Play and stop a pattern from a behavior #336

Patterns gets a section on playing one in a game, Behaviors a line on
the two nodes, Development the new check count.

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

Behaviors.md

@@ -260,6 +260,8 @@ the inspector).
   direction; every play is a voice of its own, so two in a row overlap, and the voice ends with the
   behavior that started it unless `detached` says otherwise), `Play note` (one note of an
   instrument, its parameters from an `Instrument parameters` node, see [Instruments](Instruments)),
+  `Play pattern` / `Stop pattern` (a whole pattern through its instrument, looped or once, owned
+  like a sound, see [Patterns](Patterns#playing-one-in-a-game)),
   `Load scene` (swaps the running scene once the frame is over — see [Scenes](Scenes)), `Log`, `Stop game`, `Restart game`,
   `Pause game`, `Resume game`, `Set time scale` with the data nodes `Is game paused` and `Time scale` (see [Concepts](Concepts), *The game pauses itself*),
   `Apply force`, `Apply impulse`, `Set velocity`, `Set angular velocity`, `Set gravity` (see [Physics](Physics)),

Development.md

@@ -18,7 +18,7 @@ php tests/php/accounts.test.php                               # the API's accoun
                                                               #   has and the web server's container has not (SKIP there)
 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
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1796 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1799 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

@@ -97,9 +97,40 @@ Measured (2026-10-06, e2e 64 on the CI's Windows machine): bar 1 of a pattern at
 at ticks 720, 960, 1440 and 1680 were planned exactly 0, 0.25, 0.75 and 1 s apart on the audio
 clock; a note drawn at tick 1800 while it played came in the next round with the playing going on.
 
+## Playing one in a game
+
+**Play pattern** plays a pattern through its instrument, at the pattern's own tempo, on the same
+scheduler as the tab. It plays the **whole pattern** from its first bar to its end: the loop set on
+the ruler is only for editing.
+
+| Input | |
+|---|---|
+| `pattern` | The pattern asset. |
+| `volume` | 0 to 1, how loud every note of it is next to its velocity. |
+| `loop` | On (the default): round and round until it is stopped. Off: once, and it is over by itself when its last note has ended. |
+| `detached` | As for a sound: off, the pattern belongs to the object of the behavior and stops when that object is destroyed; on, it outlives it. |
+
+It gives out `playback`, the number of this playing, and 0 where the pattern has no instrument or
+no notes. Firing it twice plays the pattern twice, overlapping. Its files are loaded first, so the
+first note may come a moment later, but always in time with the ones after it.
+
+**Stop pattern** stops every playing of the pattern it names, and every pattern where it names
+none (sounds play on). With `playback` connected it stops only that one, and nothing where it is 0.
+Its notes fade out in 10 ms; with **Let ring** a note of an instrument with an
+[Envelope](Instruments#envelopes) falls away in its release. `Stop sound` reaches patterns as well:
+naming no sound it stops everything, patterns included, and its `voice` takes a `playback`. The end
+of the run stops every pattern.
+
+This is a step ahead of songs: a song (#334) will play several patterns on tracks, and a game will
+play a song (#336). A pattern has no tempo input in the game yet, and nothing tells a graph that a
+pattern played once has ended.
+
+Measured (2026-10-06, e2e 64): a bar of quarters at 150 BPM played by `Play pattern` in a game was
+planned 0.4 s apart, round and round, owned by the behavior; stopping the game ended it, and played
+once it was gone by itself after its bar.
+
 ## Not yet
 
 No notes of other patterns in the background (ghost notes, with the song, #334), no lanes for
 pitch bend or an instrument's parameters (automation, #337), no swing. The computer keyboard does
-not play notes in this tab as it does in the Instrument tab, and there is no step input. A game
-can not play a pattern yet (#336).
+not play notes in this tab as it does in the Instrument tab, and there is no step input.