in role-select.js, selectRole() runs in more precise ordering to ensure card hand for role selection passes to the next gamer after a selection is made; previous bug allowed multiple cards at a single gamer position, which prevented the card hand from making a circuit around the table before depletion; backend fixes including to apps.epic.views.select_role; +2 FTs & +1 IT asserts these features

src/apps/epic/views.py

@@ -3,6 +3,7 @@ from datetime import timedelta
 from asgiref.sync import async_to_sync
 from channels.layers import get_channel_layer
 from django.contrib.auth.decorators import login_required
+from django.db import transaction
 from django.http import HttpResponse
 from django.shortcuts import redirect, render
 from django.utils import timezone
@@ -374,19 +375,20 @@ def select_role(request, room_id):
         room = Room.objects.get(id=room_id)
         if room.table_status != Room.ROLE_SELECT:
             return redirect("epic:gatekeeper", room_id=room_id)
-        active_seat = room.table_seats.filter(
-            role__isnull=True
-        ).order_by("slot_number").first()
-        if not active_seat or active_seat.gamer != request.user:
-            return redirect("epic:gatekeeper", room_id=room_id)
         role = request.POST.get("role")
         valid_roles = [code for code, _ in TableSeat.ROLE_CHOICES]
         if not role or role not in valid_roles:
             return redirect("epic:gatekeeper", room_id=room_id)
-        if room.table_seats.filter(role=role).exists():
-            return HttpResponse(status=409)
-        active_seat.role = role
-        active_seat.save()
+        with transaction.atomic():
+            active_seat = room.table_seats.select_for_update().filter(
+                role__isnull=True
+            ).order_by("slot_number").first()
+            if not active_seat or active_seat.gamer != request.user:
+                return redirect("epic:gatekeeper", room_id=room_id)
+            if room.table_seats.filter(role=role).exists():
+                return HttpResponse(status=409)
+            active_seat.role = role
+            active_seat.save()
         record(room, GameEvent.ROLE_SELECTED, actor=request.user,
                role=role, slot_number=active_seat.slot_number,
                role_display=dict(TableSeat.ROLE_CHOICES).get(role, role))