fix: close Human Gates review races

src/human_gate_store.py

@@ -218,15 +218,20 @@ class HumanGateStore:
                 if immutable_old != immutable_new:
                     raise GateConflict("Candidate hash is already bound to different facts")
                 if old_payload != payload:
+                    if existing["state"] == "superseded":
+                        raise GateConflict("Candidate hash was superseded by a newer candidate")
                     now = float(self.clock())
                     revision = existing["revision"] + 1
+                    reopened = existing["state"] in {"released", "held"}
+                    state = "pending" if reopened else existing["state"]
+                    action = "reopened" if reopened else "updated"
                     connection.execute(
-                        "UPDATE human_gates SET payload_json=?, revision=?, updated_at=? WHERE id=?",
-                        (_canonical(payload), revision, now, existing["id"]),
+                        "UPDATE human_gates SET payload_json=?, state=?, revision=?, updated_at=?, decision_reason='', override_reason='', checklist_json='{}' WHERE id=?",
+                        (_canonical(payload), state, revision, now, existing["id"]),
                     )
                     connection.execute(
                         "INSERT INTO human_gate_history(gate_id,action,at,details_json) VALUES (?,?,?,?)",
-                        (existing["id"], "updated", now, _canonical({"candidate_hash": payload["candidate_hash"]})),
+                        (existing["id"], action, now, _canonical({"candidate_hash": payload["candidate_hash"]})),
                     )
                     existing = connection.execute(
                         "SELECT * FROM human_gates WHERE id=? AND login=?",