refactor: clear five low-priority backlog issues (#539)

* refactor(models): format festival dates with intl and give Festival value equality

formattedDates carried its own month-name table alongside three range
branches, while intl was already a dependency used by three screens.
DateFormat replaces the table; output is byte-identical for every
existing case.

The cross-month branch printed the start year on both ends, so a
festival spanning New Year reported the wrong year on its end date.
The end date now carries its own year.

Festival also had no == or hashCode while Drink, Product and Producer
all implement identity-by-id, so two instances of the same festival
parsed from cache and from the network compared unequal in any
collection operation. Adds id-based equality with the same empty-id
identity fallback Producer uses.

Fixes #532
Fixes #529

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ER7MeRfgMqxnaKBGDaSRWy

* refactor(widgets): make AvailabilityStatus switches exhaustiveness-checked

Both switches over AvailabilityStatus in drink_card.dart were C-style
switch statements, which are not exhaustiveness-checked. The semantic
label switch had no safety net at all: a seventh enum value would fall
through and silently omit availability from the screen-reader label.

#349 established that the festival status_text vocabulary is not stable
across festivals, so a new status value is a realistic event.

Both are now switch expressions with no wildcard arm, so a new enum
value is a compile error. Verified by adding a seventh value and
confirming non_exhaustive_switch_expression fires at both sites.
Output is unchanged.

Fixes #534

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ER7MeRfgMqxnaKBGDaSRWy

* refactor(ui): extract a shared drink-count pluralisation helper

The 'count == 1 ? drink : drinks' ternary was inlined at four call
sites, past the extract-a-helper threshold in AGENTS.md. The failure
mode is silent and accessibility-facing: a new label that forgets the
ternary announces "1 drinks" to a screen reader and nothing fails. Two
of the four sites had exactly that bug until review caught it in #506.

Adds StringFormattingHelper.drinkCountLabel and routes all four sites
through it. Labels are unchanged.

Fixes #513

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ER7MeRfgMqxnaKBGDaSRWy

* refactor(widgets): read sheet height with MediaQuery.sizeOf

Five bottom-sheet builders capped their height with
MediaQuery.of(context).size.height, which subscribes the sheet to every
MediaQuery change — keyboard insets, text scale, brightness, padding —
not just size. For a bottom sheet the keyboard case is the one that
actually fires.

MediaQuery.sizeOf establishes a dependency on size alone. The value
read is identical, so there is no behaviour change.

Fixes #531

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ER7MeRfgMqxnaKBGDaSRWy

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: richardthe3rd

lib/models/festival.dart

@@ -1,3 +1,5 @@
+import 'package:intl/intl.dart';
+
 /// Status of a festival based on dates
 enum FestivalStatus {
   /// Festival is currently running (between start and end dates)
@@ -115,37 +117,45 @@ class Festival {
   }
 
   /// Format the festival dates for display
+  ///
+  /// A single day reads `May 18, 2026`; a range inside one month collapses to
+  /// `May 18-23, 2026`; a range crossing a month boundary names both months as
+  /// `Dec 30 - Jan 2, 2026`.
   String get formattedDates {
     if (startDate == null) return '';
     final start = startDate!;
     final end = endDate;
 
-    final months = [
-      'Jan',
-      'Feb',
-      'Mar',
-      'Apr',
-      'May',
-      'Jun',
-      'Jul',
-      'Aug',
-      'Sep',
-      'Oct',
-      'Nov',
-      'Dec',
-    ];
+    final dayMonth = DateFormat('MMM d');
+    final dayMonthYear = DateFormat('MMM d, y');
 
     if (end == null) {
-      return '${months[start.month - 1]} ${start.day}, ${start.year}';
+      return dayMonthYear.format(start);
     }
 
     if (start.month == end.month && start.year == end.year) {
-      return '${months[start.month - 1]} ${start.day}-${end.day}, ${start.year}';
+      return '${dayMonth.format(start)}-${end.day}, ${start.year}';
     }
 
