import { edge, node, port, variable, written } from '../lib/builders.mjs';
import { LANES, MAKE_OBJECT, pickAssetType } from './lib/scaffold.mjs';

/**
 * Sound assets (#45): uploaded like a typeface – picked from what the server holds through
 * "+ → Sound", or dropped onto the editor – and played by a graph through `Play sound`. Nothing
 * wears a sound and nothing places it; the asset says how loud it is and whether it loops, and the
 * node scales the one and can overrule the other in either direction.
 *
 * Nothing is ever *heard* here: CI runs the browser muted (see tools/lib/browser.mjs). The witness
 * is `__gm.sound.stats()` – voices started, stopped and in flight – the way `renderStats` is the
 * witness for a repaint that did not happen. No pixel check could see any of this.
 *
 * The seed puts two generated WAVs on the server without making assets of them: a 0.25 s blip and
 * a 0.75 s drone, told apart by their exact size rather than by their name.
 */
const LANE = LANES.sound;
const BLIP_BYTES = 4044;
const DRONE_BYTES = 12044;

export async function sound(t) {
  const { check, sleep, json, evaluate, mutate, click, clickText, press, play, stop, shot, showTab } = t;
  const { select, drag } = t;
  const assetsOfType = (type) =>
    json(`__gm.state.project.assets.filter((a) => a.type === ${JSON.stringify(type)})
      .map((a) => ({ id: a.id, name: a.name, file: a.file, props: a.props }))`);
  const stats = () => json('__gm.sound.stats()');
  /** A voice starts only once its bytes have been decoded, so what it changes is awaited. */
  const waitFor = async (read, done, tries = 25) => {
    let value = await read();
    for (let i = 0; i < tries && !done(value); i++) {
      await sleep(150);
      value = await read();
    }
    return value;
  };
  // Every reading up to the one `done` takes: a check holds each against its own time on the audio
  // clock, however late the first one comes in.
  const trace = async (read, done, tries = 40) => {
    const seen = [await read()];
    for (let i = 0; i < tries && !done(seen.at(-1)); i++) {
      await sleep(150);
      seen.push(await read());
    }
    return seen;
  };

  await press('Escape');
  await evaluate('document.activeElement instanceof HTMLElement && document.activeElement.blur()');
  await evaluate('__gm.state.select(null)');
  await showTab('scene');

  // 34a. What the server holds, straight from the API: the two files the seed put there.
  const stored = await evaluate(`fetch('/game-maker/api/index.php?r=sounds').then((r) => r.json())`);
  const blip = stored.find((item) => item.bytes === BLIP_BYTES);
  const drone = stored.find((item) => item.bytes === DRONE_BYTES);
  check(
    'the server holds the two seeded sounds, named by their content',
    Boolean(blip && drone) && /^[a-f0-9]{12}\/[a-f0-9]{64}\.wav$/.test(blip.file),
    JSON.stringify({ blip: blip?.file, drone: drone?.file, count: stored.length }),
  );
  if (!blip || !drone) return;
  check(
    'the listing carries the name each file was uploaded under',
    blip.name === 'blip.wav' && drone.name === 'drone.wav',
    JSON.stringify({ blip: blip.name, drone: drone.name }),
  );
  // A file of this run's own that no project uses, for the picker to delete (#344). Random bytes
  // behind a WAV header: the store reads the signature only, and no earlier run has the same.
  const spare = await evaluate(`(async () => {
    const bytes = crypto.getRandomValues(new Uint8Array(48));
    bytes.set([...'RIFF'].map((c) => c.charCodeAt(0)), 0);
    bytes.set([...'WAVE'].map((c) => c.charCodeAt(0)), 8);
    const r = await fetch('/game-maker/api/index.php?r=sounds&name=spare.wav', {
      method: 'POST', headers: { 'Content-Type': 'audio/wav' }, body: bytes,
    });
    return (await r.json()).file;
  })()`);

  // 34b. "+ → Sound" offers them; a sound is picked rather than created empty, like a typeface.
  await clickText('+');
  await pickAssetType(t, 'Sound');
  await sleep(500);
  const picker = await json('__gm.soundPicker()');
  check(
    'the + menu opens the sound picker on what the server holds, none of it in the project yet',
    Boolean(picker) && picker.files.includes(blip.file) && picker.used.length === 0,
    JSON.stringify(picker),
  );
  check(
    'a row nobody uses yet is captioned with the name the file was uploaded under',
    picker.captions[picker.files.indexOf(blip.file)] === 'blip.wav',
    JSON.stringify(picker.captions),
  );
  await shot('34-sound-picker');

  // 34b'. A file of one's own that no project uses goes from the picker (#344): the first press of
  //       Delete only asks, the second deletes it on the server.
  const spareRow = await json(`__gm.soundPickerRow(${JSON.stringify(spare)})`);
  await click(spareRow.x, spareRow.y);
  const marked = await json('__gm.soundPicker()');
  check(
    'a file of one’s own says whose it is and may be deleted',
    marked.selected === spare && marked.detail.includes('owner e2e') && marked.deleteButton.enabled,
    JSON.stringify({ selected: marked.selected, spare, detail: marked.detail, button: marked.deleteButton }),
  );
  await click(marked.deleteButton.x, marked.deleteButton.y);
  const armed = await json('__gm.soundPicker()');
  await click(armed.deleteButton.x, armed.deleteButton.y);
  const emptied = await waitFor(
    () => json('__gm.soundPicker()'),
    (p) => !p.files.includes(spare),
  );
  const served = await evaluate(`fetch('/game-maker/data/sounds/${spare}').then((r) => r.status)`);
  check(
    'the first press asks, the second deletes the file on the server',
    armed.deleteButton.shown === 'Delete for good' &&
      armed.files.includes(spare) &&
      !emptied.files.includes(spare) &&
      emptied.files.includes(blip.file) &&
      emptied.detail === 'Deleted spare.wav.' &&
      served === 404,
    JSON.stringify({ armed: armed.deleteButton, left: emptied.files.length, detail: emptied.detail, served }),
  );

  // 34c. The ▶ at a row's left is a preview: it plays that file without choosing it.
  const playAt = await json(`__gm.soundPickerPlay(${JSON.stringify(drone.file)})`);
  await click(playAt.x, playAt.y);
  const previewed = await waitFor(stats, (s) => s.started > 0);
  const afterPreview = await json('__gm.soundPicker()');
  check(
    'pressing a row’s ▶ plays that file and picks nothing',
    previewed.started === 1 &&
      previewed.last?.file === drone.file &&
      afterPreview.played === drone.file &&
      afterPreview.selected === null,
    JSON.stringify({ previewed, selected: afterPreview.selected, played: afterPreview.played }),
  );

  const row = await json(`__gm.soundPickerRow(${JSON.stringify(blip.file)})`);
  await click(row.x, row.y);
  await clickText('Use sound');
  const sounds = await assetsOfType('sound');
  check(
    'picking a row makes a sound asset of that file, named after the file rather than "Sound"',
    sounds.length === 1 && sounds[0].file === blip.file && sounds[0].name === 'blip',
    JSON.stringify(sounds),
  );
  if (sounds.length !== 1) return;
  const soundId = sounds[0].id;
  check(
    'a fresh sound asset is full volume and one-shot',
    sounds[0].props.volume === 1 && sounds[0].props.loop === false,
    JSON.stringify(sounds[0].props),
  );
  // Closing the picker silences its preview; nothing it started may outlive the dialog.
  check(
    'closing the picker leaves nothing playing',
    (await stats()).playing === 0,
    JSON.stringify(await stats()),
  );

  // 34d. Its inspector: the two rows, and the preview that is the only way to tell which sound it is.
  await select({ kind: 'asset', assetId: soundId });
  const volumeRow = await json("__gm.inspectorField('Volume', true)");
  const loopRow = await json("__gm.inspectorField('Loop', true)");
  check(
    'a sound asset has a Volume row and a Loop row',
    Boolean(volumeRow) && Boolean(loopRow),
    JSON.stringify({ volumeRow, loopRow }),
  );
  await shot('34-sound-asset');

  // 34e. A graph plays it. The behavior sits in its own lane; the node's volume is a factor on the
  //      asset's, so 0.5 × 0.4 has to reach the library as 0.2 rather than as either of the two.
  await mutate(`
    const p = __gm.state.project;
    const scene = __gm.state.activeScene;
    p.assets.find((a) => a.id === ${JSON.stringify(soundId)}).props.volume = 0.4;
    const asset = structuredClone(p.assets.find((a) => a.id === 'mover'));
    Object.assign(asset, {
      id: 'sn-logic',
      name: 'Noisy',
      props: { enabled: true, runInEditor: false },
      variables: [],
      graph: ${JSON.stringify({
        nodes: [
          node('sn-start', 'OnStart', 0, 0),
          node('sn-play', 'PlaySound', 260, 0, { sound: soundId, volume: 0.5, loop: '' }),
        ],
        edges: [edge('sn-e1', 'sn-start', 'exec', 'sn-play', 'exec')],
      })},
    });
    p.assets.unshift(asset);
    ${MAKE_OBJECT}
    scene.objects.push(
      make('sn-box', 'crate', '', ${LANE}, 'Noisy box'),
      make('sn-brain', 'sn-logic', 'sn-box', 0, 'Noisy'),
    );
    __gm.lookAt(0, ${LANE});`);

  await evaluate('__gm.sound.stopAll()');
  const before = await stats();
  await play();
  const played = await waitFor(stats, (s) => s.started > before.started);
  check(
    'a graph playing a sound reaches the library, at the asset volume scaled by the node’s',
    played.started === before.started + 1 &&
      played.last?.file === blip.file &&
      Math.abs(played.last.volume - 0.2) < 0.001 &&
      played.last.loop === false,
    JSON.stringify(played),
  );
  await stop();

  // 34f. A looping sound is music: it plays on, and ending the run ends it – nothing may outlive
  //      the world that started it.
  await mutate(`
    const p = __gm.state.project;
    p.assets.find((a) => a.id === ${JSON.stringify(soundId)}).props.loop = true;`);
  await play();
  const looping = await waitFor(stats, (s) => s.playing > 0 && s.last?.loop === true);
  check(
    'the asset’s own loop flag reaches the library even though the node never asked for one',
    looping.playing >= 1 && looping.last?.loop === true,
    JSON.stringify(looping),
  );
  // Well past the blip's own 0.25 s, so a one-shot would have ended by itself here.
  await sleep(700);
  const stillLooping = await stats();
  await stop();
  const afterStop = await stats();
  check(
    'a loop keeps playing while the run is on and ends with it',
    stillLooping.playing >= 1 && afterStop.playing === 0,
    JSON.stringify({ stillLooping, afterStop }),
  );

  // 34f-2. The node overrules the asset in both directions – the reason `loop` is a choice of three
  //        and not a checkbox: music has to be playable as a one-shot.
  const setNodeLoop = (value) =>
    mutate(`
      const p = __gm.state.project;
      const graph = p.assets.find((a) => a.id === 'sn-logic').graph;
      graph.nodes.find((n) => n.id === 'sn-play').params.loop = ${JSON.stringify(value)};`);
  await setNodeLoop('false');
  const beforeOnce = await stats();
  await play();
  const once = await waitFor(stats, (s) => s.started > beforeOnce.started);
  check('a node saying "off" plays a looping asset once', once.last?.loop === false, JSON.stringify(once));
  await stop();
  await setNodeLoop('');

  // 34g. `Stop sound` silences it from inside the graph, without ending the run.
  await mutate(`
    const p = __gm.state.project;
    const graph = p.assets.find((a) => a.id === 'sn-logic').graph;
    graph.nodes.push(${JSON.stringify(node('sn-stop', 'StopSound', 520, 0, { sound: soundId }))});
    graph.nodes.push(${JSON.stringify(node('sn-key', 'OnKeyDown', 260, 220, { key: 's' }))});
    graph.edges.push(${JSON.stringify(edge('sn-e2', 'sn-key', 'exec', 'sn-stop', 'exec'))});`);
  await play();
  await waitFor(stats, (s) => s.playing > 0);
  await press('s');
  const silenced = await waitFor(stats, (s) => s.playing === 0);
  check(
    'Stop sound silences a looping sound while the run carries on',
    silenced.playing === 0 && (await json('__gm.playInfo()')).playing === true,
    JSON.stringify(silenced),
  );
  await stop();

  // 34g-2. A voice belongs to the behavior playing it: destroy the object and its sounds go with it,
  //        without any `Stop sound` in the graph. `detached` is the one way out, for the death
  //        sound of an object that destroys itself.
  await mutate(`
    const p = __gm.state.project;
    const graph = p.assets.find((a) => a.id === 'sn-logic').graph;
    graph.nodes.push(
      ${JSON.stringify(node('sn-key2', 'OnKeyDown', 260, 440, { key: 'd' }))},
      ${JSON.stringify(node('sn-owner', 'Owner', 260, 620))},
      ${JSON.stringify(node('sn-destroy', 'Destroy', 520, 440))},
    );
    graph.edges.push(
      ${JSON.stringify(edge('sn-e3', 'sn-key2', 'exec', 'sn-destroy', 'exec'))},
      ${JSON.stringify(edge('sn-e4', 'sn-owner', 'object', 'sn-destroy', 'object'))},
    );`);
  await play();
  await waitFor(stats, (s) => s.playing > 0);
  await press('d');
  const destroyed = await waitFor(stats, (s) => s.playing === 0);
  check(
    'destroying the object silences the looping sound its behavior was playing',
    destroyed.playing === 0 && (await json('__gm.playInfo()')).playing === true,
    JSON.stringify(destroyed),
  );
  await stop();

  const setDetached = (value) =>
    mutate(`
      const p = __gm.state.project;
      const graph = p.assets.find((a) => a.id === 'sn-logic').graph;
      graph.nodes.find((n) => n.id === 'sn-play').params.detached = ${JSON.stringify(value)};`);
  await setDetached(true);
  await play();
  await waitFor(stats, (s) => s.playing > 0);
  await press('d');
  // Long enough that the reaping frame has been and gone – a voice still here now is here on purpose.
  await sleep(600);
  const detached = await stats();
  check(
    'a detached voice is nobody’s and plays on after the object that started it is gone',
    detached.playing >= 1,
    JSON.stringify(detached),
  );
  await stop();
  check(
    'ending the run silences a detached voice too',
    (await stats()).playing === 0,
    JSON.stringify(await stats()),
  );
  await setDetached(false);

