Decode a clip from a file of its own, not its whole sound (#349)

A clip was cut from its sound's file, so a game decoded the whole file
for it and held it for as long as the page was open. A long recording
played through a few short clips cost the recording. Every clip now has
a copy of its cut as Opus, with Stream on or off, and a game decodes
that instead.

- StreamKeeper makes the copy of each clip whether its sound streams
  or not. Stream only decides whether a sound gets a copy of its own.
- clipCopyTable says which cut decodes from which copy. The sound
  library loads the copy for a clip unless the whole file is decoded
  already. Then the clip is cut from that as before.
- projectFiles decodes the whole file ahead only where something may
  play the sound itself: no clips, a clip without a fitting copy, or
  the sound's id anywhere in an asset that can name one. That last
  test walks the data, not the fields, so no place is missed.
- A copy that cannot be had falls back to the whole file. A library
  that bakes keeps to the whole files, as the bake's fingerprint does.

Tests:
- Gate: CHECK EXIT 0, 280 files, 4319 tests (7 new: streams +4,
  sound-library +3).
- e2e 34: ALL PASSED, 108 checks (2 new). With Stream off a fresh
  library decodes the ten-second reversed clip's copy and not the
  five-minute file. It is the cut made from the original to within
  0.0091 a sample and 0.013 dB in any 20 ms. Once a node plays the
  sound itself, the whole file is decoded ahead again.
- e2e 65: all passed with this change.
- Counter-checks red as they should be: the library ignoring copies,
  the whole file always decoded ahead, clip copies only with Stream.

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

src/core/model/projectFiles.ts

@@ -1,9 +1,12 @@
 import { validBake } from '../music/bake';
-import { streamsOf } from '../properties/sounds';
+import { clipCopyTable } from '../music/streams';
+import { cutOf, streamsOf } from '../properties/sounds';
+import type { AssetType } from './AssetTypes';
+import type { SoundAsset } from './Asset';
 import { isFontFile } from './font';
 import { celFilesOf } from './pixelart';
 import type { Project } from './Project';
-import { isSoundFile } from './sound';
+import { clipsOf, cutName, isSoundFile } from './sound';
 import { isTextureFile } from './texture';
 
 /** The stored files a project draws and plays, per library – what is loaded before anything asks. */
@@ -20,17 +23,57 @@ export interface ProjectFiles {
  * an upload that failed – is left out, as the libraries would never get it anyway. So is a bake that
  * no longer holds (#340): it would never be played. So is a sound that streams (#349): the sound
  * library fetches the start of its copy instead, and decoded ahead it would weigh what streaming saves.
+ * A sound only played through its clips has their copies loaded rather than its whole file.
  */
 export function projectFiles(project: Project): ProjectFiles {
   const files: ProjectFiles = { textures: [], fonts: [], cels: [], sounds: [] };
+  const copies = clipCopyTable(project);
+  let named: ReadonlySet<string> | null = null;
+  const namedWhole = (asset: SoundAsset) => (named ??= namedStrings(project)).has(asset.id);
   for (const asset of project.assets) {
     if (asset.type === 'texture' && isTextureFile(asset.file)) files.textures.push(asset.file);
     else if (asset.type === 'font' && isFontFile(asset.file)) files.fonts.push(asset.file);
     else if (asset.type === 'pixelart') files.cels.push(...celFilesOf(asset));
     else if (asset.type === 'sound' && isSoundFile(asset.file) && !streamsOf(asset.props))
-      files.sounds.push(asset.file);
+      files.sounds.push(...decodedAhead(asset, copies, namedWhole));
     else if ((asset.type === 'pattern' || asset.type === 'song') && validBake(project, asset))
       files.sounds.push(asset.bake!.file);
   }
   return files;
 }
+
+/**
+ * What of a sound is decoded ahead: its file where something may play it whole – a sound without
+ * clips, one the project names itself, one with a clip whose copy is not there yet – else the cut of
+ * each clip, which the sound library plays from its copy.
+ */
+function decodedAhead(
+  asset: SoundAsset,
+  copies: ReadonlyMap<string, string>,
+  namedWhole: (asset: SoundAsset) => boolean,
+): string[] {
+  const cuts = clipsOf(asset).map((clip) => cutName(asset.file, cutOf(clip.props)));
+  const whole = cuts.length === 0 || cuts.some((cut) => !copies.has(cut)) || namedWhole(asset);
+  return whole ? [asset.file] : [...new Set(cuts)];
+}
+
+/** What holds no reference to a sound, and holds a lot: not walked for one. */
+const UNNAMING: ReadonlySet<AssetType> = new Set(['sound', 'texture', 'pixelart', 'tilemap', 'font']);
+
+/**
+ * Every text the project holds outside the assets that cannot name a sound. Where a sound is played
+ * whole – a sound field, an item of a song, a Sample, a Reverb's impulse – its id is one of them; a
+ * clip has an id of its own. Looked at as data, not field by field, so no place is missed: one that
+ * only looks like a reference loads the file as before.
+ */
+function namedStrings(project: Project): Set<string> {
+  const seen = new Set<string>();
+  const walk = (value: unknown): void => {
+    if (typeof value === 'string') seen.add(value);
+    else if (Array.isArray(value)) value.forEach(walk);
+    else if (typeof value === 'object' && value !== null && !ArrayBuffer.isView(value))
+      Object.values(value).forEach(walk);
+  };
+  for (const asset of project.assets) if (!UNNAMING.has(asset.type)) walk(asset);
+  return seen;
+}