Let the places of a song share what it keeps to itself (#357)

With clips, one take serves many items: four items on the four clips
of one take. The rule from #355 gave every further place its own copy
of an embedded asset, so a cut made in the Sound tab reached one item
only. Now the song, its tracks and its items share a sound, a pattern
or a sound FX the song keeps.

- settleEmbedded no longer copies within the song. An embedded asset
  stays as long as one place names it, and goes with the last one.
- A paste from another song still gets a copy, but one copy for all
  the places naming the same asset, with its clip ids mapped.
- The picks in a song offer what the song keeps, under a line after
  the project's assets: the Sound row of an item the song's sounds
  and their clips, the Pattern row its patterns, every sound FX pick
  its sound FX.
- Make project asset and Embed a copy are unchanged.

The project cbbf160bb7e8 was merged by hand afterwards: the items of
Song 2 on three copies of Take 1 now play the same clips of the first
one, and the copies are gone.

Tests:
- Unit embedded, sound-clips, own-fx and the song tests: 66 green,
  3 counter-checks red as expected
- e2e 65 on melektaus-atx: ALL PASSED, 52 checks
- Gate on melektaus-atx: CHECK EXIT 0, 271 files, 4198 tests

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

tests/core/embedded.test.ts

@@ -1,7 +1,7 @@
 /**
  * What a song keeps to itself (#355): an asset with the song as its owner, left out of every list,
- * with one user in the song. Split, duplicate and paste give a place a copy of its own; what nothing
- * names goes in the same step, and comes back with an undo.
+ * shared by the places of the song (#357). A paste from another song gives it a copy of its own;
+ * what nothing names goes in the same step, and comes back with an undo.
  */
 import { describe, expect, it } from 'vitest';
 import {
@@ -81,24 +81,50 @@ describe('an embedded asset (#355)', () => {
     expect(isRowHiddenWhenEmbedded(findAsset(f.project, blipId)!, 'loop')).toBe(false);
   });
 
-  it('gives the right half of a split a copy of its own, the same one again on redo', () => {
+  it('is shared by both halves of a split (#357), and stays until the last place lets go', () => {
     const { f, song, takeId, edit } = setup();
+    const before = f.project.assets.length;
     const left = song().items[0]!;
     edit([
       { ...left, length: BAR },
       { ...left, id: 'right', tick: BAR, length: BAR },
     ]);
-    const [a, b] = song().items;
-    expect(a!.asset).toBe(takeId);
-    expect(b!.asset).not.toBe(takeId);
-    const copy = findAsset(f.project, b!.asset)!;
-    expect([copy.owner, copy.name, copy.type]).toEqual([song().id, 'Take 1', 'sound']);
+    expect(song().items.map((i) => i.asset)).toEqual([takeId, takeId]);
+    expect(f.project.assets.length).toBe(before);
+    edit([song().items[1]!]);
+    expect(findAsset(f.project, takeId)?.owner).toBe(song().id);
+    edit([]);
+    expect(findAsset(f.project, takeId)).toBeUndefined();
     f.stack.undo();
-    expect(findAsset(f.project, copy.id)).toBeUndefined();
     expect(embeddedIn(f.project, song().id).map((x) => x.id)).toEqual([takeId]);
-    f.stack.redo();
-    expect(song().items[1]!.asset).toBe(copy.id);
-    expect(findAsset(f.project, copy.id)).toBe(copy);
+  });
+
+  it('is shared by the song, its tracks and its items, whichever kind (#357)', () => {
+    const { f, song, songId, track, edit } = setup();
+    const fx = new CreateAssetCommand('soundfx', 'Sound FX 1', {}, songId);
+    const pattern = new CreateAssetCommand('pattern', 'Pattern 1', {}, songId);
+    f.stack.execute(fx);
+    f.stack.execute(pattern);
+    const tracks = song().tracks.map((t) => ({ ...t, fx: fx.asset.id }));
+    const played = { track, kind: 'pattern' as const, asset: pattern.asset.id, length: BAR };
+    const items = [0, BAR].map((tick) => ({ ...newItem({ ...played, tick }), fx: fx.asset.id }));
+    f.stack.execute(new SetSongCommand(songId, { tracks, items }));
+    f.stack.execute(new SetAssetPropertyCommand(songId, 'fx', fx.asset.id));
+    expect(song().items.map((i) => [i.asset, i.fx])).toEqual([
+      [pattern.asset.id, fx.asset.id],
+      [pattern.asset.id, fx.asset.id],
+    ]);
+    expect(song().tracks[0]!.fx).toBe(fx.asset.id);
+    expect(
+      embeddedIn(f.project, songId)
+        .map((a) => a.type)
+        .sort(),
+    ).toEqual(['pattern', 'soundfx']);
+    f.stack.execute(new SetAssetPropertyCommand(songId, 'fx', ''));
+    edit(song().items.map((i) => ({ ...i, fx: '' })));
+    expect(findAsset(f.project, fx.asset.id)?.owner).toBe(songId);
+    f.stack.execute(new SetSongCommand(songId, { tracks: song().tracks.map((t) => ({ ...t, fx: '' })) }));
+    expect(findAsset(f.project, fx.asset.id)).toBeUndefined();
   });
 