  // 34g-3. A sound FX asset (#311): "+ → Sound FX" opens its tab, which says what keeps the graph
  //        from compiling; built into Input → Pitch → Gain → Output, the header plays the sound
  //        through it, and a `Play sound` naming it sends the game's voice the same way. The pitch
  //        comes from a parameter `depth` of the Input: the header has a field for it, and a
  //        `Sound FX parameters` node hands the game's value in.
  await showTab('scene');
  await clickText('+');
  await pickAssetType(t, 'Sound FX');
  const fxCreated = await json(`{
    tab: __gm.tab(),
    current: __gm.soundfx.current(),
    info: __gm.soundfx.info(),
    preview: __gm.soundfx.preview(),
    assets: __gm.state.project.assets.filter((a) => a.type === 'soundfx').map((a) => a.id),
  }`);
  check(
    'the + menu creates a sound FX asset and opens its tab, with no Output to compile and no Play',
    fxCreated.tab === 'soundfx' &&
      fxCreated.assets.length === 1 &&
      fxCreated.current === fxCreated.assets[0] &&
      fxCreated.info === 'No Output node' &&
      fxCreated.preview.sound === soundId &&
      fxCreated.preview.play === false,
    JSON.stringify(fxCreated),
  );
  const fxId = fxCreated.assets[0];
  const fxCanvas = await json('__gm.soundfx.canvasRect()');
  await click(fxCanvas.x + 80, fxCanvas.y + 60, 'right');
  const fxPalette = await json('__gm.overlayTexts()');
  check(
    'its palette offers the sound effects and no behavior node',
    ['Input', 'Output', 'Gain', 'Pitch', '5-Band-EQ', 'Mix', 'Delay'].every((label) =>
      fxPalette.includes(label),
    ) && !fxPalette.includes('Branch'),
    JSON.stringify(fxPalette.slice(0, 12)),
  );
  await press('Escape');
  await mutate(`
    const fx = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(fxId)});
    fx.name = 'Low';
    fx.graph = ${JSON.stringify({
      nodes: [
        node('fx-in', 'SoundFxInput', 0, 0, {}, [{ key: 'depth', kind: 'number', default: -12 }]),
        node('fx-pitch', 'SoundFxPitch', 220, 0),
        node('fx-gain', 'SoundFxGain', 440, 0, { gain: -6 }),
        node('fx-out', 'SoundFxOutput', 660, 0),
      ],
      edges: [
        edge('fx-e1', 'fx-in', 'out', 'fx-pitch', 'in'),
        edge('fx-e2', 'fx-pitch', 'out', 'fx-gain', 'in'),
        edge('fx-e3', 'fx-gain', 'out', 'fx-out', 'in'),
        edge('fx-e4', 'fx-in', 'depth', 'fx-pitch', 'semitones'),
      ],
    })};`);
  const fxBuilt = await json(
    '{ info: __gm.soundfx.info(), preview: __gm.soundfx.preview(), params: __gm.soundfx.params() }',
  );
  check(
    'Input → Pitch → Gain → Output compiles to two effects, Play is offered, depth starts at its default',
    fxBuilt.info === '2 effects' && fxBuilt.preview.play === true && fxBuilt.params.depth === -12,
    JSON.stringify(fxBuilt),
  );
  await evaluate('__gm.sound.stopAll()');
  const beforeFx = await stats();
  const fxPlayAt = await json('__gm.soundfx.playAt()');
  await click(fxPlayAt.x, fxPlayAt.y);
  const heardFx = await waitFor(stats, (s) => s.started > beforeFx.started);
  const blipSeconds = await json(`__gm.sound.duration(${JSON.stringify(blip.file)})`);
  check(
    'the tab’s Play sends the sound through the graph: an octave down, as long as before, one gain stage',
    heardFx.last?.file === blip.file &&
      heardFx.last.pitches.join() === '-12' &&
      heardFx.last.duration === blipSeconds &&
      heardFx.last.stages === 1,
    JSON.stringify({ ...heardFx, blipSeconds }),
  );
  await evaluate('__gm.sound.stopAll()');
  await evaluate('__gm.soundfx.setParam("depth", 5)');
  const beforeParam = await stats();
  await click(fxPlayAt.x, fxPlayAt.y);
  const heardParam = await waitFor(stats, (s) => s.started > beforeParam.started);
  check(
    'the header plays with the value its depth field is set to',
    heardParam.last?.pitches.join() === '5' && heardParam.last.stages === 1,
    JSON.stringify(heardParam),
  );
  await evaluate('__gm.sound.stopAll()');
  // #316: the Pitch → Gain way and the dry Input meet in a Mix – two sources, one per pitch.
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(fxId)}).graph;
    graph.nodes.push(${JSON.stringify(node('fx-mix', 'SoundFxMix', 550, 0, { mix: 0.5 }))});
    graph.edges = graph.edges.filter((e) => e.id !== 'fx-e3');
    graph.edges.push(
      ${JSON.stringify(edge('fx-e5', 'fx-gain', 'out', 'fx-mix', 'a'))},
      ${JSON.stringify(edge('fx-e6', 'fx-in', 'out', 'fx-mix', 'b'))},
      ${JSON.stringify(edge('fx-e7', 'fx-mix', 'out', 'fx-out', 'in'))},
    );`);
  const mixInfo = await json('__gm.soundfx.info()');
  const beforeMix = await stats();
  await click(fxPlayAt.x, fxPlayAt.y);
  const heardMix = await waitFor(stats, (s) => s.started > beforeMix.started);
  check(
    'a Mix of the pitched way and the dry Input plays one voice from two sources of the same length',
    mixInfo === '3 effects' &&
      heardMix.last?.pitches.join() === '5,0' &&
      heardMix.last.stages === 1 &&
      heardMix.last.duration === blipSeconds,
    JSON.stringify({ mixInfo, ...heardMix }),
  );
  await evaluate('__gm.sound.stopAll()');
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(fxId)}).graph;
    graph.nodes = graph.nodes.filter((n) => n.id !== 'fx-mix');
    graph.edges = graph.edges.filter((e) => !['fx-e5', 'fx-e6', 'fx-e7'].includes(e.id));
    graph.edges.push(${JSON.stringify(edge('fx-e3', 'fx-gain', 'out', 'fx-out', 'in'))});`);
  // #324, #327: a ping-pong Delay behind the gain. The blip is a quarter of a second, its echoes come
  //             0.3 s apart, each half as loud as the one before: at wet 0.5 the first is in full
  //             (#354) and ten are heard, 3 s – the voice stays that long after its sound and goes
  //             then. Asked to let ring, only the sound stops and the voice stays; a stop after that
  //             cuts it.
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(fxId)}).graph;
    graph.nodes.push(${JSON.stringify(
      node('fx-delay', 'SoundFxDelay', 550, 0, { time: 0.3, feedback: 0.5, mix: 0.5, pingPong: true }),
    )});
    graph.edges = graph.edges.filter((e) => e.id !== 'fx-e3');
    graph.edges.push(
      ${JSON.stringify(edge('fx-e8', 'fx-gain', 'out', 'fx-delay', 'in'))},
      ${JSON.stringify(edge('fx-e9', 'fx-delay', 'out', 'fx-out', 'in'))},
    );`);
  const delayInfo = await json('__gm.soundfx.info()');
  await evaluate('__gm.sound.stopAll()');
  const beforeEcho = await stats();
  await click(fxPlayAt.x, fxPlayAt.y);
  const echoStarted = await waitFor(stats, (s) => s.started > beforeEcho.started);
  // Timed on the audio clock: the page's can fall behind it (task 523 saw a 2.95 s tail end 1 s in).
  const audioNow = () => json('({ playing: __gm.sound.stats().playing, clock: __gm.sound.clock() })');
  const startedAt = (await audioNow()).clock;
  const echoLevels = await json(`__gm.sound.levels(${JSON.stringify(blip.file)})`);
  const ringing = await waitFor(audioNow, (s) => s.clock - startedAt >= 1);
  const quiet = await waitFor(audioNow, (s) => s.playing === 0, 40);
  const rangFor = quiet.clock - startedAt;
  const echoKnobs = echoLevels?.[0]?.slice(2) ?? [];
  check(
    'a Delay keeps the voice after its sound has ended, until its echoes have faded',
    delayInfo === '3 effects' &&
      echoStarted.last?.stages === 2 &&
      echoKnobs.length === 5 &&
      Math.abs(echoKnobs[0] - 0.3) < 1e-6 &&
      Math.abs(echoKnobs[1] - 0.5) < 1e-6 &&
      Math.abs(echoKnobs[2] / (20000 * 0.025 ** 0.3) - 1) < 1e-3 &&
      Math.abs(echoKnobs[3] - 1) < 1e-6 &&
      Math.abs(echoKnobs[4] - 1) < 1e-6 &&
      ringing.playing === 1 &&
      ringing.clock - startedAt < 2.4 &&
      quiet.playing === 0 &&
      rangFor > 2.4 &&
      rangFor < 4.5,
    JSON.stringify({ delayInfo, last: echoStarted.last, echoLevels, ringing, startedAt, rangFor }),
  );
  await click(fxPlayAt.x, fxPlayAt.y);
  await waitFor(stats, (s) => s.playing === 1);
  const beforeLetRing = await stats();
  await evaluate(`__gm.sound.stop(${JSON.stringify(blip.file)}, true)`);
  await sleep(500);
  const letRing = await stats();
  await evaluate(`__gm.sound.stop(${JSON.stringify(blip.file)})`);
  const cut = await stats();
  check(
    'Let ring stops the sound and keeps the voice for its echoes; a stop after that cuts it',
    letRing.playing === 1 &&
      letRing.stopped === beforeLetRing.stopped + 1 &&
      cut.playing === 0 &&
      cut.stopped === beforeLetRing.stopped + 2,
    JSON.stringify({ before: beforeLetRing.stopped, letRing, cut }),
  );
  // #354: the Delay bypassed is drawn faded and says so, and the voice plays as if it were not there.
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(fxId)}).graph;
    graph.nodes.find((n) => n.id === 'fx-delay').params.bypass = true;`);
  const bypassed = await json(
    "({ alpha: __gm.soundfx.nodeAlpha('fx-delay'), settings: __gm.soundfx.nodeSettings('fx-delay'), gain: __gm.soundfx.nodeAlpha('fx-gain') })",
  );
  const beforeBypass = await stats();
  await click(fxPlayAt.x, fxPlayAt.y);
  const heardBypass = await waitFor(stats, (s) => s.started > beforeBypass.started);
  await evaluate('__gm.sound.stopAll()');
  check(
    'a bypassed Delay is drawn faded with "Bypass: true", and the voice passes only the gain',
    bypassed.alpha < 0.5 &&
      bypassed.gain === 1 &&
      bypassed.settings?.includes('Bypass: true') &&
      heardBypass.last?.stages === 1,
    JSON.stringify({ bypassed, last: heardBypass.last }),
  );
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(fxId)}).graph;
    graph.nodes = graph.nodes.filter((n) => n.id !== 'fx-delay');
    graph.edges = graph.edges.filter((e) => !['fx-e8', 'fx-e9'].includes(e.id));
    graph.edges.push(${JSON.stringify(edge('fx-e3', 'fx-gain', 'out', 'fx-out', 'in'))});`);
  // #367: a Parametric EQ behind the gain. A double-click on the node opens its editor, one on the
  //       curve adds a peak there, a drag moves it as one undo step, the wheel narrows it, and the
  //       voice passes one filter for it.
  // #370: the editor is a tab of its own, and goes with its node.
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(fxId)}).graph;
    graph.nodes.push(${JSON.stringify(node('fx-eq', 'SoundFxParametricEq', -240, 0))});
    graph.edges = graph.edges.filter((e) => e.id !== 'fx-e3');
    graph.edges.push(
      ${JSON.stringify(edge('fx-e10', 'fx-gain', 'out', 'fx-eq', 'in'))},
      ${JSON.stringify(edge('fx-e11', 'fx-eq', 'out', 'fx-out', 'in'))},
    );`);
  const eqNode = await json("__gm.soundfx.nodeAt('fx-eq')");
  await t.doubleClick(eqNode.x, eqNode.y);
  const eqShown = await json('__gm.eq.shown()');
  const eqDocs = await json('__gm.documents()');
  const eqPeakAt = await json('__gm.eq.pointAt(1000, 6)');
  await t.doubleClick(eqPeakAt.x, eqPeakAt.y);
  const eqAdded = await json('{ bands: __gm.eq.bands(), fields: __gm.eq.fields() }');
  const bandNear = (band, hz, db) =>
    band && Math.abs(Math.log2(band.frequency / hz)) < 0.05 && Math.abs(band.gain - db) < 0.5;
  check(
    'a double-click opens the Parametric EQ in a tab, and one on its curve adds a peak there',
    eqShown?.nodeId === 'fx-eq' &&
      eqDocs.active === `eq:${fxId}:fx-eq` &&
      eqDocs.docs.includes(`asset:${fxId}`) &&
      eqAdded.bands.length === 1 &&
      eqAdded.bands[0].type === 'peaking' &&
      bandNear(eqAdded.bands[0], 1000, 6) &&
      eqAdded.fields.type === 'Peaking' &&
      eqAdded.fields.slope === null,
    JSON.stringify({ eqShown, eqDocs, eqAdded }),
  );
  const eqHandle = await json('__gm.eq.handleAt(0)');
  const eqTo = await json('__gm.eq.pointAt(4000, -6)');
  await drag(eqHandle.x, eqHandle.y, eqTo.x, eqTo.y);
  const eqDragged = (await json('__gm.eq.bands()'))[0];
  await press('z', { ctrl: true });
  const eqUndone = (await json('__gm.eq.bands()'))[0];
  await press('z', { ctrl: true, shift: true });
  const eqHandleBack = await json('__gm.eq.handleAt(0)');
  await t.wheel(eqHandleBack.x, eqHandleBack.y, -100);
  const eqWheeled = (await json('__gm.eq.bands()'))[0];
  check(
    'dragging the band moves it as one undo step, and the wheel narrows it',
    bandNear(eqDragged, 4000, -6) &&
      bandNear(eqUndone, 1000, 6) &&
      bandNear(eqWheeled, 4000, -6) &&
      eqWheeled.q > 1,
    JSON.stringify({ eqDragged, eqUndone, eqWheeled }),
  );
  await shot('34-parametric-eq');
  await evaluate(`__gm.openDocument(${JSON.stringify(`asset:${fxId}`)})`);
  await evaluate('__gm.sound.stopAll()');
  const eqBefore = await stats();
  await click(fxPlayAt.x, fxPlayAt.y);
  const eqHeard = await waitFor(stats, (s) => s.started > eqBefore.started);
  await evaluate('__gm.sound.stopAll()');
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(fxId)}).graph;
    graph.nodes = graph.nodes.filter((n) => n.id !== 'fx-eq');
    graph.edges = graph.edges.filter((e) => !['fx-e10', 'fx-e11'].includes(e.id));
    graph.edges.push(${JSON.stringify(edge('fx-e3', 'fx-gain', 'out', 'fx-out', 'in'))});`);
  const eqDocsAfter = await json('__gm.documents()');
  check(
    'the voice passes the gain and the band, and the EQ’s tab goes with its node',
    eqHeard.last?.stages === 2 && !eqDocsAfter.docs.some((doc) => doc.startsWith('eq:')),
    JSON.stringify({ last: eqHeard.last, eqDocsAfter }),
  );
  await showTab('scene');
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === 'sn-logic').graph;
    Object.assign(graph.nodes.find((n) => n.id === 'sn-play').params, { loop: 'false', fx: ${JSON.stringify(fxId)} });`);
  const beforeGameFx = await stats();
  await play();
  const gameFx = await waitFor(stats, (s) => s.started > beforeGameFx.started);
  check(
    'a Play sound naming the asset plays the game’s voice through it',
    gameFx.last?.pitches.join() === '-12' && gameFx.last.stages === 1,
    JSON.stringify(gameFx),
  );
  await stop();
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === 'sn-logic').graph;
    graph.nodes.push(${JSON.stringify(
      node('sn-fxp', 'SoundFxParameters', 0, 120, { soundFxAsset: fxId, depth: 7 }, [
        { key: 'depth', kind: 'number' },
      ]),
    )});
    graph.edges.push(${JSON.stringify(edge('sn-e-fxp', 'sn-fxp', 'params', 'sn-play', 'fxParams'))});`);
  const beforeGameParam = await stats();
  await play();
  const gameParam = await waitFor(stats, (s) => s.started > beforeGameParam.started);
  check(
    'a Sound FX parameters node hands depth 7 to the game’s voice',
    gameParam.last?.pitches.join() === '7' && gameParam.last.stages === 1,
    JSON.stringify(gameParam),
  );
  await stop();
  // #315: two looping voices of the same sound start at depth 7, the first keeps its number in a
  //       variable, and `Set sound FX parameters` hands that one voice depth 3 every frame. In a
  //       real AudioContext the first one's pitch – the AudioParam of its worklet (#317), in
  //       semitones – glides there, the second one's stays put.
  const tuneIds = ['sn-keep', 'sn-play2', 'sn-tick', 'sn-read', 'sn-tune', 'sn-fxp2'];
  const tuneEdges = [
    'sn-e-keep',
    'sn-e-voice',
    'sn-e-play2',
    'sn-e-fxp3',
    'sn-e-tick',
    'sn-e-read',
    'sn-e-fxp2',
  ];
  await mutate(`
    const logic = __gm.state.project.assets.find((a) => a.id === 'sn-logic');
    logic.variables = [${JSON.stringify(variable('voice', 'number', 0))}];
    const graph = logic.graph;
    const play = graph.nodes.find((n) => n.id === 'sn-play');
    play.params.loop = 'true';
    graph.nodes.push(
      ${JSON.stringify(node('sn-keep', 'Variables', 520, 0, {}, [written('voice', 'number')]))},
      { ...structuredClone(play), id: 'sn-play2', x: 780 },
      ${JSON.stringify(node('sn-tick', 'OnUpdate', 0, 300))},
      ${JSON.stringify(node('sn-read', 'Variables', 0, 420, {}, [port('voice', 'number')]))},
      ${JSON.stringify(node('sn-tune', 'SetSoundFxParameters', 260, 300))},
      ${JSON.stringify(
        node('sn-fxp2', 'SoundFxParameters', 0, 540, { soundFxAsset: fxId, depth: 3 }, [
          { key: 'depth', kind: 'number' },
        ]),
      )},
    );
    graph.edges.push(
      ${JSON.stringify(edge('sn-e-keep', 'sn-play', 'exec', 'sn-keep', 'exec'))},
      ${JSON.stringify(edge('sn-e-voice', 'sn-play', 'voice', 'sn-keep', 'voice'))},
      ${JSON.stringify(edge('sn-e-play2', 'sn-keep', 'exec', 'sn-play2', 'exec'))},
      ${JSON.stringify(edge('sn-e-fxp3', 'sn-fxp', 'params', 'sn-play2', 'fxParams'))},
      ${JSON.stringify(edge('sn-e-tick', 'sn-tick', 'exec', 'sn-tune', 'exec'))},
      ${JSON.stringify(edge('sn-e-read', 'sn-read', 'voice', 'sn-tune', 'voice'))},
      ${JSON.stringify(edge('sn-e-fxp2', 'sn-fxp2', 'params', 'sn-tune', 'fxParams'))},
    );`);
  const beforeTune = await stats();
  await play();
  const tunedStats = await waitFor(
    stats,
    (s) => s.tuned > beforeTune.tuned && s.started >= beforeTune.started + 2,
  );
  const glided = (levels) =>
    Array.isArray(levels) && levels.length === 2 && Math.abs(levels[0][0] - 3) < 0.05;
  const levels = await waitFor(() => json(`__gm.sound.levels(${JSON.stringify(blip.file)})`), glided);
  check(
    'Set sound FX parameters moves the one voice whose number it holds from depth 7 to 3, not the other',
    tunedStats.last?.pitches.join() === '7' &&
      tunedStats.last.loop === true &&
      tunedStats.worklet === true &&
      glided(levels) &&
      Math.abs(levels[0][1] - 10 ** (-6 / 20)) < 0.001 &&
      levels[1][0] === 7,
    JSON.stringify({ last: tunedStats.last, tuned: tunedStats.tuned, worklet: tunedStats.worklet, levels }),
  );
  await stop();
  // A `time` of 2 s takes the same voice from depth 7 to -5 evenly on the audio clock, 6 semitones
  // a second: half a second in it is still well above the end, where a quick glide would be there.
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === 'sn-logic').graph;
    graph.nodes.find((n) => n.id === 'sn-tune').params.time = 2;
    graph.nodes.find((n) => n.id === 'sn-fxp2').params.depth = -5;`);
  await play();
  const pitch = async () => (await json(`__gm.sound.levels(${JSON.stringify(blip.file)})`))?.[0]?.[0];
  const early = await waitFor(pitch, (s) => typeof s === 'number' && s < 6.9);
  const later = await waitFor(pitch, (s) => typeof s === 'number' && s < early - 0.6);
  await new Promise((resolve) => setTimeout(resolve, 500));
  const afterHalf = await pitch();
  check(
    'Set sound FX parameters with a time ramps the pitch over that time instead of jumping',
    early > -1.8 && later > -3.3 && afterHalf > -4.3 && afterHalf < later,
    JSON.stringify({ early, later, afterHalf }),
  );
  await stop();
  // The easings of an animation key: Quad in hands the clock a curve, 7 - 3 * t^2 towards -5 in 2 s,
  // where linear is 7 - 6 * t. Each reading is timed on the audio clock from the voice's start, so a
  // first one that comes in late is held against where the curve is then. Between 0.3 and 1.7 s the
  // curve is more than a semitone above linear, and it never falls below it.
  await mutate(`
    const tune = __gm.state.project.assets.find((a) => a.id === 'sn-logic').graph.nodes.find((n) => n.id === 'sn-tune');
    Object.assign(tune.params, { ease: 'quad', direction: 'in' });`);
  await play();
  const pitchNow = () =>
    json(`({ pitch: __gm.sound.levels(${JSON.stringify(blip.file)})?.[0]?.[0], clock: __gm.sound.clock() })`);
  const sinceStart = async (seen, since = 'start') => {
    const now = await stats();
    const from = since === 'tune' ? now.tunedAt : now.last.at;
    return seen
      .filter((s) => typeof s.pitch === 'number')
      .map((s) => ({ t: +(s.clock - from).toFixed(3), pitch: +s.pitch.toFixed(3) }));
  };
  const sweep = await sinceStart(await trace(pitchNow, (s) => typeof s.pitch === 'number' && s.pitch < -4.3));
  const midway = sweep.filter(({ t }) => t > 0.3 && t < 1.7);
  check(
    'Set sound FX parameters with Quad in ramps slowly first, then on to the end',
    midway.length > 0 &&
      midway.every(({ t, pitch }) => pitch > 7 - 6 * t + 1) &&
      sweep.every(({ t, pitch }) => pitch > 7 - 6 * t - 0.1) &&
      sweep.at(-1).pitch < -4.3,
    JSON.stringify(sweep),
  );
  await stop();
  // Step holds the pitch for the whole time and then jumps there: every reading before 2 s on the
  // audio clock is still 7, the first one past it is the end. Timed from the change, not from the
  // start of the voice: task 529 saw it arrive 80 ms later and the 7 held, rightly, to 2.08 s.
  await mutate(`
    const tune = __gm.state.project.assets.find((a) => a.id === 'sn-logic').graph.nodes.find((n) => n.id === 'sn-tune');
    Object.assign(tune.params, { ease: 'step', time: 2 });`);
  await play();
  const steps = await sinceStart(
    await trace(pitchNow, (s) => typeof s.pitch === 'number' && s.pitch < 6),
    'tune',
  );
  const held = steps.filter(({ pitch }) => pitch === 7);
  const jumped = steps.find(({ pitch }) => pitch < 6);
  check(
    'Set sound FX parameters with Step holds the pitch for the time, then jumps to the end',
    held.length > 0 &&
      held.every(({ t }) => t < 2.05) &&
      jumped !== undefined &&
      jumped.t > 1.95 &&
      Math.abs(jumped.pitch + 5) < 0.001,
    JSON.stringify(steps),
  );
  await stop();
  // #317: the worklet itself, rendered in an offline context of this browser – what a muted check
  //       can hear. A second of 440 Hz an octave up is 880 Hz and still a second long; a sweep from
  //       0 to -12 over it keeps that second too. Then 16 stereo voices at +5 for 2 s, timed, for
  //       how many this machine plays at once.
  const offline = await evaluate(`
    (async () => {
      const RATE = 48000;
      const render = async (voices, seconds, channels, shape) => {
        const context = new OfflineAudioContext(channels, RATE * seconds, RATE);
        await context.audioWorklet.addModule(__gm.sound.fxWorkletUrl());
        const tone = new Float32Array(RATE * seconds);
        for (let i = 0; i < tone.length; i++) tone[i] = Math.sin((2 * Math.PI * 440 * i) / RATE) * 0.5;
        for (let v = 0; v < voices; v++) {
          const node = new AudioWorkletNode(context, 'pitch-player', {
            numberOfInputs: 0,
            outputChannelCount: [channels],
            parameterData: { pitch: shape.from },
            processorOptions: { file: 'probe', channels: v === 0 ? Array(channels).fill(tone) : undefined, step: 1, loop: false },
          });
          if (shape.to !== shape.from)
            node.parameters.get('pitch').setValueAtTime(shape.from, 0).linearRampToValueAtTime(shape.to, seconds);
          node.connect(context.destination);
        }
        const started = performance.now();
        const out = (await context.startRendering()).getChannelData(0);
        return { out, ms: performance.now() - started };
      };
      const rises = (out, from, to) => {
        let count = 0;
        for (let i = from + 1; i < to; i++) if (out[i - 1] < 0 && out[i] >= 0) count++;
        return count / ((to - from) / RATE);
      };
      const heard = (out) => {
        let last = out.length;
        while (last > 0 && Math.abs(out[last - 1]) <= 1e-4) last--;
        return last;
      };
      const up = await render(1, 1, 1, { from: 12, to: 12 });
      const sweep = await render(1, 1, 1, { from: 0, to: -12 });
      const load = await render(16, 2, 2, { from: 5, to: 5 });
      return {
        upHz: rises(up.out, 12000, 36000),
        upLength: heard(up.out),
        sweepEarlyHz: rises(sweep.out, 6000, 12000),
        sweepLateHz: rises(sweep.out, 36000, 42000),
        sweepLength: heard(sweep.out),
        voices: 16,
        renderMs: Math.round(load.ms),
        realTimeVoices: Math.round((16 * 2000) / load.ms),
      };
    })()`);
  check(
    'the pitch worklet plays an octave up at the length of the sound, and a sweep down keeps it too',
    Math.abs(offline.upHz / 880 - 1) < 0.02 &&
      offline.upLength > 48000 - 100 &&
      offline.sweepEarlyHz > offline.sweepLateHz * 1.3 &&
      offline.sweepLength > 48000 - 100,
    JSON.stringify(offline),
  );
  // #327: the player's own echo, rendered offline. A 10 ms burst into a ping-pong Delay (0.3 s,
  //       feedback 0.5, mix 0.25) comes back left at 0.3 s at half its level, right at 0.6 s at
  //       half of that, left again at 0.9 s – in Chrome each round 128 samples later than that. Then
  //       64 stereo voices of it for 2 s, timed, for how many this machine plays at once (#324).
  const echo = await evaluate(`
    (async () => {
      const RATE = 48000;
      const echoOf = (pingPong) => ({ kind: 'delay', time: 0.3, feedback: 0.5, damping: 20000, mix: 0.25, pingPong });
      const render = async (voices, seconds, stage = echoOf(true)) => {
        const context = new OfflineAudioContext(2, RATE * seconds, RATE);
        const burst = context.createBuffer(1, RATE * 0.01, RATE);
        burst.getChannelData(0).fill(0.5);
        for (let v = 0; v < voices; v++) {
          const source = context.createBufferSource();
          source.buffer = burst;
          const nodes = __gm.sound.stageNodes(context, stage);
          source.connect(nodes.input);
          nodes.output.connect(context.destination);
          source.start();
        }
        const started = performance.now();
        const out = await context.startRendering();
        return { left: out.getChannelData(0), right: out.getChannelData(1), ms: performance.now() - started };
      };
      // The middle of the burst: its edges ring a little through the damping.
      const peak = (data, at) => {
        let sum = 0;
        const from = Math.round((at + 0.003) * RATE);
        const to = Math.round((at + 0.007) * RATE);
        for (let i = from; i < to; i++) sum += Math.abs(data[i]);
        return Math.round((sum / (to - from)) * 1000) / 1000;
      };
      // Samples from where each echo is due to where it is heard, in both kinds of echo.
      const late = ({ left, right }) => {
        const found = [];
        for (let k = 1; k <= 4; k++) {
          const from = Math.round((k * 0.3 - 0.05) * RATE);
          let at = from;
          while (at < from + RATE * 0.1 && Math.abs(left[at]) <= 0.002 && Math.abs(right[at]) <= 0.002) at++;
          found.push(at - Math.round(k * 0.3 * RATE));
        }
        return found;
      };
      const one = await render(1, 1.3);
      const plain = await render(1, 1.3, echoOf(false));
      const load = await render(64, 2);
      const lateBy = late(one);
      const at = (k) => k * 0.3 + lateBy[k - 1] / RATE;
      return {
        late: lateBy,
        latePlain: late(plain),
        dry: [peak(one.left, 0), peak(one.right, 0)],
        first: [peak(one.left, at(1)), peak(one.right, at(1))],
        second: [peak(one.left, at(2)), peak(one.right, at(2))],
        third: [peak(one.left, at(3)), peak(one.right, at(3))],
        between: [peak(one.left, 0.45), peak(one.right, 0.45)],
        voices: 64,
        renderMs: Math.round(load.ms),
        realTimeVoices: Math.round((64 * 2000) / load.ms),
      };
    })()`);
  const near = (value, to) => Math.abs(value - to) < 0.02;
  check(
    'the player’s ping-pong echo comes back left, then right, then left, each round half as loud',
    near(echo.dry[0], 0.5) &&
      near(echo.dry[1], 0.5) &&
      near(echo.first[0], 0.25) &&
      echo.first[1] < 0.005 &&
      echo.second[0] < 0.005 &&
      near(echo.second[1], 0.125) &&
      near(echo.third[0], 0.0625) &&
      echo.third[1] < 0.005 &&
      echo.between.every((v) => v < 0.005) &&
      // Chrome takes a render quantum more for every round of a feedback loop.
      [echo.late, echo.latePlain].every((late) => late.every((n, k) => n === 0 || n === k * 128)),
    JSON.stringify(echo),
  );
  // #322: the Bitcrusher on the worklet, rendered offline. A 440 Hz sine at 0.8 through 2 bits at
  //       4 kHz holds every value for 12 samples and leaves only steps of 0.5. 16 bits at 48 kHz
  //       leave the sound as it is, a mix of 0.5 is half of each. Then 64 stereo voices for 2 s,
  //       timed, for how many this machine crushes at once.
  const crushed = await evaluate(`
    (async () => {
      const RATE = 48000;
      const render = async (voices, seconds, channels, stage) => {
        const context = new OfflineAudioContext(channels, RATE * seconds, RATE);
        await context.audioWorklet.addModule(__gm.sound.fxWorkletUrl());
        const tone = context.createBuffer(channels, RATE * seconds, RATE);
        for (let c = 0; c < channels; c++) {
          const data = tone.getChannelData(c);
          for (let i = 0; i < data.length; i++) data[i] = Math.sin((2 * Math.PI * 440 * i) / RATE) * 0.8;
        }
        for (let v = 0; v < voices; v++) {
          const source = context.createBufferSource();
          source.buffer = tone;
          const nodes = __gm.sound.stageNodes(context, { kind: 'crush', ...stage });
          source.connect(nodes.input);
          nodes.output.connect(context.destination);
          source.start();
        }
        const started = performance.now();
        const out = (await context.startRendering()).getChannelData(0);
        return { out, tone: tone.getChannelData(0), ms: performance.now() - started };
      };
      const crush = await render(1, 0.5, 1, { bits: 2, rate: 4000, mix: 1 });
      let offStep = 0;
      let unheld = 0;
      for (let i = 0; i < crush.out.length; i++) {
        offStep = Math.max(offStep, Math.abs(crush.out[i] * 2 - Math.round(crush.out[i] * 2)));
        if (crush.out[i] !== crush.out[i - (i % 12)]) unheld++;
      }
      const levels = [...new Set(crush.out)].sort((a, b) => a - b);
      const clean = await render(1, 0.5, 1, { bits: 16, rate: 48000, mix: 1 });
      const half = await render(1, 0.5, 1, { bits: 1, rate: 48000, mix: 0.5 });
      let cleanOff = 0;
      let halfOff = 0;
      for (let i = 0; i < clean.out.length; i++) {
        cleanOff = Math.max(cleanOff, Math.abs(clean.out[i] - clean.tone[i]));
        halfOff = Math.max(halfOff, Math.abs(half.out[i] - (half.tone[i] + Math.round(half.tone[i])) / 2));
      }
      const load = await render(64, 2, 2, { bits: 6, rate: 11025, mix: 0.8 });
      return {
        levels,
        offStep,
        unheld,
        cleanOff,
        halfOff,
        voices: 64,
        renderMs: Math.round(load.ms),
        realTimeVoices: Math.round((64 * 2000) / load.ms),
      };
    })()`);
  check(
    'the Bitcrusher holds the sound at its rate and rounds it to its bits, and 16 bits at 48 kHz leave it as it is',
    JSON.stringify(crushed.levels) === JSON.stringify([-1, -0.5, 0, 0.5, 1]) &&
      crushed.offStep < 1e-6 &&
      crushed.unheld === 0 &&
      crushed.cleanOff < 2 ** -15 &&
      crushed.halfOff < 1e-6,
    JSON.stringify(crushed),
  );
  // #341: Phaser and Flanger on the worklet, rendered offline. A 1 kHz sine at 0.8 through a Phaser
  //       at 1 kHz: two stages cut it out, four leave it whole. Swept 4 octaves wide once a second,
  //       the notch passes it and is two octaves off between, where cos(28°) of it is left. A
  //       Flanger of a voice starting at 0.25 s: an impulse 1 ms later comes back after 48 samples
  //       at half. Sweeping 100 ms/s from that start, an impulse 0.1 s in comes back 533 samples
  //       later. Then 64 stereo voices of each for 2 s, timed.
  const swirled = await evaluate(`
    (async () => {
      const RATE = 48000;
      const render = async (voices, seconds, channels, stage, fill, at = 0) => {
        const context = new OfflineAudioContext(channels, RATE * seconds, RATE);
        await context.audioWorklet.addModule(__gm.sound.fxWorkletUrl());
        const sound = context.createBuffer(channels, RATE * seconds, RATE);
        for (let c = 0; c < channels; c++) fill(sound.getChannelData(c));
        for (let v = 0; v < voices; v++) {
          const source = context.createBufferSource();
          source.buffer = sound;
          const nodes = __gm.sound.stageNodes(context, stage, at);
          source.connect(nodes.input);
          nodes.output.connect(context.destination);
          source.start();
        }
        const started = performance.now();
        const out = (await context.startRendering()).getChannelData(0);
        return { out, ms: performance.now() - started };
      };
      const sine = (data) => {
        for (let i = 0; i < data.length; i++) data[i] = Math.sin((2 * Math.PI * 1000 * i) / RATE) * 0.8;
      };
      const rms = (out, from, to) => {
        let sum = 0;
        for (let i = from; i < to; i++) sum += out[i] ** 2;
        return Math.sqrt(sum / (to - from));
      };
      const phaser = (stages, rate, depth) =>
        ({ kind: 'phaser', stages, frequency: 1000, rate, depth, feedback: 0, mix: 1 });
      const notch = (await render(1, 0.3, 1, phaser(2, 0, 0), sine)).out;
      const peak = (await render(1, 0.3, 1, phaser(4, 0, 0), sine)).out;
      const swept = (await render(1, 1, 1, phaser(2, 1, 4), sine)).out;
      const windows = Array.from({ length: 40 }, (_, w) => rms(swept, w * 1200, (w + 1) * 1200));
      const flanger = (offset, sweep) =>
        ({ kind: 'flanger', offset, sweep, rate: 0, depth: 0, feedback: 0, mix: 1 });
      const impulse = (at) => (data) => { data[Math.round(at * RATE)] = 1; };
      const heard = (out, from) => {
        const found = [];
        for (let i = from; i < from + 2000; i++) if (Math.abs(out[i]) > 1e-4) found.push([i - from, +out[i].toFixed(3)]);
        return found;
      };
      const still = heard((await render(1, 0.5, 1, flanger(1, 0), impulse(0.251), 0.25)).out, Math.round(0.251 * RATE));
      const sweeping = heard((await render(1, 0.5, 1, flanger(0, 100), impulse(0.35), 0.25)).out, Math.round(0.35 * RATE));
      const noise = (data) => { for (let i = 0; i < data.length; i++) data[i] = Math.sin(i * 12.9898) % 1 * 0.5; };
      const phaserLoad = await render(64, 2, 2, { ...phaser(12, 0.5, 2), feedback: 0.6 }, noise);
      const flangerLoad = await render(64, 2, 2, { kind: 'flanger', offset: 1, sweep: 2, rate: 0.3, depth: 3, feedback: 0.5, mix: 1 }, noise);
      return {
        notch: +rms(notch, 4800, notch.length).toFixed(4),
        peak: +rms(peak, 4800, peak.length).toFixed(4),
        sweptLow: +Math.min(...windows).toFixed(3),
        sweptHigh: +Math.max(...windows).toFixed(3),
        still,
        sweeping,
        phaserVoices: Math.round((64 * 2000) / phaserLoad.ms),
        flangerVoices: Math.round((64 * 2000) / flangerLoad.ms),
      };
    })()`);
  check(
    'the Phaser cuts a notch at its frequency and sweeps it, the Flanger comes back offset ms late and sweeps from its voice',
    swirled.notch < 0.01 &&
      Math.abs(swirled.peak - 0.8 * Math.SQRT1_2) < 0.01 &&
      swirled.sweptLow < 0.1 &&
      swirled.sweptHigh > 0.46 &&
      swirled.sweptHigh < 0.51 &&
      JSON.stringify(swirled.still) ===
        JSON.stringify([
          [0, 0.5],
          [48, 0.5],
        ]) &&
      swirled.sweeping[0]?.[1] === 0.5 &&
      JSON.stringify(swirled.sweeping.slice(1).map(([i]) => i)) === JSON.stringify([533, 534]),
    JSON.stringify(swirled),
  );
  // #318: the Filter rendered offline. A 2 kHz sine at 0.5 through a low-pass at 1 kHz with no bump
  //       falls by 12.3 dB at 12 dB/oct and by four times that at 48 dB/oct. A peak of +6 dB at
  //       1 kHz raises a 1 kHz sine by 6 dB, a notch there takes it out.
  const filtered = await evaluate(`
    (async () => {
      const RATE = 48000;
      const level = async (hz, stage) => {
        const context = new OfflineAudioContext(1, RATE / 2, RATE);
        const tone = context.createOscillator();
        tone.frequency.value = hz;
        const half = context.createGain();
        half.gain.value = 0.5;
        const nodes = __gm.sound.stageNodes(context, { kind: 'pass', stages: 1, cutoff: 1000, q: 0.7071, gain: 0, ...stage });
        tone.connect(half).connect(nodes.input);
        nodes.output.connect(context.destination);
        tone.start();
        const out = (await context.startRendering()).getChannelData(0).subarray(RATE / 4);
        let sum = 0;
        for (const v of out) sum += v * v;
        return +(20 * Math.log10(Math.sqrt(sum / out.length) / (0.5 * Math.SQRT1_2))).toFixed(2);
      };
      return {
        low12: await level(2000, { filter: 'lowpass', q: -3.0103 }),
        low48: await level(2000, { filter: 'lowpass', q: -3.0103, stages: 4 }),
        peak: await level(1000, { filter: 'peaking', q: 1, gain: 6 }),
        notch: await level(1000, { filter: 'notch', q: 1 }),
      };
    })()`);
  check(
    'a Filter at 48 dB/oct falls four times as steeply as at 12, a peak raises its frequency by its gain, a notch takes it out',
    Math.abs(filtered.low12 + 12.3) < 0.2 &&
      Math.abs(filtered.low48 + 49.2) < 0.8 &&
      Math.abs(filtered.peak - 6) < 0.1 &&
      filtered.notch < -40,
    JSON.stringify(filtered),
  );
  // #319: Pan rendered offline. A mono sine at 0.5 all to the left leaves the right silent, in the
  //       middle each side gets 0.707 of it. A stereo sound panned half right keeps its right side
  //       and moves part of its left into it, as Web Audio pans stereo: left 0.707, right 1 + 0.707.
  const panned = await evaluate(`
    (async () => {
      const RATE = 48000;
      const peaks = async (pan, channels) => {
        const context = new OfflineAudioContext(2, RATE / 10, RATE);
        const sound = context.createBuffer(channels, RATE / 10, RATE);
        for (let c = 0; c < channels; c++) {
          const data = sound.getChannelData(c);
          for (let i = 0; i < data.length; i++) data[i] = Math.sin((2 * Math.PI * 1000 * i) / RATE) * 0.5;
        }
        const source = context.createBufferSource();
        source.buffer = sound;
        const nodes = __gm.sound.stageNodes(context, { kind: 'pan', pan });
        source.connect(nodes.input);
        nodes.output.connect(context.destination);
        source.start();
        const out = await context.startRendering();
        return [0, 1].map((c) => +Math.max(...out.getChannelData(c).map(Math.abs)).toFixed(3));
      };
      return { left: await peaks(-1, 1), middle: await peaks(0, 1), balance: await peaks(0.5, 2) };
    })()`);
  check(
    'Pan moves a mono sound between the sides, and a stereo one towards the side it goes to',
    JSON.stringify(panned) ===
      JSON.stringify({ left: [0.5, 0], middle: [0.354, 0.354], balance: [0.354, 0.854] }),
    JSON.stringify(panned),
  );
  // #326: Compressor and Limiter rendered offline. An impulse comes out of the Compressor 288
  //       samples late (the spec's 6 ms) and out of the Limiter 240 (5 ms). A 1 kHz sine at full
  //       scale through a hard-knee Compressor at -12 dB, 4:1 with full auto-gain comes back near
  //       full scale; with no auto-gain and no makeup it is 9 dB down. A sine at 2 through a
  //       Limiter at -6 dB never goes past it, with auto-gain 1 it sits at the ceiling of -1 dB.
  const dynamics = await evaluate(`
    (async () => {
      const RATE = 48000;
      const render = async (stage, fill) => {
        const context = new OfflineAudioContext(1, RATE / 2, RATE);
        await context.audioWorklet.addModule(__gm.sound.fxWorkletUrl());
        const sound = context.createBuffer(1, RATE / 2, RATE);
        fill(sound.getChannelData(0));
        const source = context.createBufferSource();
        source.buffer = sound;
        const nodes = __gm.sound.stageNodes(context, stage);
        source.connect(nodes.input);
        nodes.output.connect(context.destination);
        source.start();
        return (await context.startRendering()).getChannelData(0);
      };
      const impulse = (data) => { data[480] = 0.01; };
      const sine = (amplitude) => (data) => {
        for (let i = 0; i < data.length; i++) data[i] = Math.sin((2 * Math.PI * 1000 * i) / RATE) * amplitude;
      };
      const loudest = (out, from = 0) => { let at = 0; for (let i = from; i < out.length; i++) if (Math.abs(out[i]) > Math.abs(out[at])) at = i; return at; };
      const db = (out) => +(20 * Math.log10(Math.abs(out[loudest(out, RATE / 4)]))).toFixed(2);
      const compress = (gain) => ({ kind: 'compress', threshold: -12, knee: 0, ratio: 4, attack: 0.003, release: 0.25, gain });
      const limit = (autoGain) => ({ kind: 'limit', threshold: -6, ceiling: -1, release: 0.05, autoGain });
      const limited = await render(limit(0), sine(2));
      return {
        compressorLate: loudest(await render(compress(1), impulse)) - 480,
        limiterLate: loudest(await render(limit(0), impulse)) - 480,
        autoGain: db(await render(compress(10 ** (3.6 / 20)), sine(1))),
        noMakeup: db(await render(compress(10 ** (-5.4 / 20)), sine(1))),
        limitedPeak: +(20 * Math.log10(Math.max(...limited.map(Math.abs)))).toFixed(3),
        ceiling: db(await render(limit(1), sine(2))),
      };
    })()`);
  check(
    'a Compressor is 6 ms late and auto-gain brings full scale back, a Limiter is 5 ms late and never passes its limit',
    dynamics.compressorLate === 288 &&
      dynamics.limiterLate === 240 &&
      Math.abs(dynamics.autoGain) < 0.5 &&
      Math.abs(dynamics.noMakeup + 9) < 0.5 &&
      dynamics.limitedPeak <= -6 + 1e-3 &&
      dynamics.ceiling <= -1 + 1e-3 &&
      dynamics.ceiling > -1.2,
    JSON.stringify(dynamics),
  );
  // #323: Saturation rendered offline. An impulse through it comes out 192 samples late at 48 and
  //       at 44.1 kHz, the oversampling's delay. Half bent and half dry at 1125 Hz – where 192
  //       samples off would cancel – the two meet in step and the sine stays as loud. A sine at
  //       -12 dBFS driven 24 dB into tanh comes back as loud with full auto-gain.
  const saturated = await evaluate(`
    (async () => {
      const render = async (rate, stage, fill) => {
        const context = new OfflineAudioContext(1, rate / 2, rate);
        const sound = context.createBuffer(1, rate / 2, rate);
        fill(sound.getChannelData(0), rate);
        const source = context.createBufferSource();
        source.buffer = sound;
        const nodes = __gm.sound.stageNodes(context, { kind: 'saturate', curve: 'hard', drive: 0, tone: 20000, level: 1, mix: 1, ...stage });
        source.connect(nodes.input);
        nodes.output.connect(context.destination);
        source.start();
        return (await context.startRendering()).getChannelData(0);
      };
      const impulse = (data) => { data[480] = 0.5; };
      const sine = (hz, amplitude) => (data, rate) => {
        for (let i = 0; i < data.length; i++) data[i] = Math.sin((2 * Math.PI * hz * i) / rate) * amplitude;
      };
      const loudest = (out) => out.reduce((at, v, i) => (Math.abs(v) > Math.abs(out[at]) ? i : at), 0);
      const db = (out, amplitude) => {
        let sum = 0;
        const from = out.length / 2;
        for (let i = from; i < out.length; i++) sum += out[i] ** 2;
        return +(20 * Math.log10(Math.sqrt(sum / (out.length - from)) / (amplitude * Math.SQRT1_2))).toFixed(2);
      };
      return {
        late48: loudest(await render(48000, {}, impulse)) - 480,
        late44: loudest(await render(44100, {}, impulse)) - 480,
        halfDry: db(await render(48000, { mix: 0.5 }, sine(1125, 0.5)), 0.5),
        autoGain: db(await render(48000, { curve: 'soft', drive: 24, level: 10 ** (__gm.sound.saturationAutoGain('soft', 24) / 20) }, sine(1000, 0.25)), 0.25),
      };
    })()`);
  check(
    'a Saturation is 192 samples late at either rate, its dry half meets the bent one in step, auto-gain keeps it as loud',
    saturated.late48 === 192 &&
      saturated.late44 === 192 &&
      Math.abs(saturated.halfDry) < 0.1 &&
      Math.abs(saturated.autoGain) < 0.5,
    JSON.stringify(saturated),
  );
  // #320: Tremolo and Vibrato on the worklet, rendered offline. A Tremolo square at 10 Hz, depth 1,
  //       on a steady 0.5 for a voice starting at 0.1 s: silence before it, then 0.5 for 50 ms and
  //       0 for 50 ms. A Vibrato square at 5 Hz, one semitone deep, on a 1 kHz sine: the first
  //       half of a period at 1059.5 Hz, the second at 940.5 Hz.
  const swung = await evaluate(`
    (async () => {
      const RATE = 48000;
      const render = async (stage, fill, at = 0) => {
        const context = new OfflineAudioContext(1, RATE, RATE);
        await context.audioWorklet.addModule(__gm.sound.fxWorkletUrl());
        const sound = context.createBuffer(1, RATE, RATE);
        fill(sound.getChannelData(0));
        const source = context.createBufferSource();
        source.buffer = sound;
        const nodes = __gm.sound.stageNodes(context, stage, at);
        source.connect(nodes.input);
        nodes.output.connect(context.destination);
        source.start();
        return (await context.startRendering()).getChannelData(0);
      };
      const steady = (data) => data.fill(0.5);
      const sine = (data) => { for (let i = 0; i < data.length; i++) data[i] = Math.sin((2 * Math.PI * 1000 * i) / RATE); };
      const levels = (out, from, to) => [...new Set(out.subarray(from, to))].map((v) => +v.toFixed(3));
      const tremolo = await render({ kind: 'tremolo', shape: 'square', rate: 10, depth: 1 }, steady, 0.1);
      const hz = (out, from, to) => {
        const at = [];
        for (let i = Math.round(from * RATE) + 1; i < to * RATE; i++)
          if (out[i - 1] < 0 && out[i] >= 0) at.push(i - out[i] / (out[i] - out[i - 1]));
        return +(((at.length - 1) * RATE) / (at.at(-1) - at[0])).toFixed(1);
      };
      const vibrato = await render({ kind: 'vibrato', shape: 'square', rate: 5, depth: 1 }, sine);
      return {
        before: levels(tremolo, 0, 4800),
        on: levels(tremolo, 4810, 7190),
        off: levels(tremolo, 7210, 9590),
        up: hz(vibrato, 0.41, 0.49),
        down: hz(vibrato, 0.51, 0.59),
      };
    })()`);
  check(
    'a Tremolo starts its swing with its voice, a Vibrato jumps a semitone up and as far down',
    JSON.stringify([swung.before, swung.on, swung.off]) === JSON.stringify([[0], [0.5], [0]]) &&
      Math.abs(swung.up - 1059.5) < 1 &&
      Math.abs(swung.down - 940.5) < 1,
    JSON.stringify(swung),
  );
  // #328: Reverb rendered offline. An impulse at 0.05 s through a Custom reverb of 1 s with a
  //       pre-delay of 50 ms: nothing of it before 0.1 s, then it falls by 60 dB a second, 36 dB
  //       from 0.2-0.3 s to 0.8-0.9 s after it. At mix 0.5 the impulse itself is there at half.
  //       With a sound as its impulse response – one sample at 0.2 s – the impulse comes back
  //       0.2 s and the pre-delay later, and nowhere else.
  const reverbed = await evaluate(`
    (async () => {
      const RATE = 48000;
      const render = async (stage, impulse) => {
        const context = new OfflineAudioContext(1, RATE * 1.5, RATE);
        const sound = context.createBuffer(1, RATE * 1.5, RATE);
        sound.getChannelData(0)[RATE * 0.05] = 0.5;
        let ir;
        if (impulse) {
          ir = context.createBuffer(2, RATE / 2, RATE);
          for (let c = 0; c < 2; c++) ir.getChannelData(c)[RATE * impulse] = 1;
        }
        const source = context.createBufferSource();
        source.buffer = sound;
        const nodes = __gm.sound.stageNodes(context, { kind: 'reverb', decay: 1, damping: 0, predelay: 0.05, mix: 1, ...stage }, 0, ir);
        source.connect(nodes.input);
        nodes.output.connect(context.destination);
        source.start();
        return (await context.startRendering()).getChannelData(0);
      };
      const db = (out, from, to) => {
        let sum = 0;
        for (let i = from * RATE; i < to * RATE; i++) sum += out[i] ** 2;
        return 10 * Math.log10(sum / ((to - from) * RATE));
      };
      const peak = (out, from, to) => Math.max(...out.subarray(from * RATE, to * RATE).map(Math.abs));
      const wet = await render({});
      const half = await render({ mix: 0.5 });
      const sounded = await render({ impulse: 'room.wav' }, 0.2);
      const heard = [];
      sounded.forEach((v, i) => { if (Math.abs(v) > 1e-6) heard.push(i); });
      return {
        before: peak(wet, 0, 0.0999),
        fall: +(db(wet, 0.25, 0.35) - db(wet, 0.85, 0.95)).toFixed(1),
        dry: +half[RATE * 0.05].toFixed(4),
        sound: [heard[0], heard.at(-1)],
      };
    })()`);
  check(
    'a Reverb waits its pre-delay, falls 60 dB in its decay, and takes a sound as its impulse response',
    reverbed.before === 0 &&
      Math.abs(reverbed.fall - 36) < 3 &&
      reverbed.dry === 0.25 &&
      JSON.stringify(reverbed.sound) === JSON.stringify([0.3 * 48000, 0.3 * 48000]),
    JSON.stringify(reverbed),
  );
  // #354: Wet rendered offline. A steady 0.5 through a Gain of 0 at wet 0.25 is 0.375. A Delay of
  //       0.1 s without feedback on it: at wet 0.25 the sound in full and the echo at half, at 0.75
  //       the sound at half and the echo in full, at 1 the echo alone. A Compressor at 1:1 blended
  //       half and half at 1083 Hz – where its 6 ms would cancel – stays as loud: the sound as it
  //       came in is held back to meet it.
  const wetted = await evaluate(`
    (async () => {
      const RATE = 48000;
      const render = async (stage, fill) => {
        const context = new OfflineAudioContext(1, RATE / 2, RATE);
        const sound = context.createBuffer(1, RATE / 2, RATE);
        fill(sound.getChannelData(0));
        const source = context.createBufferSource();
        source.buffer = sound;
        const nodes = __gm.sound.stageNodes(context, stage);
        source.connect(nodes.input);
        nodes.output.connect(context.destination);
        source.start();
        return (await context.startRendering()).getChannelData(0);
      };
      const steady = (data) => data.fill(0.5);
      const sine = (data) => { for (let i = 0; i < data.length; i++) data[i] = Math.sin((2 * Math.PI * 1083.333 * i) / RATE) * 0.5; };
      const at = (out, seconds) => +out[Math.round(seconds * RATE)].toFixed(3);
      const delay = async (mix) => {
        const out = await render({ kind: 'delay', time: 0.1, feedback: 0, damping: 20000, mix, pingPong: false }, steady);
        return [at(out, 0.05), at(out, 0.2)];
      };
      const compress = { kind: 'compress', threshold: 0, knee: 0, ratio: 1, attack: 0.003, release: 0.25, gain: 1 };
      const blended = await render({ kind: 'wet', wet: 0.5, stages: [compress] }, sine);
      let sum = 0;
      for (let i = RATE / 4; i < RATE / 2; i++) sum += blended[i] ** 2;
      return {
        gain: at(await render({ kind: 'wet', wet: 0.25, stages: [{ kind: 'gain', gain: 0 }] }, steady), 0.1),
        quarter: await delay(0.25),
        threeQuarters: await delay(0.75),
        echoOnly: await delay(1),
        compressed: +(20 * Math.log10(Math.sqrt(sum / (RATE / 4)) / (0.5 * Math.SQRT1_2))).toFixed(2),
      };
    })()`);
  check(
    'Wet blends a node with the sound as it came in, a Delay crossfades its echo, a late node meets it in step',
    wetted.gain === 0.375 &&
      JSON.stringify([wetted.quarter, wetted.threeQuarters, wetted.echoOnly]) ===
        JSON.stringify([
          [0.5, 0.75],
          [0.25, 0.75],
          [0, 0.5],
        ]) &&
      Math.abs(wetted.compressed) < 0.1,
    JSON.stringify(wetted),
  );
  // #329: the Chip on the worklet, rendered offline. A square at 220 Hz with a pitch of 12 and a duty
  //       of 0.25, starting at 0.25 s: silence until then, 440 periods a second after it, up a
  //       quarter of each. Sliding two octaves a second down from 440 Hz with a lowest frequency of
  //       110 Hz, it ends at 1 s and tells the page. Then 64 voices for 2 s, timed.
  const chipped = await evaluate(`
    (async () => {
      const RATE = 48000;
      const shape = { wave: 'square', dutySweep: 0, slide: 0, deltaSlide: 0, minFrequency: 0, vibratoDepth: 0,
        vibratoSpeed: 6, arpeggio: 0, arpeggioTime: 0.1, repeat: 0, startAt: 0 };
      const render = async (voices, seconds, params, options) => {
        const context = new OfflineAudioContext(1, RATE * seconds, RATE);
        await context.audioWorklet.addModule(__gm.sound.fxWorkletUrl());
        const said = [];
        for (let v = 0; v < voices; v++) {
          const node = new AudioWorkletNode(context, 'chip-player', {
            numberOfInputs: 0,
            outputChannelCount: [1],
            parameterData: params,
            processorOptions: { ...shape, ...options },
          });
          node.port.onmessage = (event) => said.push(event.data);
          node.connect(context.destination);
        }
        const started = performance.now();
        const out = (await context.startRendering()).getChannelData(0);
        const ms = performance.now() - started;
        await new Promise((resolve) => setTimeout(resolve, 100));
        return { out, ms, said };
      };
      const cycles = (out, from, to) => {
        let n = 0;
        for (let i = Math.round(from * RATE) + 1; i < Math.round(to * RATE); i++) if (out[i - 1] <= 0 && out[i] > 0) n++;
        return n;
      };
      const tone = await render(1, 1, { frequency: 220, duty: 0.25, pitch: 12 }, { startAt: 0.25 });
      const heard = tone.out.subarray(0.25 * RATE);
      const firstHeard = tone.out.findIndex((v) => v !== 0);
      const slid = await render(1, 1.5, { frequency: 440, duty: 0.5, pitch: 0 }, { slide: -24, minFrequency: 110 });
      const lastHeard = slid.out.findLastIndex((v) => v !== 0);
      const load = await render(64, 2, { frequency: 330, duty: 0.5, pitch: 0 }, { wave: 'noise', slide: -6, vibratoDepth: 0.5 });
      return {
        firstHeard,
        periods: cycles(tone.out, 0.25, 1),
        up: Math.round((heard.filter((v) => v > 0).length / heard.length) * 1000) / 1000,
        peak: heard.reduce((top, v) => Math.max(top, Math.abs(v)), 0),
        lastHeard: lastHeard / RATE,
        said: slid.said,
        voices: 64,
        renderMs: Math.round(load.ms),
        realTimeVoices: Math.round((64 * 2000) / load.ms),
      };
    })()`);
  check(
    'the Chip plays its wave at its frequency and pitch from its start, and ends by itself below its lowest frequency',
    chipped.firstHeard === 0.25 * 48000 &&
      Math.abs(chipped.periods - 330) <= 1 &&
      Math.abs(chipped.up - 0.25) < 0.01 &&
      Math.abs(chipped.peak - 0.5) < 0.01 &&
      Math.abs(chipped.lastHeard - 1) < 0.01 &&
      chipped.said.join() === 'ended',
    JSON.stringify(chipped),
  );
  // A Mix "Both at center", rendered offline: a steady 1 on a and 0.5 on b in two channels, so each
  // share reads off as it is. Then mix glides 0 → 1 over a second: at its middle both stay full.
  const atCenter = await evaluate(`
    (async () => {
      const RATE = 48000;
      const render = async (mix, glide) => {
        const context = new OfflineAudioContext(2, RATE, RATE);
        const merger = context.createChannelMerger(2);
        merger.connect(context.destination);
        const shareA = context.createGain();
        const shareB = context.createGain();
        shareA.gain.value = 0;
        shareB.gain.value = 0;
        const driver = __gm.sound.bothAtCenter(context, mix, shareA, shareB);
        for (const [share, level, side] of [[shareA, 1, 0], [shareB, 0.5, 1]]) {
          const steady = context.createConstantSource();
          steady.offset.value = level;
          steady.connect(share).connect(merger, 0, side);
          steady.start();
        }
        if (glide) driver.offset.setValueAtTime(0, 0).linearRampToValueAtTime(1, 1);
        driver.start();
        const out = await context.startRendering();
        const at = (s) => [out.getChannelData(0)[Math.round(s * RATE)], out.getChannelData(1)[Math.round(s * RATE)] * 2];
        return glide ? [0.25, 0.5, 0.75].map(at) : at(0.5);
      };
      const round = (pair) => pair.map((v) => Math.round(v * 1000) / 1000);
      const fixed = {};
      for (const mix of [0, 0.25, 0.5, 0.75, 1]) fixed[mix] = round(await render(mix, false));
      return { fixed, glide: (await render(0, true)).map(round) };
    })()`);
  const pairNear = (pair, a, b) => near(pair[0], a) && near(pair[1], b);
  check(
    'a Mix "Both at center" keeps a full up to the middle and b full from it, also while mix glides',
    pairNear(atCenter.fixed[0], 1, 0) &&
      pairNear(atCenter.fixed[0.25], 1, 0.5) &&
      pairNear(atCenter.fixed[0.5], 1, 1) &&
      pairNear(atCenter.fixed[0.75], 0.5, 1) &&
      pairNear(atCenter.fixed[1], 0, 1) &&
      pairNear(atCenter.glide[0], 1, 0.5) &&
      pairNear(atCenter.glide[1], 1, 1) &&
      pairNear(atCenter.glide[2], 0.5, 1),
    JSON.stringify(atCenter),
  );
  await mutate(`
    const logic = __gm.state.project.assets.find((a) => a.id === 'sn-logic');
    logic.variables = [];
    const graph = logic.graph;
    graph.nodes = graph.nodes.filter((n) => !${JSON.stringify(tuneIds)}.includes(n.id));
    graph.edges = graph.edges.filter((e) => !${JSON.stringify(tuneEdges)}.includes(e.id));`);
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === 'sn-logic').graph;
    graph.nodes = graph.nodes.filter((n) => n.id !== 'sn-fxp');
    graph.edges = graph.edges.filter((e) => e.id !== 'sn-e-fxp');
    Object.assign(graph.nodes.find((n) => n.id === 'sn-play').params, { loop: '', fx: '' });
    const project = __gm.state.project;
    project.assets = project.assets.filter((a) => a.id !== ${JSON.stringify(fxId)});`);

