PINK: fix ctypes dangling-pointer + venue.submit guard

Two bugs causing INVALID_INTENT_PARSE at FFI boundary:

1. Dangling pointer: ctypes.c_char_p stores a raw C pointer without
   incrementing the Python refcount. Temporaries passed inline are freed
   by CPython before the Rust FFI call executes, giving Rust a dangling
   pointer whose freed memory looks like truncated JSON (column 41).
   Fix: assign bytes to local vars (_pb/_mb/_vb) to hold refs alive.

2. venue.submit guard: process_intent() called venue.submit() even when
   the kernel returned INVALID_INTENT, cascading a 30s BingX timeout
   into a fatal crash. Fix: gate on outcome.accepted.

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

prod/clean_arch/dita_v2/rust_backend.py

@@ -231,11 +231,18 @@ class _RustKernelLib:
         mode: str,
         verbosity: str,
     ) -> Dict[str, Any]:
+        # Keep local refs so CPython's ref-count doesn't free the bytes objects
+        # before the Rust FFI call completes. ctypes.c_char_p stores a raw pointer
+        # without incrementing the Python refcount; a temporary would be freed
+        # after c_char_p() returns, giving Rust a dangling pointer.
+        _pb = _to_rust_bytes(payload)
+        _mb = mode.encode("ascii")
+        _vb = verbosity.encode("ascii")
         raw = self.lib.dita_kernel_process_intent_json(
             handle,
-            ctypes.c_char_p(_to_rust_bytes(payload)),
+            ctypes.c_char_p(_pb),
-            ctypes.c_char_p(mode.encode("ascii")),
+            ctypes.c_char_p(_mb),
-            ctypes.c_char_p(verbosity.encode("ascii")),
+            ctypes.c_char_p(_vb),
         )
         return json.loads(self._take_string(raw))
 
@@ -247,11 +254,14 @@ class _RustKernelLib:
         mode: str,
         verbosity: str,
     ) -> Dict[str, Any]:
+        _pb = _to_rust_bytes(payload)
+        _mb = mode.encode("ascii")
+        _vb = verbosity.encode("ascii")
         raw = self.lib.dita_kernel_on_venue_event_json(
             handle,
-            ctypes.c_char_p(_to_rust_bytes(payload)),
+            ctypes.c_char_p(_pb),
-            ctypes.c_char_p(mode.encode("ascii")),
+            ctypes.c_char_p(_mb),
-            ctypes.c_char_p(verbosity.encode("ascii")),
+            ctypes.c_char_p(_vb),
         )
         return json.loads(self._take_string(raw))
 
@@ -263,11 +273,14 @@ class _RustKernelLib:
         mode: str,
         verbosity: str,
     ) -> Dict[str, Any]:
+        _pb = _to_rust_bytes(list(payload))
+        _mb = mode.encode("ascii")
+        _vb = verbosity.encode("ascii")
         raw = self.lib.dita_kernel_reconcile_slots_json(
             handle,
-            ctypes.c_char_p(_to_rust_bytes(list(payload))),
+            ctypes.c_char_p(_pb),
-            ctypes.c_char_p(mode.encode("ascii")),
+            ctypes.c_char_p(_mb),
-            ctypes.c_char_p(verbosity.encode("ascii")),
+            ctypes.c_char_p(_vb),
         )
         return json.loads(self._take_string(raw))
 
@@ -294,7 +307,8 @@ class _RustKernelLib:
     def on_account_event(
         self, handle: ctypes.c_void_p, event: Dict[str, Any]
     ) -> Dict[str, Any]:
-        raw = self.lib.dita_kernel_on_account_event_json(handle, ctypes.c_char_p(_to_rust_bytes(event)))
+        _eb = _to_rust_bytes(event)
+        raw = self.lib.dita_kernel_on_account_event_json(handle, ctypes.c_char_p(_eb))
         if not raw:
             return {}
         return json.loads(self._take_string(raw))
@@ -761,7 +775,7 @@ class ExecutionKernel:
             self._last_settled_pnl[intent.slot_id] = 0.0
         emitted_events = []
         all_venue_transitions: List[KernelTransition] = []
-        if intent.action in {KernelCommandType.ENTER, KernelCommandType.EXIT}:
+        if outcome.accepted and intent.action in {KernelCommandType.ENTER, KernelCommandType.EXIT}:
             emitted_events = self.venue.submit(intent)
             for event in emitted_events:
                 evt_outcome = self.on_venue_event(event)