fix: persist uncertain cancel outcomes

trex_core/adapters/broker/paper.py

@@ -14,6 +14,8 @@ from typing import Optional
 from trex_core.adapters.broker.seq_store import SeqStore
 from trex_core.application.broker_port import (
     BalanceItem,
+    CancelOutcome,
+    CancelState,
     FillStatus,
     OrderAck,
     OrderRequest,
@@ -105,16 +107,24 @@ class PaperBroker:
                 )
             return FillStatus(state="partially_filled", filled_qty=o.filled, avg_price=o.price)
 
-    def cancel_order(self, broker_order_id: str, *, side: str, symbol: str, qty: int, venue: str = "KRX") -> bool:
+    def cancel_order(
+        self,
+        broker_order_id: str,
+        *,
+        side: str,
+        symbol: str,
+        qty: int,
+        venue: str = "KRX",
+    ) -> CancelOutcome:
         """Cancel a paper order. venue is accepted for BrokerPort protocol conformance
         (REQ-118) but ignored — paper has no exchange concept. Existing behavior preserved.
         """
         with self._lock:
             o = self._orders.get(broker_order_id)
             if o is None or o.filled >= o.qty:
-                return False
+                return CancelOutcome(CancelState.REJECTED, "order_not_cancellable")
             o.cancelled = True
-            return True
+            return CancelOutcome(CancelState.REQUESTED)
 
     def get_balance(self) -> list[BalanceItem]:
         """Deterministic per-symbol fill aggregate (REQ-031 AC-3).