Tray follows the ?seat-selected seat, not the canonical PC seat

A multi-seat (CARTE) gamer clicking a pos-circle switched the sig overlay
(via the ?seat=N override) but the tray stayed pinned to the role-canonical
PC seat — my_tray_role read assigned_seats[0] (role-sorted, always PC) and
my_tray_sig read _canonical_user_seat. So every circle put the PC icon in
the tray regardless of which one was clicked.

Re-point both tray keys to the seat occupying current_slot (the acting
seat). Single-seat gamers are unaffected — their lone slot IS current_slot,
so selected_seat == their canonical seat.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/apps/epic/tests/integrated/test_views.py

@@ -810,6 +810,81 @@ class PositionTooltipCarteRenderTest(TestCase):
         self.assertNotIn("drop-token-btn", content)
 
 
+class CarteTrayFollowsSelectedSeatTest(TestCase):
+    """A multi-seat (CARTE) gamer's tray must mirror the seat at the
+    ?seat-selected pos-circle (current_slot), not the canonical PC seat.
+
+    Regression: my_tray_role / my_tray_sig were pinned to the role-sorted
+    assigned_seats[0] (always PC) and _canonical_user_seat, so clicking ANY
+    pos-circle put the PC icon in the tray. The seat-switch (?seat=N) only
+    re-pointed the sig OVERLAY; the tray ignored it entirely."""
+
+    # Reverse canonical pick order: select_role fills the lowest open slot
+    # each turn, so picking BC,AC,SC,EC,NC,PC seats them at slots 1..6.
+    SLOT_ROLES = {1: "BC", 2: "AC", 3: "SC", 4: "EC", 5: "NC", 6: "PC"}
+
+    def setUp(self):
+        self.viewer = User.objects.create(email="disco@test.io", username="disco")
+        self.deck, _ = DeckVariant.objects.get_or_create(
+            slug="earthman",
+            defaults={"name": "Earthman", "card_count": 106, "is_default": True},
+        )
+        self.room = Room.objects.create(name="Carte Room", owner=self.viewer)
+        self.room.gate_slots.update(
+            gamer=self.viewer, status=GateSlot.FILLED,
+            filled_at=timezone.now(), debited_token_type=Token.CARTE,
+        )
+        Token.objects.create(
+            user=self.viewer, token_type=Token.CARTE,
+            current_room=self.room, slots_claimed=6,
+        )
+        self.room.gate_status = Room.OPEN
+        self.room.table_status = Room.ROLE_SELECT
+        self.room.save()
+        for n, role in self.SLOT_ROLES.items():
+            TableSeat.objects.create(
+                room=self.room, gamer=self.viewer, slot_number=n,
+                role=role, deck_variant=self.deck,
+            )
+        self.client.force_login(self.viewer)
+        self.room_url = reverse("epic:room", kwargs={"room_id": self.room.id})
+
+    def test_seat_param_points_tray_role_at_that_seat(self):
+        # ?seat=4 → pos-circle 4 holds EC, so the tray role card is EC, not PC.
+        response = self.client.get(self.room_url + "?seat=4")
+        self.assertEqual(response.context["my_tray_role"], "EC")
+
+    def test_each_owned_circle_yields_its_own_seat_role(self):
+        for n, role in self.SLOT_ROLES.items():
+            response = self.client.get(self.room_url + f"?seat={n}")
+            self.assertEqual(
+                response.context["my_tray_role"], role,
+                f"pos-circle {n} should put role {role} in the tray",
+            )
+
+    def test_default_no_seat_tray_follows_lowest_owned_circle(self):
+        # No ?seat → current_slot is the lowest owned pos-circle (1 = BC),
+        # NOT the role-canonical PC seat (slot 6).
+        response = self.client.get(self.room_url)
+        self.assertEqual(response.context["my_tray_role"], "BC")
+
+    def test_seat_param_points_tray_sig_at_that_seat(self):
+        sig = TarotCard.objects.create(
+            deck_variant=self.deck, slug="ec-sig",
+            arcana="MIDDLE", suit="BRANDS", number=13, name="Queen of Brands",
+        )
+        ec_seat = TableSeat.objects.get(room=self.room, slot_number=4)
+        ec_seat.significator = sig
+        ec_seat.save(update_fields=["significator"])
+        # Switch to EC's circle → its sig rides the tray.
+        response = self.client.get(self.room_url + "?seat=4")
+        self.assertEqual(response.context["my_tray_sig"], sig)
+        # The PC circle (slot 6) has no sig → switching there shows none
+        # (proving the tray no longer falls back to a single canonical seat).
+        response = self.client.get(self.room_url + "?seat=6")
+        self.assertIsNone(response.context["my_tray_sig"])
+
+
 class PickRolesViewTest(TestCase):
     def setUp(self):
         self.founder = User.objects.create(email="founder@test.io")