feat: use broker-authoritative qty in slots RPC holdings

Co-authored-by: genichin <4282227+genichin@users.noreply.github.com>

tests/application/test_account_snapshot.py

@@ -1,7 +1,7 @@
 """Bounded account-read recovery (dcy-041 / GitHub #45)."""
 from __future__ import annotations
 
-from datetime import datetime, timedelta, timezone
+from datetime import UTC, datetime, timedelta
 
 import pytest
 
@@ -37,7 +37,7 @@ class FakeAccountBroker:
 
 
 def _wire():
-    now = [datetime(2026, 7, 29, tzinfo=timezone.utc)]
+    now = [datetime(2026, 7, 29, tzinfo=UTC)]
     broker = FakeAccountBroker()
     store = InMemoryAccountSnapshotStore()
     service = AccountSnapshotService(
@@ -162,3 +162,18 @@ def test_invalid_or_missing_buy_notional_fails_closed():
     assert service.buy_guard(qty=1, limit_price=None) == (
         "account_snapshot_price_required"
     )
+
+
+def test_slots_rpc_uses_snapshot_only_with_sell_ttl_freshness():
+    broker, _, service, now = _wire()
+    assert service.refresh()
+    broker.balance = [BalanceItem("005930", 999)]
+
+    holdings, captured_at = service.holdings_for_slots_rpc()
+    assert holdings == [BalanceItem("005930", 2)]
+    assert captured_at == now[0]
+
+    now[0] += timedelta(seconds=3601)
+    with pytest.raises(AccountSnapshotUnavailable) as raised:
+        service.holdings_for_slots_rpc()
+    assert raised.value.code == "expired"