refactor(screens): migrate remaining screens to shared header and selection components

- album/playlist/library-folder/track-metadata adopt
  CollapsingHeaderScrollMixin; artist/library-folder adopt
  SelectionModeMixin
- HeaderCircleButton and HeaderMetaRow replace per-screen copies
  in album and playlist headers; dead _tallHeader flag removed
- SelectionBottomBar gains optional subtitle labels and backs the
  playlist selection bar in queue tab

lib/screens/album_screen.dart

@@ -11,6 +11,7 @@ import 'package:spotiflac_android/services/platform_bridge.dart';
 import 'package:spotiflac_android/utils/image_cache_utils.dart';
 import 'package:spotiflac_android/utils/string_utils.dart';
 import 'package:spotiflac_android/utils/cover_art_utils.dart';
+import 'package:spotiflac_android/screens/collapsing_header_scroll_mixin.dart';
 import 'package:spotiflac_android/widgets/error_card.dart';
 import 'package:spotiflac_android/widgets/album_detail_header.dart';
 import 'package:spotiflac_android/utils/nav_bar_inset.dart';
@@ -64,20 +65,17 @@ class AlbumScreen extends ConsumerStatefulWidget {
   ConsumerState<AlbumScreen> createState() => _AlbumScreenState();
 }
 
-class _AlbumScreenState extends ConsumerState<AlbumScreen> {
+class _AlbumScreenState extends ConsumerState<AlbumScreen>
+    with CollapsingHeaderScrollMixin<AlbumScreen> {
   List<Track>? _tracks;
   bool _isLoading = false;
   String? _error;
-  bool _showTitleInAppBar = false;
   String? _artistId;
   String? _albumType;
   int? _albumTotalTracks;
   String? _headerVideoUrl;
   String? _headerImageUrl;
   List<String> _audioTraits = const [];
-  bool _tallHeader = false;
-  final ScrollController _scrollController = ScrollController();
-
 
   String _effectiveMetadataProviderIdFromAlbumId() {
     if (widget.extensionId != null && widget.extensionId!.isNotEmpty) {
@@ -89,13 +87,10 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
     );
   }
 
-
   @override
   void initState() {
     super.initState();
 
-    _scrollController.addListener(_onScroll);
-
     WidgetsBinding.instance.addPostFrameCallback((_) {
       final providerId = _effectiveMetadataProviderIdFromAlbumId();
       ref
@@ -129,30 +124,6 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
     }
   }
 
-  @override
-  void dispose() {
-    _scrollController.removeListener(_onScroll);
-    _scrollController.dispose();
-    super.dispose();
-  }
-
-  void _onScroll() {
-    final expandedHeight = _calculateExpandedHeight(context, tall: _tallHeader);
-    final shouldShow =
-        _scrollController.offset > (expandedHeight - kToolbarHeight - 20);
-    if (shouldShow != _showTitleInAppBar) {
-      setState(() => _showTitleInAppBar = shouldShow);
-    }
-  }
-
-  double _calculateExpandedHeight(BuildContext context, {bool tall = false}) {
-    final mediaSize = MediaQuery.sizeOf(context);
-    if (tall) {
-      return (mediaSize.height * 0.68).clamp(440.0, 660.0);
-    }
-    return (mediaSize.height * 0.6).clamp(400.0, 580.0);
-  }
-
   Future<void> _fetchTracks() async {
     setState(() => _isLoading = true);
     try {
@@ -258,25 +229,6 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
     return stripPrefixedResourceId(widget.albumId);
   }
 
-  Widget _metaInlineItem(IconData? icon, String label) {
-    const textStyle = TextStyle(
-      color: Colors.white,
-      fontSize: 13,
-      fontWeight: FontWeight.w500,
-    );
-    if (icon == null) {
-      return Text(label, style: textStyle);
-    }
-    return Row(
-      mainAxisSize: MainAxisSize.min,
-      children: [
-        Icon(icon, size: 15, color: Colors.white),
-        const SizedBox(width: 4),
-        Text(label, style: textStyle),
-      ],
-    );
-  }
-
   List<Widget> _audioTraitInline() {
     final traits = _audioTraits
         .map((t) => t.toLowerCase().trim())
@@ -288,15 +240,15 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
 
     final items = <Widget>[];
     if (has(['atmos', 'dolby_atmos', 'dolby-atmos'])) {
-      items.add(_metaInlineItem(Icons.surround_sound, 'Dolby Atmos'));
+      items.add(HeaderMetaItem('Dolby Atmos', icon: Icons.surround_sound));
     } else if (has(['spatial'])) {
-      items.add(_metaInlineItem(Icons.surround_sound, 'Spatial Audio'));
+      items.add(HeaderMetaItem('Spatial Audio', icon: Icons.surround_sound));
     }
 
     if (has(['hi-res-lossless', 'hi_res_lossless', 'hires-lossless'])) {
-      items.add(_metaInlineItem(Icons.graphic_eq, 'Hi-Res Lossless'));
+      items.add(HeaderMetaItem('Hi-Res Lossless', icon: Icons.graphic_eq));
     } else if (has(['lossless'])) {
-      items.add(_metaInlineItem(Icons.graphic_eq, 'Lossless'));
+      items.add(HeaderMetaItem('Lossless', icon: Icons.graphic_eq));
     }
 
     return items;
@@ -305,38 +257,13 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
   Widget _buildHeaderMeta(BuildContext context, String? releaseDate) {
     final items = <Widget>[];
 
-    void add(Widget widget) {
-      if (items.isNotEmpty) {
-        items.add(
-          const Padding(
-            padding: EdgeInsets.symmetric(horizontal: 6),
-            child: Text(
-              '•',
-              style: TextStyle(color: Colors.white70, fontSize: 12),
-            ),
-          ),
-        );
-      }
-      items.add(widget);
-    }
-
     final year = _releaseYear(releaseDate);
-    if (year != null) {
-      add(_metaInlineItem(null, year));
-    }
-    for (final trait in _audioTraitInline()) {
-      add(trait);
-    }
+    if (year != null) items.add(HeaderMetaItem(year));
+    items.addAll(_audioTraitInline());
 
     return ConstrainedBox(
       constraints: const BoxConstraints(minHeight: 20),
-      child: Wrap(
-        alignment: WrapAlignment.center,
-        crossAxisAlignment: WrapCrossAlignment.center,
-        spacing: 0,
-        runSpacing: 4,
-        children: items,
-      ),
+      child: HeaderMetaRow(items: items),
     );
   }
 
