docs(vector): add local backup restore and parity gate

harness/tht/adapters/vector/pgvector.py

@@ -257,7 +257,7 @@ class PgVectorStore:
                     where = sql.SQL(" WHERE kind = ANY(%s)") if collection_kinds else sql.SQL("")
                     query = sql.SQL(
                         "SELECT metadata, 1 - (embedding {} %s::{}) AS similarity "
-                        "FROM {}{} ORDER BY embedding {} %s::{} LIMIT %s"
+                        "FROM {}{} ORDER BY embedding {} %s::{}, record_key LIMIT %s"
                     ).format(
                         _cosine_operator(self._schema),
                         _vector_type(self._schema),
@@ -274,7 +274,7 @@ class PgVectorStore:
                     hits.extend(hit_from_metadata(row[1], row[0]) for row in cursor.fetchall())
         finally:
             raw.close()
-        return sorted(hits, key=lambda hit: hit.similarity, reverse=True)[:limit]
+        return sorted(hits, key=lambda hit: (-hit.similarity, hit.id))[:limit]
 
     def _require_writer(self) -> Engine:
         if self._writer is None: