feat(ledger): quiet idle outbox polling

trex_core/application/messaging_handlers.py

@@ -259,6 +259,7 @@ def make_slots_rpc_handler(
     watchdog_store: Optional[WatchdogStore] = None,
     watchdog_timeout_sec: int = 120,
     ledger_outbox=None,
+    ledger_outbox_metrics_reader=None,
     max_active_slots: Optional[int] = None,
     strategy_state_store=None,
     broker_quantity_reader: Optional[SlotsBrokerQuantityReader] = None,
@@ -512,6 +513,23 @@ def make_slots_rpc_handler(
                     )
             if health_payload:
                 base_payload["broker_balance_health"] = health_payload
+        if spy:
+            unavailable_metrics = {
+                "available": False,
+                "scope": "process_lifetime",
+                "instance_key": instance_key,
+                "reason": "ledger_outbox_metrics_unavailable",
+            }
+            if ledger_outbox_metrics_reader is None:
+                base_payload["ledger_outbox_metrics"] = unavailable_metrics
+            else:
+                try:
+                    metrics = ledger_outbox_metrics_reader.metrics_snapshot()
+                    if not isinstance(metrics, dict):
+                        raise TypeError("metrics snapshot must be a dict")
+                    base_payload["ledger_outbox_metrics"] = metrics
+                except Exception:  # noqa: BLE001 - status response must stay available
+                    base_payload["ledger_outbox_metrics"] = unavailable_metrics
         if warn_store is not None:
             base_payload["excluded_slots"] = {
                 "reconcile_quantity_mismatch": excluded_count,