Fix PostgreSQL file visibility queries

tests/test_share_lifecycle.py

@@ -5,6 +5,7 @@ from datetime import timedelta
 from unittest.mock import patch
 
 from sqlalchemy import create_engine
+from sqlalchemy.dialects import postgresql
 from sqlalchemy.orm import sessionmaker
 
 from govoplan_access.backend.db.models import Account, Group, User
@@ -13,6 +14,7 @@ from govoplan_core.db.base import Base
 from govoplan_files.backend.db.models import FileAsset, FileShare
 from govoplan_files.backend.storage.common import FileStorageError, utcnow
 from govoplan_files.backend.storage.files import (
+    _asset_visibility_query_for_user,
     get_asset_for_user,
     list_file_shares,
     revoke_file_share,
@@ -214,6 +216,22 @@ class FileShareLifecycleTests(unittest.TestCase):
                 expires_at=utcnow() - timedelta(seconds=1),
             )
 
+    @patch(
+        "govoplan_files.backend.storage.files.user_group_ids",
+        return_value=[],
+    )
+    def test_visibility_query_is_postgresql_json_safe(self, _groups) -> None:
+        query = _asset_visibility_query_for_user(
+            self.session,
+            tenant_id=TENANT_ID,
+            user_id=RECIPIENT_ID,
+        )
+
+        compiled = str(query.statement.compile(dialect=postgresql.dialect()))
+
+        self.assertNotIn("SELECT DISTINCT", compiled.upper())
+        self.assertIn("EXISTS", compiled.upper())
+
 
 if __name__ == "__main__":
     unittest.main()