fix(app): repair Dart constant initialization

.github/workflows/format-fix.yml

@@ -0,0 +1,49 @@
+name: Format Fix
+
+on:
+  push:
+    branches:
+      - chatgpt/unitflow-dart-fixes-20260819
+
+permissions:
+  contents: write
+
+jobs:
+  format:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout branch
+        uses: actions/checkout@v4
+        with:
+          ref: chatgpt/unitflow-dart-fixes-20260819
+          fetch-depth: 0
+
+      - name: Install Rust formatter
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt
+
+      - name: Install Flutter
+        uses: subosito/flutter-action@v2
+        with:
+          channel: stable
+          cache: true
+
+      - name: Format Rust
+        run: cargo fmt --all
+
+      - name: Format Flutter sources and tests
+        run: dart format apps/unitflow_app/lib apps/unitflow_app/test
+
+      - name: Commit formatter output
+        shell: bash
+        run: |
+          if git diff --quiet; then
+            echo "No formatter changes required."
+            exit 0
+          fi
+          git config user.name "Sanskar"
+          git config user.email "sanskarin@outlook.in"
+          git add -A
+          git commit -m "style: apply automated formatters"
+          git push origin HEAD:chatgpt/unitflow-dart-fixes-20260819

apps/unitflow_app/lib/app/app_controller.dart

@@ -7,7 +7,8 @@ import '../features/converter/domain/conversion_engine.dart';
 import '../features/converter/domain/unit_models.dart';
 
 final class AppController extends ChangeNotifier {
-  AppController({required UserStateRepository repository}) : _repository = repository;
+  AppController({required UserStateRepository repository})
+    : _repository = repository;
 
   final UserStateRepository _repository;
   UserState _state = UserState();
@@ -76,7 +77,10 @@ final class AppController extends ChangeNotifier {
   Future<void> togglePinnedPair(PinnedPair pair) {
     final from = _engine.catalog.byId(pair.fromUnitId);
     final to = _engine.catalog.byId(pair.toUnitId);
-    if (from == null || to == null || from.category != pair.category || to.category != pair.category) {
+    if (from == null ||
+        to == null ||
+        from.category != pair.category ||
+        to.category != pair.category) {
       throw ArgumentError('Pinned pair references invalid units.');
     }
     final next = _state.pinnedPairs.toList();
@@ -127,7 +131,11 @@ final class AppController extends ChangeNotifier {
   Future<void> addCustomUnit(CustomUnitData customUnit) {
     final definition = customUnit.toUnitDefinition();
     if (_engine.catalog.byId(definition.id) != null) {
-      throw ArgumentError.value(definition.id, 'id', 'unit identifier already exists');
+      throw ArgumentError.value(
+        definition.id,
+        'id',
+        'unit identifier already exists',
+      );
     }
     final next = <CustomUnitData>[..._state.customUnits, customUnit];
     final newState = _state.copyWith(customUnits: next);
@@ -140,8 +148,12 @@ final class AppController extends ChangeNotifier {
     if (existing.isEmpty) {
       return Future<void>.value();
     }
-    final nextCustom = _state.customUnits.where((item) => item.id != id).toList();
-    final nextFavorites = _state.favoriteUnitIds.where((item) => item != id).toSet();
+    final nextCustom = _state.customUnits
+        .where((item) => item.id != id)
+        .toList();
+    final nextFavorites = _state.favoriteUnitIds
+        .where((item) => item != id)
+        .toSet();
     final nextPins = _state.pinnedPairs
         .where((pair) => pair.fromUnitId != id && pair.toUnitId != id)
         .toList();

apps/unitflow_app/lib/app/app_shell.dart

@@ -36,12 +36,18 @@ final class _AppShellState extends State<AppShell> {
     animation: widget.appController,
     builder: (context, _) => CallbackShortcuts(
       bindings: <ShortcutActivator, VoidCallback>{
-        const SingleActivator(LogicalKeyboardKey.digit1, control: true): () => _select(0),
-        const SingleActivator(LogicalKeyboardKey.digit2, control: true): () => _select(1),
-        const SingleActivator(LogicalKeyboardKey.comma, control: true): () => _select(2),
-        const SingleActivator(LogicalKeyboardKey.digit1, meta: true): () => _select(0),
-        const SingleActivator(LogicalKeyboardKey.digit2, meta: true): () => _select(1),
-        const SingleActivator(LogicalKeyboardKey.comma, meta: true): () => _select(2),
+        const SingleActivator(LogicalKeyboardKey.digit1, control: true): () =>
+            _select(0),
+        const SingleActivator(LogicalKeyboardKey.digit2, control: true): () =>
+            _select(1),
+        const SingleActivator(LogicalKeyboardKey.comma, control: true): () =>
+            _select(2),
+        const SingleActivator(LogicalKeyboardKey.digit1, meta: true): () =>
+            _select(0),
+        const SingleActivator(LogicalKeyboardKey.digit2, meta: true): () =>
+            _select(1),
+        const SingleActivator(LogicalKeyboardKey.comma, meta: true): () =>
+            _select(2),
       },
       child: Focus(
         autofocus: true,
@@ -54,7 +60,10 @@ final class _AppShellState extends State<AppShell> {
                 title: Row(
                   mainAxisSize: MainAxisSize.min,
                   children: <Widget>[
-                    Icon(Icons.swap_calls, color: Theme.of(context).colorScheme.primary),
+                    Icon(
+                      Icons.swap_calls,
+                      color: Theme.of(context).colorScheme.primary,
+                    ),
                     const SizedBox(width: AppSpacing.xs),
                     const Text('UnitFlow'),
                   ],
@@ -149,10 +158,7 @@ final class _AppShellState extends State<AppShell> {
     index: _selectedIndex,
     children: <Widget>[
       ConverterScreen(controller: _converterController),
-      LibraryScreen(
-        appController: widget.appController,
-        onOpenPair: _openPair,
-      ),
+      LibraryScreen(appController: widget.appController, onOpenPair: _openPair),
       SettingsScreen(
         appController: widget.appController,
         onOpenAbout: _openAbout,
@@ -173,6 +179,8 @@ final class _AppShellState extends State<AppShell> {
   }
 
