diff --git a/WORK-RECORDS.md b/WORK-RECORDS.md
index ec11c2f..c143a2e 100644
--- a/WORK-RECORDS.md
+++ b/WORK-RECORDS.md
@@ -27,7 +27,7 @@
 | task | HARNESS-WP-0002-T03 | done | — | workplans/HARNESS-WP-0002-rename-and-glas-harness-alignment.md |
 | task | HARNESS-WP-0002-T04 | done | — | workplans/HARNESS-WP-0002-rename-and-glas-harness-alignment.md |
 | task | HARNESS-WP-0003-T01 | progress | — | workplans/HARNESS-WP-0003-governed-runtime-integrity.md |
-| task | HARNESS-WP-0003-T02 | wait | — | workplans/HARNESS-WP-0003-governed-runtime-integrity.md |
+| task | HARNESS-WP-0003-T02 | progress | — | workplans/HARNESS-WP-0003-governed-runtime-integrity.md |
 | task | HARNESS-WP-0003-T03 | wait | — | workplans/HARNESS-WP-0003-governed-runtime-integrity.md |
 | task | HARNESS-WP-0003-T04 | wait | — | workplans/HARNESS-WP-0003-governed-runtime-integrity.md |
 | task | HARNESS-WP-0003-T05 | wait | — | workplans/HARNESS-WP-0003-governed-runtime-integrity.md |
diff --git a/rein_aharness/claim_loop.py b/rein_aharness/claim_loop.py
index 510ae19..eefeeed 100644
--- a/rein_aharness/claim_loop.py
+++ b/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(
diff --git a/rein_aharness/lease_monitor.py b/rein_aharness/lease_monitor.py
new file mode 100644
index 0000000..aa36a59
--- /dev/null
+++ b/rein_aharness/lease_monitor.py
@@ -0,0 +1,77 @@
+"""Observable lease state for long-running executions.
+
+The monitor is deliberately independent of an adapter.  A heartbeat worker can
+mark a lease lost, while the executor observes that fact and decides how to
+cancel or refuse acceptance at its own boundary.
+"""
+
+from __future__ import annotations
+
+import threading
+from dataclasses import dataclass
+from datetime import datetime, timezone
+from typing import Callable
+
+
+@dataclass(frozen=True)
+class LeaseLoss:
+    """Bounded evidence that the worker no longer owns a lease."""
+
+    error_type: str
+    observed_at: str
+
+
+class LeaseMonitor:
+    """Thread-safe active/lost/stopped state with a one-shot loss callback."""
+
+    def __init__(self, on_lost: Callable[[LeaseLoss], None] | None = None) -> None:
+        self._lock = threading.Lock()
+        self._lost = threading.Event()
+        self._stopped = False
+        self._evidence: LeaseLoss | None = None
+        self._on_lost = on_lost
+
+    @property
+    def lost(self) -> bool:
+        return self._lost.is_set()
+
+    @property
+    def stopped(self) -> bool:
+        with self._lock:
+            return self._stopped
+
+    @property
+    def evidence(self) -> LeaseLoss | None:
+        with self._lock:
+            return self._evidence
+
+    def wait_lost(self, timeout: float | None = None) -> bool:
+        """Wait until lease loss is observed; return whether it occurred."""
+        return self._lost.wait(timeout)
+
+    def mark_lost(self, error_type: str) -> LeaseLoss:
+        """Record the first loss and invoke the callback once.
+
+        Error text is intentionally not retained: provider responses can carry
+        credentials, prompts, or other unbounded data.