  // 34g-5. An instrument (#331): "+ → Instrument" opens its tab on Notes → Sample → Output, which
  //        plays nothing until the Sample has a sound. With the blip, looped, every key of C4–B4
  //        sounds; a key held by the pointer plays until it is let go, the computer keyboard plays
  //        as a tracker does, and a game's `Play note` releases its note after its duration.
  await showTab('scene');
  await clickText('+');
  await pickAssetType(t, 'Instrument');
  const insCreated = await json(`{
    tab: __gm.tab(),
    current: __gm.instrument.current(),
    info: __gm.instrument.info(),
    keys: __gm.instrument.keys(),
    assets: __gm.state.project.assets.filter((a) => a.type === 'instrument')
      .map((a) => ({ id: a.id, nodes: a.graph.nodes.map((n) => n.type) })),
  }`);
  check(
    'the + menu creates an instrument, Notes → Sample → Output, and opens its tab; no key sounds yet',
    insCreated.tab === 'instrument' &&
      insCreated.assets.length === 1 &&
      insCreated.current === insCreated.assets[0].id &&
      insCreated.assets[0].nodes.join() === 'InstrumentNotes,InstrumentSample,InstrumentOutput' &&
      insCreated.info === 'No sound picked' &&
      insCreated.keys.sounding.length === 0,
    JSON.stringify(insCreated),
  );
  const insId = insCreated.assets[0]?.id;
  // Bottom left: the fitted graph is one row of three nodes, its links among them.
  const insCanvas = await json('__gm.instrument.canvasRect()');
  await click(insCanvas.x + 30, insCanvas.y + insCanvas.h - 30, 'right');
  const insPalette = await json('__gm.overlayTexts()');
  check(
    'its palette offers its own nodes and the effects, but no Input and no behavior node',
    ['Notes', 'Sample', 'Parameters', 'Sound FX', 'Envelope', 'Gain', 'Filter', 'Delay'].every((label) =>
      insPalette.includes(label),
    ) &&
      !insPalette.includes('Input') &&
      !insPalette.includes('Branch'),
    JSON.stringify(insPalette.slice(0, 14)),
  );
  await press('Escape');
  await mutate(`
    const ins = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(insId)});
    Object.assign(ins.graph.nodes.find((n) => n.type === 'InstrumentSample').params, {
      sound: ${JSON.stringify(soundId)},
      play: 'loop',
    });`);
  const insReady = await json('{ info: __gm.instrument.info(), keys: __gm.instrument.keys() }');
  check(
    'with a sound picked the twelve keys from C4 to B4 sound, the others stay grey',
    insReady.info === '12 notes' &&
      insReady.keys.sounding.join() === [60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71].join(),
    JSON.stringify(insReady),
  );
  await shot('34-instrument');

