Smooth mobile post swipes and export providers

lib/backend/services/settings_service.dart

@@ -227,18 +227,44 @@ class SettingsService {
 
   Future<Result<String>> exportSettingsToJson() async {
     final result = await getSettings();
-    return result.fold(
-      onSuccess: (settings) => Success(jsonEncode(settings.toJson())),
-      onError: Error<String>.new,
+    if (result is Error<AppSettings>) return Error(result.failure);
+    final settings = (result as Success<AppSettings>).data;
+    final providers = <ContentProviderConfig>[];
+    final repository = _providerRepository;
+    if (repository != null) {
+      final providersResult = await repository.getProviders(enabledOnly: false);
+      if (providersResult is Success<List<ContentProviderConfig>>) {
+        providers.addAll(providersResult.data);
+      }
+    }
+    return Success(
+      const JsonEncoder.withIndent('  ').convert({
+        'schemaVersion': 2,
+        'settings': settings.toJson(),
+        'providers': providers.map((provider) => provider.toJson()).toList(),
+      }),
     );
   }
 
   Future<Result<void>> importSettingsFromJson(String json) async {
     try {
-      final settings =
-          AppSettings.fromJson(jsonDecode(json) as Map<String, dynamic>);
+      final decoded = jsonDecode(json) as Map<String, dynamic>;
+      final settingsJson =
+          (decoded['settings'] as Map?)?.cast<String, dynamic>() ?? decoded;
+      final settings = AppSettings.fromJson(settingsJson);
       final result = await updateSettings(settings);
       if (result is Error<void>) return result;
+      final repository = _providerRepository;
+      final providerItems = decoded['providers'];
+      if (repository != null && providerItems is List) {
+        for (final item in providerItems.whereType<Map>()) {
+          await repository.saveProvider(
+            ContentProviderConfig.fromJson(
+              Map<String, dynamic>.from(item),
+            ).copyWith(updatedAt: DateTime.now()),
+          );
+        }
+      }
       await saveEnabledProviders(settings.enabledProviderIds);
       return result;
     } catch (error) {

lib/features/post/presentation/post_details_screen.dart

@@ -79,15 +79,13 @@ class PostDetailsScreen extends ConsumerWidget {
               : null;
           if (Responsive.isMobile(context)) {
             if (currentIndex >= 0 && feedPosts.length > 1) {
-              return PageView.builder(
-                controller: PageController(initialPage: currentIndex),
-                itemCount: feedPosts.length,
-                onPageChanged: (index) =>
-                    _replacePost(context, feedPosts[index]),
-                itemBuilder: (context, index) => _buildMobileDetails(
+              return _MobilePostPager(
+                posts: feedPosts,
+                initialIndex: currentIndex,
+                buildDetails: (context, post) => _buildMobileDetails(
                   context,
                   ref,
-                  feedPosts[index],
+                  post,
                   settings,
                   favoriteKeys,
                 ),
@@ -303,6 +301,77 @@ class PostDetailsScreen extends ConsumerWidget {
   }
 }
 
+class _MobilePostPager extends StatefulWidget {
+  const _MobilePostPager({
+    required this.posts,
+    required this.initialIndex,
+    required this.buildDetails,
+  });
+
+  final List<Post> posts;
+  final int initialIndex;
+  final Widget Function(BuildContext context, Post post) buildDetails;
+
+  @override
+  State<_MobilePostPager> createState() => _MobilePostPagerState();
+}
+
+class _MobilePostPagerState extends State<_MobilePostPager> {
+  late final PageController _controller;
+  late int _currentIndex;
+
+  @override
+  void initState() {
+    super.initState();
+    _currentIndex = widget.initialIndex;
+    _controller = PageController(initialPage: widget.initialIndex);
+  }
+
+  @override
+  void didUpdateWidget(covariant _MobilePostPager oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (widget.initialIndex != _currentIndex &&
+        widget.initialIndex >= 0 &&
+        widget.initialIndex < widget.posts.length) {
+      _currentIndex = widget.initialIndex;
+      if (_controller.hasClients) {
+        _controller.jumpToPage(widget.initialIndex);
+      }
+    }
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return PageView.builder(
+      controller: _controller,
+      itemCount: widget.posts.length,
+      onPageChanged: (index) {
+        _currentIndex = index;
+        final post = widget.posts[index];
+        WidgetsBinding.instance.addPostFrameCallback((_) {
+          if (!mounted) return;
+          GoRouter.of(context).replace(
+            '/post/${post.providerId}/${post.id}',
+            extra: post,
+          );
+        });
+      },
+      itemBuilder: (context, index) {
+        return KeyedSubtree(
+          key: ValueKey(widget.posts[index].cacheKey),
+          child: widget.buildDetails(context, widget.posts[index]),
+        );
+      },
+    );
+  }
+}
+
 class _CommentsSection extends ConsumerStatefulWidget {
   const _CommentsSection({required this.post});
 

lib/features/settings/presentation/settings_screen.dart

@@ -107,13 +107,13 @@ class SettingsScreen extends ConsumerWidget {
                 }
               },
               icon: const Icon(Icons.upload_file_rounded),
-              label: const Text('Export settings JSON'),
+              label: const Text('Export settings and providers JSON'),
             ),
             const SizedBox(height: 12),
             FilledButton.tonalIcon(
               onPressed: () => _importDialog(context, ref),
               icon: const Icon(Icons.download_for_offline_rounded),
-              label: const Text('Import settings JSON'),
+              label: const Text('Import settings and providers JSON'),
             ),
             const SizedBox(height: 24),
             const Text('Version 0.1.0'),