@@ -397,7 +324,7 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
     return Scaffold(
       backgroundColor: pageBackgroundColor,
       body: CustomScrollView(
-        controller: _scrollController,
+        controller: scrollController,
         slivers: [
           _buildAppBar(context, colorScheme, pageBackgroundColor),
           if (_isLoading)
@@ -444,8 +371,7 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
         Uri.tryParse(motionUrl)?.hasAuthority == true;
     final coverThumbUrl = widget.coverUrl ?? _headerImageUrl;
     final showSquareCover = !hasMotion;
-    _tallHeader = false;
-    final expandedHeight = _calculateExpandedHeight(context);
+    final expandedHeight = calculateExpandedHeight(context);
     final cacheWidth = coverCacheWidthForViewport(context);
     final headerBgUrl =
         _headerImageUrl ?? widget.headerImageUrl ?? widget.coverUrl;
@@ -470,7 +396,7 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
     return AlbumDetailHeader(
       title: widget.albumName,
       expandedHeight: expandedHeight,
-      showTitleInAppBar: _showTitleInAppBar,
+      showTitleInAppBar: showTitleInAppBar,
       backgroundColor: pageBackgroundColor,
       background: hasMotion
           ? MotionHeaderBanner(videoUrl: motionUrl, fallback: headerBgImage)
@@ -656,54 +582,25 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
         tracks.isNotEmpty &&
         tracks.every((t) => collectionsState.isLoved(t));
 
-    return Container(
-      width: 48,
-      height: 48,
-      decoration: BoxDecoration(
-        shape: BoxShape.circle,
-        color: Colors.white.withValues(alpha: 0.15),
-        border: Border.all(
-          color: Colors.white.withValues(alpha: 0.3),
-          width: 1,
-        ),
-      ),
-      child: IconButton(
-        onPressed: tracks == null || tracks.isEmpty
-            ? null
-            : () => _loveAll(tracks),
-        icon: Icon(
-          allLoved ? Icons.favorite : Icons.favorite_border,
-          size: 22,
-          color: allLoved ? Colors.redAccent : Colors.white,
-        ),
-        tooltip: allLoved
-            ? context.l10n.trackOptionRemoveFromLoved
-            : context.l10n.tooltipLoveAll,
-        padding: EdgeInsets.zero,
-      ),
+    return HeaderCircleButton(
+      icon: allLoved ? Icons.favorite : Icons.favorite_border,
+      iconColor: allLoved ? Colors.redAccent : Colors.white,
+      tooltip: allLoved
+          ? context.l10n.trackOptionRemoveFromLoved
+          : context.l10n.tooltipLoveAll,
+      onPressed: tracks == null || tracks.isEmpty
+          ? null
+          : () => _loveAll(tracks),
     );
   }
 
   Widget _buildAddToPlaylistButton(BuildContext context) {
-    return Container(
-      width: 48,
-      height: 48,
-      decoration: BoxDecoration(
-        shape: BoxShape.circle,
-        color: Colors.white.withValues(alpha: 0.15),
-        border: Border.all(
-          color: Colors.white.withValues(alpha: 0.3),
-          width: 1,
-        ),
-      ),
-      child: IconButton(
-        onPressed: _tracks == null || _tracks!.isEmpty
-            ? null
-            : () => showAddTracksToPlaylistSheet(context, ref, _tracks!),
-        icon: const Icon(Icons.add, size: 22, color: Colors.white),
-        tooltip: context.l10n.tooltipAddToPlaylist,
-        padding: EdgeInsets.zero,
-      ),
+    return HeaderCircleButton(
+      icon: Icons.add,
+      tooltip: context.l10n.tooltipAddToPlaylist,
+      onPressed: _tracks == null || _tracks!.isEmpty
+          ? null
+          : () => showAddTracksToPlaylistSheet(context, ref, _tracks!),
     );
   }
 
@@ -728,5 +625,6 @@ class _AlbumScreenState extends ConsumerState<AlbumScreen> {
     );
   }
 
-  Future<void> _loveAll(List<Track> tracks) => loveAllTracks(context, ref, tracks);
+  Future<void> _loveAll(List<Track> tracks) =>
+      loveAllTracks(context, ref, tracks);
 }

lib/screens/artist_screen.dart

@@ -25,6 +25,7 @@ import 'package:spotiflac_android/widgets/error_card.dart';
 import 'package:spotiflac_android/widgets/in_library_badge.dart';
 import 'package:spotiflac_android/widgets/track_collection_quick_actions.dart';
 import 'package:spotiflac_android/widgets/animation_utils.dart';
+import 'package:spotiflac_android/screens/selection_mode_mixin.dart';
 import 'package:spotiflac_android/utils/clickable_metadata.dart';
 import 'package:spotiflac_android/widgets/cached_cover_image.dart';
 import 'package:spotiflac_android/widgets/motion_header_banner.dart';
@@ -104,7 +105,8 @@ class ArtistScreen extends ConsumerStatefulWidget {
   ConsumerState<ArtistScreen> createState() => _ArtistScreenState();
 }
 
-class _ArtistScreenState extends ConsumerState<ArtistScreen> {
+class _ArtistScreenState extends ConsumerState<ArtistScreen>
+    with SelectionModeMixin<ArtistScreen> {
   bool _isLoadingDiscography = false;
   List<ArtistAlbum>? _albums;
   List<ArtistAlbum>? _releases;
@@ -119,8 +121,6 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
   final PageController _popularPageController = PageController();
   int _popularCurrentPage = 0;
 
-  bool _isSelectionMode = false;
-  final Set<String> _selectedAlbumIds = {};
   bool _isFetchingDiscography = false;
   List<ArtistAlbum>? _albumBucketSource;
   List<ArtistAlbum> _albumsOnlyBucket = const [];
@@ -162,7 +162,6 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
     return _directMetadataProviderId();
   }
 
-
   String _effectiveMetadataProviderIdFromArtistId() {
     if (widget.extensionId != null && widget.extensionId!.isNotEmpty) {
       return widget.extensionId!;
@@ -173,7 +172,6 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
     );
   }
 
-
   String? _directMetadataProviderId() {
     final providerId = _effectiveMetadataProviderIdFromArtistId();
     return providerId.isEmpty ? null : providerId;
@@ -464,10 +462,10 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
         !_isLoadingDiscography && _error == null && albums.isNotEmpty;
 
     return PopScope(
-      canPop: !_isSelectionMode,
+      canPop: !isSelectionMode,
       onPopInvokedWithResult: (didPop, result) {
-        if (!didPop && _isSelectionMode) {
-          _exitSelectionMode();
+        if (!didPop && isSelectionMode) {
+          exitSelectionMode();
         }
       },
       child: Scaffold(
@@ -500,7 +498,10 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                   SliverToBoxAdapter(
                     child: Padding(
                       padding: const EdgeInsets.all(16),
-                      child: ErrorCard(error: _error!, colorScheme: colorScheme),
+                      child: ErrorCard(
+                        error: _error!,
+                        colorScheme: colorScheme,
+                      ),
                     ),
                   ),
                 if (!_isLoadingDiscography && _error == null) ...[
@@ -543,12 +544,12 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                     ),
                 ],
                 SliverToBoxAdapter(
-                  child: SizedBox(height: _isSelectionMode ? 120 : 32),
+                  child: SizedBox(height: isSelectionMode ? 120 : 32),
                 ),
                 SliverToBoxAdapter(child: SizedBox(height: bottomInset)),
               ],
             ),
-            if (_isSelectionMode)
+            if (isSelectionMode)
               _buildSelectionBar(context, colorScheme, albums),
           ],
         ),
@@ -556,45 +557,21 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
     );
   }
 