  await evaluate('__gm.sound.stopAll()');
  const beforeKey = await stats();
  const e4 = await json('__gm.instrument.keyAt(64)');
  await t.mouse('mouseMoved', e4.x, e4.y);
  await t.mouse('mousePressed', e4.x, e4.y);
  const heldKey = await waitFor(stats, (s) => s.started > beforeKey.started);
  // Longer than the blip: a looped note that ended with its sound would be gone by now.
  await sleep(600);
  const stillHeld = await json('{ stats: __gm.sound.stats(), keys: __gm.instrument.keys() }');
  check(
    'holding E4 plays the blip four semitones up, looped, as one layer of the instrument, and lights the key',
    heldKey.last?.file === `instrument:${insId}` &&
      heldKey.last.pitches.join() === '4' &&
      heldKey.last.layers === 1 &&
      stillHeld.stats.playing === 1 &&
      stillHeld.keys.held.join() === '64',
    JSON.stringify({ heldKey, stillHeld }),
  );
  await t.mouse('mouseReleased', e4.x, e4.y);
  const letGo = await waitFor(stats, (s) => s.playing === 0);
  check(
    'letting go of the key ends the note: its sample fades out and the voice goes',
    letGo.playing === 0 && (await json('__gm.instrument.keys()')).held.length === 0,
    JSON.stringify(letGo),
  );

