Describe baking a pattern or song (#340)

- Songs: a section Baking, what is in a bake and what stays live, when
  it holds, the loop, the file and its memory, measured in e2e 64.
- Patterns: Play pattern plays a bake that holds, with a link there.
- Architecture: bake and ogg in core/music, bakeRender, the bake voice
  and the offline library in viewport, BakeButton in editor/music.
- Development: 1928 checks.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Architecture.md

@@ -170,7 +170,10 @@ src/core/music/        time (ticks, 480 to the quarter, tempo and meter, a posit
                        plays on, mute and solo as gates), mixer (the master bus and `mix:<id>`), needs (a
                        sound FX with its parameters, or none), playbacks (what a sequence loads before it
                        plays), embedded (#355: what a song keeps to itself), ghosts (#339: the notes around a
-                       pattern item), take (#342: a recorded take as 16-bit WAV, cut to where the song started)
+                       pattern item), take (#342: a recorded take as 16-bit WAV, cut to where the song started),
+                       bake (#340: what a bake is made from as a print, where the parts of its file lie, how they
+                       are put together from the playing looped and the one played once, and played back) +
+                       ogg (#340: Opus in Ogg, the pages around an encoder's packets and back)
 src/core/soundfx/      the sound FX graph (#311): nodes (every effect and what it adds to a plan), compile (the
                        graph walked back from the Output to a plan; a parameter stays open until a voice
                        starts; a tapped node gets a `tap` in front and behind, #374), parametricEq (#367:
@@ -247,7 +250,10 @@ src/viewport/          WorldViewport (the drawing of a world or a holder, the ba
                        voice of what reaches its Output, each way with its own file, #331; a voice can start and
                        be released at a second of the audio clock, #332; a clip of a song from a second into its
                        sound until its end, a bus per track of a song with its level and pan, #334; the buses of
-                       the mix and the Master routing, #325/#351), music (the scheduler on
+                       the mix and the Master routing, #325/#351; a bake as one voice on the master of its
+                       playing, and a library of its own on an offline context to bake with, #340; a channel
+                       probe that says whether a bake is mono), bakeRender (#340: a pattern or song played
+                       offline, what reaches its master taken, encoded as Opus with WebCodecs), music (the scheduler on
                        the library's clock, its notes played by the project's instruments and its clips by
                        the library: the player of the Pattern and Song tabs, #333/#334, and `__gm.music`) + musicTimer
                        (the Web Worker whose interval is the scheduler's beat, #332), takeRecorder + takeWorklet
@@ -383,13 +389,14 @@ src/editor/curve/      CurveEditor (header: Preset, the picked point's type, Pre
                        graph drawn from curveValue, points and handles edited with the vector art gestures, the
                        preview dot and its rail) + curveView (the curve laid onto a picture for those gestures and
                        read back, a point held between its neighbours, a point put down on free space)
-src/editor/pattern/    PatternEditor (header: Play, Grid; plays through the scheduler and follows edits, #333),
+src/editor/pattern/    PatternEditor (header: Play, Grid, Bake; plays through the scheduler and follows edits, #333),
                        PianoRoll (keys, ruler, notes and velocity lane in one widget, the gestures and keys) +
                        rollView (its geometry: rows, hits, bands) + rollEdit (what a gesture does to the notes)
 src/editor/music/      timeView (the time axis: ticks to pixels, zoom, the lines of bars, beats and grid) + TimeRuler
                        (bars, loop, start and playhead) — for the piano roll and the song tab — + transport (one
-                       piece plays at a time: a song or a pattern, #334)
-src/editor/song/       SongEditor (header: Play, Grid; plays through the scheduler, sets the tracks' buses and
+                       piece plays at a time: a song or a pattern, #334) + BakeButton (#340: bakes the pattern
+                       or song shown, lit while its bake holds)
+src/editor/song/       SongEditor (header: Play, Grid, Bake; plays through the scheduler, sets the tracks' buses and
                        follows edits, #334), SongTimeline (heads, ruler and lanes in one widget, dropping assets
                        in, the gestures and keys) + songView (its geometry: tracks, items and their ends, the
                        parts of a head) + songEdit (what a gesture does to the items) + songActions (deleting

Development.md

@@ -19,7 +19,7 @@ php tests/php/accounts.test.php                               # the API's accoun
 php tests/php/snapshots.test.php                              # the snapshot store (#231), the same way
 php tests/php/releases.test.php                               # the release store (#266), the same way
 php tests/php/files.test.php                                  # uploaded files in a folder per account (#344), the same way
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1922 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1928 editor checks, screenshots in /tmp/gm-e2e-*.png
 GM_STEPS=20 node tools/e2e.mjs                                # or 1-12, or 6,20 — a subset while working on one step
 ./e2e.sh start [GM_STEPS]                                     # the same run detached, see below
 ./e2e.sh status                                               # live progress, or the last run's result

Patterns.md

@@ -173,6 +173,10 @@ Its notes fade out in 10 ms; with **Let ring** a note of an instrument with an
 naming no sound it stops everything, patterns included, and its `voice` takes a `playback`. The end
 of the run stops every pattern.
 