   it('goes with the item that names it, and comes back on undo where it was', () => {
@@ -144,6 +170,22 @@ describe('an embedded asset (#355)', () => {
     expect(findAsset(f.project, takeId)?.owner).toBe(song().id);
   });
 
+  it('is copied once for all the items of another song that name it (#357)', () => {
+    const { f, takeId } = setup();
+    const other = new CreateAssetCommand('song', 'Other');
+    f.stack.execute(other);
+    const otherSong = other.asset as SongAsset;
+    const track = otherSong.tracks[0]!.id;
+    const pasted = [0, BAR].map((tick) =>
+      newItem({ track, kind: 'sound', asset: takeId, tick, length: BAR }),
+    );
+    f.stack.execute(new SetSongCommand(otherSong.id, { items: pasted }));
+    const named = findAssetOf(f.project, otherSong.id, 'song')!.items.map((i) => i.asset);
+    expect(named[0]).not.toBe(takeId);
+    expect(named[1]).toBe(named[0]);
+    expect(embeddedIn(f.project, otherSong.id).map((a) => a.id)).toEqual([named[0]]);
+  });
+
   it('leaves a project asset named by several items alone', () => {
     const { f, song, blipId, edit, track } = setup();
     const before = f.project.assets.length;

tests/core/sound-clips.test.ts

@@ -172,20 +172,17 @@ describe('a clip in a song (#357)', () => {
     expect(itemFx(f.project, song().items[0]!)).toBe('some-fx');
   });
 
-  it('keeps its take, and a second item on a clip of it gets a copy with its own clip ids', () => {
+  it('keeps its take, which a second item shares, on the same clip or the whole take', () => {
     const { f, song, songId, track, takeId, takeClipId } = setup();
     expect(embeddedUsedBy(f.project, song().items).map((a) => a.id)).toEqual([takeId]);
+    const before = f.project.assets.length;
     const [item] = song().items;
-    f.stack.execute(new SetSongCommand(songId, { items: [item!, { ...item!, id: 'second', tick: BAR }] }));
-    const named = song().items[1]!.asset;
-    const copy = findSound(f.project, named)!;
-    expect(copy.asset.id).not.toBe(takeId);
-    expect(copy.asset.owner).toBe(songId);
-    expect(copy.clip?.name).toBe('Clip 1');
-    expect(named).not.toBe(takeClipId);
-    expect(findSound(f.project, takeClipId)?.asset.id).toBe(takeId);
-    // The take nothing else names stays.
-    expect(song().items[0]!.asset).toBe(takeClipId);
+    const second = { ...item!, id: 'second', tick: BAR };
+    f.stack.execute(new SetSongCommand(songId, { items: [item!, second] }));
+    expect(song().items.map((i) => i.asset)).toEqual([takeClipId, takeClipId]);
+    f.stack.execute(new SetSongCommand(songId, { items: [item!, { ...second, asset: takeId }] }));
+    expect(song().items.map((i) => i.asset)).toEqual([takeClipId, takeId]);
+    expect(f.project.assets.length).toBe(before);
     expect(song().items.map((i) => i.track)).toEqual([track, track]);
   });