  // "Loop, then release": held, it loops 0.05 to 0.1 s; let go, it plays the 0.15 s after the loop.
  const setPlay = (fields) =>
    mutate(`
      const ins = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(insId)});
      Object.assign(ins.graph.nodes.find((n) => n.type === 'InstrumentSample').params, ${JSON.stringify(fields)});`);
  await setPlay({ play: 'release', loopStart: 0.05, loopEnd: 0.1 });
  const beforeRelease = await stats();
  await t.mouse('mousePressed', e4.x, e4.y);
  await waitFor(stats, (s) => s.started > beforeRelease.started);
  await sleep(600);
  const heldLoop = await stats();
  await t.mouse('mouseReleased', e4.x, e4.y);
  const leftAt = await audioNow();
  const ringingKeys = await json('__gm.instrument.keys()');
  const playedOut = await waitFor(audioNow, (s) => s.playing === 0);
  const afterKeys = await waitFor(
    () => json('__gm.instrument.keys()'),
    (keys) => keys.ringing.length === 0,
  );
  // 0.15 s after the loop, up to two rounds more (the one it is in, the one the worklet read into)
  // and the 150 ms waitFor polls at: a fade would be gone in 0.01 s.
  const outFor = playedOut.clock - leftAt.clock;
  check(
    '"Loop, then release" loops while held, and let go plays on past the loop with its key half lit',
    heldLoop.playing === 1 &&
      ringingKeys.held.length === 0 &&
      ringingKeys.ringing.join() === '64' &&
      outFor > 0.12 &&
      outFor < 0.5 &&
      afterKeys.ringing.length === 0,
    JSON.stringify({ heldLoop: heldLoop.playing, ringingKeys, outFor, afterKeys }),
  );
  await setPlay({ play: 'loop', loopStart: 0, loopEnd: 0 });

