fix(lobby): avoid orphaned round configs on round start

lobby/tests.py

@@ -308,6 +308,23 @@ class StartRoundTests(TestCase):
         self.assertEqual(response.json()["locale"], "en")
         self.assertEqual(response.json()["error"], "Only host can start round")
 
+    @patch("lobby.views._select_round_question", side_effect=ValueError("no_available_questions"))
+    def test_start_round_does_not_persist_round_config_when_question_selection_fails(self, _mock_select_round_question):
+        self.client.login(username="host", password="secret123")
+
+        response = self.client.post(
+            reverse("lobby:start_round", kwargs={"code": self.session.code}),
+            data={"category_slug": self.category.slug},
+            content_type="application/json",
+        )
+
+        self.assertEqual(response.status_code, 400)
+        self.assertEqual(response.json()["error_code"], "no_available_questions")
+        self.session.refresh_from_db()
+        self.assertEqual(self.session.status, GameSession.Status.LOBBY)
+        self.assertFalse(RoundConfig.objects.filter(session=self.session, number=1).exists())
+        self.assertFalse(RoundQuestion.objects.filter(session=self.session, round_number=1).exists())
+
 
 class LieSubmissionTests(TestCase):
     def setUp(self):
@@ -1329,6 +1346,26 @@ class RevealRoundFlowTests(TestCase):
         self.assertEqual(response.json()["locale"], "da")
         self.assertEqual(response.json()["error"], "Næste runde kan kun starte fra scoreboard-fasen")
 
+    def test_start_next_round_does_not_persist_round_config_when_question_selection_fails(self):
+        self.client.login(username="host_reveal", password="secret123")
+        self.client.get(reverse("lobby:reveal_scoreboard", kwargs={"code": self.session.code}))
+        self.next_question.delete()
+
+        response = self.client.post(
+            reverse(
+                "lobby:start_next_round",
+                kwargs={"code": self.session.code},
+            )
+        )
+
+        self.assertEqual(response.status_code, 400)
+        self.assertEqual(response.json()["error_code"], "no_available_questions")
+        self.session.refresh_from_db()
+        self.assertEqual(self.session.status, GameSession.Status.SCOREBOARD)
+        self.assertEqual(self.session.current_round, 1)
+        self.assertFalse(RoundConfig.objects.filter(session=self.session, number=2).exists())
+        self.assertFalse(RoundQuestion.objects.filter(session=self.session, round_number=2).exists())
+
     def test_reveal_scoreboard_unsupported_locale_falls_back_to_en_deterministically(self):
         self.client.login(username="other_reveal", password="secret123")
 

lobby/views.py

@@ -528,23 +528,25 @@ def start_round(request: HttpRequest, code: str) -> JsonResponse:
                 status=400,
             )
 
-        round_config, created = RoundConfig.objects.get_or_create(
+        if RoundConfig.objects.filter(session=session, number=session.current_round).exists():
-            session=session,
-            number=session.current_round,
-            defaults={"category": category},
-        )
-        if not created:
             return api_error(
                 request,
                 code="round_already_configured",
                 status=409,
             )
 
+        round_config = RoundConfig(
+            session=session,
+            number=session.current_round,
+            category=category,
+        )
+
         try:
             round_question = _select_round_question(session, round_config)
         except ValueError as exc:
             return api_error(request, code=str(exc), status=400)
 
+        round_config.save()
         session.status = GameSession.Status.LIE
         session.save(update_fields=["status"])
 
@@ -1101,22 +1103,24 @@ def start_next_round(request: HttpRequest, code: str) -> JsonResponse:
         if previous_round_config is None:
             return api_error(request, code="round_config_missing", status=400)
 
-        locked_session.current_round += 1
+        next_round_number = locked_session.current_round + 1
-        next_round_config = RoundConfig.objects.create(
+        next_round_config = RoundConfig(
             session=locked_session,
-            number=locked_session.current_round,
+            number=next_round_number,
             category=previous_round_config.category,
             lie_seconds=previous_round_config.lie_seconds,
             guess_seconds=previous_round_config.guess_seconds,
             points_correct=previous_round_config.points_correct,
             points_bluff=previous_round_config.points_bluff,
         )
+        locked_session.current_round = next_round_number
 
         try:
             round_question = _select_round_question(locked_session, next_round_config)
         except ValueError as exc:
             return api_error(request, code=str(exc), status=400)
 
+        next_round_config.save()
         locked_session.status = GameSession.Status.LIE
         locked_session.save(update_fields=["current_round", "status"])