Protocol 10 presence gate, drop/paste anywhere, quick UI fixes

Ready gate: whoever is in the server while it is not playing counts (joining
while playing does not pause anyone); a swap counts everyone present and
keeps ready flags; the quorum rule is gone. Optional 'Unready when the
video changes'. No 'Skip 1:30' guess when the media has chapters.

Drag & drop and Ctrl+V anywhere (fox_utils): files, folders and links get a
small card asking how to open them. Files series start collapsed.

UI: Tab never moves focus and Space is always ready outside text fields;
chat focuses its field; unread badge on uosc and a chip in fullscreen;
people-only chat with an Activity toggle; skip pills show 5 s then with
the controls; volume up to 150%; own avatar same size as the party.

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

apps/desktop/lib/src/files/ui/file_tiles.dart

@@ -35,7 +35,11 @@ Widget _offlineTip(bool offline, Widget child) =>
 class SeriesHeader extends StatelessWidget {
   final SeriesGroup group;
   final ThumbCache thumbs;
-  const SeriesHeader({super.key, required this.group, required this.thumbs});
+  /// Its episodes are listed below; [onTap] opens or closes them.
+  final bool expanded;
+  final VoidCallback? onTap;
+  const SeriesHeader(
+      {super.key, required this.group, required this.thumbs, this.expanded = true, this.onTap});
 
   @override
   Widget build(BuildContext context) {
@@ -49,34 +53,48 @@ class SeriesHeader extends StatelessWidget {
       ?first.parsed.group,
     ].join(' · ');
     return Padding(
-      padding: const EdgeInsets.only(top: 18, bottom: 4),
-      child: Row(
-        children: [
-          ClipRRect(
-            borderRadius: BorderRadius.circular(8),
-            child: ThumbBuilder(
-              cache: thumbs,
-              path: first.path,
-              builder: (context, t, _) => ThumbImage(t, width: 96, height: 54),
-            ),
+      padding: const EdgeInsets.only(top: 14),
+      child: InkWell(
+        onTap: onTap,
+        borderRadius: BorderRadius.circular(10),
+        child: Padding(
+          padding: const EdgeInsets.symmetric(vertical: 4),
+          child: Row(
+            children: [
+              ClipRRect(
+                borderRadius: BorderRadius.circular(8),
+                child: ThumbBuilder(
+                  cache: thumbs,
+                  path: first.path,
+                  builder: (context, t, _) => ThumbImage(t, width: 96, height: 54),
+                ),
+              ),
+              const SizedBox(width: 12),
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Text(group.title,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                        style: Theme.of(context).textTheme.titleMedium),
+                    Text(detail,
+                        maxLines: 1,
+                        overflow: TextOverflow.ellipsis,
+                        style: TextStyle(color: scheme.onSurfaceVariant, fontSize: 12)),
+                  ],
+                ),
+              ),
+              if (onTap != null)
+                AnimatedRotation(
+                  turns: expanded ? 0.5 : 0,
+                  duration: const Duration(milliseconds: 200),
+                  child: Icon(Icons.expand_more, color: scheme.onSurfaceVariant),
+                ),
+              const SizedBox(width: 8),
+            ],
           ),
-          const SizedBox(width: 12),
-          Expanded(
-            child: Column(
-              crossAxisAlignment: CrossAxisAlignment.start,
-              children: [
-                Text(group.title,
-                    maxLines: 1,
-                    overflow: TextOverflow.ellipsis,
-                    style: Theme.of(context).textTheme.titleMedium),
-                Text(detail,
-                    maxLines: 1,
-                    overflow: TextOverflow.ellipsis,
-                    style: TextStyle(color: scheme.onSurfaceVariant, fontSize: 12)),
-              ],
-            ),
-          ),
-        ],
+        ),
       ),
     );
   }

apps/desktop/lib/src/files/ui/files_page.dart

@@ -17,7 +17,8 @@ export 'thumb.dart' show ThumbnailLoader;
 // The Files source: watched folders on the left (chips on top when
 // narrow), the open one on the right grouped into series and loose
 // videos, or Recent. A folder is scanned when first opened and on Rescan;
-// scans are kept for the app session. Playing goes through [onPlay].
+// scans are kept for the app session. Series start collapsed; the ones
+// opened stay open for the app session. Playing goes through [onPlay].
 