  // The click left the keys focused. Z is C3 there – no sound in this instrument –, one octave up C4.
  const beforeZ = await stats();
  await press('z');
  await sleep(200);
  const lowZ = await stats();
  await press('ArrowRight');
  await t.keyDown('z');
  const typed = await waitFor(stats, (s) => s.started > lowZ.started);
  const typedKeys = await json('__gm.instrument.keys()');
  await t.keyUp('z');
  const typedOff = await waitFor(stats, (s) => s.playing === 0);
  check(
    'the computer keyboard plays as a tracker: Z is C3 and silent here, one octave up it is C4 until let go',
    lowZ.started === beforeZ.started &&
      typedKeys.octave === 4 &&
      typedKeys.held.join() === '60' &&
      typed.last?.pitches.join() === '0' &&
      typedOff.playing === 0,
    JSON.stringify({ beforeZ: beforeZ.started, lowZ: lowZ.started, typed, typedKeys, typedOff }),
  );
  await press('ArrowLeft');

  // Twice the eleven keys off the root, all held at once: each plays through the pitch worklet, and
  // the ten oldest are cut, so no more than twelve phase vocoders run and the audio thread keeps up.
  await evaluate('__gm.sound.stopAll()');
  const crowd = await json(`(() => {
    const voices = [...Array(22)].map((_, i) => __gm.instrument.play(61 + (i % 11)));
    return { started: voices.filter((v) => v > 0).length, playing: voices.map((v) => __gm.sound.playing(v)), stats: __gm.sound.stats() };
  })()`);
  check(
    'held at once, 22 notes off the root keep only the 12 newest on the pitch worklet',
    crowd.started === 22 &&
      crowd.playing.join() === [...Array(22)].map((_, i) => i >= 10).join() &&
      crowd.stats.vocoders === 12 &&
      crowd.stats.playing === 12,
    JSON.stringify({ started: crowd.started, playing: crowd.playing, vocoders: crowd.stats.vocoders }),
  );

  // Closing the tab ends what it plays: E4, looped and held by no key, falls silent with it.
  await evaluate('__gm.sound.stopAll()');
  await json('__gm.instrument.play(64)');
  const heldBeforeClose = await stats();
  await evaluate(`__gm.closeDocument('asset:${insId}')`);
  await sleep(300);
  const afterClose = await stats();
  await evaluate(`__gm.openDocument('asset:${insId}')`);
  check(
    'closing the Instrument tab ends a note it still plays',
    heldBeforeClose.playing === 1 && afterClose.playing === 0,
    JSON.stringify({ held: heldBeforeClose.playing, closed: afterClose.playing }),
  );

  // 34g-6. Presets (#329): Preset → Laser makes the instrument one Chip through Envelope, Filter and
  //        Bitcrusher and plays nothing. Randomize and Mutate play the note last played; a change
  //        only plays with Audition on. Three undos bring the blip back.
  const insGraph = () =>
    json(`(() => {
      const graph = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(insId)}).graph;
      const of = (type) => graph.nodes.find((n) => n.type === type)?.params ?? null;
      return { types: graph.nodes.map((n) => n.type), chip: of('InstrumentChip'), envelope: of('InstrumentEnvelope') };
    })()`);
  const clickHook = async (hook) => {
    const at = await json(`__gm.instrument.${hook}()`);
    await click(at.x, at.y);
  };
  await evaluate('__gm.sound.stopAll()');
  const beforePreset = await stats();
  await clickHook('presetAt');
  const presetMenu = await json('__gm.overlayTexts()');
  await clickText('Laser');
  await sleep(400);
  const preset = await stats();
  const laser = await insGraph();
  const presetInfo = await json('__gm.instrument.info()');
  check(
    'Preset → Laser makes Notes → Chip → Envelope → Filter → Bitcrusher → Output and plays nothing',
    ['Pickup', 'Laser', 'Explosion', 'Powerup', 'Hit', 'Jump', 'Blip'].every((label) =>
      presetMenu.includes(label),
    ) &&
      laser.types.join() ===
        'InstrumentNotes,InstrumentChip,InstrumentEnvelope,SoundFxFilter,SoundFxBitcrusher,InstrumentOutput' &&
      laser.chip?.followNote === false &&
      laser.chip.slide < 0 &&
      laser.envelope?.sustain === 0 &&
      preset.started === beforePreset.started &&
      presetInfo === '128 notes',
    JSON.stringify({ presetMenu, laser, started: [beforePreset.started, preset.started], presetInfo }),
  );
  await shot('34-instrument-preset');

  const beforeRandom = await stats();
  await clickHook('randomizeAt');
  const randomized = await waitFor(stats, (s) => s.started > beforeRandom.started);
  const drawn = await insGraph();
  await clickHook('mutateAt');
  const mutated = await waitFor(stats, (s) => s.started > randomized.started);
  const moved = await insGraph();
  check(
    'Randomize draws the numbers anew and keeps the wave, Mutate moves some; both play at once',
    randomized.started > beforeRandom.started &&
      drawn.chip?.wave === laser.chip.wave &&
      drawn.chip.frequency !== laser.chip.frequency &&
      mutated.started > randomized.started &&
      JSON.stringify([moved.chip, moved.envelope]) !== JSON.stringify([drawn.chip, drawn.envelope]),
    JSON.stringify({ laser: laser.chip, drawn: drawn.chip, moved: moved.chip }),
  );

  const setFrequency = (hz) =>
    mutate(`__gm.state.project.assets.find((a) => a.id === ${JSON.stringify(insId)})
      .graph.nodes.find((n) => n.type === 'InstrumentChip').params.frequency = ${hz}`);
  await sleep(300);
  const silent = await stats();
  await setFrequency(300);
  await sleep(500);
  const unheard = await stats();
  await clickHook('auditionAt');
  const auditionOn = (await json('__gm.instrument.auditionAt()')).toggled;
  await setFrequency(400);
  const auditioned = await waitFor(stats, (s) => s.started > unheard.started);
  await clickHook('auditionAt');
  check(
    'a change to the instrument is heard only with Audition on',
    unheard.started === silent.started && auditionOn && auditioned.started > unheard.started,
    JSON.stringify({
      silent: silent.started,
      unheard: unheard.started,
      auditionOn,
      auditioned: auditioned.started,
    }),
  );

  for (let i = 0; i < 3; i++) await t.clickToolbar('undo');
  const restored = await insGraph();
  check(
    'three undos take back Mutate, Randomize and the preset: Notes → Sample → Output again',
    restored.types.join() === 'InstrumentNotes,InstrumentSample,InstrumentOutput',
    JSON.stringify(restored.types),
  );

  // 34g-7. An instrument to play tunes on: Preset → Square Lead follows the note and holds it, and
  //        plays nothing. One undo takes it back.
  await evaluate('__gm.sound.stopAll()');
  const beforeLead = await stats();
  await clickHook('presetAt');
  await clickText('Square Lead');
  await sleep(400);
  const lead = await stats();
  const leadGraph = await insGraph();
  const leadInfo = await json('__gm.instrument.info()');
  await t.clickToolbar('undo');
  const unled = await insGraph();
  check(
    'Preset → Square Lead plays every note at its own pitch, holds it and plays nothing; one undo takes it back',
    ['Square Lead', 'Phased Pad', 'Organ', 'Bell', 'Drum Kit'].every((label) => presetMenu.includes(label)) &&
      leadGraph.chip?.followNote === true &&
      leadGraph.envelope?.sustain > 0 &&
      lead.started === beforeLead.started &&
      leadInfo === '128 notes' &&
      unled.types.join() === 'InstrumentNotes,InstrumentSample,InstrumentOutput',
    JSON.stringify({
      chip: leadGraph.chip,
      envelope: leadGraph.envelope,
      started: [beforeLead.started, lead.started],
      leadInfo,
      unled,
    }),
  );
  await evaluate('__gm.sound.stopAll()');

  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === 'sn-logic').graph;
    graph.nodes.push(${JSON.stringify(
      node('sn-note', 'PlayNote', 260, 220, { instrument: insId, note: 67, duration: 1.5 }),
    )});
    graph.edges.find((e) => e.id === 'sn-e1').to = { node: 'sn-note', port: 'exec' };`);
  // A key still held in the Instrument tab is not part of the game: Play ends it.
  const preview = await json('__gm.instrument.play(64)');
  const previewHeld = await json(`__gm.sound.playing(${preview})`);
  await showTab('scene');
  const beforeNote = await stats();
  await play();
  const previewAfterPlay = await json(`__gm.sound.playing(${preview})`);
  check(
    'Play ends what the tabs play: a note held in the Instrument tab is gone',
    preview > 0 && previewHeld && !previewAfterPlay,
    JSON.stringify({ preview, previewHeld, previewAfterPlay }),
  );
  // The sample loops, so only the release after 1.5 s on the audio clock ends the note: it is heard
  // well past the 0.25 s of the blip, never past its duration, and is gone soon after.
  const noteNow = () => json('({ stats: __gm.sound.stats(), clock: __gm.sound.clock() })');
  const noted = await waitFor(noteNow, (s) => s.stats.started > beforeNote.started);
  const heard = await trace(noteNow, (s) => s.stats.playing === 0);
  const noteAt = noted.stats.last?.at ?? 0;
  const heardAt = heard.filter((s) => s.stats.playing === 1).map((s) => +(s.clock - noteAt).toFixed(3));
  const goneAt = +(heard.at(-1).clock - noteAt).toFixed(3);
  check(
    'a game’s Play note plays G4 – the blip seven semitones up – and lets it go after its duration',
    noted.stats.last?.file === `instrument:${insId}` &&
      noted.stats.last.pitches.join() === '7' &&
      heardAt.some((t) => t > 0.5) &&
      heardAt.every((t) => t < 1.6) &&
      heard.at(-1).stats.playing === 0 &&
      goneAt < 3,
    JSON.stringify({ last: noted.stats.last, heardAt, goneAt }),
  );
  await stop();

  // #332: the scheduler, driven by the hook – nothing in the editor plays a sequence yet. A bar of
  //       quarters at 150 BPM in a loop: every note is planned before its second comes, each 0.4 s
  //       after the one before, also across the seam into the next round. Where the music stands
  //       is the audio clock less the output latency, counted from the first note.
  // #366: the audio clock moves on by a render block even between two reads in one expression, so
  //       it is read before and after the position, and the position lies between the two.
  const bar = [60, 62, 64, 65].map((pitch, i) => ({
    tick: i * 480,
    length: 240,
    note: pitch,
    velocity: 1,
    instrument: insId,
  }));
  await evaluate(
    `__gm.music.play(${JSON.stringify({ notes: bar })}, { tempo: 150, loop: { start: 0, end: 1920 } })`,
  );
  const planned = await waitFor(
    () => json('__gm.music.planned()'),
    (p) => p.length >= 9,
    40,
  );
  const where = await json(
    `({
      before: __gm.sound.clock(),
      position: __gm.music.position(),
      after: __gm.sound.clock(),
      latency: __gm.music.latency(),
    })`,
  );
  await evaluate('__gm.music.stop()');
  const musicOff = await waitFor(stats, (s) => s.playing === 0);
  const apart = planned.slice(1, 9).map((p, i) => +(p.at - planned[i].at).toFixed(6));
  const ahead = planned.map((p) => +(p.at - p.planned).toFixed(3));
  const ticksHeardAt = (clock) => ((clock - where.latency - planned[0].at) * 150 * 480) / 60;
  const heardTicks = [ticksHeardAt(where.before), ticksHeardAt(where.after)];
  // How far the position lies past the first read, around the loop of 1920 ticks.
  const pastBefore = (((where.position.ticks - heardTicks[0]) % 1920) + 1920) % 1920;
  check(
    'the scheduler plans a looped bar on the audio clock: every note ahead of its second, 0.4 s apart across the seam',
    planned.length >= 9 &&
      planned
        .slice(0, 9)
        .map((p) => p.note)
        .join() === '60,62,64,65,60,62,64,65,60' &&
      planned.every((p) => p.voice > 0 && Math.abs(p.duration - 0.2) < 1e-9 && p.tempo === 150) &&
      apart.every((gap) => Math.abs(gap - 0.4) < 1e-6) &&
      ahead.every((s) => s > 0 && s <= 0.16) &&
      (pastBefore <= heardTicks[1] - heardTicks[0] + 1 || pastBefore > 1919) &&
      where.position.bar === 1 &&
      musicOff.playing === 0 &&
      (await json('__gm.music.playing()')) === false,
    JSON.stringify({ apart, ahead, where, heardTicks, pastBefore, playing: musicOff.playing }),
  );

  // A note planned ahead through the pitch worklet starts on its sample, also inside a render block:
  // rendered offline at pitch 0, which plays the sound as it is, so the first sample heard is it.
  const onsets = await evaluate(`
    (async () => {
      const RATE = 48000;
      const onset = async (startAt) => {
        const context = new OfflineAudioContext(1, RATE / 2, RATE);
        await context.audioWorklet.addModule(__gm.sound.fxWorkletUrl());
        const node = new AudioWorkletNode(context, 'pitch-player', {
          numberOfInputs: 0,
          outputChannelCount: [1],
          parameterData: { pitch: 0 },
          processorOptions: { file: 'onset', channels: [new Float32Array(RATE).fill(0.5)], step: 1, loop: false, startAt },
        });
        node.connect(context.destination);
        const out = (await context.startRendering()).getChannelData(0);
        return out.findIndex((v) => Math.abs(v) > 1e-6);
      };
      const at = [0.0123, 0.25, 0.05 + 0.4 * 2 / 3];
      return { expected: at.map((s) => Math.round(s * RATE)), heard: await Promise.all(at.map(onset)) };
    })()`);
  check(
    'a pitched note planned ahead starts on its very sample, inside a render block too',
    onsets.heard.join() === onsets.expected.join() && onsets.expected.some((i) => i % 128 !== 0),
    JSON.stringify(onsets),
  );

