +1,20 @@
+# [XS] moq-audio's strip pan is pinned
+
+## Goal
+
+The `moq` submodule includes a pan on moq-audio's bus `Strip`, from
+[Pan a bus source](https://github.com/moq-dev/moq/blob/main/quest/m3/audio-strip-pan.md).
+
+## Plan
+
+Once the wait clears, advance it with `just upgrade-moq` in its own PR,
+fixing whatever the new API breaks here.
+
+## Waiting
+
+- moq-dev/moq: the upstream quest above lands. Check: that quest's PR has
+  merged on moq's `main`, deleting its file, and `moq_audio::bus::Strip`
+  there has a pan. A quest file that moved, or went away without its work
+  landing, does not count. The quest itself is planned in
+  [moq-dev/moq#8133](https://github.com/moq-dev/moq/pull/8133), not merged
+  yet.

quest/m0/scenes/README.md

@@ -1,4 +1,4 @@
-# Composable scenes
+# [M] Composable scenes
 
 ## Goal
 
@@ -49,6 +49,7 @@ picks a picture scene and an audio scene; a scene no panel shows and no output
 reads skips drawing. Per-scene cost grows only with what that scene draws;
 `compositor::bench` measures it.
 
-## Required
-
-- [Audio scenes](/quest/m0/scenes/audio.md) - mixes become audio-only scenes that nest
+Changed 2026-11-07 with the maintainer, on
+[moq-dev/studio#77](https://github.com/moq-dev/studio/pull/77): pan left
+this epic for [its own quest](/quest/m0/audio-pan.md), since it waits on
+moq-audio, so it no longer holds up this end-to-end test.

quest/m2/publish-independently.md

@@ -18,7 +18,7 @@ rendition, as every source track does, while the program keeps its
 two sizes. It counts as used, so it encodes for as long as it is published
 (decided 2026-11-04, maintainer): a source encodes while it is on program
 (shown in a scene on air, or, for a microphone or system audio, played by the
-mix on program) or while something reads its track, and naming a published
+audio scene on program) or while something reads its track, and naming a published
 source among those on program (`Publish::set_on_program` in
 `rs/moq-scene/src/publish.rs`) keeps it encoding.
 

rs/moq-scene/src/clip.rs

@@ -7,9 +7,7 @@ use std::path::Path;
 use serde::{Deserialize, Serialize};
 
 use crate::Error;
-use crate::collection::{
-	Audio, Collection, Filter, Item, Layer, Mixes, Scene, Source, Video, validate_filters, versioned,
-};
+use crate::collection::{Audio, Collection, Filter, Item, Layer, Scene, Source, Video, validate_filters, versioned};
 use crate::edit::Draft;
 
 /// What a copy holds: items, or a filter chain.
@@ -101,13 +99,9 @@ impl Clip {
 		let clip = Self::deserialize(table).map_err(|err| Error::Format(err.to_string()))?;
 		match &clip {
 			// The rules a collection holding just the clip would break, such as
-			// an item showing a source the clip lacks. It has whatever mixes the
-			// clip's sources are left out of, and an empty scene for each its
-			// scene sources draw, which pasting checks.
+			// an item showing a source the clip lacks. It has an empty scene for
+			// each its scene sources draw, which pasting checks.
 			Self::Items(items) => {
-				let excluded = items.audio.values().flat_map(|audio| &audio.exclude);
-				let mut names: BTreeSet<String> = excluded.cloned().collect();
-				names.insert(Mixes::DEFAULT.into());
 				let drawn: BTreeSet<&str> = items
 					.sources
 					.values()
@@ -124,11 +118,6 @@ impl Clip {
 				let drawn = drawn.into_iter().map(Scene::new);
 				Collection {
 					sources: items.sources.clone(),
-					mixes: Mixes {
-						names: names.into_iter().collect(),
-						program: Mixes::DEFAULT.into(),
-						recording: None,
-					},
 					audio: items.audio.clone(),
 					video: items.video.clone(),
 					// In a scene, where keyframes play; pasting into the top
@@ -172,8 +161,8 @@ impl Draft {
 	/// one shown, so items pasted within a collection are linked to the ones
 	/// copied. A source whose name is taken by a different one is added under
 	/// a new name, which clones and filters naming it follow, and an added
-	/// source brings its audio and video settings, left out of only the mixes
-	/// both collections have. An image or LUT under `dir`
+	/// source brings its audio and video settings, its sound joining the
+	/// audio scene on program. An image or LUT under `dir`
 	/// is named relative to it, as the scene file would.
 	pub fn paste(&mut self, layer: &Layer, items: &Items, dir: &Path) -> Result<(), Error> {
 		let mut names = BTreeMap::new();
@@ -225,11 +214,10 @@ impl Draft {
 		};
 		for (name, renamed) in added {
 			if let Some(audio) = items.audio.get(name) {
-				// Left out only of the mixes this collection has too.
-				let mut audio = audio.clone();
-				let mixes = &self.collection().mixes.names;
-				audio.exclude.retain(|mix| mixes.contains(mix));
-				self.set_audio(&renamed, Some(audio))?;
+				self.set_audio(&renamed, Some(audio.clone()))?;
+			}
+			if items.sources[name].has_audio() {
+				self.hear(&renamed)?;
 			}
 			if let Some(video) = items.video.get(name) {
 				let filters = rename(&video.filters);
@@ -391,12 +379,12 @@ mod tests {
 		assert_eq!(pasted.scenes[0].items, source.scenes[0].items);
 	}
 
-	/// A pasted source keeps its sound's settings, left out of only the mixes
-	/// the collection it lands in has.
+	/// A pasted source keeps its sound's settings, and is heard on program
+	/// wherever it lands.
 	#[test]
-	fn pastes_audio_into_the_mixes_there() {
+	fn pastes_audio_into_the_audio_scene_on_program() {
 		let mut source = Collection::new();
-		source.mixes.names.push("Stream".into());
+		source.audio_scenes[0].name = "Stream".into();
 		source.sources.insert(
 			"guest".into(),
 			Source::Broadcast {
@@ -405,7 +393,6 @@ mod tests {
 		);
 		let audio = crate::Audio {
 			gain: 0.5,
-			exclude: ["Program".to_string(), "Stream".to_string()].into(),
 			..Default::default()
 		};
 		source.audio.insert("guest".into(), audio.clone());
@@ -418,11 +405,8 @@ mod tests {
 			.unwrap();
 
 		let pasted = paste(&Collection::new(), &Layer::top(), &text, DIR);
-		let expected = crate::Audio {
-			exclude: ["Program".to_string()].into(),
-			..audio
-		};
-		assert_eq!(pasted.audio["guest"], expected);
+		assert_eq!(pasted.audio["guest"], audio);
+		assert_eq!(pasted.heard(crate::AudioScene::DEFAULT), ["guest"].into());
 	}
 
 	/// A relative image path names the same file wherever the clip is pasted,