Expose lease loss to execution boundaries

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a02b6f-7db1-7222-918b-e813a6bda38d

rein_aharness/claim_loop.py

@@ -28,6 +28,7 @@ from rein_aharness.glas_execution import (
     GlasExecutionError,
     execute_profiled_run,
 )
+from rein_aharness.lease_monitor import LeaseMonitor
 from rein_aharness.ops_run_client import (
     ActivityCoreOpsClient,
     OpsRun,
@@ -68,6 +69,7 @@ class _Heartbeat:
         self._lease = lease_seconds
         self._stop = threading.Event()
         self._thread: threading.Thread | None = None
+        self.monitor = LeaseMonitor()
 
     def start(self) -> None:
         interval = _heartbeat_interval(self._lease)
@@ -78,7 +80,13 @@ class _Heartbeat:
                     self._client.heartbeat(self._run_id, lease_seconds=self._lease)
                     logger.info("heartbeat ok run_id=%s", self._run_id)
                 except OpsRunError as exc:
-                    logger.warning("heartbeat failed run_id=%s: %s", self._run_id, exc)
+                    evidence = self.monitor.mark_lost(type(exc).__name__)
+                    logger.warning(
+                        "heartbeat lost run_id=%s error_type=%s observed_at=%s",
+                        self._run_id,
+                        evidence.error_type,
+                        evidence.observed_at,
+                    )
 
         self._thread = threading.Thread(
             target=_loop, name=f"ops-hb-{self._run_id[:8]}", daemon=True
@@ -89,6 +97,7 @@ class _Heartbeat:
         self._stop.set()
         if self._thread is not None:
             self._thread.join(timeout=5.0)
+        self.monitor.stop()
 
 
 def process_one(