Page links played here only also go through a reader of their own: Bilibili's cuts never end playback

Alone, or with Everyone fetches it, a page link with plain-file tracks
plays through SharedLinks.local (a SharedSource without the upload): it
resumes after a cut, backs off on 412/429/5xx and resolves the page again
on 403/410/412, where ffmpeg's own reconnect gave up for good. Pieces
tracks and a reader that cannot open keep yt-dlp's URLs as before.

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

apps/desktop/lib/src/session/media_pipeline.dart

@@ -233,9 +233,24 @@ class MediaPipeline {
       throw ResolveFailure(probe.ytDlpError ?? (probe.info == null ? 'Not a video page yt-dlp knows' : 'no format a player opens'),
           cookies: probe.cookies);
     }
+    if (headers == null || headers.isEmpty) {
+      // Played here only: through a reader of its own too, which resumes
+      // after a cut and gets a fresh address (a CDN cuts mpv's reconnects
+      // off). Pieces tracks, or a reader that cannot open: the site as is.
+      final y = await l.ytDlp;
+      final local =
+          await shared.local(url, probe, () => LinkRelayMedia(Uri.parse(url), ytDlp: y, probe: probe), fresh: fresh);
+      if (local != null) {
+        return _Target(local.source.playerUrl, const {}, subtitles: local.subtitles, shared: true, local: true);
+      }
+    }
     return _Target(play.mpvUrl, {...play.headers, ...?headers}, subtitles: play.subtitles);
   }
 
+  /// The [SharedLinks.local] readers the player and the preload use stay;
+  /// the rest close.
+  void _trimLocal() => shared.trimLocal({_openUrl, _pre?.url});
+
   /// The page's subtitles on [p] once its media is in (not selected: the
   /// usual choice applies).
   Future<void> _addSubtitles(HostedPlayer p, List<YtDlpSubtitle> subs) async {
@@ -303,6 +318,7 @@ class MediaPipeline {
     _openHeaders = headers;
     _openResolve = resolve;
     _opening = true;
+    _trimLocal();
     try {
       trace.mark(mediaId, SwitchTrace.open);
       final promoted = await _openInPlayer(url, headers,
@@ -360,6 +376,7 @@ class MediaPipeline {
     }
     if (headers != null && headers.isNotEmpty) return 'Jellyfin, own sign-in';
     if (shared.has(url)) return 'link passed on, read once here';
+    if (shared.hasLocal(url)) return 'link, read here with resume';
     return 'link, fetched here';
   }
 
@@ -465,6 +482,7 @@ class MediaPipeline {
     _openUrl = null;
     _openHeaders = null;
     await playback.stop();
+    _trimLocal();
   }
 
   /// The same media came back as [r.mediaId] (a restarted server put back
@@ -546,6 +564,7 @@ class MediaPipeline {
     _openHeaders = null;
     _recovery = null;
     if (ready) await playback.stop();
+    _trimLocal();
   }
 
   /// The next state's media is new to this player: it opens again from
@@ -794,9 +813,10 @@ class MediaPipeline {
     _pre = null;
     if (had != null) unawaited(_disposePrepared(had));
     final pre = _pre = _Prepared(url, headers ?? const {});
+    _trimLocal();
     try {
       final target = await _resolve(url, headers, fresh: fresh);
-      pre.shared = target.shared;
+      pre.shared = target.shared && !target.local;
       if (!identical(_pre, pre)) {
         pre.fail();
         return false;
@@ -857,6 +877,7 @@ class MediaPipeline {
     await pre.logSub?.cancel();
     final p = pre.player;
     if (p != null) await host.dispose(p);
+    if (!identical(_pre, pre)) _trimLocal();
   }
 
   /// [pre] becomes the session player; its buffer comes along.
@@ -935,7 +956,10 @@ class _Target {
 
   /// A link this member passes on, read through its shared reader.
   final bool shared;
-  const _Target(this.url, this.headers, {this.subtitles = const [], this.shared = false});
+
+  /// Read through a [SharedLinks.local] reader (played here only).
+  final bool local;
+  const _Target(this.url, this.headers, {this.subtitles = const [], this.shared = false, this.local = false});
 }
 
 /// A page could not be resolved: why ([message], yt-dlp's words) and which

apps/desktop/lib/src/session/shared_links.dart

@@ -20,6 +20,8 @@ class SharedLink {
 /// Each one's player opens [SharedSource.playerUrl] and its relay serves
 /// [SharedSource.upload]. A page with a pieces track (HLS/DASH) is not
 /// shared ([fits]): its player and relay keep their own fetches.
+/// Page links played here only ([local]) get a reader of their own too,
+/// for its resume after cuts.
 class SharedLinks {
   SharedLink? _current;
   ({String queueId, SharedLink link})? _warm;
@@ -146,6 +148,57 @@ class SharedLinks {
   /// [url] is shared here (the current media's or the warm one).
   bool has(String url) => _current?.url == url || _warm?.link.url == url;
 
+  // Page links this app plays without passing them on (alone, or
+  // everyone fetches it), by page URL: the session player's and the
+  // preload's.
+  final _local = <String, Future<SharedLink?>>{};
+
+  /// A page link played here only: read through its own [SharedSource]
+  /// over [media] too, so the player gets the reader's resume after a cut,
+  /// back-off and fresh address (403/410/412) instead of ffmpeg's
+  /// reconnect, which a CDN like Bilibili cuts off for good. The one [url]
+  /// has is kept unless [fresh]. Null when the page does not fit ([fits]:
+  /// a pieces track) or the reader cannot open it: the player reads the
+  /// site itself. [trimLocal] closes the ones no longer needed.
+  Future<SharedLink?> local(String url, LinkProbe probe, RelayMedia Function() media,
+      {bool fresh = false, Duration timeout = const Duration(seconds: 15)}) {
+    final had = _local[url];
+    if (had != null && !fresh) return had;
+    if (had != null) _local.remove(url)!.then((l) => l?.source.close());
+    if (!fits(probe)) return Future.value();
+    Future<SharedLink?> make() async {
+      final s = SharedSource(media());
+      try {
+        // The sizes too: a format URL the site refuses (403) fails here,
+        // and the player then gets the site's own answer.
+        await s.start().timeout(timeout);
+        return SharedLink(url, s, subtitles: _subs(probe));
+      } catch (e) {
+        _log.info('link ${logUrl(url)} read by the player itself: $e');
+        unawaited(s.close());
+        return null;
+      }
+    }
+
+    final f = _local[url] = make();
+    unawaited(f.then((l) {
+      if (l == null && identical(_local[url], f)) _local.remove(url);
+    }));
+    return f;
+  }
+
+  /// [url] is read here through a [local] reader.
+  bool hasLocal(String url) => _local.containsKey(url);
+
+  /// Closes the [local] readers of every URL but [keep] (the player's and
+  /// the preload's).
+  void trimLocal(Set<String?> keep) {
+    for (final url in [..._local.keys]) {
+      if (keep.contains(url)) continue;
+      unawaited(_local.remove(url)!.then((l) => l?.source.close()));
+    }
+  }
+
   Future<void> closeCurrent() async {
     final c = _current;
     _current = null;
@@ -156,6 +209,7 @@ class SharedLinks {
   Future<void> closeAll() async {
     _dropPending();
     dropWarm();
+    trimLocal(const {});
     await closeCurrent();
   }
 }