-  void _exitSelectionMode() {
+  @override
+  void exitSelectionMode() {
     HapticFeedback.lightImpact();
-    setState(() {
-      _isSelectionMode = false;
-      _selectedAlbumIds.clear();
-    });
+    super.exitSelectionMode();
   }
 
-  void _enterSelectionMode(String albumId) {
-    HapticFeedback.mediumImpact();
-    setState(() {
-      _isSelectionMode = true;
-      _selectedAlbumIds.add(albumId);
-    });
-  }
-
-  void _toggleAlbumSelection(String albumId) {
+  @override
+  void toggleSelection(String itemId) {
     HapticFeedback.selectionClick();
-    setState(() {
-      if (_selectedAlbumIds.contains(albumId)) {
-        _selectedAlbumIds.remove(albumId);
-        if (_selectedAlbumIds.isEmpty) {
-          _isSelectionMode = false;
-        }
-      } else {
-        _selectedAlbumIds.add(albumId);
-      }
-    });
-  }
-
-  void _selectAll(List<ArtistAlbum> albums) {
-    setState(() {
-      _selectedAlbumIds.addAll(albums.map((a) => a.id));
-    });
+    super.toggleSelection(itemId);
   }
 
   void _deselectAll() {
     setState(() {
-      _selectedAlbumIds.clear();
+      selectedIds.clear();
     });
   }
 
@@ -603,10 +580,10 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
     ColorScheme colorScheme,
     List<ArtistAlbum> allAlbums,
   ) {
-    final allSelected = _selectedAlbumIds.length == allAlbums.length;
-    final selectedCount = _selectedAlbumIds.length;
+    final allSelected = selectedIds.length == allAlbums.length;
+    final selectedCount = selectedIds.length;
     final selectedAlbums = allAlbums
-        .where((a) => _selectedAlbumIds.contains(a.id))
+        .where((a) => selectedIds.contains(a.id))
         .toList();
     final totalTracks = selectedAlbums.fold<int>(
       0,
@@ -643,7 +620,7 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                       Row(
                         children: [
                           IconButton(
-                            onPressed: _exitSelectionMode,
+                            onPressed: exitSelectionMode,
                             icon: const Icon(Icons.close),
                             tooltip: context.l10n.dialogCancel,
                           ),
@@ -684,7 +661,7 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                             child: OutlinedButton(
                               onPressed: allSelected
                                   ? _deselectAll
-                                  : () => _selectAll(allAlbums),
+                                  : () => selectAll(allAlbums.map((a) => a.id)),
                               child: FittedBox(
                                 fit: BoxFit.scaleDown,
                                 child: Text(
@@ -719,7 +696,7 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                 : Row(
                     children: [
                       IconButton(
-                        onPressed: _exitSelectionMode,
+                        onPressed: exitSelectionMode,
                         icon: const Icon(Icons.close),
                         tooltip: context.l10n.dialogCancel,
                       ),
@@ -754,7 +731,7 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                       TextButton(
                         onPressed: allSelected
                             ? _deselectAll
-                            : () => _selectAll(allAlbums),
+                            : () => selectAll(allAlbums.map((a) => a.id)),
                         child: Text(
                           allSelected
                               ? context.l10n.actionDeselect
@@ -880,7 +857,7 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                 subtitle: context.l10n.discographySelectAlbumsSubtitle,
                 onTap: () {
                   Navigator.pop(context);
-                  _enterSelectionMode(albums.first.id);
+                  enterSelectionMode(albums.first.id);
                 },
               ),
               const SizedBox(height: 8),
@@ -913,7 +890,7 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
     BuildContext context,
     List<ArtistAlbum> albums,
   ) async {
-    _exitSelectionMode();
+    exitSelectionMode();
     await _downloadAlbums(context, albums);
   }
 
@@ -1308,7 +1285,7 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                       ],
                     ),
                   ),
-                  if (!_isSelectionMode) ...[
+                  if (!isSelectionMode) ...[
                     const SizedBox(width: 12),
                     Container(
                       width: 52,
@@ -1334,7 +1311,7 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                       ),
                     ),
                   ],
-                  if (hasDiscography && !_isSelectionMode) ...[
+                  if (hasDiscography && !isSelectionMode) ...[
                     const SizedBox(width: 12),
                     Container(
                       width: 52,
@@ -1745,25 +1722,25 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
     required double sectionHeight,
     bool showTypeBadge = false,
   }) {
-    final isSelected = _selectedAlbumIds.contains(album.id);
+    final isSelected = selectedIds.contains(album.id);
 
     return Semantics(
       button: true,
-      selected: _isSelectionMode && isSelected,
-      label: _isSelectionMode
+      selected: isSelectionMode && isSelected,
+      label: isSelectionMode
           ? context.l10n.a11ySelectAlbum(album.name)
           : context.l10n.a11yOpenAlbum(album.name),
       child: GestureDetector(
         onTap: () {
-          if (_isSelectionMode) {
-            _toggleAlbumSelection(album.id);
+          if (isSelectionMode) {
+            toggleSelection(album.id);
           } else {
             _navigateToAlbum(album);
           }
         },
         onLongPress: () {
-          if (!_isSelectionMode) {
-            _enterSelectionMode(album.id);
+          if (!isSelectionMode) {
+            enterSelectionMode(album.id);
           }
         },
         child: Container(
@@ -1809,7 +1786,7 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                               ),
                             ),
                     ),
-                    if (_isSelectionMode)
+                    if (isSelectionMode)
                       Positioned.fill(
                         child: AnimatedContainer(
                           duration: const Duration(milliseconds: 200),
@@ -1827,7 +1804,7 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
                           ),
                         ),
                       ),
-                    if (_isSelectionMode)
+                    if (isSelectionMode)
                       Positioned(
                         top: 8,
                         right: 8,
@@ -1938,7 +1915,6 @@ class _ArtistScreenState extends ConsumerState<ArtistScreen> {
       );
     }
   }
-
 }
 
 class _DiscographyOptionTile extends StatelessWidget {

lib/screens/library_tracks_folder_screen.dart

@@ -4,7 +4,6 @@ import 'package:file_picker/file_picker.dart';
 import 'package:flutter/material.dart';
 import 'package:spotiflac_android/widgets/album_detail_header.dart';
 import 'package:spotiflac_android/widgets/cached_cover_image.dart';
-import 'package:flutter/services.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:spotiflac_android/l10n/l10n.dart';
 import 'package:spotiflac_android/models/track.dart';
@@ -16,6 +15,8 @@ import 'package:spotiflac_android/providers/local_library_provider.dart';
 import 'package:spotiflac_android/providers/settings_provider.dart';
 import 'package:spotiflac_android/utils/nav_bar_inset.dart';
 import 'package:spotiflac_android/utils/cover_art_utils.dart';
+import 'package:spotiflac_android/screens/collapsing_header_scroll_mixin.dart';
+import 'package:spotiflac_android/screens/selection_mode_mixin.dart';
 import 'package:spotiflac_android/screens/track_metadata_screen.dart';
 import 'package:spotiflac_android/widgets/selection_action_button.dart';
 import 'package:spotiflac_android/widgets/selection_bottom_bar.dart';
@@ -50,41 +51,12 @@ class LibraryTracksFolderScreen extends ConsumerStatefulWidget {
 }
 
