feat: add authenticated engine processing boundary

site/services/grouping.py

@@ -15,6 +15,7 @@ from db import supplements as db_supplements
 from db import dossiers as db_dossiers
 from db import exceptions as db_exceptions
 from db import extractions as db_extractions
+from db.connection import transaction
 
 
 _HOMOGLYPHS = str.maketrans({
@@ -164,6 +165,12 @@ def _dossier_exception(batch_id, document_id, title, source_quote):
 
 
 def build_dossiers_for_batch(batch_id):
+    """Atomically rebuild the dossier graph, retaining the old graph on failure."""
+    with transaction():
+        return _build_dossiers_for_batch(batch_id)
+
+
+def _build_dossiers_for_batch(batch_id):
     """Построить и сохранить dossier graph из паспортов документов одного batch.
 
     Полные номера и ссылки образуют рёбра только при совместимом контрагенте.