   Future<void> _openAbout() => Navigator.of(context).push<void>(
-    MaterialPageRoute<void>(builder: (_) => const Scaffold(body: SafeArea(child: AboutScreen()))),
+    MaterialPageRoute<void>(
+      builder: (_) => const Scaffold(body: SafeArea(child: AboutScreen())),
+    ),
   );
 }

apps/unitflow_app/lib/app/theme/app_theme.dart

@@ -29,7 +29,10 @@ abstract final class AppTheme {
   static ThemeData dark() => _build(Brightness.dark);
 
   static ThemeData _build(Brightness brightness) {
-    final colors = ColorScheme.fromSeed(seedColor: _seed, brightness: brightness);
+    final colors = ColorScheme.fromSeed(
+      seedColor: _seed,
+      brightness: brightness,
+    );
     final base = ThemeData(
       useMaterial3: true,
       brightness: brightness,
@@ -80,7 +83,9 @@ abstract final class AppTheme {
       ),
       tooltipTheme: TooltipThemeData(
         waitDuration: const Duration(milliseconds: 450),
-        textStyle: base.textTheme.bodySmall?.copyWith(color: colors.onInverseSurface),
+        textStyle: base.textTheme.bodySmall?.copyWith(
+          color: colors.onInverseSurface,
+        ),
       ),
     );
   }

apps/unitflow_app/lib/core/format/decimal_format.dart

@@ -69,20 +69,26 @@ final class DecimalDisplayFormatter {
       whole = chunks.join(symbols.GROUP_SEP);
     }
 
-    final fraction = parts.length == 2 ? '${symbols.DECIMAL_SEP}${parts[1]}' : '';
+    final fraction = parts.length == 2
+        ? '${symbols.DECIMAL_SEP}${parts[1]}'
+        : '';
     return '${negative ? '-' : ''}$whole$fraction';
   }
 
   String _localizeMantissa(String formatted, String localeName) {
-    final separator = NumberFormat.decimalPattern(localeName).symbols.DECIMAL_SEP;
+    final separator = NumberFormat.decimalPattern(localeName)
+        .symbols
+        .DECIMAL_SEP;
     if (separator == '.') {
       return formatted;
     }
     final exponentIndex = formatted.indexOf('e');
     if (exponentIndex < 0) {
       return formatted.replaceFirst('.', separator);
     }
-    final mantissa = formatted.substring(0, exponentIndex).replaceFirst('.', separator);
+    final mantissa = formatted
+        .substring(0, exponentIndex)
+        .replaceFirst('.', separator);
     return '$mantissa${formatted.substring(exponentIndex)}';
   }
 

apps/unitflow_app/lib/core/math/exact_decimal.dart

@@ -27,9 +27,8 @@ final class ExactDecimal implements Comparable<ExactDecimal> {
       throw const FormatException('Invalid decimal input');
     }
 
-    final match = RegExp(
-      r'^([+-]?)(\d*)(?:\.(\d*))?(?:[eE]([+-]?\d+))?$',
-    ).firstMatch(input);
+    final match = RegExp(r'^([+-]?)(\d*)(?:\.(\d*))?(?:[eE]([+-]?\d+))?$')
+        .firstMatch(input);
     if (match == null) {
       throw const FormatException('Invalid decimal input');
     }
@@ -61,7 +60,8 @@ final class ExactDecimal implements Comparable<ExactDecimal> {
 
   const ExactDecimal._(this.coefficient, this.scale);
 
