fix(exercice): score par défaut à 0 et affichage des répétitions en séance (tickets #44, #45)

Autorise un score par défaut à 0 (#44) et corrige l'affichage des
répétitions à 0 pendant l'exécution au lieu de la vraie cible (#45),
sur exercise_library_screen.dart et workout_execution_screen.dart,
avec les ajustements domain/use cases associés. flutter analyze
propre (mêmes 8 infos préexistantes), 79/79 tests verts, build APK
debug validé.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/application/use_cases.dart

@@ -1646,8 +1646,8 @@ void _validateExerciseDefaultTargets({
   }
   if (hasScoreMeasure &&
       scoreInputMode == ScoreInputMode.manual &&
-      (defaultTargetScore == null || defaultTargetScore <= 0)) {
-    throw const DomainException('Default target score must be positive.');
+      (defaultTargetScore == null || defaultTargetScore < 0)) {
+    throw const DomainException('Default target score must not be negative.');
   }
   if (defaultTargetScore != null &&
       (!hasScoreMeasure || scoreInputMode != ScoreInputMode.manual)) {

lib/domain/entities.dart

@@ -167,7 +167,10 @@ final class Exercise {
       'Default target time seconds',
     );
     _requireNullablePositive(defaultTargetReps, 'Default target reps');
-    _requireNullablePositiveDouble(defaultTargetScore, 'Default target score');
+    _requireNullableNonNegativeDouble(
+      defaultTargetScore,
+      'Default target score',
+    );
     _requireNullablePositive(
       defaultTargetScoreTimeMs,
       'Default target score time ms',
@@ -1035,12 +1038,6 @@ void _requireNullableNonNegativeDouble(double? value, String label) {
   }
 }
 
-void _requireNullablePositiveDouble(double? value, String label) {
-  if (value != null && value <= 0) {
-    throw DomainException('$label must be positive.');
-  }
-}
-
 void _requireScoreTargetShape({
   required bool scoreEnabled,
   required ScoreInputMode scoreInputMode,

lib/presentation/exercise_library_screen.dart

@@ -635,9 +635,9 @@ final class _ExerciseFormScreenState extends State<ExerciseFormScreen> {
                         _scoreInputMode != ScoreInputMode.manual) {
                       return null;
                     }
-                    return _positiveDoubleValidator(
+                    return _nonNegativeDoubleValidator(
                       value,
-                      'Saisis un score supérieur à 0.',
+                      'Saisis un score positif ou nul.',
                     );
                   },
                 ),
@@ -914,6 +914,14 @@ final class _ExerciseFormScreenState extends State<ExerciseFormScreen> {
     return null;
   }
 
+  String? _nonNegativeDoubleValidator(String? value, String message) {
+    final number = double.tryParse(value?.trim() ?? '');
+    if (number == null || number < 0) {
+      return message;
+    }
+    return null;
+  }
+
   String _optionalIntText(int? value) {
     return value == null ? '' : '$value';
   }

lib/presentation/workout_execution_screen.dart

@@ -72,6 +72,7 @@ final class _WorkoutExecutionScreenState extends State<WorkoutExecutionScreen> {
     _mode = _session.status == ActiveWorkoutStatus.running
         ? WorkoutExecutionMode.active
         : WorkoutExecutionMode.paused;
+    _reps = _initialRepsFor(_exercise);
     _seriesStartedAt = DateTime.now().toUtc();
     _ticker = Timer.periodic(const Duration(seconds: 1), (_) {
       if (mounted) setState(() {});
@@ -808,7 +809,7 @@ final class _WorkoutExecutionScreenState extends State<WorkoutExecutionScreen> {
 
   Future<void> _moveTo(ExecutionPosition position) async {
     _scoreController.clear();
-    _reps = 0;
+    _reps = _initialRepsFor(_plan.exerciseAt(position));
     _activeRestStateId = null;
     _scoreStopwatch = null;
     _manualScoreTimeMs = null;
@@ -889,6 +890,11 @@ final class _WorkoutExecutionScreenState extends State<WorkoutExecutionScreen> {
       ),
     );
   }
+
+  int _initialRepsFor(ExecutionExercise exercise) {
+    if (!exercise.repsEnabled) return 0;
+    return exercise.targetReps ?? 0;
+  }
 }
 
 final class SetMeasureInput extends StatelessWidget {

test/application/use_cases_test.dart

@@ -55,7 +55,7 @@ void main() {
     },
   );
 
