feat(ledger): quiet idle outbox polling

tests/runtime/test_daemon_ledger_loop_exception_logging.py

@@ -0,0 +1,47 @@
+"""Ledger writer loop failures remain visible without leaking exception text."""
+from __future__ import annotations
+
+import logging
+import threading
+from typing import Any
+
+from trex_core.runtime.daemon import Daemon
+
+_SENTINEL = "SECRET-LEDGER-DSN-PAYLOAD-DO-NOT-LOG"
+
+
+def test_ledger_loop_logs_sanitized_error_and_continues(caplog):
+    call_count = 0
+    stop_event = threading.Event()
+
+    class _Writer:
+        def run_once(self):
+            nonlocal call_count
+            call_count += 1
+            if call_count == 1:
+                raise RuntimeError(f"dsn=postgresql://user:{_SENTINEL}@host/db")
+            stop_event.set()
+
+    class _Config:
+        ledger_interval_sec = 0.001
+        instance_key = "instance-a"
+
+    daemon: Any = object.__new__(Daemon)
+    daemon.stop = stop_event
+    daemon.config = _Config()
+    daemon.ledger_writer = _Writer()
+
+    with caplog.at_level(logging.ERROR, logger="trex_core.runtime.daemon"):
+        thread = threading.Thread(target=daemon._ledger_loop, daemon=True)
+        thread.start()
+        thread.join(timeout=2.0)
+
+    assert not thread.is_alive()
+    assert call_count >= 2
+    assert len(caplog.records) == 1
+    record = caplog.records[0]
+    assert "reason=ledger_writer_run_once_failed" in record.getMessage()
+    assert "instance_key=instance-a" in record.getMessage()
+    assert "exc_type=RuntimeError" in record.getMessage()
+    assert _SENTINEL not in caplog.text
+    assert record.exc_info is None