-  static const zero = ExactDecimal._(BigInt.zero, 0);
+  /// Canonical zero. `BigInt.zero` is a runtime getter, so this cannot be a Dart `const`.
+  static final ExactDecimal zero = ExactDecimal._(BigInt.zero, 0);
 
   final BigInt coefficient;
   final int scale;

apps/unitflow_app/lib/core/persistence/user_state.dart

@@ -32,11 +32,17 @@ final class RecentConversion {
     final from = value['fromUnitId'];
     final to = value['toUnitId'];
     final created = value['createdAt'];
-    if (input is! String || from is! String || to is! String || created is! String) {
+    if (input is! String ||
+        from is! String ||
+        to is! String ||
+        created is! String) {
       return null;
     }
     final timestamp = DateTime.tryParse(created);
-    if (timestamp == null || from.isEmpty || to.isEmpty || input.length > 1024) {
+    if (timestamp == null ||
+        from.isEmpty ||
+        to.isEmpty ||
+        input.length > 1024) {
       return null;
     }
     return RecentConversion(
@@ -79,15 +85,18 @@ final class CustomUnitData {
     if (symbol.trim().isEmpty || symbol.length > 32) {
       throw const FormatException('Custom unit symbol is invalid.');
     }
-    if (aliases.length > 32 || aliases.any((value) => value.isEmpty || value.length > 64)) {
+    if (aliases.length > 32 ||
+        aliases.any((value) => value.isEmpty || value.length > 64)) {
       throw const FormatException('Custom unit aliases are invalid.');
     }
     if (description.length > 512) {
       throw const FormatException('Custom unit description is too long.');
     }
     final parsedScale = ExactDecimal.parse(scale);
     if (parsedScale.compareTo(ExactDecimal.zero) <= 0) {
-      throw const FormatException('Custom unit scale must be greater than zero.');
+      throw const FormatException(
+        'Custom unit scale must be greater than zero.',
+      );
     }
     return UnitDefinition(
       id: id,
@@ -176,10 +185,18 @@ final class UserState {
     List<PinnedPair>? pinnedPairs,
     List<RecentConversion>? recents,
     List<CustomUnitData>? customUnits,
-  }) : favoriteUnitIds = Set<String>.unmodifiable(favoriteUnitIds ?? <String>{}),
-       pinnedPairs = List<PinnedPair>.unmodifiable(pinnedPairs ?? const <PinnedPair>[]),
-       recents = List<RecentConversion>.unmodifiable(recents ?? const <RecentConversion>[]),
-       customUnits = List<CustomUnitData>.unmodifiable(customUnits ?? const <CustomUnitData>[]);
+  }) : favoriteUnitIds = Set<String>.unmodifiable(
+         favoriteUnitIds ?? <String>{},
+       ),
+       pinnedPairs = List<PinnedPair>.unmodifiable(
+         pinnedPairs ?? const <PinnedPair>[],
+       ),
+       recents = List<RecentConversion>.unmodifiable(
+         recents ?? const <RecentConversion>[],
+       ),
+       customUnits = List<CustomUnitData>.unmodifiable(
+         customUnits ?? const <CustomUnitData>[],
+       );
 
   static const schemaVersion = 1;
 
@@ -223,9 +240,13 @@ final class UserState {
     'useGrouping': useGrouping,
     'onboardingComplete': onboardingComplete,
     'favoriteUnitIds': favoriteUnitIds.toList(growable: false),
-    'pinnedPairs': pinnedPairs.map((pair) => pair.storageValue).toList(growable: false),
+    'pinnedPairs': pinnedPairs
+        .map((pair) => pair.storageValue)
+        .toList(growable: false),
     'recents': recents.map((recent) => recent.toJson()).toList(growable: false),
-    'customUnits': customUnits.map((unit) => unit.toJson()).toList(growable: false),
+    'customUnits': customUnits
+        .map((unit) => unit.toJson())
+        .toList(growable: false),
   };
 
   static UserState fromJson(Map<String, Object?> json) {
@@ -245,8 +266,12 @@ final class UserState {
       throw const FormatException('Invalid UnitFlow preferences.');
     }
 
-    final theme = ThemePreference.values.where((item) => item.name == json['theme']).firstOrNull;
-    final notation = DecimalNotation.values.where((item) => item.name == json['notation']).firstOrNull;
+    final theme = ThemePreference.values
+        .where((item) => item.name == json['theme'])
+        .firstOrNull;
+    final notation = DecimalNotation.values
+        .where((item) => item.name == json['notation'])
+        .firstOrNull;
     if (theme == null || notation == null) {
       throw const FormatException('Invalid UnitFlow appearance settings.');
     }

apps/unitflow_app/lib/core/persistence/user_state_repository.dart

@@ -16,7 +16,8 @@ abstract interface class UserStateRepository {
   UserState importJson(String content);
 }
 
-final class SharedPreferencesUserStateRepository implements UserStateRepository {
+final class SharedPreferencesUserStateRepository
+    implements UserStateRepository {
   SharedPreferencesUserStateRepository({SharedPreferencesAsync? preferences})
     : _preferences = preferences ?? SharedPreferencesAsync();
 
@@ -77,7 +78,8 @@ final class SharedPreferencesUserStateRepository implements UserStateRepository
 }
 
 final class MemoryUserStateRepository implements UserStateRepository {
-  MemoryUserStateRepository([UserState? initial]) : _state = initial ?? UserState();
+  MemoryUserStateRepository([UserState? initial])
+    : _state = initial ?? UserState();
 
   UserState _state;