fix(anime): keep browser state in sync and alias HLS segments

- Toggle the player Anime Browser without losing its state
- Share active playback state and support rotating fake segment extensions

src/animeui/episode-list.test.ts

@@ -0,0 +1,51 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { nextPlaybackCue, playingEpisodeForAnime } from './episode-playback';
+
+const selected = { sourceId: 'source.one', url: '/anime/one', title: 'One' };
+
+test('playing episode sync applies only to the matching source and anime', () => {
+  assert.equal(
+    playingEpisodeForAnime(
+      { sourceId: 'source.one', animeUrl: '/anime/one', episodeUrl: '/episode/3' },
+      selected,
+    ),
+    '/episode/3',
+  );
+  assert.equal(
+    playingEpisodeForAnime(
+      { sourceId: 'source.two', animeUrl: '/anime/one', episodeUrl: '/episode/3' },
+      selected,
+    ),
+    null,
+  );
+  assert.equal(
+    playingEpisodeForAnime(
+      { sourceId: 'source.one', animeUrl: '/anime/two', episodeUrl: '/episode/3' },
+      selected,
+    ),
+    null,
+  );
+  assert.equal(playingEpisodeForAnime(null, selected), null);
+});
+
+test('live playback sync preserves a pending episode cue until resolution finishes', () => {
+  const loading = { url: '/episode/4', state: 'loading' as const };
+
+  assert.equal(
+    nextPlaybackCue(
+      { sourceId: 'source.one', animeUrl: '/anime/one', episodeUrl: '/episode/3' },
+      selected,
+      loading,
+    ),
+    loading,
+  );
+  assert.deepEqual(
+    nextPlaybackCue(
+      { sourceId: 'source.one', animeUrl: '/anime/one', episodeUrl: '/episode/3' },
+      selected,
+      { url: '/episode/2', state: 'playing' },
+    ),
+    { url: '/episode/3', state: 'playing' },
+  );
+});