Jellyfin end to end: per-viewer playback, progress, episodes, swap browser

- Host/swap send refs only; pasted Jellyfin links become refs; the host
  hands the relay its own app-obtained credential.
- Each viewer resolves with their own account (token in a header) or
  via the relay, else a clear blocked card with Link account.
- Per-account progress reporting (Playing/Progress/Stopped), 401 marks
  the account expired.
- Previous/next episode in the controls (< > / Shift+P/N), floating
  Next episode pill near the end, auto-advance countdown (one
  designated swapper), track carry-over per series.
- Swap panel uses the shared MediaPicker; browser location remembered
  per server and opens on the current series.
- Fix: states are applied one at a time (a stale pause could land
  after a newer play).

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

apps/desktop/lib/src/screens/home/connect_flow.dart

@@ -1,6 +1,7 @@
 import 'dart:io';
 
 import 'package:flutter/foundation.dart';
+import 'package:sync_relay_core/core.dart' show HelloMedia;
 
 import '../../session/session_coordinator.dart';
 import '../../state/session_state.dart';
@@ -91,11 +92,11 @@ class ConnectFlow extends ChangeNotifier {
   }
 
   /// [edit] fills the card's fields into a copy of the last form, so the
-  /// other card's saved values survive. [linkOverride] (host only) is played
-  /// as the link but never stored in the form: the interim Jellyfin stream
-  /// URL carries a token.
+  /// other card's saved values survive. [media] (host only) is put up
+  /// instead of the form's link or file (a Jellyfin ref; the pick itself is
+  /// remembered in the Jellyfin box, not the form).
   Future<void> submit(ConnectMode mode, void Function(ConnectForm f) edit,
-      {String? linkOverride}) async {
+      {HelloMedia? media}) async {
     if (busy != null) return;
     final myAttempt = ++_attempt;
     final form = _session.lastForm.copy();
@@ -113,15 +114,10 @@ class ConnectFlow extends ChangeNotifier {
     notices[mode] = null;
     _notify();
 
-    final ConnectParams params;
+    ConnectParams params;
     try {
-      params = await buildParams(
-          mode,
-          linkOverride == null || mode != ConnectMode.host
-              ? form
-              : (form.copy()
-                ..mediaPath = ''
-                ..linkUrl = linkOverride));
+      params = await buildParams(mode, form);
+      if (media != null && mode == ConnectMode.host) params = params.withMedia(media);
     } catch (e) {
       if (myAttempt != _attempt) return;
       busy = null;

apps/desktop/lib/src/screens/home/host_tab.dart

@@ -1,7 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:signals/signals_flutter.dart';
+import 'package:sync_relay_core/core.dart' show HelloMedia;
 
 import '../../jellyfin/accounts.dart';
+import '../../jellyfin/session_media.dart';
 import '../../state/session_state.dart';
 import 'connect_flow.dart';
 import 'connect_status.dart';
@@ -48,20 +50,17 @@ class HostFields {
   }
 }
 
-/// INTERIM(jellyfin-protocol): until the protocol carries a Jellyfin item,
-/// the host plays it as a link: this install's authorised static stream URL
-/// (token in the query, so viewers stream with the host's sign-in and the
-/// URL must not be persisted). Throws [FormatException] with a user-facing
-/// message when the server is not linked any more.
-String interimJellyfinLink(JellyfinAccounts accounts, JellyfinMedia media) {
-  final client = accounts.clientFor(media.serverId);
-  if (client == null) {
+/// What hosting a picked Jellyfin item sends: its ref (no URL, no token).
+/// Throws [FormatException] with a user-facing message when the server is
+/// not linked any more or its sign-in expired.
+HelloMedia hostJellyfinMedia(JellyfinAccounts accounts, JellyfinMedia media) {
+  if (accounts.account(media.serverId) == null) {
     throw const FormatException('that Jellyfin server is not linked any more — pick again');
   }
   if (accounts.statusOf(media.serverId) == JellyfinAccountStatus.expired) {
     throw const FormatException('Jellyfin sign-in expired — reconnect it in Integrations');
   }
-  return client.streamUrl(media.itemId, mediaSourceId: media.mediaSourceId).toString();
+  return mediaForPick(media);
 }
 
 /// Below this width the server column moves under the media picker.
@@ -79,10 +78,10 @@ class HostTab extends StatelessWidget {
   void _host() {
     if (flow.busy != null) return;
     final media = fields.media.selection;
-    String? link;
+    HelloMedia? jellyfinMedia;
     if (media is JellyfinMedia) {
       try {
-        link = interimJellyfinLink(fields.jellyfin, media);
+        jellyfinMedia = hostJellyfinMedia(fields.jellyfin, media);
       } on FormatException catch (e) {
         flow.showError(ConnectMode.host, CardError('Check the form', e.message));
         return;
@@ -96,7 +95,7 @@ class HostTab extends StatelessWidget {
         ..hostSecret = fields.secret.text
         ..mediaPath = media is FileMedia ? media.path : ''
         ..linkUrl = media is LinkMedia ? media.url : '',
-      linkOverride: link,
+      media: jellyfinMedia,
     );
   }
 