 class _LibraryTracksFolderScreenState
-    extends ConsumerState<LibraryTracksFolderScreen> {
-  bool _showTitleInAppBar = false;
-  final ScrollController _scrollController = ScrollController();
-
-  bool _isSelectionMode = false;
-  final Set<String> _selectedKeys = {};
+    extends ConsumerState<LibraryTracksFolderScreen>
+    with
+        SelectionModeMixin<LibraryTracksFolderScreen>,
+        CollapsingHeaderScrollMixin<LibraryTracksFolderScreen> {
   UserPlaylistCollection? playlist;
 
-  @override
-  void initState() {
-    super.initState();
-    _scrollController.addListener(_onScroll);
-  }
-
-  @override
-  void dispose() {
-    _scrollController.removeListener(_onScroll);
-    _scrollController.dispose();
-    super.dispose();
-  }
-
-  void _onScroll() {
-    final expandedHeight = _calculateExpandedHeight(context);
-    final shouldShow =
-        _scrollController.offset > (expandedHeight - kToolbarHeight - 20);
-    if (shouldShow != _showTitleInAppBar) {
-      setState(() => _showTitleInAppBar = shouldShow);
-    }
-  }
-
-  double _calculateExpandedHeight(BuildContext context) {
-    final mediaSize = MediaQuery.sizeOf(context);
-    return (mediaSize.height * 0.6).clamp(400.0, 580.0);
-  }
-
   IconData _modeIcon() {
     return switch (widget.mode) {
       LibraryTracksFolderMode.wishlist => Icons.bookmark,
@@ -104,42 +76,8 @@ class _LibraryTracksFolderScreenState
     return null;
   }
 
-  void _enterSelectionMode(String key) {
-    HapticFeedback.mediumImpact();
-    setState(() {
-      _isSelectionMode = true;
-      _selectedKeys.add(key);
-    });
-  }
-
-  void _exitSelectionMode() {
-    setState(() {
-      _isSelectionMode = false;
-      _selectedKeys.clear();
-    });
-  }
-
-  void _toggleSelection(String key) {
-    setState(() {
-      if (_selectedKeys.contains(key)) {
-        _selectedKeys.remove(key);
-        if (_selectedKeys.isEmpty) {
-          _isSelectionMode = false;
-        }
-      } else {
-        _selectedKeys.add(key);
-      }
-    });
-  }
-
-  void _selectAll(List<CollectionTrackEntry> entries) {
-    setState(() {
-      _selectedKeys.addAll(entries.map((e) => e.key));
-    });
-  }
-
   Future<void> _removeSelected(List<CollectionTrackEntry> entries) async {
-    final keysToRemove = _selectedKeys.toSet();
+    final keysToRemove = selectedIds.toSet();
     if (keysToRemove.isEmpty) return;
 
     final count = keysToRemove.length;
@@ -161,7 +99,7 @@ class _LibraryTracksFolderScreenState
       }
     }
 
-    _exitSelectionMode();
+    exitSelectionMode();
 
     if (!mounted) return;
     ScaffoldMessenger.of(context).showSnackBar(
@@ -202,12 +140,12 @@ class _LibraryTracksFolderScreenState
     var count = 0;
 
     for (final entry in entries) {
-      if (!_selectedKeys.contains(entry.key)) continue;
+      if (!selectedIds.contains(entry.key)) continue;
       queueNotifier.addToQueue(entry.track, service);
       count++;
     }
 
-    _exitSelectionMode();
+    exitSelectionMode();
 
     if (!mounted || count == 0) return;
     ScaffoldMessenger.of(context).showSnackBar(
@@ -217,7 +155,7 @@ class _LibraryTracksFolderScreenState
 
   void _addSelectedToPlaylist(List<CollectionTrackEntry> entries) {
     final selectedTracks = entries
-        .where((e) => _selectedKeys.contains(e.key))
+        .where((e) => selectedIds.contains(e.key))
         .map((e) => e.track)
         .toList(growable: false);
     if (selectedTracks.isEmpty) return;
@@ -257,15 +195,7 @@ class _LibraryTracksFolderScreenState
         break;
     }
 
-    if (_isSelectionMode) {
-      final validKeys = entries.map((e) => e.key).toSet();
-      _selectedKeys.removeWhere((key) => !validKeys.contains(key));
-      if (_selectedKeys.isEmpty && _isSelectionMode) {
-        WidgetsBinding.instance.addPostFrameCallback((_) {
-          if (mounted) setState(() => _isSelectionMode = false);
-        });
-      }
-    }
+    pruneSelection(entries.map((e) => e.key).toSet());
 
     final title = switch (widget.mode) {
       LibraryTracksFolderMode.wishlist => context.l10n.collectionWishlist,
@@ -308,17 +238,17 @@ class _LibraryTracksFolderScreenState
     final bottomInset = context.navBarBottomInset;
 