-    return '${months[start.month - 1]} ${start.day} - ${months[end.month - 1]} ${end.day}, ${start.year}';
+    // The end date carries its own year so a festival spanning New Year does
+    // not report both ends under the start year.
+    return '${dayMonth.format(start)} - ${dayMonthYear.format(end)}';
+  }
+
+  /// Festivals are identified by [id] — a festival read from cache and the same
+  /// festival read from the network are the same festival.
+  ///
+  /// An empty [id] falls back to identity, matching [Producer] and [Product]:
+  /// an unidentifiable festival must not collapse into every other one.
+  @override
+  bool operator ==(Object other) {
+    if (id.isEmpty) return identical(this, other);
+    return other is Festival && other.id == id;
   }
 
+  @override
+  int get hashCode => id.isEmpty ? identityHashCode(this) : id.hashCode;
+
   /// Check if the festival is currently live (between start and end dates)
   bool isLive([DateTime? now]) {
     if (startDate == null) return false;

lib/screens/my_festival_screen.dart

@@ -220,7 +220,7 @@ class _MyFestivalScreenState extends State<MyFestivalScreen> {
   Widget _buildSectionHeader(BuildContext context, String title, int count) {
     return Semantics(
       header: true,
-      label: '$title section, $count ${count == 1 ? 'drink' : 'drinks'}',
+      label: '$title section, ${StringFormattingHelper.drinkCountLabel(count)}',
       child: Padding(
         padding: const EdgeInsets.fromLTRB(16, 16, 16, 8),
         // Use the theme's titleLarge (the app's Playfair "poster" voice) rather

lib/utils/string_formatting_helper.dart

@@ -14,4 +14,14 @@ class StringFormattingHelper {
     if (text.isEmpty) return text;
     return text[0].toUpperCase() + text.substring(1);
   }
+
+  /// Format a drink count with the correctly pluralised noun.
+  ///
+  /// Used in screen-reader labels, where an inlined `count == 1 ? ... : ...`
+  /// ternary has twice been forgotten and announced '1 drinks' (#506, #513).
+  ///
+  /// Example: 0 -> '0 drinks', 1 -> '1 drink', 2 -> '2 drinks'
+  static String drinkCountLabel(int count) {
+    return '$count ${count == 1 ? 'drink' : 'drinks'}';
+  }
 }

lib/widgets/drink_card.dart

@@ -159,26 +159,18 @@ class DrinkCard extends StatelessWidget {
       buffer.write(', ${drink.breweryLocation}');
     }
     if (drink.availabilityStatus != null) {
-      switch (drink.availabilityStatus!) {
-        case AvailabilityStatus.plenty:
-          buffer.write(', Available');
-          break;
-        case AvailabilityStatus.good:
-          buffer.write(', Some remaining');
-          break;
-        case AvailabilityStatus.low:
-          buffer.write(', Low availability');
-          break;
-        case AvailabilityStatus.veryLow:
-          buffer.write(', Very low availability');
-          break;
-        case AvailabilityStatus.out:
-          buffer.write(', Sold out');
-          break;
-        case AvailabilityStatus.unknown:
-          buffer.write(', ${drink.statusText ?? 'Unknown availability'}');
-          break;
-      }
+      // Switch *expression*, deliberately without a wildcard arm: a new
+      // AvailabilityStatus value must break the build here rather than
+      // silently drop availability from the screen-reader label (#534).
+      buffer.write(switch (drink.availabilityStatus!) {
+        AvailabilityStatus.plenty => ', Available',
+        AvailabilityStatus.good => ', Some remaining',
+        AvailabilityStatus.low => ', Low availability',
+        AvailabilityStatus.veryLow => ', Very low availability',
+        AvailabilityStatus.out => ', Sold out',
+        AvailabilityStatus.unknown =>
+          ', ${drink.statusText ?? 'Unknown availability'}',
+      });
     }
     if (drink.rating != null) {
       buffer.write(', Rated ${drink.rating} out of 5 stars');
@@ -274,35 +266,15 @@ class _AvailabilityChip extends StatelessWidget {
       status,
       theme.colorScheme,
     );
-    String label;
-    IconData icon;
-
-    switch (status) {
-      case AvailabilityStatus.plenty:
-        label = 'Available';
-        icon = Icons.check_circle;
-        break;
-      case AvailabilityStatus.good:
-        label = 'Some Left';
-        icon = Icons.check_circle_outline;
-        break;
-      case AvailabilityStatus.low:
-        label = 'Low';
-        icon = Icons.warning;
-        break;
-      case AvailabilityStatus.veryLow:
-        label = 'Nearly Gone';
-        icon = Icons.warning_amber;
-        break;
-      case AvailabilityStatus.out:
-        label = 'Sold Out';
-        icon = Icons.cancel;
-        break;
-      case AvailabilityStatus.unknown:
-        label = rawText ?? 'Unknown';
-        icon = Icons.info_outline;
-        break;
-    }
+    // Switch *expression*, deliberately without a wildcard arm — see #534.
+    final (label, icon) = switch (status) {
+      AvailabilityStatus.plenty => ('Available', Icons.check_circle),
+      AvailabilityStatus.good => ('Some Left', Icons.check_circle_outline),
+      AvailabilityStatus.low => ('Low', Icons.warning),
+      AvailabilityStatus.veryLow => ('Nearly Gone', Icons.warning_amber),
+      AvailabilityStatus.out => ('Sold Out', Icons.cancel),
+      AvailabilityStatus.unknown => (rawText ?? 'Unknown', Icons.info_outline),
+    };
 
