fix: server-qualify TvBrowseRail hub keys to avoid duplicate GlobalKey

lib/widgets/tv_browse_rail.dart

@@ -397,7 +397,7 @@ class TvBrowseRailState extends State<TvBrowseRail> {
   final Map<String, GlobalKey<MediaCardState>> _mediaCardKeys = {};
   final Map<String, TvBrowseRailLayoutMetrics> _metricsByHub = {};
   final Map<String, double> _scaleByHub = {};
-  final Map<String, TvRailTrailing> _lastTrailingByHubId = {};
+  final Map<String, TvRailTrailing> _lastTrailingByHubKey = {};
 
   int _hubIndex = 0;
   int _itemIndex = 0;
@@ -490,9 +490,9 @@ class TvBrowseRailState extends State<TvBrowseRail> {
       return;
     }
 
-    final oldActiveHubId = oldWidget.hubs.isEmpty
+    final oldActiveHubKey = oldWidget.hubs.isEmpty
         ? null
-        : oldWidget.hubs[_hubIndex.clamp(0, oldWidget.hubs.length - 1)].id;
+        : _hubKey(oldWidget.hubs[_hubIndex.clamp(0, oldWidget.hubs.length - 1)]);
 
     if (widget.hubs.isEmpty) {
       _hubIndex = 0;
@@ -503,8 +503,8 @@ class TvBrowseRailState extends State<TvBrowseRail> {
     }
 
     final selectedInitialHub = _selectInitialHubIfPossible();
-    if (!selectedInitialHub && oldActiveHubId != null) {
-      final preservedIndex = widget.hubs.indexWhere((hub) => hub.id == oldActiveHubId);
+    if (!selectedInitialHub && oldActiveHubKey != null) {
+      final preservedIndex = widget.hubs.indexWhere((hub) => _hubKey(hub) == oldActiveHubKey);
       if (preservedIndex != -1) {
         _hubIndex = preservedIndex;
       } else {
@@ -521,7 +521,8 @@ class TvBrowseRailState extends State<TvBrowseRail> {
     // notify:false — this runs during the build phase and the enclosing
     // rebuild already refreshes every selector.
     _focusPosition.set(_hubIndex, _itemIndex, notify: false);
-    final activeHubChanged = oldActiveHubId != _activeHub?.id;
+    final newActiveHub = _activeHub;
+    final activeHubChanged = oldActiveHubKey != (newActiveHub == null ? null : _hubKey(newActiveHub));
     final activeHubStateChanged =
         _hubStateChanged(oldWidget.hubs, widget.hubs, _hubIndex) ||
         (_activeHub != null && _trailingStateChanged(_activeHub!));
@@ -554,7 +555,9 @@ class TvBrowseRailState extends State<TvBrowseRail> {
     if (index < 0 || index >= oldHubs.length || index >= newHubs.length) return true;
     final oldHub = oldHubs[index];
     final newHub = newHubs[index];
-    if (oldHub.id != newHub.id || oldHub.more != newHub.more || oldHub.items.length != newHub.items.length) {
+    if (_hubKey(oldHub) != _hubKey(newHub) ||
+        oldHub.more != newHub.more ||
+        oldHub.items.length != newHub.items.length) {
       return true;
     }
     for (var j = 0; j < oldHub.items.length; j++) {
@@ -571,14 +574,14 @@ class TvBrowseRailState extends State<TvBrowseRail> {
   }
 
   bool _trailingStateChanged(MediaHub hub) {
-    final previous = _lastTrailingByHubId[hub.id];
+    final previous = _lastTrailingByHubKey[_hubKey(hub)];
     return previous != null && previous != _trailingFor(hub);
   }
 
   void _rememberTrailingStates() {
-    _lastTrailingByHubId
+    _lastTrailingByHubKey
       ..clear()
-      ..addEntries(widget.hubs.map((hub) => MapEntry(hub.id, _trailingFor(hub))));
+      ..addEntries(widget.hubs.map((hub) => MapEntry(_hubKey(hub), _trailingFor(hub))));
   }
 