     return PopScope(
-      canPop: !_isSelectionMode,
+      canPop: !isSelectionMode,
       onPopInvokedWithResult: (didPop, result) {
-        if (!didPop && _isSelectionMode) {
-          _exitSelectionMode();
+        if (!didPop && isSelectionMode) {
+          exitSelectionMode();
         }
       },
       child: Scaffold(
         body: Stack(
           children: [
             CustomScrollView(
-              controller: _scrollController,
+              controller: scrollController,
               slivers: [
                 _buildAppBar(context, colorScheme, title, entries, playlist),
                 if (entries.isEmpty)
@@ -333,7 +263,7 @@ class _LibraryTracksFolderScreenState
                   SliverList(
                     delegate: SliverChildBuilderDelegate((context, index) {
                       final entry = entries[index];
-                      final isSelected = _selectedKeys.contains(entry.key);
+                      final isSelected = selectedIds.contains(entry.key);
                       final isInHistory = existingHistoryKeys.contains(
                         historyLookups[index].lookupKey,
                       );
@@ -347,21 +277,21 @@ class _LibraryTracksFolderScreenState
                             playlistId: widget.playlistId,
                             folderTracks: folderTracks,
                             isInHistory: isInHistory,
-                            isSelectionMode: _isSelectionMode,
+                            isSelectionMode: isSelectionMode,
                             isSelected: isSelected,
-                            onTap: _isSelectionMode
-                                ? () => _toggleSelection(entry.key)
+                            onTap: isSelectionMode
+                                ? () => toggleSelection(entry.key)
                                 : null,
-                            onLongPress: _isSelectionMode
+                            onLongPress: isSelectionMode
                                 ? null
-                                : () => _enterSelectionMode(entry.key),
+                                : () => enterSelectionMode(entry.key),
                           ),
                         ),
                       );
                     }, childCount: entries.length),
                   ),
                 SliverToBoxAdapter(
-                  child: SizedBox(height: _isSelectionMode ? 200 : 32),
+                  child: SizedBox(height: isSelectionMode ? 200 : 32),
                 ),
                 SliverToBoxAdapter(child: SizedBox(height: bottomInset)),
               ],
@@ -372,7 +302,7 @@ class _LibraryTracksFolderScreenState
               curve: Curves.easeOutCubic,
               left: 0,
               right: 0,
-              bottom: _isSelectionMode ? 0 : -(280 + bottomPadding),
+              bottom: isSelectionMode ? 0 : -(280 + bottomPadding),
               child: _buildSelectionBottomBar(
                 context,
                 colorScheme,
@@ -392,19 +322,19 @@ class _LibraryTracksFolderScreenState
     List<CollectionTrackEntry> entries,
     double bottomPadding,
   ) {
-    final selectedCount = _selectedKeys.length;
+    final selectedCount = selectedIds.length;
     final allSelected = selectedCount == entries.length && entries.isNotEmpty;
     final isWishlist = widget.mode == LibraryTracksFolderMode.wishlist;
 
     return SelectionBottomBar(
       selectedCount: selectedCount,
       allSelected: allSelected,
-      onClose: _exitSelectionMode,
+      onClose: exitSelectionMode,
       onToggleSelectAll: () {
         if (allSelected) {
-          _exitSelectionMode();
+          exitSelectionMode();
         } else {
-          _selectAll(entries);
+          selectAll(entries.map((e) => e.key));
         }
       },
       bottomPadding: bottomPadding,
@@ -502,7 +432,7 @@ class _LibraryTracksFolderScreenState
     List<CollectionTrackEntry> entries,
     UserPlaylistCollection? playlist,
   ) {
-    final expandedHeight = _calculateExpandedHeight(context);
+    final expandedHeight = calculateExpandedHeight(context);
     final customCoverPath = playlist?.coverImagePath;
     final isLovedMode = widget.mode == LibraryTracksFolderMode.loved;
     final isPlaylistMode = widget.mode == LibraryTracksFolderMode.playlist;
@@ -563,11 +493,11 @@ class _LibraryTracksFolderScreenState
 
     return AlbumDetailHeader(
       title: title,
-      appBarTitle: _isSelectionMode
-          ? context.l10n.selectionSelected(_selectedKeys.length)
+      appBarTitle: isSelectionMode
+          ? context.l10n.selectionSelected(selectedIds.length)
           : title,
       expandedHeight: expandedHeight,
-      showTitleInAppBar: _showTitleInAppBar,
+      showTitleInAppBar: showTitleInAppBar,
       background: background,
       blurAndScrimBackground: hasCustomCover || hasCoverUrl,
       coverBuilder: (context, coverSize) {
@@ -633,7 +563,7 @@ class _LibraryTracksFolderScreenState
             )
           : null,
       appBarActions: [
-        if (isPlaylistMode && !_isSelectionMode) ...[
+        if (isPlaylistMode && !isSelectionMode) ...[
           IconButton(
             tooltip: context.l10n.collectionRenamePlaylist,
             icon: Container(
@@ -672,7 +602,7 @@ class _LibraryTracksFolderScreenState
         ],
       ],
       leading: IconButton(
-        tooltip: _isSelectionMode
+        tooltip: isSelectionMode
             ? MaterialLocalizations.of(context).closeButtonTooltip
             : MaterialLocalizations.of(context).backButtonTooltip,
         icon: Container(
@@ -682,12 +612,12 @@ class _LibraryTracksFolderScreenState
             shape: BoxShape.circle,
           ),
           child: Icon(
-            _isSelectionMode ? Icons.close : Icons.arrow_back,
+            isSelectionMode ? Icons.close : Icons.arrow_back,
             color: Colors.white,
           ),
         ),
-        onPressed: _isSelectionMode
-            ? _exitSelectionMode
+        onPressed: isSelectionMode
+            ? exitSelectionMode
             : () => Navigator.pop(context),
       ),
     );
@@ -712,7 +642,11 @@ class _LibraryTracksFolderScreenState
   }
 
   void _confirmDownloadAll(List<Track> tracks) {
-    confirmDownloadAllDialog(context, tracks.length, () => _downloadAll(tracks));
+    confirmDownloadAllDialog(
+      context,
+      tracks.length,
+      () => _downloadAll(tracks),
+    );
   }
 
   Future<void> _downloadAll(List<Track> tracks) async {

lib/screens/playlist_screen.dart

@@ -17,6 +17,7 @@ import 'package:spotiflac_android/widgets/cached_cover_image.dart';
 import 'package:spotiflac_android/widgets/motion_header_banner.dart';
 import 'package:spotiflac_android/widgets/track_list_tile.dart';
 import 'package:spotiflac_android/widgets/track_detail_actions.dart';
+import 'package:spotiflac_android/screens/collapsing_header_scroll_mixin.dart';
 import 'package:spotiflac_android/widgets/error_card.dart';
 
 class PlaylistScreen extends ConsumerStatefulWidget {
@@ -41,9 +42,8 @@ class PlaylistScreen extends ConsumerStatefulWidget {
   ConsumerState<PlaylistScreen> createState() => _PlaylistScreenState();
 }
 
-class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
-  bool _showTitleInAppBar = false;
-  final ScrollController _scrollController = ScrollController();
+class _PlaylistScreenState extends ConsumerState<PlaylistScreen>
+    with CollapsingHeaderScrollMixin<PlaylistScreen> {
   List<Track>? _fetchedTracks;
   bool _isLoading = false;
   String? _error;
@@ -57,8 +57,6 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
   String? get _headerVideoUrl =>
       _resolvedHeaderVideoUrl ?? widget.headerVideoUrl;
 
-
-
   String? _metadataProviderId(String playlistId) {
     final providerId = legacyProviderIdFromResourceId(playlistId);
     if (providerId == null) return null;
@@ -109,17 +107,9 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
   @override
   void initState() {
     super.initState();
-    _scrollController.addListener(_onScroll);
     _fetchTracksIfNeeded();
   }
 
-  @override
-  void dispose() {
-    _scrollController.removeListener(_onScroll);
-    _scrollController.dispose();
-    super.dispose();
-  }
-
   Future<void> _fetchTracksIfNeeded() async {
     if (widget.tracks.isNotEmpty || widget.playlistId == null) return;
 
@@ -178,27 +168,13 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
     }
   }
 