     return Container(
       padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),

lib/widgets/drink_filter_sheets.dart

@@ -49,7 +49,7 @@ class CategoryFilterSheet extends StatelessWidget {
         return Container(
           padding: const EdgeInsets.all(16),
           constraints: BoxConstraints(
-            maxHeight: MediaQuery.of(context).size.height * 0.7,
+            maxHeight: MediaQuery.sizeOf(context).height * 0.7,
           ),
           child: Column(
             mainAxisSize: MainAxisSize.min,
@@ -113,8 +113,8 @@ class CategoryFilterSheet extends StatelessWidget {
                         );
                         return Semantics(
                           label:
-                              'Filter by $formattedCategory, $count '
-                              '${count == 1 ? 'drink' : 'drinks'}',
+                              'Filter by $formattedCategory, '
+                              '${StringFormattingHelper.drinkCountLabel(count)}',
                           value: isSelected ? 'Selected' : 'Not selected',
                           selected: isSelected,
                           button: true,
@@ -156,7 +156,7 @@ class SortOptionsSheet extends StatelessWidget {
     return Container(
       padding: const EdgeInsets.all(16),
       constraints: BoxConstraints(
-        maxHeight: MediaQuery.of(context).size.height * 0.7,
+        maxHeight: MediaQuery.sizeOf(context).height * 0.7,
       ),
       child: Column(
         mainAxisSize: MainAxisSize.min,
@@ -233,7 +233,7 @@ class StyleFilterSheet extends StatelessWidget {
         return Container(
           padding: const EdgeInsets.all(16),
           constraints: BoxConstraints(
-            maxHeight: MediaQuery.of(context).size.height * 0.7,
+            maxHeight: MediaQuery.sizeOf(context).height * 0.7,
           ),
           child: Column(
             mainAxisSize: MainAxisSize.min,
@@ -337,8 +337,8 @@ class StyleFilterSheet extends StatelessWidget {
                           final isSelected = selectedStyles.contains(style);
                           return Semantics(
                             label:
-                                'Filter by $style, $count '
-                                '${count == 1 ? 'drink' : 'drinks'}',
+                                'Filter by $style, '
+                                '${StringFormattingHelper.drinkCountLabel(count)}',
                             value: isSelected ? 'Selected' : 'Not selected',
                             selected: isSelected,
                             button: true,
@@ -382,7 +382,7 @@ class VisibilityFilterSheet extends StatelessWidget {
         return Container(
           padding: const EdgeInsets.all(16),
           constraints: BoxConstraints(
-            maxHeight: MediaQuery.of(context).size.height * 0.7,
+            maxHeight: MediaQuery.sizeOf(context).height * 0.7,
           ),
           child: Column(
             mainAxisSize: MainAxisSize.min,

lib/widgets/festival_header.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import '../models/models.dart';
 import '../providers/providers.dart';
+import '../utils/utils.dart';
 
