test: cut low-value tests, rewrite the rest around behavior, parallelize lanes (#285)

src/core/services/youtube/ytdlp-single-video-args.test.ts

@@ -4,7 +4,6 @@ import { buildYoutubeMetadataProbeArgs } from './metadata-probe';
 import { buildYoutubePlaybackResolveArgs } from './playback-resolve';
 import { buildDownloadArgs } from './track-download';
 import { buildYoutubeTrackProbeArgs } from './track-probe';
-import { YTDLP_SINGLE_VIDEO_ARG } from './ytdlp-command';
 
 // Regression guard for issue #179: a `list=`/`index=` URL made yt-dlp enumerate the whole
 // playlist (e.g. Watch Later) and blow past our 15s timeouts on every single-video call.
@@ -26,10 +25,6 @@ const cases: Array<{ name: string; args: string[] }> = [
   },
 ];
 
-test('YTDLP_SINGLE_VIDEO_ARG is the yt-dlp flag that disables playlist expansion', () => {
-  assert.equal(YTDLP_SINGLE_VIDEO_ARG, '--no-playlist');
-});
-
 for (const { name, args } of cases) {
   test(`${name} passes --no-playlist for playlist-scoped URLs`, () => {
     assert.ok(args.includes('--no-playlist'), `${name} args: ${args.join(' ')}`);