+        """
+        callback: Callable[[LeaseLoss], None] | None = None
+        with self._lock:
+            if self._evidence is None:
+                evidence = LeaseLoss(
+                    error_type=error_type[:80] or "OpsRunError",
+                    observed_at=datetime.now(timezone.utc).isoformat(),
+                )
+                self._evidence = evidence
+                self._lost.set()
+                callback = self._on_lost
+            else:
+                evidence = self._evidence
+        if callback is not None:
+            callback(evidence)
+        return evidence
+
+    def stop(self) -> None:
+        with self._lock:
+            self._stopped = True
+
diff --git a/tests/test_lease_monitor.py b/tests/test_lease_monitor.py
new file mode 100644
index 0000000..c2f8484
--- /dev/null
+++ b/tests/test_lease_monitor.py
@@ -0,0 +1,65 @@
+from __future__ import annotations
+
+import time
+from unittest.mock import MagicMock, patch
+
+from rein_aharness.claim_loop import _Heartbeat
+from rein_aharness.lease_monitor import LeaseMonitor
+from rein_aharness.ops_run_client import OpsRunError
+
+
+def test_loss_is_one_shot_and_bounded() -> None:
+    seen = []
+    monitor = LeaseMonitor(seen.append)
+
+    first = monitor.mark_lost("ProviderError" * 20)
+    second = monitor.mark_lost("OtherError")
+
+    assert monitor.lost is True
+    assert first == second
+    assert len(first.error_type) <= 80
+    assert first.error_type.startswith("ProviderError")
+    assert seen == [first]
+
+
+def test_wait_lost_and_stop_are_distinct() -> None:
+    monitor = LeaseMonitor()
+
+    assert monitor.wait_lost(timeout=0) is False
+    monitor.stop()
+    assert monitor.stopped is True
+    assert monitor.lost is False
+    monitor.mark_lost("OpsRunError")
+    assert monitor.wait_lost(timeout=0) is True
+
+
+def test_concurrent_loss_still_notifies_once() -> None:
+    seen = []
+    monitor = LeaseMonitor(seen.append)
+
+    import threading
+
+    threads = [threading.Thread(target=monitor.mark_lost, args=("OpsRunError",)) for _ in range(8)]
+    for thread in threads:
+        thread.start()
+    for thread in threads:
+        thread.join()
+
+    assert len(seen) == 1
+
+
+def test_heartbeat_publishes_loss_without_raw_exception_text() -> None:
+    client = MagicMock()
+    client.heartbeat.side_effect = OpsRunError("secret provider response")
+    heartbeat = _Heartbeat(client, "run-1", lease_seconds=90)
+
+    with patch("rein_aharness.claim_loop._heartbeat_interval", return_value=0.01):
+        heartbeat.start()
+        deadline = time.monotonic() + 1.0
+        while not heartbeat.monitor.lost and time.monotonic() < deadline:
+            time.sleep(0.005)
+        heartbeat.stop()
+
+    assert heartbeat.monitor.lost is True
+    assert heartbeat.monitor.evidence is not None
+    assert "secret" not in heartbeat.monitor.evidence.error_type
diff --git a/workplans/HARNESS-WP-0003-governed-runtime-integrity.md b/workplans/HARNESS-WP-0003-governed-runtime-integrity.md
index b5b09fb..389049f 100644
--- a/workplans/HARNESS-WP-0003-governed-runtime-integrity.md
+++ b/workplans/HARNESS-WP-0003-governed-runtime-integrity.md
@@ -145,7 +145,7 @@ and T02–T06 can cite stable decisions rather than infer ownership from code.
 
 ```task
 id: HARNESS-WP-0003-T02
-status: wait
+status: progress
 priority: high
 state_hub_task_id: "47816469-b5c0-5252-8b71-041e65d203fd"
 ```
@@ -189,7 +189,19 @@ The primitive is intentionally not wired into `runner.py`, legacy approaches,
 or the claim loop while ADR-002 still awaits Activity Core, sand-boxer, and
 llm-connect acknowledgements. Controlled moved-`HEAD` acceptance is prepared
 under T03 below; lease-loss cancellation, timeout/signal integration, and
-result-close reconciliation remain outstanding. T02 therefore remains `wait`.
+result-close reconciliation remain outstanding; T02 is now `progress`.
+
+### Lease observability slice — 2026-08-23
+
+Added `rein_aharness/lease_monitor.py`, a thread-safe, adapter-neutral lease
+state primitive. It records one bounded loss envelope, provides a waitable loss
+event, and invokes an optional cancellation callback exactly once. The claim
+loop heartbeat now feeds this monitor and emits only bounded error type/time
+evidence instead of raw provider exception text. This establishes the signal
+needed by execution and acceptance boundaries without pretending that adapters
+can already cancel in-flight work. Remaining work is to classify Activity Core
+responses, connect cancellation at each adapter boundary, and refuse result
+acceptance/close after loss.
 
 ## Verify accepted commits and reconcile metrics/reporting