-  void _onScroll() {
-    final expandedHeight = _calculateExpandedHeight(context);
-    final shouldShow =
-        _scrollController.offset > (expandedHeight - kToolbarHeight - 20);
-    if (shouldShow != _showTitleInAppBar) {
-      setState(() => _showTitleInAppBar = shouldShow);
-    }
-  }
-
-  double _calculateExpandedHeight(BuildContext context) {
-    final mediaSize = MediaQuery.of(context).size;
-    return (mediaSize.height * 0.6).clamp(400.0, 580.0);
-  }
-
   @override
   Widget build(BuildContext context) {
     final colorScheme = Theme.of(context).colorScheme;
 
     return Scaffold(
       body: CustomScrollView(
-        controller: _scrollController,
+        controller: scrollController,
         slivers: [
           _buildAppBar(context, colorScheme),
           _buildTrackList(context, colorScheme),
@@ -212,7 +188,7 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
   }
 
   Widget _buildAppBar(BuildContext context, ColorScheme colorScheme) {
-    final expandedHeight = _calculateExpandedHeight(context);
+    final expandedHeight = calculateExpandedHeight(context);
     final cacheWidth = coverCacheWidthForViewport(context);
     final motionUrl = _headerVideoUrl;
     final hasMotion =
@@ -243,7 +219,7 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
     return AlbumDetailHeader(
       title: _playlistName,
       expandedHeight: expandedHeight,
-      showTitleInAppBar: _showTitleInAppBar,
+      showTitleInAppBar: showTitleInAppBar,
       background: hasMotion
           ? MotionHeaderBanner(videoUrl: motionUrl, fallback: coverImage)
           : coverImage,
@@ -403,59 +379,18 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
     );
   }
 
-  Widget _buildCircleButton({
-    required IconData icon,
-    required String tooltip,
-    required VoidCallback? onPressed,
-  }) {
-    return Container(
-      width: 48,
-      height: 48,
-      decoration: BoxDecoration(
-        shape: BoxShape.circle,
-        color: Colors.white.withValues(alpha: 0.15),
-        border: Border.all(
-          color: Colors.white.withValues(alpha: 0.3),
-          width: 1,
-        ),
-      ),
-      child: IconButton(
-        onPressed: onPressed,
-        icon: Icon(icon, size: 22, color: Colors.white),
-        tooltip: tooltip,
-        padding: EdgeInsets.zero,
-      ),
-    );
-  }
-
   Widget _buildLoveAllButton() {
     final collectionsState = ref.watch(libraryCollectionsProvider);
     final allLoved =
         _tracks.isNotEmpty && _tracks.every((t) => collectionsState.isLoved(t));
 
-    return Container(
-      width: 48,
-      height: 48,
-      decoration: BoxDecoration(
-        shape: BoxShape.circle,
-        color: Colors.white.withValues(alpha: 0.15),
-        border: Border.all(
-          color: Colors.white.withValues(alpha: 0.3),
-          width: 1,
-        ),
-      ),
-      child: IconButton(
-        onPressed: _tracks.isEmpty ? null : () => _loveAll(_tracks),
-        icon: Icon(
-          allLoved ? Icons.favorite : Icons.favorite_border,
-          size: 22,
-          color: allLoved ? Colors.redAccent : Colors.white,
-        ),
-        tooltip: allLoved
-            ? context.l10n.trackOptionRemoveFromLoved
-            : context.l10n.tooltipLoveAll,
-        padding: EdgeInsets.zero,
-      ),
+    return HeaderCircleButton(
+      icon: allLoved ? Icons.favorite : Icons.favorite_border,
+      iconColor: allLoved ? Colors.redAccent : Colors.white,
+      tooltip: allLoved
+          ? context.l10n.trackOptionRemoveFromLoved
+          : context.l10n.tooltipLoveAll,
+      onPressed: _tracks.isEmpty ? null : () => _loveAll(_tracks),
     );
   }
 
@@ -478,7 +413,7 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
   }
 
   Widget _buildAddToPlaylistButton(BuildContext context) {
-    return _buildCircleButton(
+    return HeaderCircleButton(
       icon: Icons.playlist_add,
       tooltip: context.l10n.tooltipAddToPlaylist,
       onPressed: _tracks.isEmpty
@@ -500,7 +435,8 @@ class _PlaylistScreenState extends ConsumerState<PlaylistScreen> {
     );
   }
 
-  Future<void> _loveAll(List<Track> tracks) => loveAllTracks(context, ref, tracks);
+  Future<void> _loveAll(List<Track> tracks) =>
+      loveAllTracks(context, ref, tracks);
 
   void _downloadAll(BuildContext context) {
     _downloadTracks(context, _tracks);

lib/screens/queue_tab_selection.dart

@@ -336,158 +336,77 @@ extension _QueueTabSelectionActions on _QueueTabState {
     final allSelected =
         selectedCount == playlists.length && playlists.isNotEmpty;
 