apps/desktop/lib/src/screens/home/media_picker.dart

@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 import '../../jellyfin/accounts.dart';
+import '../../jellyfin/browse_scope.dart' show BrowseStart;
 import '../../jellyfin/picker_source.dart';
 import '../../widgets/media_input.dart';
 import 'picked_media.dart';
@@ -114,8 +115,17 @@ class MediaPicker extends StatefulWidget {
   /// Jellyfin source only: the browser's "bigger" toggle.
   final VoidCallback? onToggleExpanded;
   final bool expanded;
+  /// Where the Jellyfin browser opens instead of its remembered location.
+  final BrowseStart? jellyfinStart;
+  /// False hides the File source (only the host can serve a file).
+  final bool allowFile;
+  /// Shown under the Link field instead of the default help.
+  final String? linkHelp;
   const MediaPicker({
     super.key,
+    this.jellyfinStart,
+    this.allowFile = true,
+    this.linkHelp,
     required this.controller,
     this.onChanged,
     this.onSubmit,
@@ -221,6 +231,7 @@ class _MediaPickerState extends State<MediaPicker> {
           onOpenIntegrations: widget.onOpenIntegrations,
           onToggleExpanded: widget.onToggleExpanded,
           expanded: widget.expanded,
+          start: widget.jellyfinStart,
         ),
       MediaKind.link => _FieldRow(
           key: const ValueKey('media-link'),
@@ -236,7 +247,9 @@ class _MediaPickerState extends State<MediaPicker> {
             icon: const Icon(Icons.content_paste, size: 18),
             label: const Text('Paste'),
           ),
-          help: 'A direct http(s) link to a video file; everyone streams it from there.',
+          help: widget.linkHelp ??
+              'A direct http(s) link to a video file; everyone streams it from there. '
+                  'Jellyfin links are shared as the item, without your sign-in.',
           notice: _c.notice,
         ),
       MediaKind.file => _FieldRow(
@@ -260,17 +273,17 @@ class _MediaPickerState extends State<MediaPicker> {
       child: SegmentedButton<MediaKind>(
         key: const ValueKey('media-source'),
         showSelectedIcon: false,
-        segments: const [
-          ButtonSegment(
+        segments: [
+          const ButtonSegment(
               value: MediaKind.jellyfin,
               icon: Icon(Icons.video_library_outlined),
               label: Text('Jellyfin')),
-          ButtonSegment(value: MediaKind.link, icon: Icon(Icons.link), label: Text('Link')),
-          ButtonSegment(
+          const ButtonSegment(value: MediaKind.link, icon: Icon(Icons.link), label: Text('Link')),
+          const ButtonSegment(
               value: MediaKind.file,
               icon: Icon(Icons.insert_drive_file_outlined),
               label: Text('File')),
-        ],
+        ].where((s) => widget.allowFile || s.value != MediaKind.file).toList(),
         selected: {source},
         onSelectionChanged: (s) => _c.source = s.first,
       ),

apps/desktop/lib/src/screens/home/settings_page.dart

@@ -17,6 +17,7 @@ const sessionShortcuts = [
   ('F', 'Toggle fullscreen'),
   ('Tab', 'Open / close the people & chat panel'),
   ('Ctrl+R', 'Reload the video'),
+  ('> or Shift+N', 'Put up the next Jellyfin episode'),
   ('Ctrl+1…6', 'Shaders: Anime4K mode A, B, C, A+A, B+B, C+A'),
   ('Ctrl+0', 'Shaders off'),
   ('Esc', 'Close panel or fullscreen, else ask to leave'),
@@ -34,6 +35,7 @@ class SettingsPage extends StatelessWidget {
         const PageTitle('Settings'),
         const _Section(title: 'Profile', child: ProfileEditor()),
         const _Section(title: 'Player', child: _HwdecSetting()),
+        const _Section(title: 'Jellyfin', child: _AutoAdvanceSetting()),
         _Section(title: 'Updates', child: _UpdateSettings(controller: updates)),
         const _Section(title: 'Keyboard shortcuts', child: _ShortcutList()),
         const _Section(title: 'Video quality & shaders', child: _ShaderSettings()),
@@ -290,6 +292,26 @@ class _UpdateSettings extends StatelessWidget {
   }
 }
 
+class _AutoAdvanceSetting extends StatelessWidget {
+  const _AutoAdvanceSetting();
+
+  @override
+  Widget build(BuildContext context) {
+    final s = AppSettings.instance;
+    return SignalBuilder(
+      builder: (context) => SwitchListTile(
+        key: const ValueKey('auto-advance'),
+        contentPadding: EdgeInsets.zero,
+        title: const Text('Play the next episode automatically'),
+        subtitle: const Text('When an episode ends, a 10 s countdown puts up the next one; '
+            'anyone can cancel it on their screen.'),
+        value: s.autoAdvance.value,
+        onChanged: s.setAutoAdvance,
+      ),
+    );
+  }
+}
+
 class _ShortcutList extends StatelessWidget {
   const _ShortcutList();