fix: newest lease marker wins so release ends prior claims

find_active_reviewer_lease walked past terminal markers and re-armed
older claimed leases after gitea_release_reviewer_pr_lease. Treat the
newest marker as authoritative (append-only ledger).

Closes #577

reviewer_pr_lease.py

@@ -190,18 +190,28 @@ def find_active_reviewer_lease(
     pr_number: int,
     now: datetime | None = None,
 ) -> dict[str, Any] | None:
-    """Newest non-terminal, unexpired lease for *pr_number*."""
+    """Return the newest unexpired non-terminal lease for *pr_number*.
+
+    Append-only lease markers form a ledger: the **newest** marker is
+    authoritative. A later terminal phase (``released`` / ``done`` /
+    ``blocked``) ends the lease even when older ``claimed`` markers remain
+    on the thread (#577). Skipping only terminal markers and walking older
+    claims incorrectly re-arms a lease after a successful release.
+    """
     now = now or datetime.now(timezone.utc)
-    for lease in reversed(_lease_entries(comments, pr_number=pr_number)):
-        phase = (lease.get("phase") or "").strip().lower()
-        if phase in _TERMINAL_PHASES:
-            continue
-        if _lease_expired(lease, now=now):
-            continue
-        if phase in _ACTIVE_PHASES or phase:
-            lease = dict(lease)
-            lease["freshness"] = classify_lease_freshness(lease, now=now)
-            return lease
+    entries = list(reversed(_lease_entries(comments, pr_number=pr_number)))
+    if not entries:
+        return None
+    newest = entries[0]
+    phase = (newest.get("phase") or "").strip().lower()
+    if phase in _TERMINAL_PHASES:
+        return None
+    if _lease_expired(newest, now=now):
+        return None
+    if phase in _ACTIVE_PHASES or phase:
+        lease = dict(newest)
+        lease["freshness"] = classify_lease_freshness(lease, now=now)
+        return lease
     return None