   @override
@@ -649,6 +652,8 @@ class TvBrowseRailState extends State<TvBrowseRail> {
   bool _selectInitialHubIfPossible() {
     final initialHubId = widget.initialHubId;
     if (_hasUserChangedHub || initialHubId == null || widget.hubs.isEmpty) return false;
+    // External contract: `initialHubId` is a bare `hub.id` supplied by the
+    // single-server media-detail caller, so match on `hub.id` (not `_hubKey`).
     final initialIndex = widget.hubs.indexWhere((hub) => hub.id == initialHubId);
     if (initialIndex == -1) return false;
     if (initialIndex != _hubIndex) {
@@ -770,7 +775,7 @@ class TvBrowseRailState extends State<TvBrowseRail> {
     final currentHub = _activeHub;
     if (currentHub != null) _rememberFocus(currentHub);
     final nextHub = widget.hubs[next];
-    final remembered = HubFocusMemory.getForHubOnly(nextHub.id, _totalItemCount(nextHub));
+    final remembered = HubFocusMemory.getForHubOnly(_hubKey(nextHub), _totalItemCount(nextHub));
     setState(() {
       _hubIndex = next;
       _itemIndex = remembered.clamp(0, _totalItemCount(nextHub) == 0 ? 0 : _totalItemCount(nextHub) - 1);
@@ -818,7 +823,10 @@ class TvBrowseRailState extends State<TvBrowseRail> {
   }
 
   void _setHoveredItem(MediaHub hub, int index) {
-    if (_activeHub?.id != hub.id || index >= hub.items.length || _itemIndex == index) return;
+    final active = _activeHub;
+    if (active == null || _hubKey(active) != _hubKey(hub) || index >= hub.items.length || _itemIndex == index) {
+      return;
+    }
     _itemIndex = index;
     _hasUserChangedItem = true;
     _focusPosition.set(_hubIndex, _itemIndex);
@@ -849,18 +857,18 @@ class TvBrowseRailState extends State<TvBrowseRail> {
   }
 
   void _rememberFocus(MediaHub hub) {
-    HubFocusMemory.setForHub(hub.id, _itemIndex);
+    HubFocusMemory.setForHub(_hubKey(hub), _itemIndex);
   }
 
   void _scrollToItem({bool animate = true, Duration duration = _navigationScrollDuration}) {
     final hub = _activeHub;
     if (hub == null) return;
-    final controller = _scrollControllers[hub.id];
+    final controller = _scrollControllers[_hubKey(hub)];
     if (controller == null) return;
     if (controller.positions.length != 1) return;
-    final metrics = _metricsByHub[hub.id];
+    final metrics = _metricsByHub[_hubKey(hub)];
     if (metrics == null) return;
-    final scale = _scaleByHub[hub.id] ?? 1.0;
+    final scale = _scaleByHub[_hubKey(hub)] ?? 1.0;
     final position = controller.position;
     final viewportWidth = position.viewportDimension;
     final maxScrollExtent = position.maxScrollExtent;
@@ -898,7 +906,7 @@ class TvBrowseRailState extends State<TvBrowseRail> {
     double scale,
     int initialItemIndex,
   ) {
-    return _scrollControllers.putIfAbsent(hub.id, () {
+    return _scrollControllers.putIfAbsent(_hubKey(hub), () {
       final maxScrollExtent = TvBrowseRailLayout.estimatedMaxScrollExtent(
         hub: hub,
         metrics: metrics,
@@ -919,8 +927,14 @@ class TvBrowseRailState extends State<TvBrowseRail> {
     });
   }
 
+  /// Stable, collision-free per-hub key. `hub.id` (the backend hub key) is only
+  /// unique within one server; Discover aggregates hubs from several servers, so
+  /// prefix the server id to keep two same-id hubs from sharing rail state
+  /// (scroll position, metrics, card GlobalKeys, focus memory).
+  String _hubKey(MediaHub hub) => '${hub.serverId ?? ''}:${hub.id}';
+
   GlobalKey<MediaCardState> _cardKeyFor(MediaHub hub, int itemIndex) {
-    return _mediaCardKeys.putIfAbsent('${hub.id}:$itemIndex', () => GlobalKey<MediaCardState>());
+    return _mediaCardKeys.putIfAbsent('${_hubKey(hub)}:$itemIndex', () => GlobalKey<MediaCardState>());
   }
 