  // #335: an Envelope's curve as Chrome renders it – up in the attack, easing towards the sustain,
  //       and from wherever it is when the note ends down to silence in the release, mid-attack too –
  //       and a Gain it moves through a WaveShaper, from a quarter to full in equal ratios.
  const curves = await evaluate(`
    (async () => {
      const RATE = 48000;
      const envelope = { id: 'e', attack: 0.1, decay: 0.2, sustain: 0.5, release: 0.3 };
      const render = async (releaseAt, moved) => {
        const context = new OfflineAudioContext(1, RATE, RATE);
        const driver = __gm.sound.envelopeDriver(context, envelope, 0);
        if (releaseAt !== null) __gm.sound.releaseEnvelope(driver.offset, envelope, 0, releaseAt);
        if (moved) {
          const steady = context.createConstantSource();
          const stage = { kind: 'gain', gain: 1, mod: { envelope, from: 0.25, to: 1 } };
          const made = __gm.sound.stageWith(context, stage, driver);
          steady.connect(made.input);
          made.output.connect(context.destination);
          steady.start();
        } else driver.connect(context.destination);
        driver.start();
        const out = (await context.startRendering()).getChannelData(0);
        return (s) => Math.round(out[Math.round(s * RATE)] * 10000) / 10000;
      };
      const held = await render(0.5, false);
      const early = await render(0.05, false);
      const gain = await render(null, true);
      return {
        held: [0.05, 0.1, 0.3, 0.5, 0.65, 0.8].map(held),
        early: [0.05, 0.15, 0.35].map(early),
        gain: [0.05, 0.1, 0.9].map(gain),
      };
    })()`);
  const closeTo = (values, expected) => values.every((v, i) => Math.abs(v - expected[i]) < 0.002);
  check(
    'an Envelope rises, eases to its sustain and releases from where it is, and moves a Gain with that curve',
    closeTo(curves.held, [0.5, 1, 0.5005, 0.5, 0.0158, 0.0005]) &&
      closeTo(curves.early, [0.5, 0.05, 0.0005]) &&
      closeTo(curves.gain, [0.5, 1, 0.5]),
    JSON.stringify(curves),
  );

  // A note of 0.2 s through an Envelope with a release of 1 s: the looped blip plays on through the
  //  release, and the voice goes with it – without one it would end 10 ms after the note.
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(insId)}).graph;
    const into = graph.edges.find((e) => e.to.node === graph.nodes.find((n) => n.type === 'InstrumentOutput').id);
    graph.nodes.push(${JSON.stringify(node('ins-env', 'InstrumentEnvelope', 300, 120, { release: 1 }))});
    graph.edges.push({ id: 'ins-e-env', from: { node: 'ins-env', port: 'out' }, to: { ...into.to } });
    into.to = { node: 'ins-env', port: 'in' };`);
  await evaluate('__gm.sound.stopAll()');
  const beforeShaped = await stats();
  await evaluate(
    `__gm.music.play(${JSON.stringify({ notes: [{ tick: 0, length: 240, note: 60, velocity: 1, instrument: insId }] })}, { tempo: 150 })`,
  );
  const shaped = await waitFor(noteNow, (s) => s.stats.started > beforeShaped.started);
  const ringOut = await trace(noteNow, (s) => s.stats.playing === 0);
  await evaluate('__gm.music.stop()');
  const shapedAt = shaped.stats.last?.at ?? 0;
  const shapedGone = +(ringOut.at(-1).clock - shapedAt).toFixed(3);
  // 0.2 s of note and 1 s of release; up to the 150 ms waitFor polls at on top.
  check(
    'a note through an Envelope plays on through its release and goes with it',
    shaped.stats.last?.envelopes === 1 &&
      ringOut.some((s) => s.stats.playing === 1 && s.clock - shapedAt > 0.8) &&
      ringOut.at(-1).stats.playing === 0 &&
      shapedGone > 1.15 &&
      shapedGone < 1.6,
    JSON.stringify({ last: shaped.stats.last, shapedGone }),
  );

  // #329: the Sample swapped for a Chip, the Envelope's sustain at 0 and its decay 0.1 s. The note of
  //       0.2 s is over once the decay is, on its own – held to its end and through the release of
  //       1 s it would take 1.2 s.
  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(insId)}).graph;
    const notes = graph.nodes.find((n) => n.type === 'InstrumentNotes');
    graph.nodes.push(${JSON.stringify(node('ins-chip', 'InstrumentChip', 120, 200, { wave: 'saw', slide: -12 }))});
    graph.edges.find((e) => e.to.node === 'ins-env' && e.to.port === 'in').from = { node: 'ins-chip', port: 'out' };
    graph.edges.push({ id: 'ins-e-chip', from: { node: notes.id, port: 'any' }, to: { node: 'ins-chip', port: 'trigger' } });
    Object.assign(graph.nodes.find((n) => n.id === 'ins-env').params, { attack: 0.005, decay: 0.1, sustain: 0 });`);
  const beforeChip = await stats();
  await evaluate(
    `__gm.music.play(${JSON.stringify({ notes: [{ tick: 0, length: 240, note: 60, velocity: 1, instrument: insId }] })}, { tempo: 150 })`,
  );
  const chipNote = await waitFor(noteNow, (s) => s.stats.started > beforeChip.started);
  const chipOut = await trace(noteNow, (s) => s.stats.playing === 0);
  await evaluate('__gm.music.stop()');
  const chipGone = +(chipOut.at(-1).clock - (chipNote.stats.last?.at ?? 0)).toFixed(3);
  // 0.105 s of attack and decay; up to the 150 ms the polls take on top.
  check(
    'a Chip plays a note without a sound file, and an Envelope with sustain 0 ends it after its decay',
    chipNote.stats.worklet === true &&
      chipNote.stats.last?.file === `instrument:${insId}` &&
      chipNote.stats.last?.envelopes === 1 &&
      chipNote.stats.last?.duration === 0 &&
      chipOut.at(-1).stats.playing === 0 &&
      chipGone < 0.5,
    JSON.stringify({ last: chipNote.stats.last, chipGone }),
  );

  await mutate(`
    const graph = __gm.state.project.assets.find((a) => a.id === 'sn-logic').graph;
    graph.nodes = graph.nodes.filter((n) => n.id !== 'sn-note');
    graph.edges.find((e) => e.id === 'sn-e1').to = { node: 'sn-play', port: 'exec' };
    const project = __gm.state.project;
    project.assets = project.assets.filter((a) => a.id !== ${JSON.stringify(insId)});`);

  // 34h. Dropping a sound file onto the editor uploads it and makes an asset named after the file.
  const dropped = await evaluate(`
    (async () => {
      const bytes = await fetch('/game-maker/data/sounds/${drone.file}').then((r) => r.arrayBuffer());
      const file = new File([bytes], 'drone.wav', { type: 'audio/wav' });
      const data = new DataTransfer();
      data.items.add(file);
      const canvas = document.querySelector('canvas');
      canvas.dispatchEvent(new DragEvent('drop', { dataTransfer: data, bubbles: true, cancelable: true }));
      return file.size;
    })()`);
  await waitFor(
    () => assetsOfType('sound'),
    (list) => list.length === 2,
  );
  const both = await assetsOfType('sound');
  check(
    'a dropped sound is uploaded and becomes an asset named after the file',
    dropped === DRONE_BYTES &&
      both.length === 2 &&
      both.some((a) => a.file === drone.file && a.name === 'drone'),
    JSON.stringify({ dropped, both, notice: await json('__gm.state.notice') }),
  );

  // 34h-2. The Sound tab (#343): the drone's 0.75 s as a wave, the sound itself the whole file. Its
  //        clips (#357) stand as bands in a strip under the ruler: a drag there spans a new one, a
  //        click picks one, and the picked clip stands between two handles. A clip is played by a
  //        name of its own, its samples cut to the sample and ramped from silence at an edge inside
  //        the file. One drag is one undo step.
  const droneId = both.find((a) => a.file === drone.file)?.id;
  await evaluate(`__gm.state.openAsset(${JSON.stringify(droneId)})`);
  const tab = () => json('__gm.soundTab.span()');
  const clips = () => json('__gm.soundTab.clips()');
  const picked = () => json('__gm.soundTab.pickedClip()');
  await waitFor(tab, (span) => span !== null);
  const tabOpened = {
    current: await json('__gm.soundTab.current()'),
    span: await tab(),
    info: await json('__gm.soundTab.info()'),
    clips: await clips(),
    picked: await picked(),
    reverse: await json('__gm.soundTab.reverseButton()'),
    played: await json(`__gm.soundTab.played(${JSON.stringify(droneId)})`),
  };
  check(
    'opening a sound shows its tab: the whole file, no clip, nothing to turn or fade',
    tabOpened.current === droneId &&
      tabOpened.span?.start === 0 &&
      Math.abs(tabOpened.span?.end - 0.75) < 0.001 &&
      tabOpened.info === '0.75 s' &&
      tabOpened.clips.length === 0 &&
      tabOpened.picked === null &&
      tabOpened.reverse.enabled === false &&
      tabOpened.played === drone.file,
    JSON.stringify(tabOpened),
  );
  // 34h-2a. The wheel over the level scale left of the wave zooms its height (#357): out leaves room
  //         above a full-scale wave, in takes it past the top of the tab, the seconds stay where they
  //         are, and Fit brings back the full height.
  const levelScale = await json('__gm.soundTab.scale()');
  const levelRect = await json('__gm.soundTab.rect()');
  const fullTop = await json('__gm.soundTab.fullScaleTop()');
  const secondAt = (await json('__gm.soundTab.at(0.5)')).x;
  await t.wheel(levelScale.x, levelScale.y, 924);
  const zoomedOut = {
    level: await json('__gm.soundTab.level()'),
    top: await json('__gm.soundTab.fullScaleTop()'),
    secondAt: (await json('__gm.soundTab.at(0.5)')).x,
  };
  await t.wheel(levelScale.x, levelScale.y, -1848);
  const zoomedIn = {
    level: await json('__gm.soundTab.level()'),
    top: await json('__gm.soundTab.fullScaleTop()'),
  };
  const levelFit = await json('__gm.soundTab.fitButton()');
  await click(levelFit.x, levelFit.y);
  await sleep(100);
  const refitted = {
    level: await json('__gm.soundTab.level()'),
    top: await json('__gm.soundTab.fullScaleTop()'),
  };
  check(
    'the wheel over the level scale zooms the height alone, and Fit puts it back',
    Math.abs(zoomedOut.level - 0.25) < 0.01 &&
      Math.abs(zoomedOut.top - levelScale.y - (fullTop - levelScale.y) * 0.25) < 1 &&
      zoomedOut.secondAt === secondAt &&
      Math.abs(zoomedIn.level - 4) < 0.05 &&
      zoomedIn.top < levelRect.y &&
      refitted.level === 1 &&
      Math.abs(refitted.top - fullTop) < 0.5,
    JSON.stringify({ levelScale, levelRect, fullTop, secondAt, zoomedOut, zoomedIn, refitted }),
  );
  // 34h-2b. A pan moves the wave drawn already and leaves each ruler label on its second (#360):
  //         drawing both anew on every move took the frames down.
  const panFrom = await json('__gm.soundTab.at(0.375)');
  await t.wheel(panFrom.x, panFrom.y, -924);
  const panInfo = async () => ({
    ...(await json('__gm.soundTab.drawInfo()')),
    at: (await json('__gm.soundTab.at(0.375)')).x,
  });
  const panBefore = await panInfo();
  await t.mouse('mouseMoved', panFrom.x, panFrom.y);
  await t.mouse('mousePressed', panFrom.x, panFrom.y, 'middle');
  for (let i = 1; i <= 8; i++) {
    await t.mouse('mouseMoved', panFrom.x - 30 * i, panFrom.y, 'middle', { buttons: 4 });
    await sleep(20);
  }
  await t.mouse('mouseReleased', panFrom.x - 240, panFrom.y, 'middle');
  await sleep(100);
  const panAfter = await panInfo();
  const panMoved = panAfter.at - panBefore.at;
  await click(levelFit.x, levelFit.y);
  await sleep(100);
  check(
    'a pan moves the wave drawn already, and the ruler labels keep their seconds',
    Math.abs(panMoved + 240) < 1 &&
      panAfter.waveDraws === panBefore.waveDraws &&
      Math.abs(panAfter.shift - panBefore.shift - panMoved) < 0.5 &&
      panAfter.rulerTexts - panBefore.rulerTexts <= 2,
    JSON.stringify({ panBefore, panAfter, panMoved }),
  );
  const clipProps = async () => (await clips())[0]?.props;
  let dragFrom = await json('__gm.soundTab.stripAt(0.1)');
  let dragTo = await json('__gm.soundTab.stripAt(0.3)');
  await t.drag(dragFrom.x, dragFrom.y, dragTo.x, dragTo.y);
  const spanned = { clips: await clips(), picked: await picked(), info: await json('__gm.soundTab.info()') };
  const clipId = spanned.clips[0]?.id;
  check(
    'a drag in the strip spans a new clip, "Clip 1", picked, and the sound stays the whole file',
    spanned.clips.length === 1 &&
      spanned.clips[0].name === 'Clip 1' &&
      Math.abs(spanned.clips[0].props.start - 0.1) < 0.01 &&
      Math.abs(spanned.clips[0].props.end - 0.3) < 0.01 &&
      spanned.picked === clipId &&
      spanned.info ===
        `${(spanned.clips[0].props.end - spanned.clips[0].props.start).toFixed(2)} s of 0.75 s` &&
      (await json(`__gm.soundTab.played(${JSON.stringify(droneId)})`)) === drone.file,
    JSON.stringify(spanned),
  );
  await press('z', { ctrl: true });
  const undoneClip = { clips: await clips(), picked: await picked() };
  await press('z', { ctrl: true, shift: true });
  const redoneClip = await clips();
  const beside = await json('__gm.soundTab.stripAt(0.5)');
  await click(beside.x, beside.y);
  const pickedBeside = await picked();
  const faintBeside = await json('__gm.soundTab.faintClips()');
  await shot('34-sound-faint-clip');
  const onBand = await json('__gm.soundTab.stripAt(0.2)');
  await click(onBand.x, onBand.y);
  const faintPicked = await json('__gm.soundTab.faintClips()');
  check(
    'one undo takes the clip away, a redo brings it back; a click in the strip picks it, beside it the sound, the clip then faint over the wave',
    undoneClip.clips.length === 0 &&
      undoneClip.picked === null &&
      redoneClip.map((c) => c.id).join() === clipId &&
      pickedBeside === null &&
      faintBeside.join() === 'Clip 1' &&
      faintPicked.length === 0 &&
      (await picked()) === clipId,
    JSON.stringify({
      undoneClip,
      redoneClip,
      pickedBeside,
      faintBeside,
      faintPicked,
      picked: await picked(),
    }),
  );
  const inClip = await json('__gm.soundTab.at(0.2)');
  await click(inClip.x, inClip.y);
  const pickedInClip = await picked();
  const besideClip = await json('__gm.soundTab.at(0.6)');
  await click(besideClip.x, besideClip.y);
  const pickedBesideClip = await picked();
  await click(onBand.x, onBand.y);
  check(
    'a click over the wave inside the picked clip keeps it, beside it picks the sound',
    pickedInClip === clipId && pickedBesideClip === null && (await picked()) === clipId,
    JSON.stringify({ pickedInClip, pickedBesideClip, picked: await picked() }),
  );
  dragFrom = await json('__gm.soundTab.at(0.3)');
  dragTo = await json('__gm.soundTab.at(0.5)');
  await t.mouse('mouseMoved', dragFrom.x - 1, dragFrom.y);
  await t.mouse('mouseMoved', dragFrom.x, dragFrom.y);
  const onHandle = await json('__gm.soundTab.cursor()');
  await t.drag(dragFrom.x, dragFrom.y, dragTo.x, dragTo.y);
  const lengthened = await clipProps();
  await press('z', { ctrl: true });
  check(
    'dragging the end handle moves that edge of the picked clip, the handle showing it can be dragged',
    onHandle === 'ew-resize' &&
      Math.abs(lengthened?.start - 0.1) < 0.01 &&
      Math.abs(lengthened?.end - 0.5) < 0.01 &&
      Math.abs((await clipProps())?.end - 0.3) < 0.01,
    JSON.stringify({ onHandle, lengthened, undone: await clipProps() }),
  );
  const clipCut = await clipProps();
  const cutPlayed = await json(`__gm.soundTab.played(${JSON.stringify(clipId)})`);
  const cutSamples = await evaluate(`__gm.soundTab.samples(${JSON.stringify(cutPlayed)})`);
  const keptSamples = clipCut ? Math.round((clipCut.end - clipCut.start) * (cutSamples?.rate ?? 0)) : -1;
  check(
    'the clip is played by a name of its own, cut to the sample',
    cutPlayed === `${drone.file}#${clipCut?.start}~${clipCut?.end}~0.005~0.005~linear~linear` &&
      cutSamples?.length === keptSamples,
    JSON.stringify({ clipCut, cutPlayed, cutSamples, keptSamples }),
  );
  check(
    'the cut rises from silence and falls back to it, the default 5 ms at each edge inside the file',
    cutSamples?.head[0] === 0 && Math.abs(cutSamples?.tail.at(-1)) < 0.01,
    JSON.stringify(cutSamples),
  );
  // 34h-ii. Each edge of the picked clip has a fade of its own, each shaped by its own curve (#345).
  const tabFadeOut = await json('__gm.soundTab.fadeOutField()');
  await click(tabFadeOut.x, tabFadeOut.y);
  await t.typeText('40');
  await press('Enter');
  await sleep(150);
  const curveOutButton = await json('__gm.soundTab.curveOutButton()');
  await click(curveOutButton.x, curveOutButton.y);
  await clickText('Exponential');
  await sleep(150);
  const curved = await json(`__gm.soundTab.played(${JSON.stringify(clipId)})`);
  const curvedSamples = await evaluate(`__gm.soundTab.samples(${JSON.stringify(curved)})`);
  check(
    'the header sets the fade out and its curve on their own, the fade in staying Linear',
    (await clipProps())?.fadeOut === 40 &&
      (await clipProps())?.fadeOutCurve === 'exponential' &&
      ((await clipProps())?.fadeInCurve ?? 'linear') === 'linear' &&
      (await json('__gm.soundTab.curveOutButton()')).tooltip === 'Fade out curve: Exponential' &&
      (await json('__gm.soundTab.curveInButton()')).tooltip === 'Fade in curve: Linear' &&
      curved.endsWith('~0.005~0.04~linear~exponential'),
    JSON.stringify({ props: await clipProps(), curved }),
  );
  await press('z', { ctrl: true });
  await press('z', { ctrl: true });
  const tabFadeIn = await json('__gm.soundTab.fadeInField()');
  await click(tabFadeIn.x, tabFadeIn.y);
  await t.typeText('0');
  await press('Enter');
  const fadeOutField = await json('__gm.soundTab.fadeOutField()');
  await click(fadeOutField.x, fadeOutField.y);
  await t.typeText('0');
  await press('Enter');
  await sleep(150);
  const unfaded = await json(`__gm.soundTab.played(${JSON.stringify(clipId)})`);
  check(
    'after two undos the curve is Linear again, and both fades go to 0 in the header',
    (await clipProps())?.fadeIn === 0 &&
      (await clipProps())?.fadeOut === 0 &&
      ((await clipProps())?.fadeOutCurve ?? 'linear') === 'linear' &&
      unfaded.endsWith('~0~0~linear~linear'),
    JSON.stringify({ props: await clipProps(), unfaded }),
  );
  // The same stretch unfaded is the drone itself: against it, the i-th sample before the end of the
  // exponential fall is (i / ramp)² of it, where a straight line would leave i / ramp.
  const rawSamples = await evaluate(`__gm.soundTab.samples(${JSON.stringify(unfaded)})`);
  const outRamp = Math.round(0.04 * (rawSamples?.rate ?? 0));
  const fall = [1, 2, 3]
    .map((i) => ({ i, raw: rawSamples?.tail.at(-1 - i), curved: curvedSamples?.tail.at(-1 - i) }))
    .filter((s) => Math.abs(s.raw) > 1e-3);
  check(
    'the end falls along the curve: (i / ramp)² of the drone on an exponential one',
    curvedSamples?.tail.at(-1) === 0 &&
      fall.length > 0 &&
      fall.every((s) => Math.abs(s.curved / s.raw / (s.i / outRamp) ** 2 - 1) < 1e-3),
    JSON.stringify({ fall, outRamp }),
  );
  await evaluate('__gm.sound.stopAll()');
  const tabPlay = await json('__gm.soundTab.playButton()');
  await click(tabPlay.x, tabPlay.y);
  const tabHeard = await waitFor(stats, (s) => s.last?.file === unfaded);
  const tabPlayhead = await waitFor(
    () => json('__gm.soundTab.playhead()'),
    (seconds) => seconds !== null && seconds > 0.1,
    10,
  );
  const tabEnded = await waitFor(
    () => json('__gm.soundTab.playing()'),
    (on) => on === false,
  );
  check(
    'Play plays only the picked clip, its playhead running inside it, and stops when it ends',
    tabHeard.last?.file === unfaded &&
      Math.abs(tabHeard.last?.duration - 0.2) < 0.01 &&
      tabPlayhead !== null &&
      tabPlayhead >= 0.1 &&
      tabPlayhead <= 0.3 &&
      tabEnded === false &&
      (await json('__gm.soundTab.playhead()')) === null,
    JSON.stringify({ last: tabHeard.last, tabPlayhead, tabEnded }),
  );
  // 34h-iii. Reverse plays the picked clip backwards, the playhead running from its end (#321).
  const reverseButton = await json('__gm.soundTab.reverseButton()');
  await click(reverseButton.x, reverseButton.y);
  await sleep(150);
  const reversed = await json(`__gm.soundTab.played(${JSON.stringify(clipId)})`);
  const reversedSamples = await evaluate(`__gm.soundTab.samples(${JSON.stringify(reversed)})`);
  check(
    'Reverse turns the clip around: its first samples are the last of the clip played forwards',
    (await clipProps())?.reverse === true &&
      (await json('__gm.soundTab.reverseButton()')).on === true &&
      reversed === `${unfaded}~reverse` &&
      reversedSamples?.length === rawSamples?.length &&
      reversedSamples?.head.every((v, i) => v === rawSamples?.tail.at(-1 - i)),
    JSON.stringify({ reversed, head: reversedSamples?.head, tail: rawSamples?.tail }),
  );
  // Over the whole file (0.75 s) the playhead has time for several readings: the handles are dragged
  // past both ends of it.
  for (const [from, to] of [
    [0.1, -0.1],
    [0.3, 0.9],
  ]) {
    const a = await json(`__gm.soundTab.at(${from})`);
    const b = await json(`__gm.soundTab.at(${to})`);
    await t.drag(a.x, a.y, b.x, b.y);
  }
  const whole = await clipProps();
  await click(tabPlay.x, tabPlay.y);
  await waitFor(
    () => json('__gm.soundTab.playhead()'),
    (seconds) => seconds !== null,
    10,
  );
  const backwards = (
    await trace(
      () => json('__gm.soundTab.playhead()'),
      (seconds) => seconds === null,
    )
  ).filter((seconds) => seconds !== null);
  check(
    'played backwards, the playhead runs from the end of the clip towards its start',
    whole?.reverse === true &&
      whole?.start === 0 &&
      whole?.end === 0 &&
      backwards.length >= 2 &&
      backwards.every((seconds) => seconds >= 0 && seconds <= 0.75) &&
      backwards.every((seconds, i) => i === 0 || seconds <= backwards[i - 1]) &&
      backwards.at(-1) < backwards[0],
    JSON.stringify({ whole, backwards }),
  );
  await shot('34-sound-tab');
  // 34h-iv. A sound field offers the clip after its sound, as "drone / Clip 1".
  await select({ kind: 'node', assetId: 'sn-logic', nodeId: 'sn-play' });
  // The row is named after the port, as the node body names it.
  const soundRow = await json("__gm.inspectorField('sound', true)");
  await click(soundRow.x, soundRow.y);
  const soundOffered = await json('__gm.overlayTexts()');
  await clickText('drone / Clip 1');
  await sleep(150);
  const playNode = async () =>
    (await json("__gm.state.project.assets.find((a) => a.id === 'sn-logic').graph")).nodes.find(
      (n) => n.id === 'sn-play',
    );
  check(
    'a sound field offers each clip after its sound, and picking one names the clip',
    soundOffered.indexOf('drone / Clip 1') === soundOffered.indexOf('drone') + 1 &&
      (await playNode())?.params.sound === clipId,
    JSON.stringify({ soundOffered, node: await playNode() }),
  );
  // 34h-v. Delete takes the picked clip away, and the sound stays.
  await evaluate(
    `__gm.state.select({ kind: 'clip', assetId: ${JSON.stringify(droneId)}, clipId: ${JSON.stringify(clipId)} })`,
  );
  await waitFor(picked, (id) => id === clipId);
  await press('Delete');
  check(
    'Delete takes the picked clip away, the sound staying on screen',
    (await clips()).length === 0 &&
      (await picked()) === null &&
      (await json('__gm.soundTab.current()')) === droneId,
    JSON.stringify({ clips: await clips(), current: await json('__gm.soundTab.current()') }),
  );