 /// App-bar title for the drinks screen: app icon, current festival name, the
 /// drink count, and a coloured status badge.
@@ -17,8 +18,7 @@ class FestivalHeader extends StatelessWidget {
       provider.sortedFestivals,
     );
     final drinkCount = provider.drinks.length;
-    final drinkCountLabel =
-        '$drinkCount ${drinkCount == 1 ? 'drink' : 'drinks'}';
+    final drinkCountLabel = StringFormattingHelper.drinkCountLabel(drinkCount);
 
     // Fold the status into the label and exclude child semantics so screen
     // readers announce one coherent phrase instead of the name, count, and

lib/widgets/festival_menu_sheets.dart

@@ -85,7 +85,7 @@ class FestivalSelectorSheet extends StatelessWidget {
     return Container(
       padding: const EdgeInsets.all(16),
       constraints: BoxConstraints(
-        maxHeight: MediaQuery.of(context).size.height * 0.7,
+        maxHeight: MediaQuery.sizeOf(context).height * 0.7,
       ),
       child: Column(
         mainAxisSize: MainAxisSize.min,

test/models_test.dart

@@ -1424,6 +1424,61 @@ void main() {
           expect(festival.formattedDates, contains(months[i]));
         }
       });
+
+      test('carries both years for a range spanning New Year', () {
+        final festival = Festival(
+          id: 'cbfw2025',
+          name: 'Cambridge Winter Beer Festival',
+          startDate: DateTime(2025, 12, 30),
+          endDate: DateTime(2026, 1, 2),
+          dataBaseUrl: 'https://example.com/cbfw2025',
+        );
+
+        expect(festival.formattedDates, 'Dec 30 - Jan 2, 2026');
+      });
+    });
+
+    group('equality', () {
+      const json = {
+        'id': 'cbf2025',
+        'name': 'Cambridge Beer Festival 2025',
+        'data_base_url': 'https://example.com/cbf2025',
+      };
+
+      test('two instances parsed from the same JSON are equal', () {
+        final a = Festival.fromJson(Map<String, dynamic>.from(json));
+        final b = Festival.fromJson(Map<String, dynamic>.from(json));
+
+        expect(a, equals(b));
+        expect(a.hashCode, equals(b.hashCode));
+      });
+
+      test('a Set de-duplicates instances with the same id', () {
+        final cached = Festival.fromJson(Map<String, dynamic>.from(json));
+        final fromNetwork = Festival.fromJson(Map<String, dynamic>.from(json));
+
+        expect({cached, fromNetwork}, hasLength(1));
+      });
+
+      test('festivals with different ids are not equal', () {
+        final a = Festival.fromJson(Map<String, dynamic>.from(json));
+        final b = Festival.fromJson({...json, 'id': 'cbf2026'});
+
+        expect(a, isNot(equals(b)));
+      });
+
+      test('an empty id falls back to identity', () {
+        // Built via fromJson so the two instances are distinct objects — a
+        // const literal pair would be canonicalised to the same instance and
+        // could not distinguish identity equality from id equality.
+        final emptyIdJson = <String, dynamic>{...json, 'id': ''};
+        final a = Festival.fromJson(Map<String, dynamic>.from(emptyIdJson));
+        final b = Festival.fromJson(Map<String, dynamic>.from(emptyIdJson));
+
+        expect(a, equals(a));
+        expect(a, isNot(equals(b)));
+        expect({a, b}, hasLength(2));
+      });
     });
 
     group('fromJson', () {

test/string_formatting_helper_test.dart

@@ -28,5 +28,20 @@ void main() {
         expect(StringFormattingHelper.capitalizeFirst('a'), 'A');
       });
     });
+
+    group('drinkCountLabel', () {
+      test('pluralises zero', () {
+        expect(StringFormattingHelper.drinkCountLabel(0), '0 drinks');
+      });
+
+      test('uses the singular for exactly one', () {
+        expect(StringFormattingHelper.drinkCountLabel(1), '1 drink');
+      });
+
+      test('pluralises counts above one', () {
+        expect(StringFormattingHelper.drinkCountLabel(2), '2 drinks');
+        expect(StringFormattingHelper.drinkCountLabel(147), '147 drinks');
+      });
+    });
   });
 }