/errors/authentication_error.proto 

--- v18/errors/authentication_error.proto   2025-08-05 14:36:12.000000000 +0000
+++ v19/errors/authentication_error.proto   2025-08-05 14:36:15.000000000 +0000
@@ -108,5 +108,8 @@
     // The Cloud organization associated with the project is not associated with
     // the developer token.
     ORGANIZATION_NOT_ASSOCIATED_WITH_DEVELOPER_TOKEN = 28;
+
+    // The developer token is not valid.
+    DEVELOPER_TOKEN_INVALID = 29;
   }
 }