 /// Below this width the sidebar turns into chips above the list.
 const filesNarrowWidth = 700.0;
@@ -26,12 +27,23 @@ const filesNarrowWidth = 700.0;
 final _scans = <String, FolderScan>{};
 final _running = <String, Future<FolderScan>>{};
 String? _lastOpen;
+/// Series opened this session, by `folder\nseries key`.
+final _expanded = <String>{};
+final _showRequests = ValueNotifier(0);
 
-/// Forgets the session's scans and the open folder.
+/// Opens [dir] (null: Recent) in the Files page: now if one is showing,
+/// else when it next opens.
+void showFilesFolder(String? dir) {
+  _lastOpen = dir;
+  _showRequests.value++;
+}
+
+/// Forgets the session's scans, open series and the open folder.
 @visibleForTesting
 void resetFilesPageSession() {
   _scans.clear();
   _running.clear();
+  _expanded.clear();
   _lastOpen = null;
 }
 
@@ -73,22 +85,21 @@ class FilesPage extends StatefulWidget {
 /// A scan grouped for display, made once per scan.
 class _Library {
   final GroupedVideos grouped;
-  /// Series rows in order: a header (video null), then its episodes and
-  /// extras.
-  final List<(SeriesGroup, VideoFile?)> rows;
   final int subtitleFiles;
 
   _Library(FolderScan scan)
       : grouped = groupBySeries(scan.videos),
-        rows = [],
-        subtitleFiles = {for (final l in scan.subtitles.values) ...l}.length {
-    for (final g in grouped.series) {
-      rows.add((g, null));
-      for (final v in [...g.episodes, ...g.extras]) {
-        rows.add((g, v));
-      }
-    }
-  }
+        subtitleFiles = {for (final l in scan.subtitles.values) ...l}.length;
+
+  /// Series rows in order: a header (video null), then, for the series
+  /// [open] says, its episodes and extras.
+  List<(SeriesGroup, VideoFile?)> rows(bool Function(SeriesGroup g) open) => [
+        for (final g in grouped.series) ...[
+          (g, null),
+          if (open(g))
+            for (final v in [...g.episodes, ...g.extras]) (g, v),
+        ],
+      ];
 }
 
 final _libraries = Expando<_Library>();
@@ -107,6 +118,7 @@ class _FilesPageState extends State<FilesPage> {
   @override
   void initState() {
     super.initState();
+    _showRequests.addListener(_shown);
     _store.ensureLoaded().then((_) {
       if (!mounted) return;
       final open = _open;
@@ -118,6 +130,14 @@ class _FilesPageState extends State<FilesPage> {
     });
   }
 
+  @override
+  void dispose() {
+    _showRequests.removeListener(_shown);
+    super.dispose();
+  }
+
+  void _shown() => _select(_lastOpen);
+
   Future<FolderScan> _runScan(String dir) => (widget.scan ?? scanFolder)(dir);
 
   void _select(String? dir) {
@@ -477,6 +497,8 @@ class _FilesPageState extends State<FilesPage> {
       if (scan.truncated) 'stopped after $maxScannedFiles files',
     ].join(' · ');
     final loose = lib.grouped.loose;
+    String seriesId(SeriesGroup g) => '$dir\n${g.key}';
+    final rows = lib.rows((g) => _expanded.contains(seriesId(g)));
     return [
       SliverToBoxAdapter(
         child: Wrap(
@@ -547,13 +569,21 @@ class _FilesPageState extends State<FilesPage> {
                   'It may have been moved, renamed or be on a drive that is not connected.',
                 ),
         ),
-      // Series: files whose names carry an episode number.
+      // Series: files whose names carry an episode number; a header
+      // click opens or closes its episodes.
       SliverList.builder(
-        itemCount: lib.rows.length,
+        itemCount: rows.length,
         itemBuilder: (context, i) {
-          final (group, v) = lib.rows[i];
+          final (group, v) = rows[i];
           if (v == null) {
-            return SeriesHeader(key: ValueKey('series:${group.key}'), group: group, thumbs: _thumbs);
+            final id = seriesId(group);
+            return SeriesHeader(
+              key: ValueKey('series:${group.key}'),
+              group: group,
+              thumbs: _thumbs,
+              expanded: _expanded.contains(id),
+              onTap: () => setState(() => _expanded.contains(id) ? _expanded.remove(id) : _expanded.add(id)),
+            );
           }
           return FileRow(
             key: ValueKey(v.path),