-  test('Exercise use case rejects non-positive default targets', () async {
+  test('Exercise use case rejects invalid default targets', () async {
     final useCase = _exerciseUseCase(_FakeExerciseRepository());
 
     await expectLater(
@@ -86,12 +86,33 @@ void main() {
         hasScoreMeasure: true,
         scoreLabel: 'Charge',
         scoreUnit: 'kg',
-        defaultTargetScore: 0,
+        defaultTargetScore: -1,
       ),
       throwsA(isA<DomainException>()),
     );
   });
 
+  test(
+    'Exercise use case accepts a zero manual score default target',
+    () async {
+      final repository = _FakeExerciseRepository();
+      final useCase = _exerciseUseCase(repository);
+
+      final exercise = await useCase.create(
+        name: 'Charge',
+        hasTimeMeasure: false,
+        hasRepsMeasure: false,
+        hasScoreMeasure: true,
+        scoreLabel: 'Charge',
+        scoreUnit: 'kg',
+        defaultTargetScore: 0,
+      );
+
+      expect(exercise.defaultTargetScore, 0);
+      expect(repository.saved.single.defaultTargetScore, 0);
+    },
+  );
+
   test(
     'Exercise use case accepts stopwatch score without default target',
     () async {

test/presentation/workout_execution_screen_test.dart

@@ -43,6 +43,42 @@ void main() {
     expect(find.text('00:45'), findsOneWidget);
   });
 
+  testWidgets('les répétitions sont initialisées avec la cible', (
+    tester,
+  ) async {
+    final clock = _FakeClock(DateTime.utc(2026, 7, 17, 12));
+    final session = ActiveWorkoutSession(
+      metadata: _metadata('session-1'),
+      sourceWorkoutTemplateId: 'template-1',
+      status: ActiveWorkoutStatus.running,
+      startedAt: DateTime.utc(2026, 7, 17, 12),
+      lastPersistedAt: DateTime.utc(2026, 7, 17, 12),
+      elapsedActiveMs: 0,
+      currentProgramIndex: 0,
+      currentExerciseIndex: 0,
+      currentSetIndex: 0,
+      resolvedTemplateSnapshotJson: _sessionSnapshot(targetReps: 8),
+    );
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: WorkoutExecutionScreen(
+          initialSession: session,
+          activeUseCases: _activeUseCases(
+            _FakeActiveSessionRepository(),
+            clock,
+          ),
+          closeUseCase: _closeUseCase(_FakeActiveSessionRepository(), clock),
+          historyUseCases: _historyUseCases(clock),
+          workoutTemplateUseCases: _workoutTemplateUseCases(),
+        ),
+      ),
+    );
+
+    expect(find.text('Répétitions'), findsOneWidget);
+    expect(find.text('8'), findsOneWidget);
+  });
+
   testWidgets('les mesures cumulées respectent la hiérarchie visuelle', (
     tester,
   ) async {
@@ -618,8 +654,8 @@ void main() {
       expect(find.text('2 / 3'), findsOneWidget);
       expect(find.text('30 s'), findsOneWidget);
 
-      for (var i = 0; i < 3; i++) {
-        await tester.tap(find.byIcon(Icons.add));
+      for (var i = 0; i < 2; i++) {
+        await tester.tap(find.byIcon(Icons.remove));
         await tester.pump();
       }
       await tester.enterText(
@@ -637,6 +673,7 @@ void main() {
       expect(repository.session?.currentSetIndex, 2);
       expect(find.text('Programme 1/1 · Exercice 1/1'), findsOneWidget);
       expect(find.text('3 / 3'), findsOneWidget);
+      expect(find.text('5'), findsOneWidget);
     },
   );