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/files/ui/files_page.dart

@@ -6,6 +6,7 @@ import 'package:flutter/material.dart';
 import 'package:signals/signals_flutter.dart';
 
 import '../../shell/motion.dart';
+import '../../widgets/app_menu.dart';
 import '../folder_store.dart';
 import '../name_parser.dart';
 import '../scanner.dart';
@@ -54,6 +55,8 @@ class FilesPage extends StatefulWidget {
   final bool relayed;
   /// Plays [path] in the session; returns an error text, or null.
   final Future<String?> Function(String path) onPlay;
+  /// Adds [path] to Up next (right-click on a video); null: no server.
+  final Future<String?> Function(String path, {bool next})? onAddToQueue;
   final String? nowPlayingPath;
   /// Defaults to [thumbnailFor].
   final ThumbnailLoader? thumbnails;
@@ -70,6 +73,7 @@ class FilesPage extends StatefulWidget {
     this.solo = false,
     required this.relayed,
     required this.onPlay,
+    this.onAddToQueue,
     this.nowPlayingPath,
     this.thumbnails,
     this.scan,
@@ -238,6 +242,35 @@ class _FilesPageState extends State<FilesPage> {
 
   VoidCallback _tapOf(String path) => () => _play(path);
 
+  /// Right-click on a video ([context]: its tile): Put it up, Add to
+  /// queue, Play next.
+  Future<void> _menu(BuildContext context, String path) async {
+    final add = widget.onAddToQueue;
+    if (add == null) return;
+    final pick = await showAppMenu<int>(context, items: [
+      AppMenuItem(value: 0, label: widget.solo ? 'Play' : 'Put it up'),
+      const AppMenuItem(value: 1, label: 'Add to queue'),
+      const AppMenuItem(value: 2, label: 'Play next'),
+    ]);
+    if (pick == null || !mounted) return;
+    if (pick == 0) return _play(path);
+    String? error;
+    try {
+      error = await add(path, next: pick == 2);
+    } catch (e) {
+      error = '$e';
+    }
+    if (error != null) _showError(error);
+  }
+
+  /// [child] with the right-click menu (when there is a server).
+  Widget _menuable(String path, Widget child) => widget.onAddToQueue == null
+      ? child
+      : KeyedSubtree(
+          key: ValueKey('menu:$path'),
+          child: Builder(
+              builder: (context) => GestureDetector(onSecondaryTap: () => _menu(context, path), child: child)));
+
   @override
   Widget build(BuildContext context) => LayoutBuilder(
         builder: (context, box) {
@@ -468,14 +501,16 @@ class _FilesPageState extends State<FilesPage> {
         itemCount: recent.length,
         itemBuilder: (context, i) {
           final path = recent[i];
-          return _RecentRow(
-            key: ValueKey(path),
-            path: path,
-            state: _stateOf(path),
-            thumbs: _thumbs,
-            onTap: _tapOf(path),
-            onRemove: () => _store.removeRecent(path),
-          );
+          return _menuable(
+              path,
+              _RecentRow(
+                key: ValueKey(path),
+                path: path,
+                state: _stateOf(path),
+                thumbs: _thumbs,
+                onTap: _tapOf(path),
+                onRemove: () => _store.removeRecent(path),
+              ));
         },
       ),
     ];
@@ -582,16 +617,18 @@ class _FilesPageState extends State<FilesPage> {
               onTap: () => setState(() => _expanded.contains(id) ? _expanded.remove(id) : _expanded.add(id)),
             );
           }
-          return FileRow(
-            key: ValueKey(v.path),
-            path: v.path,
-            title: v.parsed.label.isEmpty ? v.parsed.series : v.parsed.label,
-            subtitle: v.name,
-            size: formatSize(v.size),
-            state: _stateOf(v.path),
-            thumbs: _thumbs,
-            onTap: _tapOf(v.path),
-          );
+          return _menuable(
+              v.path,
+              FileRow(
+                key: ValueKey(v.path),
+                path: v.path,
+                title: v.parsed.label.isEmpty ? v.parsed.series : v.parsed.label,
+                subtitle: v.name,
+                size: formatSize(v.size),
+                state: _stateOf(v.path),
+                thumbs: _thumbs,
+                onTap: _tapOf(v.path),
+              ));
         },
       ),
       // Everything else (movies, clips) as a thumbnail grid.
@@ -620,13 +657,15 @@ class _FilesPageState extends State<FilesPage> {
             itemCount: loose.length,
             itemBuilder: (context, i) {
               final v = loose[i];
-              return VideoCard(
-                key: ValueKey(v.path),
-                video: v,
-                state: _stateOf(v.path),
-                thumbs: _thumbs,
-                onTap: _tapOf(v.path),
-              );
+              return _menuable(
+                  v.path,
+                  VideoCard(
+                    key: ValueKey(v.path),
+                    video: v,
+                    state: _stateOf(v.path),
+                    thumbs: _thumbs,
+                    onTap: _tapOf(v.path),
+                  ));
             },
           );
         }),