refill hearts like Duolingo: one every 5 hours, all of them after 24

Each heart used to take 24 hours, so a student who lost all five waited up to
five days. Now one heart returns every 5 hours, and 24 hours after the first
heart was lost they all come back at once (the owner's call). /api/user/hearts
reports both times (nextRefillAt, fullRefillAt); an existing timer longer than
5 hours is shortened the first time it is read.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

progress/tests_live_gamification.py

@@ -129,3 +129,64 @@ class SummaryShowsTheActivePlanTests(TestCase):
         Subscription.objects.create(user_id=user.id, plan=plan, status='active')
 
         self.assertEqual(self.client.get('/api/user/summary', **auth).json()['subscription'], 'طلایی')
+
+
+class HeartsLikeDuolingoTests(TestCase):
+    """هر ۵ ساعت یک قلب؛ ۲۴ ساعت بعد از اولین قلبِ ازدست‌رفته، همه پر."""
+
+    def _hearts_after_losing(self, n):
+        from progress.models import UserHearts
+        h = UserHearts.objects.create(user_id=1)
+        for _ in range(n):
+            h.lose_heart()
+        h.save()
+        return h
+
+    def _at(self, hours):
+        from django.utils import timezone
+        from datetime import timedelta
+        return mock.patch('django.utils.timezone.now', return_value=timezone.now() + timedelta(hours=hours))
+
+    def test_one_heart_comes_back_every_five_hours(self):
+        h = self._hearts_after_losing(5)
+        with self._at(4.9):
+            h.apply_regen()
+            self.assertEqual(h.current_hearts, 0)
+        with self._at(5.1):
+            h.apply_regen()
+            self.assertEqual(h.current_hearts, 1)
+        with self._at(15.1):
+            h.apply_regen()
+            self.assertEqual(h.current_hearts, 3)
+
+    def test_everything_refills_24_hours_after_the_first_loss(self):
+        h = self._hearts_after_losing(5)
+        with self._at(24.1):
+            h.apply_regen()
+        self.assertEqual(h.current_hearts, 5)
+        self.assertIsNone(h.next_refill_at)
+        self.assertIsNone(h.full_refill_at)
+
+    def test_an_old_24_hour_timer_is_shortened_to_five(self):
+        from datetime import timedelta
+        from django.utils import timezone
+        from progress.models import UserHearts
+        h = UserHearts.objects.create(
+            user_id=2, current_hearts=2, next_refill_at=timezone.now() + timedelta(hours=23),
+        )
+        h.apply_regen()
+        self.assertLessEqual(h.next_refill_at, timezone.now() + timedelta(hours=5, seconds=1))
+        self.assertIsNotNone(h.full_refill_at)
+
+    def test_api_reports_both_timers(self):
+        user = User.objects.create(phone='09120000033')
+        from progress.models import UserHearts
+        h = UserHearts.objects.create(user_id=user.id)
+        h.lose_heart()
+        h.save()
+        body = self.client.get(
+            '/api/user/hearts', HTTP_AUTHORIZATION=f'Bearer {issue_access_token(user.id)}',
+        ).json()
+        self.assertEqual(body['currentHearts'], 4)
+        self.assertIsNotNone(body['nextRefillAt'])
+        self.assertIsNotNone(body['fullRefillAt'])