fix: persist uncertain cancel outcomes

trex_core/domain/slot/models.py

@@ -59,6 +59,11 @@ class Slot:
     # Order venue carried from the admitted intent through dispatch/cancel.
     # It is reset to KRX when the permanent asset slot returns to INACTIVE.
     venue: str = "KRX"
+    # Immediate cancel-request result. The slot remains pending until fill
+    # polling confirms cancelled/filled. Persisted to prevent blind retries
+    # across ticks and restarts.
+    cancel_state: Optional[str] = None
+    cancel_requested_at: Optional[datetime] = None
 
 
 # Canonical column contract for `Slot` (dcy-001 OQ-2 / FR-5).
@@ -88,6 +93,8 @@ EXPECTED_SLOT_FIELDS: frozenset[str] = frozenset({
     "slippage_pct",       # dcy-022 / REQ-068 (BAT-032)
     "occupancy_seq",      # dcy-028 / REQ-081 (BAT-042)
     "venue",
+    "cancel_state",
+    "cancel_requested_at",
 })