+A pattern can be **baked** with the icon in the header of its tab (#340): `Play pattern` then plays
+the bake, one voice of a file, in place of its notes, as long as nothing it is made of has changed.
+The tab plays the notes. See [Baking](Songs#baking).
+
 To play several patterns and sounds together, lay them out in a [song](Songs) and play that with
 [Play song](Songs#playing-one-in-a-game). A pattern has no tempo input in the game yet, and nothing
 tells a graph that a pattern played once has ended.

Songs.md

@@ -348,6 +348,55 @@ there, played by `Play song` at 120 BPM: the clip once, the pattern's notes 2 s
 left sat inside it at 0.501 and -0.5. The toolbar's pause held the clock, and `Stop song` with a
 fade of 1 s ended it, its buses with it.
 
+## Baking
+
+**Bake** (#340), the icon with a wave in a frame in the header of the Song and the
+[Pattern](Patterns) tab, works out once what the song or pattern plays and keeps it on the asset as a
+file. `Play song` and `Play pattern` in a game then play that file instead of every note: one voice
+in place of many, and nothing for the scheduler to plan. The tab itself always plays live, so an
+edit is heard at once.
+
+- **What is in it:** everything up to the output of the song or pattern. For a pattern, its notes
+  through the instrument and the instrument's sound FX. For a song, its tracks, items and clips, the
+  FX of tracks and items, the routing, mute and solo.
+- **What stays live:** everything after that: the sound FX of the node (or of the asset), `fx params`
+  and `Set sound FX parameters`, `volume`, `fade in`, the bus, the Master routing and a stop with a
+  fade. A node behaves the same with a bake and without.
+- **When it holds:** a bake keeps a print of what it was made from: the notes and clips, tempo,
+  length and loop, the tracks with their level, pan and FX, how each instrument plays each of its
+  notes with its sound FX, and the files, cuts and levels of the sounds. A change to any of them
+  outdates it, also one to an instrument or a sound the pattern only names. Then the icon is no
+  longer lit, the info of the tab says *bake outdated*, and a game plays the notes again. Renaming
+  changes nothing. An undo back to what was baked makes it hold again without baking anew. Baking
+  and removing a bake are no undo steps.
+- **Looped:** the file holds the playing straight from the start, then the loop once more as it
+  sounds the second time round, with what rings on from the first round in it. Played looped it runs
+  to the loop end and then round that second round, to the sample. Played once it runs to the end
+  and fades out over its last 10 ms. What would ring on past the end is not in it: to keep a tail,
+  make the song or pattern longer, by an empty bar for instance.
+- **Stopping:** `Stop song` and `Stop pattern` with **Let ring** fade a bake out over 0.3 s, as its
+  notes cannot ring on one by one.
+- **The click:** not baked, it bakes. While it bakes, the toolbar says how far it has got and a
+  click cancels it. Baked, it offers **Bake again** and **Remove bake**. A change made while it bakes
+  throws the result away.
+- **The file:** Opus in Ogg, 160 kbit/s in stereo, 96 kbit/s where everything reaching the output is
+  mono, encoded in the browser with WebCodecs. Baking therefore needs Chrome. Where a browser
+  cannot decode the file, a game plays the notes. It is raised to full scale and played at the
+  level it had. It goes up into the sounds of your account under *[bake] name*, and the sound picker
+  leaves it out. The old file of a bake made again or removed is deleted once the project is saved
+  without it, unless a snapshot or a release still names it.
+- **Memory:** a bake that holds is loaded and decoded with the project like a sound, at 48 kHz:
+  about 23 MB a minute in stereo. An outdated one is not loaded. Streaming it instead is #349.
+
+Measured (2026-10-09, e2e 64 on the CI's Windows machine): a bar of quarters at 150 BPM with one
+more note just before its end, baked: 76800 frames for the bar and 76800 for the second round,
+38 KB. Played offline from its notes and from its bake for 4 s, looped, the level of every 20 ms in
+which it was heard differed by at most 0.06 dB (114 windows, two loop ends among them). The game
+played it as one voice with no note planned; a note drawn outdated it, Ctrl+Z made it hold again,
+and Remove bake deleted its file once the project was saved. With the pre-skip of the Opus file
+left out on purpose, the same comparison was 4.8 dB off. In a probe, Chrome worked out 60 s of
+sound in 0.3 s, or in 2.1 s with many pitched voices, and encoded it in 0.6 s.
+
 ## Sound FX on tracks, items and whole songs
 
 A [sound FX](Sounds#sound-fx) can sit on a track, on a pattern item, and on a whole `Play pattern` or