Play every tab's preview straight into the master (#368)

Since #351 the tabs played their asset along its links in the Master
routing, as the game does. A song linked into a reverb bus was heard
through that bus while it was edited. A preview should sound like the
asset itself, so the tabs leave the Master routing out again.

- The Sound, Sound FX, Instrument, Pattern and Song tab play into the
  master. The sound FX of the asset still applies, and so does the
  master's own volume and FX.
- Inside a song its own routing of tracks and sends still counts.
- The game is unchanged: Play nodes go along the routing as before.

Tests:
- e2e 34 (melektaus-atx): ALL PASSED, 96 checks. The routing check
  now holds the mix of the two buses as before, and the Sound tab on
  the master with the bus silent.
- Counter-probe e2e: the Sound tab along the routing again, the
  routing check red.
- Gate (melektaus-atx): CHECK EXIT 0, 274 files, 4230 tests.

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

tools/e2e/34-sound.mjs

@@ -2339,8 +2339,9 @@ export async function sound(t) {
 
   // 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, as the Sound
-  //        tab then plays it. A click on a node shows its asset, on the master the master's volume.
+  //        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');
@@ -2395,6 +2396,9 @@ export async function sound(t) {
   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);
@@ -2402,22 +2406,23 @@ export async function sound(t) {
   const buses = await json('__gm.sound.buses()');
   const heardOn = (await stats()).last?.bus;
   const peak = await waitFor(
-    () => json(`__gm.routing.peaks([${JSON.stringify(`mix:${busB.id}`)}])`),
-    (peaks) => Math.max(...(peaks[`mix:${busB.id}`] ?? [0])) > 0.01,
+    () => json(`__gm.routing.peaks(${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 Sound tab plays the sound on its bus, into the bus that one goes to, on into the master',
+    '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:${busB.id}` &&
+      heardOn === 'mix' &&
       levelOf(`mix:${busB.id}`)?.into === `mix:${busA.id}` &&
       levelOf(`mix:${busA.id}`)?.into === 'mix' &&
       levelOf(`mix:${busA.id}`)?.gain === 0.5 &&
       levelOf('mix')?.into === null &&
-      Math.max(...(peak?.[`mix:${busB.id}`] ?? [0])) > 0.01,
+      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 }),
   );