From c2a4bd6fcef9a77d7fe2870c2330d05f95f972b2 Mon Sep 17 00:00:00 2001
From: Richard Alcock <richard.alcock@gmail.com>
Date: Sun, 10 May 2026 08:56:00 +0100
Subject: [PATCH] fix(festival-selector): avoid GoRouterState.of() inside
 gesture callback
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Calling GoRouterState.of(context) from an onTap handler causes a
complete app freeze when a notifyListeners() continuation is pending
on the Dart microtask queue at tap time — reproduces reliably when
switching festivals immediately after data finishes loading.

Fix: capture the current path in showFestivalBrowser() before the
modal opens, where it is safe to call InheritedWidget lookups, and
pass it as a constructor parameter to FestivalSelectorSheet.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 lib/providers/beer_provider.dart      |  3 ---
 lib/services/beer_api_service.dart    |  1 -
 lib/widgets/festival_menu_sheets.dart | 38 +++++++++++++++++----------
 3 files changed, 24 insertions(+), 18 deletions(-)

diff --git a/lib/providers/beer_provider.dart b/lib/providers/beer_provider.dart
index b121cb25..87dc4f31 100644
--- a/lib/providers/beer_provider.dart
+++ b/lib/providers/beer_provider.dart
@@ -289,15 +289,12 @@ class BeerProvider extends ChangeNotifier {
     _error = null;
     notifyListeners();
 
-    // Log analytics event
     await _analyticsService.logFestivalSelected(festival);
 
-    // Persist festival selection only if requested
     if (persist) {
       await _festivalRepository?.setSelectedFestivalId(festival.id);
     }
 
-    // Load drinks for the new festival (loadDrinks will call notifyListeners when done)
     await _loadDrinksInternal();
   }
 
diff --git a/lib/services/beer_api_service.dart b/lib/services/beer_api_service.dart
index a19586a5..ae83e3ef 100644
--- a/lib/services/beer_api_service.dart
+++ b/lib/services/beer_api_service.dart
@@ -52,7 +52,6 @@ class BeerApiService {
         try {
           return await fetchDrinks(festival, beverageType);
         } catch (e) {
-          // Track the error for this beverage type
           errors[beverageType] = e.toString();
           return <Drink>[];
         }
diff --git a/lib/widgets/festival_menu_sheets.dart b/lib/widgets/festival_menu_sheets.dart
index 246fb3a3..ddafc4db 100644
--- a/lib/widgets/festival_menu_sheets.dart
+++ b/lib/widgets/festival_menu_sheets.dart
@@ -8,10 +8,21 @@ import '../utils/utils.dart';
 /// Shows the festival browser/selector as a modal bottom sheet
 void showFestivalBrowser(BuildContext context) {
   final provider = context.read<BeerProvider>();
+  // Capture current route before opening modal — GoRouterState must not be
+  // accessed inside an onTap handler (gesture callbacks are not build phase).
+  String? currentPath;
+  try {
+    currentPath = GoRouterState.of(context).uri.path;
+  } catch (_) {
+    // GoRouterState unavailable (e.g., in tests)
+  }
   showModalBottomSheet(
     context: context,
     isScrollControlled: true,
-    builder: (context) => FestivalSelectorSheet(provider: provider),
+    builder: (context) => FestivalSelectorSheet(
+      provider: provider,
+      currentPath: currentPath,
+    ),
   );
 }
 
@@ -27,8 +38,13 @@ void showSettingsSheet(BuildContext context) {
 /// Festival selector sheet for browsing all festivals
 class FestivalSelectorSheet extends StatelessWidget {
   final BeerProvider provider;
+  final String? currentPath;
 
-  const FestivalSelectorSheet({required this.provider, super.key});
+  const FestivalSelectorSheet({
+    required this.provider,
+    this.currentPath,
+    super.key,
+  });
 
   String _getStatusLabel(FestivalStatus status) {
     switch (status) {
@@ -185,20 +201,14 @@ class FestivalSelectorSheet extends StatelessWidget {
                           sortedFestivals: festivals,
                           isSelected: isSelected,
                           onTap: () {
-                            // Capture current path first, before any state changes
-                            // Default to festival home; override if currently on favorites
+                            // Preserve user's tab: if on favorites, stay on favorites.
+                            // currentPath was captured before the modal opened to avoid
+                            // calling GoRouterState.of() inside a gesture callback,
+                            // which can cause a freeze during active widget rebuilds.
                             String targetPath = buildFestivalHome(festival.id);
-                            try {
-                              final currentPath = GoRouterState.of(context).uri.path;
-                              // Preserve user's tab: if on favorites, stay on favorites
-                              if (currentPath.endsWith('/favorites')) {
-                                targetPath = buildFavoritesPath(festival.id);
-                              }
-                            } catch (e) {
-                              // GoRouterState unavailable (e.g., in tests), keep default path
-                              debugPrint('Festival selector: Unable to get current route, using default: $e');
+                            if (currentPath?.endsWith('/favorites') == true) {
+                              targetPath = buildFavoritesPath(festival.id);
                             }
-                            
                             final router = GoRouter.maybeOf(context);
                             provider.setFestival(festival);
                             Navigator.pop(context);