-    return Container(
-      decoration: BoxDecoration(
-        color: colorScheme.surfaceContainerHigh,
-        borderRadius: const BorderRadius.vertical(top: Radius.circular(28)),
-        boxShadow: [
-          BoxShadow(
-            color: Colors.black.withValues(alpha: 0.15),
-            blurRadius: 12,
-            offset: const Offset(0, -4),
-          ),
-        ],
-      ),
-      child: SafeArea(
-        top: false,
-        child: Padding(
-          padding: EdgeInsets.fromLTRB(16, 16, 16, bottomPadding > 0 ? 8 : 16),
-          child: Column(
-            mainAxisSize: MainAxisSize.min,
-            children: [
-              Container(
-                width: 32,
-                height: 4,
-                margin: const EdgeInsets.only(bottom: 16),
-                decoration: BoxDecoration(
-                  color: colorScheme.outlineVariant,
-                  borderRadius: BorderRadius.circular(2),
-                ),
+    return SelectionBottomBar(
+      selectedCount: selectedCount,
+      allSelected: allSelected,
+      onClose: _exitPlaylistSelectionMode,
+      onToggleSelectAll: () {
+        if (allSelected) {
+          _exitPlaylistSelectionMode();
+        } else {
+          _selectAllPlaylists(playlists);
+        }
+      },
+      bottomPadding: bottomPadding,
+      allSelectedLabel: context.l10n.selectionAllPlaylistsSelected,
+      tapToSelectLabel: context.l10n.selectionTapPlaylistsToSelect,
+      children: [
+        SizedBox(
+          width: double.infinity,
+          child: FilledButton.icon(
+            onPressed: selectedCount > 0
+                ? () => _downloadAllSelectedPlaylists(context)
+                : null,
+            icon: const Icon(Icons.download_rounded),
+            label: Text(
+              selectedCount > 0
+                  ? context.l10n.bulkDownloadPlaylistsButton(selectedCount)
+                  : context.l10n.bulkDownloadSelectPlaylists,
+            ),
+            style: FilledButton.styleFrom(
+              backgroundColor: selectedCount > 0
+                  ? colorScheme.primary
+                  : colorScheme.surfaceContainerHighest,
+              foregroundColor: selectedCount > 0
+                  ? colorScheme.onPrimary
+                  : colorScheme.onSurfaceVariant,
+              padding: const EdgeInsets.symmetric(vertical: 16),
+              shape: RoundedRectangleBorder(
+                borderRadius: BorderRadius.circular(16),
               ),
-
-              Row(
-                children: [
-                  IconButton.filledTonal(
-                    onPressed: _exitPlaylistSelectionMode,
-                    tooltip: MaterialLocalizations.of(
-                      context,
-                    ).closeButtonTooltip,
-                    icon: const Icon(Icons.close),
-                    style: IconButton.styleFrom(
-                      backgroundColor: colorScheme.surfaceContainerHighest,
-                    ),
-                  ),
-                  const SizedBox(width: 12),
-
-                  Expanded(
-                    child: Column(
-                      crossAxisAlignment: CrossAxisAlignment.start,
-                      children: [
-                        Text(
-                          context.l10n.selectionSelected(selectedCount),
-                          style: Theme.of(context).textTheme.titleMedium
-                              ?.copyWith(fontWeight: FontWeight.bold),
-                        ),
-                        Text(
-                          allSelected
-                              ? context.l10n.selectionAllPlaylistsSelected
-                              : context.l10n.selectionTapPlaylistsToSelect,
-                          style: Theme.of(context).textTheme.bodySmall
-                              ?.copyWith(color: colorScheme.onSurfaceVariant),
-                        ),
-                      ],
-                    ),
-                  ),
-
-                  TextButton.icon(
-                    onPressed: () {
-                      if (allSelected) {
-                        _exitPlaylistSelectionMode();
-                      } else {
-                        _selectAllPlaylists(playlists);
-                      }
-                    },
-                    icon: Icon(
-                      allSelected ? Icons.deselect : Icons.select_all,
-                      size: 20,
-                    ),
-                    label: Text(
-                      allSelected
-                          ? context.l10n.actionDeselect
-                          : context.l10n.actionSelectAll,
-                    ),
-                    style: TextButton.styleFrom(
-                      foregroundColor: colorScheme.primary,
-                    ),
-                  ),
-                ],
-              ),
-
-              const SizedBox(height: 12),
-
-              SizedBox(
-                width: double.infinity,
-                child: FilledButton.icon(
-                  onPressed: selectedCount > 0
-                      ? () => _downloadAllSelectedPlaylists(context)
-                      : null,
-                  icon: const Icon(Icons.download_rounded),
-                  label: Text(
-                    selectedCount > 0
-                        ? context.l10n.bulkDownloadPlaylistsButton(
-                            selectedCount,
-                          )
-                        : context.l10n.bulkDownloadSelectPlaylists,
-                  ),
-                  style: FilledButton.styleFrom(
-                    backgroundColor: selectedCount > 0
-                        ? colorScheme.primary
-                        : colorScheme.surfaceContainerHighest,
-                    foregroundColor: selectedCount > 0
-                        ? colorScheme.onPrimary
-                        : colorScheme.onSurfaceVariant,
-                    padding: const EdgeInsets.symmetric(vertical: 16),
-                    shape: RoundedRectangleBorder(
-                      borderRadius: BorderRadius.circular(16),
-                    ),
-                  ),
-                ),
-              ),
-
-              const SizedBox(height: 8),
-
-              SizedBox(
-                width: double.infinity,
-                child: FilledButton.icon(
-                  onPressed: selectedCount > 0
-                      ? () => _deleteSelectedPlaylists(context)
-                      : null,
-                  icon: const Icon(Icons.delete_outline),
-                  label: Text(
-                    selectedCount > 0
-                        ? context.l10n.selectionDeletePlaylistsCount(
-                            selectedCount,
-                          )
-                        : context.l10n.selectionSelectPlaylistsToDelete,
-                  ),
-                  style: FilledButton.styleFrom(
-                    backgroundColor: selectedCount > 0
-                        ? colorScheme.error
-                        : colorScheme.surfaceContainerHighest,
-                    foregroundColor: selectedCount > 0
-                        ? colorScheme.onError
-                        : colorScheme.onSurfaceVariant,
-                    padding: const EdgeInsets.symmetric(vertical: 16),
-                    shape: RoundedRectangleBorder(
-                      borderRadius: BorderRadius.circular(16),
-                    ),
-                  ),
-                ),
-              ),
-            ],
+            ),
           ),
         ),
-      ),
+
+        const SizedBox(height: 8),
+
+        SizedBox(
+          width: double.infinity,
+          child: FilledButton.icon(
+            onPressed: selectedCount > 0
+                ? () => _deleteSelectedPlaylists(context)
+                : null,
+            icon: const Icon(Icons.delete_outline),
+            label: Text(
+              selectedCount > 0
+                  ? context.l10n.selectionDeletePlaylistsCount(selectedCount)
+                  : context.l10n.selectionSelectPlaylistsToDelete,
+            ),
+            style: FilledButton.styleFrom(
+              backgroundColor: selectedCount > 0
+                  ? colorScheme.error
+                  : colorScheme.surfaceContainerHighest,
+              foregroundColor: selectedCount > 0
+                  ? colorScheme.onError
+                  : colorScheme.onSurfaceVariant,
+              padding: const EdgeInsets.symmetric(vertical: 16),
+              shape: RoundedRectangleBorder(
+                borderRadius: BorderRadius.circular(16),
+              ),
+            ),
+          ),
+        ),
+      ],
     );
   }
 
@@ -585,5 +504,4 @@ extension _QueueTabSelectionActions on _QueueTabState {
   Future<int?> _readFileModTimeMillis(String? filePath) async {
     return DownloadedEmbeddedCoverResolver.readFileModTimeMillis(filePath);
   }
-
 }

lib/screens/track_metadata_screen.dart

@@ -33,6 +33,7 @@ import 'package:spotiflac_android/widgets/batch_convert_sheet.dart';
 import 'package:spotiflac_android/widgets/cached_cover_image.dart';
 import 'package:spotiflac_android/widgets/settings_group.dart';
 import 'package:spotiflac_android/constants/music_services.dart';
+import 'package:spotiflac_android/screens/collapsing_header_scroll_mixin.dart';
 
 part 'track_metadata_edit_sheet.dart';
 part 'track_metadata_cards.dart';
@@ -92,7 +93,8 @@ class TrackMetadataScreen extends ConsumerStatefulWidget {
       _TrackMetadataScreenState();
 }
 