   bool _isContinueWatchingHub(MediaHub hub) => widget.isContinueWatchingHub?.call(hub) ?? false;
@@ -1182,12 +1196,9 @@ class TvBrowseRailState extends State<TvBrowseRail> {
     final iconColor = isActive ? colorScheme.onSurface : colorScheme.onSurface.withValues(alpha: 0.42);
     final showServerName = widget.showServerName && hub.serverName != null;
     final serverColor = colorScheme.primary.withValues(alpha: isActive ? 0.7 : 0.4);
-    final serverStyle = Theme.of(context).textTheme.titleMedium?.copyWith(
-      color: serverColor,
-      fontSize: 15 * scale,
-      height: 1,
-      fontWeight: FontWeight.w700,
-    );
+    final serverStyle = Theme.of(
+      context,
+    ).textTheme.titleMedium?.copyWith(color: serverColor, fontSize: 15 * scale, height: 1, fontWeight: FontWeight.w700);
 
     return SizedBox(
       height: TvBrowseRailLayout.hubStripHeightForScale(scale),
@@ -1251,11 +1262,11 @@ class TvBrowseRailState extends State<TvBrowseRail> {
   }) {
     final isActiveHub = hubIndex == _hubIndex;
     final totalCount = _totalItemCount(hub);
-    final inactiveIndex = HubFocusMemory.getForHubOnly(hub.id, totalCount);
+    final inactiveIndex = HubFocusMemory.getForHubOnly(_hubKey(hub), totalCount);
     final focusedIndex = isActiveHub ? _itemIndex : inactiveIndex;
     final scrollController = _scrollControllerForHub(hub, metrics, railViewportWidth, scale, focusedIndex);
-    _metricsByHub[hub.id] = metrics;
-    _scaleByHub[hub.id] = scale;
+    _metricsByHub[_hubKey(hub)] = metrics;
+    _scaleByHub[_hubKey(hub)] = scale;
 
     return Transform.translate(
       offset: Offset(-interactionExpansion, 0),

test/widgets/tv_browse_rail_test.dart

@@ -350,6 +350,47 @@ void main() {
     expect(headerText.style?.color, theme.colorScheme.onSurface);
   });
 
+  testWidgets('two hubs sharing a backend id across servers do not collide on card GlobalKeys', (tester) async {
+    final serverManager = MultiServerManager();
+    // Multi-server aggregation: two servers return a hub with the SAME backend
+    // id ('recently_added'). Per-card GlobalKeys must be qualified by serverId,
+    // or both rows hand the same GlobalKey<MediaCardState> to different cards
+    // and finalizeTree throws "Duplicate GlobalKey".
+    MediaHub hubFor(String serverId) => MediaHub(
+      id: 'recently_added',
+      title: 'Recently Added ($serverId)',
+      type: 'movie',
+      serverId: serverId,
+      size: 2,
+      items: [
+        MediaItem(id: 'movie_1', backend: MediaBackend.plex, kind: MediaKind.movie, title: 'A', serverId: serverId),
+        MediaItem(id: 'movie_2', backend: MediaBackend.plex, kind: MediaKind.movie, title: 'B', serverId: serverId),
+      ],
+    );
+
+    await tester.pumpWidget(
+      ChangeNotifierProvider<MultiServerProvider>(
+        create: (_) => MultiServerProvider(serverManager, DataAggregationService(serverManager)),
+        child: MaterialApp(
+          theme: monoTheme(dark: true),
+          home: Scaffold(
+            body: SizedBox(
+              width: 1280,
+              height: 720,
+              child: TvBrowseRail(
+                hubs: [hubFor('serverA'), hubFor('serverB')],
+                iconForHub: (_, _) => Icons.movie_rounded,
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+    await tester.pump();
+
+    expect(tester.takeException(), isNull);
+  });
+
   testWidgets('full card layout hides media text and overlays actor text when enabled', (tester) async {
     await SettingsService.instanceOrNull!.write(SettingsService.tvFullCardLayout, true);
 
@@ -986,7 +1027,10 @@ void main() {
     final serverManager = MultiServerManager();
     final activeHubIds = <String>[];
     var parentRebuilds = 0;
-    HubFocusMemory.setForHub(episodeHub.id, 5);
+    // Seed remembered focus under the rail's server-qualified hub key (mirrors
+    // _TvBrowseRailState._hubKey: '<serverId>:<id>'), so the multi-server keying
+    // resolves it the same way the rail does.
+    HubFocusMemory.setForHub('${episodeHub.serverId ?? ''}:${episodeHub.id}', 5);
 
     await tester.pumpWidget(
       ChangeNotifierProvider<MultiServerProvider>(