refactor(gameplay): keep host transition payloads in cartridge

lobby/views.py

@@ -10,12 +10,10 @@ from django.views.decorators.http import require_GET, require_POST
 
 from fupogfakta.models import Category, GameSession, Guess, LieAnswer, Player, Question, RoundConfig, RoundQuestion, ScoreEvent
 from fupogfakta.payloads import (
-    build_finish_game_response as _build_finish_game_response,
     build_leaderboard as _build_leaderboard,
     build_lie_started_payload as _build_lie_started_payload,
     build_reveal_payload as _build_reveal_payload,
     build_scoreboard_phase_event as _build_scoreboard_phase_event,
-    build_start_next_round_response as _build_start_next_round_response,
 )
 from fupogfakta.services import (
     finish_game as _finish_game,
@@ -75,11 +73,10 @@ def _create_unique_session_code() -> str:
 def _maybe_promote_reveal_to_scoreboard(session: GameSession) -> GameSession:
     transition = _promote_reveal_to_scoreboard(session)
     if transition.should_broadcast:
-        phase_event = _build_scoreboard_phase_event(transition.session, transition.leaderboard)
         sync_broadcast_phase_event(
             transition.session.code,
-            phase_event["name"],
-            phase_event["payload"],
+            transition.phase_event_name,
+            transition.phase_event_payload,
         )
     return transition.session
 
@@ -872,28 +869,16 @@ def reveal_scoreboard(request: HttpRequest, code: str) -> JsonResponse:
 
     transition = _promote_reveal_to_scoreboard(session)
     if transition.should_broadcast:
-        phase_event = _build_scoreboard_phase_event(transition.session, transition.leaderboard)
         sync_broadcast_phase_event(
             transition.session.code,
-            phase_event["name"],
-            phase_event["payload"],
+            transition.phase_event_name,
+            transition.phase_event_payload,
         )
     session = transition.session
     if session.status not in {GameSession.Status.SCOREBOARD, GameSession.Status.FINISHED}:
         return api_error(request, code="scoreboard_invalid_phase", status=400)
 
-    leaderboard = transition.leaderboard
-
-    return JsonResponse(
-        {
-            "session": {
-                "code": session.code,
-                "status": session.status,
-                "current_round": session.current_round,
-            },
-            "leaderboard": leaderboard,
-        }
-    )
+    return JsonResponse(transition.response_payload)
 
 
 @require_POST
@@ -921,13 +906,7 @@ def start_next_round(request: HttpRequest, code: str) -> JsonResponse:
             transition.phase_event_payload,
         )
 
-    return JsonResponse(
-        _build_start_next_round_response(
-            transition.session,
-            transition.round_config,
-            transition.round_question,
-        )
-    )
+    return JsonResponse(transition.response_payload)
 
 @require_POST
 @login_required
@@ -954,7 +933,7 @@ def finish_game(request: HttpRequest, code: str) -> JsonResponse:
             transition.phase_event_payload,
         )
 
-    return JsonResponse(_build_finish_game_response(transition.session))
+    return JsonResponse(transition.response_payload)
 
 
 @require_POST