-class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
+class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen>
+    with CollapsingHeaderScrollMixin<TrackMetadataScreen> {
   static const int _maxCoverPreviewCacheEntries = 96;
   static final Map<String, _EmbeddedCoverPreviewCacheEntry>
   _embeddedCoverPreviewCache = {};
@@ -105,7 +107,6 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   bool _lyricsLoading = false;
   String? _lyricsError;
   String? _lyricsSource;
-  bool _showTitleInAppBar = false;
   bool _lyricsEmbedded = false;
   bool _isEmbedding = false;
   bool _isInstrumental = false;
@@ -121,7 +122,6 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   late int? _currentNavigationIndex;
   Map<String, dynamic>? _editedMetadata;
   String? _embeddedCoverPreviewPath;
-  final ScrollController _scrollController = ScrollController();
   static final RegExp _lrcTimestampPattern = RegExp(
     r'^\[\d{2}:\d{2}\.\d{2,3}\]',
   );
@@ -247,15 +247,12 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
     _currentDownloadItem = widget.item;
     _currentLocalLibraryItem = widget.localItem;
     _currentNavigationIndex = widget.navigationIndex;
-    _scrollController.addListener(_onScroll);
     _checkFile();
   }
 
   @override
   void dispose() {
     unawaited(_cleanupTempFileAndParentIfNotCached(_embeddedCoverPreviewPath));
-    _scrollController.removeListener(_onScroll);
-    _scrollController.dispose();
     super.dispose();
   }
 
@@ -263,16 +260,8 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   /// through this forwarder.
   void _setState(VoidCallback fn) => setState(fn);
 
-  void _onScroll() {
-    final expandedHeight = _calculateExpandedHeight(context);
-    final shouldShow =
-        _scrollController.offset > (expandedHeight - kToolbarHeight - 20);
-    if (shouldShow != _showTitleInAppBar) {
-      setState(() => _showTitleInAppBar = shouldShow);
-    }
-  }
-
-  double _calculateExpandedHeight(BuildContext context) {
+  @override
+  double calculateExpandedHeight(BuildContext context) {
     final mediaSize = MediaQuery.sizeOf(context);
     return (mediaSize.height * 0.55).clamp(360.0, 520.0);
   }
@@ -775,7 +764,8 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   String? get _localCoverPath =>
       _isLocalItem ? _localLibraryItem!.coverPath : null;
   String? get _spotifyId => _isLocalItem ? null : _downloadItem!.spotifyId;
-  String get _service => _isLocalItem ? MusicServices.local : _downloadItem!.service;
+  String get _service =>
+      _isLocalItem ? MusicServices.local : _downloadItem!.service;
   DateTime get _addedAt {
     if (_isLocalItem) {
       final modTime = _localLibraryItem!.fileModTime;
@@ -1083,7 +1073,7 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
         _lyricsLoading = false;
         _lyricsError = null;
         _lyricsSource = null;
-        _showTitleInAppBar = false;
+        showTitleInAppBar = false;
         _lyricsEmbedded = false;
         _isInstrumental = false;
         _embeddedLyricsChecked = false;
@@ -1092,8 +1082,8 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
         _embeddedCoverPreviewPath = null;
       });
 
-      if (_scrollController.hasClients) {
-        _scrollController.jumpTo(0);
+      if (scrollController.hasClients) {
+        scrollController.jumpTo(0);
       }
 
       if (oldPreviewPath != null) {
@@ -1110,7 +1100,7 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
   @override
   Widget build(BuildContext context) {
     final colorScheme = Theme.of(context).colorScheme;
-    final expandedHeight = _calculateExpandedHeight(context);
+    final expandedHeight = calculateExpandedHeight(context);
     final bottomInset = context.navBarBottomInset;
 
     return GestureDetector(
@@ -1118,7 +1108,7 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
       onHorizontalDragEnd: _handleHorizontalDragEnd,
       child: Scaffold(
         body: CustomScrollView(
-          controller: _scrollController,
+          controller: scrollController,
           slivers: [
             SliverAppBar(
               expandedHeight: expandedHeight,
@@ -1128,7 +1118,7 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
               surfaceTintColor: Colors.transparent,
               title: AnimatedOpacity(
                 duration: const Duration(milliseconds: 200),
-                opacity: _showTitleInAppBar ? 1.0 : 0.0,
+                opacity: showTitleInAppBar ? 1.0 : 0.0,
                 child: Text(
                   trackName,
                   style: TextStyle(
@@ -1500,7 +1490,6 @@ class _TrackMetadataScreenState extends ConsumerState<TrackMetadataScreen> {
 
     return placeholder();
   }
-
 }
 
 class _MetadataOption {

lib/widgets/album_detail_header.dart

@@ -283,6 +283,45 @@ class AlbumPlayActions extends StatelessWidget {
   }
 }
 
+/// 48x48 translucent-white circle icon button used in album/playlist headers
+/// (add-to-playlist, love-all, ...).
+class HeaderCircleButton extends StatelessWidget {
+  const HeaderCircleButton({
+    super.key,
+    required this.icon,
+    required this.tooltip,
+    required this.onPressed,
+    this.iconColor = Colors.white,
+  });
+
+  final IconData icon;
+  final String tooltip;
+  final VoidCallback? onPressed;
+  final Color iconColor;
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      width: 48,
+      height: 48,
+      decoration: BoxDecoration(
+        shape: BoxShape.circle,
+        color: Colors.white.withValues(alpha: 0.15),
+        border: Border.all(
+          color: Colors.white.withValues(alpha: 0.3),
+          width: 1,
+        ),
+      ),
+      child: IconButton(
+        onPressed: onPressed,
+        icon: Icon(icon, size: 22, color: iconColor),
+        tooltip: tooltip,
+        padding: EdgeInsets.zero,
+      ),
+    );
+  }
+}
+
 /// "•"-joined row of white [HeaderMetaItem]s shown under the header subtitle
 /// (track count, duration, quality, ...).
 class HeaderMetaRow extends StatelessWidget {

lib/widgets/selection_bottom_bar.dart

@@ -13,6 +13,8 @@ class SelectionBottomBar extends StatelessWidget {
     required this.onToggleSelectAll,
     required this.bottomPadding,
     required this.children,
+    this.allSelectedLabel,
+    this.tapToSelectLabel,
   });
 
   final int selectedCount;
@@ -22,6 +24,12 @@ class SelectionBottomBar extends StatelessWidget {
   final double bottomPadding;
   final List<Widget> children;
 
+  /// Overrides the default "All tracks selected" subtitle.
+  final String? allSelectedLabel;
+
+  /// Overrides the default "Tap tracks to select" subtitle.
+  final String? tapToSelectLabel;
+
   @override
   Widget build(BuildContext context) {
     final colorScheme = Theme.of(context).colorScheme;
@@ -80,8 +88,10 @@ class SelectionBottomBar extends StatelessWidget {
                         ),
                         Text(
                           allSelected
-                              ? context.l10n.selectionAllSelected
-                              : context.l10n.downloadedAlbumTapToSelect,
+                              ? allSelectedLabel ??
+                                    context.l10n.selectionAllSelected
+                              : tapToSelectLabel ??
+                                    context.l10n.downloadedAlbumTapToSelect,
                           style: Theme.of(context).textTheme.bodySmall
                               ?.copyWith(color: colorScheme.onSurfaceVariant),
                         ),