PINK: fix trade_seq always-zero — unique trade_id per position

trade_seq was missing from the kernel account snapshot dict, so the
intent engine always computed trade_id = "BTCUSDT-T-000000000001".
The Rust FSM SLOT_BUSY guard only fires on *different* trade_ids; with
the same ID it resets the slot and submits a new exchange order on each
ENTER signal tick (~86 duplicate orders observed in one session).

Fix:
- Add _slot_was_closed dict to ExecutionKernel; set False on ENTER
  accepted (both sync/async), True on on_venue_event when slot.closed
- Increment account.snapshot.trade_seq on the IDLE→CLOSED transition
- Expose trade_seq in snapshot()["account"] so DecisionContext carries
  the correct counter → intent engine generates unique IDs per trade

451/451 tests green.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

prod/clean_arch/dita_v2/rust_backend.py

@@ -668,6 +668,7 @@ class ExecutionKernel:
         self._backend = _get_rust().create(self.max_slots)
         self._control_snapshot = self.control_plane.read()
         self._last_settled_pnl: Dict[int, float] = {}
+        self._slot_was_closed: Dict[int, bool] = {}
         self.projection.write_control(self._control_snapshot)
         self.zinc_plane.update_control(self._control_snapshot)
         self.state = KernelStateView(self)
@@ -796,6 +797,7 @@ class ExecutionKernel:
         self.state.refresh()
         if intent.action == KernelCommandType.ENTER and outcome.accepted:
             self._last_settled_pnl[intent.slot_id] = 0.0
+            self._slot_was_closed[intent.slot_id] = False
         emitted_events = []
         all_venue_transitions: List[KernelTransition] = []
         if outcome.accepted and intent.action in {KernelCommandType.ENTER, KernelCommandType.EXIT}:
@@ -943,6 +945,7 @@ class ExecutionKernel:
         self.state.refresh()
         if intent.action == KernelCommandType.ENTER and outcome.accepted:
             self._last_settled_pnl[intent.slot_id] = 0.0
+            self._slot_was_closed[intent.slot_id] = False
         emitted_events: List[VenueEvent] = []
         all_venue_transitions: List[KernelTransition] = []
         if outcome.accepted and intent.action in {KernelCommandType.ENTER, KernelCommandType.EXIT}:
@@ -1040,6 +1043,14 @@ class ExecutionKernel:
         if abs(incremental_pnl) > 1e-12:
             self.account.settle(incremental_pnl)
             self._last_settled_pnl[slot.slot_id] = slot.realized_pnl
+        # Increment trade_seq when a slot transitions from open → closed so
+        # the next ENTER gets a unique trade_id.  Without this increment the
+        # intent engine always generates "…-T-000000000001" and the Rust FSM
+        # resets (not SLOT_BUSYs) the slot on every duplicate ENTER signal.
+        was_closed = self._slot_was_closed.get(slot.slot_id, True)
+        if slot.closed and not was_closed:
+            self.account.snapshot.trade_seq += 1
+        self._slot_was_closed[slot.slot_id] = slot.closed
         slots = [self._get_slot(i) for i in range(self.max_slots)]
         self.account.observe_slots(slots)
         current = self._get_slot(slot.slot_id)
@@ -1192,6 +1203,7 @@ class ExecutionKernel:
                 "open_positions": self.account.snapshot.open_positions,
                 "open_notional": self.account.snapshot.open_notional,
                 "leverage": self.account.snapshot.leverage,
+                "trade_seq": self.account.snapshot.trade_seq,
                 # V2 — kernel atomic K/E account (E rules; K is parallel check)
                 "k_capital": rust_account.get("k_capital", self.account.snapshot.capital),
                 "k_realized_pnl": rust_account.get("k_realized_pnl", self.account.snapshot.realized_pnl),