wip(watch): sauvegarde travail en cours lot critique (#157 #163 #164 #174 #175 #178)

packages/watch_bridge_contract/test/watch_bridge_contract_test.dart

@@ -52,6 +52,55 @@ void main() {
     });
   });
 
+  group('WatchAlertEnvelope', () {
+    test('round-trips every alert kind through JSON', () {
+      for (final kind in WatchAlertKind.values) {
+        final alert = WatchAlertEnvelope(
+          alertId: 'alert-${kind.name}',
+          sessionId: 'session-1',
+          revision: 7,
+          kind: kind,
+          timerKind: WatchTimerKind.step,
+          programIndex: 0,
+          exerciseIndex: 1,
+          setIndex: 2,
+          passageIndex: 3,
+          stepIndex: 4,
+          scheduledForEpochMs: 1710000000700,
+          expiresAtEpochMs: 1710000002700,
+          pattern: kind == WatchAlertKind.countdownTick
+              ? WatchAlertPattern.countdownTick
+              : WatchAlertPattern.timerFinished,
+        );
+
+        final decoded = WatchAlertEnvelope.fromJson(
+          jsonDecode(jsonEncode(alert.toJson())) as Map<String, Object?>,
+        );
+
+        expect(decoded, alert);
+      }
+    });
+
+    test('falls back safely for absent fields', () {
+      final alert = WatchAlertEnvelope.fromJson({});
+
+      expect(alert.schemaVersion, watchBridgeSchemaVersion);
+      expect(alert.alertId, '');
+      expect(alert.sessionId, '');
+      expect(alert.revision, 0);
+      expect(alert.kind, WatchAlertKind.countdownTick);
+      expect(alert.timerKind, WatchTimerKind.step);
+      expect(alert.programIndex, isNull);
+      expect(alert.exerciseIndex, isNull);
+      expect(alert.setIndex, isNull);
+      expect(alert.passageIndex, isNull);
+      expect(alert.stepIndex, isNull);
+      expect(alert.scheduledForEpochMs, 0);
+      expect(alert.expiresAtEpochMs, 0);
+      expect(alert.pattern, WatchAlertPattern.countdownTick);
+    });
+  });
+
   group('WatchSensorSummary', () {
     test('round-trips heart rate summary through JSON', () {
       const summary = WatchSensorSummary(