feat(f3): mix correct answer with lies and open guess phase

lobby/views.py

@@ -335,3 +335,66 @@ def submit_lie(request: HttpRequest, code: str, round_question_id: int) -> JsonR
         },
         status=201,
     )
+
+@require_POST
+@login_required
+def mix_answers(request: HttpRequest, code: str, round_question_id: int) -> JsonResponse:
+    session_code = code.strip().upper()
+
+    try:
+        session = GameSession.objects.get(code=session_code)
+    except GameSession.DoesNotExist:
+        return JsonResponse({"error": "Session not found"}, status=404)
+
+    if session.host_id != request.user.id:
+        return JsonResponse({"error": "Only host can mix answers"}, status=403)
+
+    if session.status != GameSession.Status.LIE:
+        return JsonResponse({"error": "Answers can only be mixed in lie phase"}, status=400)
+
+    try:
+        round_question = RoundQuestion.objects.get(
+            pk=round_question_id,
+            session=session,
+            round_number=session.current_round,
+        )
+    except RoundQuestion.DoesNotExist:
+        return JsonResponse({"error": "Round question not found"}, status=404)
+
+    lie_texts = list(round_question.lies.values_list("text", flat=True))
+
+    deduped_answers = []
+    seen = set()
+    for text in [round_question.correct_answer, *lie_texts]:
+        normalized = text.strip().casefold()
+        if not normalized or normalized in seen:
+            continue
+        seen.add(normalized)
+        deduped_answers.append(text.strip())
+
+    if len(deduped_answers) < 2:
+        return JsonResponse({"error": "Not enough answers to mix"}, status=400)
+
+    random.shuffle(deduped_answers)
+
+    with transaction.atomic():
+        locked_session = GameSession.objects.select_for_update().get(pk=session.pk)
+        if locked_session.status != GameSession.Status.LIE:
+            return JsonResponse({"error": "Answers can only be mixed in lie phase"}, status=400)
+        locked_session.status = GameSession.Status.GUESS
+        locked_session.save(update_fields=["status"])
+
+    return JsonResponse(
+        {
+            "session": {
+                "code": session.code,
+                "status": GameSession.Status.GUESS,
+                "current_round": session.current_round,
+            },
+            "round_question": {
+                "id": round_question.id,
+                "round_number": round_question.round_number,
+            },
+            "answers": [{"text": text} for text in deduped_answers],
+        }
+    )