  // 34h-3. Buses and the master (#325), routed in the Master routing tab (#351). "+ → Bus" makes
  //        one; the tab has a node for it and for the sound, each linked to the master. Links drawn
  //        there and one deleted send the sound into a bus and that bus into the other; the Sound
  //        tab still plays it on the master (#368). A click on a node shows its asset, on the
  //        master the master's volume.
  for (let i = 0; i < 2; i++) {
    await clickText('+');
    await pickAssetType(t, 'Bus');
    await sleep(150);
  }
  const [busA, busB] = await assetsOfType('bus');
  await t.clickToolbar('menu');
  await clickText('Master routing');
  await sleep(300);
  const routing = () => json('__gm.routing.graph()');
  const links = (graph) => graph.edges.map((e) => `${e.from.node}>${e.to.node}`);
  const opened = { shown: await json('__gm.routing.shown()'), graph: await routing() };
  const labels = await json(
    `[${JSON.stringify(droneId)}, ${JSON.stringify(busA.id)}, '#master'].map((id) => __gm.routing.label(id))`,
  );
  await select({ kind: 'asset', assetId: droneId });
  const busRow = await json("__gm.inspectorField('Bus', true)");
  await select({ kind: 'asset', assetId: busA.id });
  const intoRow = await json("__gm.inspectorField('Into', true)");
  check(
    'Menu → Master routing has a node per sound and bus and the master, each linked to the master; no Bus or Into rows',
    opened.shown &&
      [droneId, busA.id, busB.id, '#master'].every((id) => opened.graph.nodes.some((n) => n.id === id)) &&
      [droneId, busA.id, busB.id].every((id) => links(opened.graph).includes(`${id}>#master`)) &&
      JSON.stringify(labels) === JSON.stringify(['drone', busA.name, 'Master']) &&
      [busA, busB].every((bus) => bus.props.volume === 1 && bus.props.fx === '' && !('into' in bus.props)) &&
      busRow === null &&
      intoRow === null,
    JSON.stringify({ opened, labels, busRow, intoRow, busA, busB }),
  );

  const portOf = (nodeId, key, isOutput) =>
    json(`__gm.routing.portAt(${JSON.stringify(nodeId)}, ${JSON.stringify(key)}, ${isOutput})`);
  const link = async (from, to) => {
    const a = await portOf(from, 'out', true);
    const b = await portOf(to, 'in', false);
    await drag(a.x, a.y, b.x, b.y);
    await sleep(200);
  };
  // The link is picked by the model: its line may run behind a node, as lines do.
  const unlink = async (from, to) => {
    const edge = (await routing()).edges.find((e) => e.from.node === from && e.to.node === to);
    await select({ kind: 'edge', assetId: '#routing', edgeId: edge.id, edgeIds: [edge.id] });
    await press('Delete');
    await sleep(150);
  };
  await link(droneId, busB.id);
  await link(busB.id, busA.id);
  await unlink(droneId, '#master');
  await unlink(busB.id, '#master');
  await shot('h3-routing');
  await mutate(`
    __gm.state.project.assets.find((a) => a.id === ${JSON.stringify(busA.id)}).props.volume = 0.5;`);
  await evaluate(`__gm.state.openAsset(${JSON.stringify(droneId)})`);
  // The preview of a tab leaves the routing out (#368): heard on the master, the buses stay silent.
  const tapped = JSON.stringify(['mix', `mix:${busB.id}`]);
  await json(`__gm.routing.peaks(${tapped})`);
  const startedBefore = (await stats()).started;
  await click(tabPlay.x, tabPlay.y);
  await waitFor(stats, (s) => s.started > startedBefore, 10);
  await sleep(300);
  const buses = await json('__gm.sound.buses()');
  const heardOn = (await stats()).last?.bus;
  const peak = await waitFor(
    () => json(`__gm.routing.peaks(${tapped})`),
    (peaks) => Math.max(...(peaks.mix ?? [0])) > 0.01,
  );
  await click(tabPlay.x, tabPlay.y);
  const levelOf = (name) => buses.find((bus) => bus.name === name);
  check(
    'linked in the routing, the mix sends the sound’s bus into the other; the Sound tab plays it on the master, past both',
    links(await routing())
      .filter((l) => l.startsWith(droneId) || l.startsWith(busB.id))
      .join() === `${droneId}>${busB.id},${busB.id}>${busA.id}` &&
      heardOn === 'mix' &&
      levelOf(`mix:${busB.id}`)?.into === `mix:${busA.id}` &&
      levelOf(`mix:${busA.id}`)?.into === 'mix' &&
      levelOf(`mix:${busA.id}`)?.gain === 0.5 &&
      levelOf('mix')?.into === null &&
      Math.max(...(peak?.mix ?? [0])) > 0.01 &&
      Math.max(...(peak?.[`mix:${busB.id}`] ?? [0])) < 0.001,
    JSON.stringify({ links: links(await routing()), heardOn, buses, peak }),
  );

  await t.clickToolbar('menu');
  await clickText('Master routing');
  await sleep(200);
  let at = await json(`__gm.routing.nodeAt(${JSON.stringify(busA.id)})`);
  await click(at.x, at.y);
  await sleep(200);
  const busShown = await json("__gm.inspectorField('Volume', true)");
  at = await json("__gm.routing.nodeAt('#master')");
  await click(at.x, at.y);
  await sleep(200);
  await shot('h3-master');
  const masterField = await json("__gm.inspectorField('Volume', true)");
  await click(masterField.x, masterField.y);
  await press('a', { ctrl: true });
  await t.typeText('0.6');
  await press('Enter');
  await sleep(150);
  const masterSet = await json('__gm.state.project.masterVolume');
  await t.clickToolbar('undo');
  await sleep(150);
  const masterShown = { set: masterSet, undone: await json('__gm.state.project.masterVolume') };
  at = await json(`__gm.routing.nodeAt(${JSON.stringify(droneId)})`);
  await click(at.x, at.y);
  await click(at.x, at.y);
  await sleep(300);
  check(
    'a click on a node shows its asset in the inspector, on the master the master volume, a double click opens the sound',
    busShown !== null &&
      masterShown.set === 0.6 &&
      masterShown.undone === 1 &&
      (await json('__gm.soundTab.current()')) === droneId &&
      (await json('__gm.routing.shown()')) === false,
    JSON.stringify({ busShown, masterShown, current: await json('__gm.soundTab.current()') }),
  );

  await t.clickToolbar('menu');
  await clickText('Project settings…');
  const masterAt = await json('__gm.projectSettingsMasterAt()');
  await click(masterAt.volume.x, masterAt.volume.y);
  await press('a', { ctrl: true });
  await t.typeText('0.6');
  await press('Enter');
  await clickText('Apply');
  await sleep(200);
  const mastered = {
    project: await json('__gm.state.project.masterVolume'),
    heard: await json("__gm.sound.mixVolume('mix')"),
  };
  await t.clickToolbar('undo');
  await sleep(200);
  const undone = {
    project: await json('__gm.state.project.masterVolume'),
    heard: await json("__gm.sound.mixVolume('mix')"),
  };
  check(
    'the master volume is a project setting the mix follows, and undo gives the old one back',
    mastered.project === 0.6 && mastered.heard === 0.6 && undone.project === 1 && undone.heard === 1,
    JSON.stringify({ masterAt, mastered, undone }),
  );
  // The routing starts again from the assets with the next edit: everything on the master.
  await mutate(`
    const p = __gm.state.project;
    p.assets = p.assets.filter((a) => a.type !== 'bus');
    p.routing = { nodes: [], edges: [] };`);

  // 34i. The step takes back everything it made, so the steps after it see the fixture again.
  await mutate(`
    const gone = new Set(['sn-logic', ...${JSON.stringify(both.map((a) => a.id))}]);
    const project = __gm.state.project;
    project.assets = project.assets.filter((a) => !gone.has(a.id));
    __gm.state.activeScene.objects = __gm.state.activeScene.objects.filter(
      (o) => !['sn-box', 'sn-brain'].includes(o.id));
    __gm.state.select(null);
    __gm.lookAt(0, 0);`);
  check(
    'the step leaves nothing of its own behind',
    (await assetsOfType('sound')).length === 0 && (await stats()).playing === 0,
    JSON.stringify(await assetsOfType('sound')),
  );
}