Protocol 12: Up next (a shared queue) and where the video comes from

Up next: a server-side queue anyone edits by item id (add at end or
next, move, remove, play now, skip); each item says who added it and
how it plays. At the real end the first item swaps in after the end
card's countdown, put up by whoever can (its adder for through-me links
and files, someone with access for Jellyfin, else anyone); items that
can't play are skipped with the reason. The next item's link is
resolved ahead. Greyed "Continues with" episodes below. A chip with the
controls opens it as a popover (leaf_widgets, local path dependency for
now); "Add to queue" next to Put it up everywhere.

Delivery: the server measures the source's rate, the media's bitrate
and each member's read rate; the members card shows a source line
(who passes it on, through what, keeping up or not, source left) and
each member's route and buffer. A slow source is told once per media.
A failed server fetch is announced to everyone.

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

apps/desktop/lib/src/jellyfin/browse_scope.dart

@@ -6,6 +6,7 @@ import 'package:sync_relay_core/core.dart';
 
 import 'accounts.dart';
 import 'format.dart';
+import '../widgets/app_menu.dart';
 
 /// One level of the library browser's back stack.
 sealed class BrowseRoute {
@@ -274,6 +275,9 @@ class BrowseScope extends InheritedWidget {
   final ValueChanged<JellyfinItem> onSelect;
   /// Double-click: put it up (a series: its next episode).
   final ValueChanged<JellyfinItem> onPutUp;
+  /// Adds it to Up next (with next: right after what plays); null: no
+  /// server, the cards have no menu.
+  final void Function(JellyfinItem item, {bool next})? onAddToQueue;
   /// Home shows the library chips itself (the Library tab has them in its
   /// header instead).
   final bool libraryStrip;
@@ -287,6 +291,7 @@ class BrowseScope extends InheritedWidget {
     required this.selectedItemId,
     required this.onSelect,
     required this.onPutUp,
+    this.onAddToQueue,
     this.libraryStrip = true,
     required super.child,
   });
@@ -296,6 +301,26 @@ class BrowseScope extends InheritedWidget {
 
   void onOpen(BrowseRoute route) => controller.open(route);
 
+  /// Right-click on a playable card ([context]: the card): Put it up, Add
+  /// to queue, Play next. Nothing without a server.
+  Future<void> cardMenu(BuildContext context, JellyfinItem item) async {
+    final queue = onAddToQueue;
+    if (queue == null || !isSelectable(item)) return;
+    final pick = await showAppMenu<int>(context, items: const [
+      AppMenuItem(value: 0, label: 'Put it up'),
+      AppMenuItem(value: 1, label: 'Add to queue'),
+      AppMenuItem(value: 2, label: 'Play next'),
+    ]);
+    switch (pick) {
+      case 0:
+        onPutUp(item);
+      case 1:
+        queue(item);
+      case 2:
+        queue(item, next: true);
+    }
+  }
+
   /// Cached browse call on this server.
   Future<T> load<T>(String key, Future<T> Function(JellyfinClient c) fn) =>
       accounts.cached(account.serverId, key, () => fn(client));