fix(playlists): prevent overlapping picker submissions

lib/widgets/playlist_picker_sheet.dart

@@ -7,12 +7,15 @@ import 'package:spotiflac_android/l10n/l10n.dart';
 import 'package:spotiflac_android/models/track.dart';
 import 'package:spotiflac_android/providers/library_collections_provider.dart';
 import 'package:spotiflac_android/theme/mornye_theme.dart';
+import 'package:spotiflac_android/utils/logger.dart';
 import 'package:spotiflac_android/widgets/app_action_button.dart';
 import 'package:spotiflac_android/widgets/app_alert_dialog.dart';
 import 'package:spotiflac_android/widgets/app_bottom_sheet.dart';
 import 'package:spotiflac_android/widgets/cached_cover_image.dart';
 import 'package:spotiflac_android/widgets/mornye_chrome.dart';
 
+final _log = AppLogger('PlaylistPicker');
+
 Future<void> showAddTrackToPlaylistSheet(
   BuildContext context,
   WidgetRef ref,
@@ -68,6 +71,7 @@ class _PlaylistPickerSheetContentState
   late final PlaylistPickerSummaryRequest _summaryRequest;
   final Set<String> _selectedPlaylistIds = {};
   final Set<String> _committedPlaylistIds = {};
+  bool _isSubmitting = false;
 
   @override
   void initState() {
@@ -75,7 +79,9 @@ class _PlaylistPickerSheetContentState
     _summaryRequest = PlaylistPickerSummaryRequest.fromTracks(widget.tracks);
   }
 
-  void _handleDone(List<PlaylistPickerSummary> playlists) async {
+  Future<void> _handleDone(List<PlaylistPickerSummary> playlists) async {
+    if (_isSubmitting) return;
+    setState(() => _isSubmitting = true);
     final notifier = ref.read(libraryCollectionsProvider.notifier);
     final effectiveDisabledIds = <String>{
       ..._committedPlaylistIds,
@@ -88,12 +94,23 @@ class _PlaylistPickerSheetContentState
     };
     final addedNames = <String>[];
 
-    for (final playlistId in idsToAdd) {
-      final playlistName = playlistNamesById[playlistId];
-      if (playlistName != null && playlistName.isNotEmpty) {
-        addedNames.add(playlistName);
+    try {
+      for (final playlistId in idsToAdd) {
+        await notifier.addTracksToPlaylist(playlistId, widget.tracks);
+        _committedPlaylistIds.add(playlistId);
+        final playlistName = playlistNamesById[playlistId];
+        if (playlistName != null && playlistName.isNotEmpty) {
+          addedNames.add(playlistName);
+        }
       }
-      await notifier.addTracksToPlaylist(playlistId, widget.tracks);
+    } catch (error, stack) {
+      _log.e('Failed to add tracks to selected playlists', error, stack);
+      if (!mounted) return;
+      setState(() => _isSubmitting = false);
+      ScaffoldMessenger.of(
+        context,
+      ).showSnackBar(SnackBar(content: Text(context.friendlyError(error))));
+      return;
     }
 
     if (!mounted) return;
@@ -134,9 +151,11 @@ class _PlaylistPickerSheetContentState
     final hasNewSelections = idsToAdd.isNotEmpty;
 
     void onDone() {
+      if (_isSubmitting) return;
       if (hasNewSelections) {
         _handleDone(resolvedPlaylists);
       } else {
+        setState(() => _isSubmitting = true);
         Navigator.of(context).pop();
       }
     }
@@ -187,7 +206,9 @@ class _PlaylistPickerSheetContentState
               color: Theme.of(context).colorScheme.primary,
             ),
             title: Text(context.l10n.collectionCreatePlaylist),
+            enabled: !_isSubmitting,
             onTap: () async {
+              if (_isSubmitting) return;
               final name = await _promptPlaylistName(
                 context,
                 widget.playlistNamePrefill,
@@ -250,10 +271,11 @@ class _PlaylistPickerSheetContentState
                             playlist.trackCount,
                           ),
                         ),
-                        enabled: !isAlreadyIn,
+                        enabled: !isAlreadyIn && !_isSubmitting,
                         selected: isSelected,
-                        onTap: !isAlreadyIn
+                        onTap: !isAlreadyIn && !_isSubmitting
                             ? () {
+                                if (_isSubmitting) return;
                                 setState(() {
                                   if (_selectedPlaylistIds.contains(
                                     playlist.id,
@@ -295,12 +317,12 @@ class _PlaylistPickerSheetContentState
               width: double.infinity,
               child: context.isMornye
                   ? AppActionButton(
-                      onPressed: onDone,
+                      onPressed: _isSubmitting ? null : onDone,
                       icon: const Icon(CupertinoIcons.checkmark),
                       label: Text(context.l10n.dialogDone),
                     )
                   : FilledButton(
-                      onPressed: onDone,
+                      onPressed: _isSubmitting ? null : onDone,
                       child: Text(context.l10n.dialogDone),
                     ),
             ),

test/mornye_collection_sheets_test.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
@@ -10,6 +12,7 @@ import 'package:spotiflac_android/models/track.dart';
 import 'package:spotiflac_android/providers/library_collections_provider.dart';
 import 'package:spotiflac_android/providers/settings_provider.dart';
 import 'package:spotiflac_android/theme/mornye_theme.dart';
+import 'package:spotiflac_android/widgets/app_action_button.dart';
 import 'package:spotiflac_android/widgets/app_alert_dialog.dart';
 import 'package:spotiflac_android/widgets/mornye_chrome.dart';
 import 'package:spotiflac_android/widgets/playlist_picker_sheet.dart';
@@ -32,6 +35,7 @@ class _Collections extends LibraryCollectionsNotifier {
   List<PlaylistPickerSummary> _summaries = [];
   final additions = <String>[];
   final createdNames = <String>[];
+  final pendingAdditions = <Completer<void>>[];
 
