feat: first-class control-plane lease lifecycle (Closes #601)

Make active leases queryable workflow state with canonical adopt, release,
expire/reclaim, and abandon operations on the #613 control-plane DB substrate.

- lease_lifecycle.py: policy, proof gates, safe_next_action vocabulary
- control_plane_db: schema v3 provenance columns + list/inspect/adopt/abandon
- MCP tools: gitea_*_workflow_lease(s) for list/inspect/adopt/release/expire/abandon/reclaim
- issue_lock_store: sanctioned reclaim of expired author locks (dead pid / missing wt)
- Tests cover lifecycle, foreign steal refusal, allocator compatibility, merger handoff

issue_lock_store.py

@@ -375,6 +375,64 @@ def _same_realpath(left: str | None, right: str | None) -> bool:
         return left == right
 
 
+
+def assess_expired_lock_reclaim(
+    existing_lock: dict[str, Any] | None,
+    *,
+    now: datetime | None = None,
+) -> dict[str, Any]:
+    """Decide whether an expired/stale author issue lock may be reclaimed (#601).
+
+    Required proof (any reclaim of non-live lock):
+    * lease not live (expired or dead pid)
+    * owner process dead OR worktree missing
+    * no force-delete of live foreign ownership
+    """
+    if not existing_lock:
+        return {
+            "reclaim_allowed": True,
+            "reasons": ["no existing lock"],
+            "freshness": assess_lock_freshness(None, now=now),
+        }
+    freshness = assess_lock_freshness(existing_lock, now=now)
+    if freshness.get("live"):
+        return {
+            "reclaim_allowed": False,
+            "reasons": ["lock is still live; cannot reclaim (fail closed)"],
+            "freshness": freshness,
+        }
+    pid = existing_lock.get("session_pid")
+    if pid is None:
+        pid = existing_lock.get("pid")
+    dead = not is_process_alive(pid) if pid is not None else True
+    wt = str(existing_lock.get("worktree_path") or "")
+    missing_wt = (not wt) or (not os.path.isdir(os.path.realpath(wt)))
+    if not (dead or missing_wt):
+        return {
+            "reclaim_allowed": False,
+            "reasons": [
+                "expired/stale lock still has live owner pid and present worktree; "
+                "recovery review required (fail closed)"
+            ],
+            "freshness": freshness,
+            "owner_pid_dead": dead,
+            "worktree_missing": missing_wt,
+        }
+    return {
+        "reclaim_allowed": True,
+        "reasons": [
+            "non-live lock with dead process and/or missing worktree; "
+            "sanctioned reclaim allowed"
+        ],
+        "freshness": freshness,
+        "owner_pid_dead": dead,
+        "worktree_missing": missing_wt,
+        "prior_branch": existing_lock.get("branch_name"),
+        "prior_worktree": existing_lock.get("worktree_path"),
+        "prior_pid": pid,
+    }
+
+
 def assess_same_issue_lease_conflict(
     existing_lock: dict[str, Any] | None,
     *,
@@ -405,6 +463,11 @@ def assess_same_issue_lease_conflict(
         and _same_realpath(str(existing_worktree or ""), worktree_path)
     )
     if is_lease_expired(existing_lock, now=now):
+        reclaim = assess_expired_lock_reclaim(existing_lock, now=now)
+        if reclaim.get("reclaim_allowed"):
+            # #601: expired + dead pid / missing worktree may be reclaimed
+            # through the normal lock path (sanctioned overwrite).
+            return None
         return (
             f"Issue #{issue_number} has an expired {operation_type} lease on "
             f"branch '{existing_branch}' from worktree '{existing_worktree}'. "