   @override
   LibraryCollectionsState build() => LibraryCollectionsState(isLoaded: true);
@@ -50,6 +54,9 @@ class _Collections extends LibraryCollectionsNotifier {
     Iterable<Track> tracks,
   ) async {
     additions.add(playlistId);
+    if (pendingAdditions.isNotEmpty) {
+      await pendingAdditions.removeAt(0).future;
+    }
     return PlaylistAddBatchResult(
       addedCount: tracks.length,
       alreadyInPlaylistCount: 0,
@@ -57,6 +64,19 @@ class _Collections extends LibraryCollectionsNotifier {
   }
 }
 
+class _PopObserver extends NavigatorObserver {
+  int pops = 0;
+
+  @override
+  void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) {
+    pops++;
+  }
+}
+
+VoidCallback? _doneAction(WidgetTester tester, bool mornye) => mornye
+    ? tester.widget<AppActionButton>(find.byType(AppActionButton)).onPressed
+    : tester.widget<FilledButton>(find.byType(FilledButton)).onPressed;
+
 PlaylistPickerSummary _playlist(String name, {bool contains = false}) =>
     PlaylistPickerSummary(
       id: name,
@@ -73,6 +93,7 @@ Widget _app(
   required Brightness brightness,
   bool mornye = true,
   double textScale = 1,
+  List<NavigatorObserver> navigatorObservers = const [],
 }) => ProviderScope(
   overrides: [
     settingsProvider.overrideWith(_Settings.new),
@@ -82,6 +103,7 @@ Widget _app(
     ),
   ],
   child: MaterialApp(
+    navigatorObservers: navigatorObservers,
     theme: mornye ? MornyeTheme.build(brightness) : ThemeData(),
     localizationsDelegates: AppLocalizations.localizationsDelegates,
     supportedLocales: AppLocalizations.supportedLocales,
@@ -157,6 +179,102 @@ void main() {
   }
 
   for (final mornye in [true, false]) {
+    testWidgets('picker submits and closes once (Mornye: $mornye)', (
+      tester,
+    ) async {
+      final addition = Completer<void>();
+      final collections = _Collections()
+        .._summaries = [_playlist('Road trip')]
+        ..pendingAdditions.add(addition);
+      final observer = _PopObserver();
+      await tester.pumpWidget(
+        _app(
+          Consumer(
+            builder: (context, ref, _) => TextButton(
+              onPressed: () =>
+                  showAddTracksToPlaylistSheet(context, ref, [_track]),
+              child: const Text('Open'),
+            ),
+          ),
+          collections,
+          brightness: Brightness.light,
+          mornye: mornye,
+          navigatorObservers: [observer],
+        ),
+      );
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Road trip'));
+      await tester.pump();
+      final submit = _doneAction(tester, mornye)!;
+      // A repeated callback can arrive before the disabled button is rebuilt.
+      submit();
+      submit();
+      await tester.pump();
+      expect(collections.additions, ['Road trip']);
+      expect(_doneAction(tester, mornye), isNull);
+      expect(observer.pops, 0);
+
+      addition.complete();
+      await tester.pump();
+      // The route remains mounted while its closing animation runs.
+      submit();
+      await tester.pumpAndSettle();
+      expect(collections.additions, ['Road trip']);
+      expect(observer.pops, 1);
+      expect(find.text('Open'), findsOneWidget);
+      expect(tester.takeException(), isNull);
+    });
+
+    testWidgets('picker retains selections after failure (Mornye: $mornye)', (
+      tester,
+    ) async {
+      final firstAddition = Completer<void>()..complete();
+      final secondAddition = Completer<void>();
+      final collections = _Collections()
+        .._summaries = [_playlist('Road trip'), _playlist('Evening music')]
+        ..pendingAdditions.addAll([firstAddition, secondAddition]);
+      final observer = _PopObserver();
+      await tester.pumpWidget(
+        _app(
+          Consumer(
+            builder: (context, ref, _) => TextButton(
+              onPressed: () =>
+                  showAddTracksToPlaylistSheet(context, ref, [_track]),
+              child: const Text('Open'),
+            ),
+          ),
+          collections,
+          brightness: Brightness.light,
+          mornye: mornye,
+          navigatorObservers: [observer],
+        ),
+      );
+      await tester.tap(find.text('Open'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Road trip'));
+      await tester.tap(find.text('Evening music'));
+      await tester.pump();
+      await tester.tap(find.text('Done'));
+      await tester.pump();
+      expect(collections.additions, ['Road trip', 'Evening music']);
+      secondAddition.completeError(StateError('write failed'));
+      await tester.pump();
+      expect(observer.pops, 0);
+      expect(_doneAction(tester, mornye), isNotNull);
+
+      // Retrying keeps the failed selection and skips the persisted playlist.
+      await tester.tap(find.text('Done'));
+      await tester.pumpAndSettle();
+      expect(collections.additions, [
+        'Road trip',
+        'Evening music',
+        'Evening music',
+      ]);
+      expect(observer.pops, 1);
+      expect(tester.takeException(), isNull);
+    });
+
     testWidgets('picker adds only new selections (Mornye: $mornye)', (
       tester,
     ) async {