diff --git a/contracts/fee/tests/err_stab.rs b/contracts/fee/tests/err_stab.rs
index d0f132dd..c77a4693 100644
--- a/contracts/fee/tests/err_stab.rs
+++ b/contracts/fee/tests/err_stab.rs
@@ -2,6 +2,8 @@
 
 use callora_fee::errors::ContractError;
 
+/// Asserts that every error discriminant is pinned to its declared u32 value.
+/// These values are part of the public ABI — never renumber them.
 #[test]
 fn test_fee_error_stability() {
     assert_eq!(ContractError::NotInitialized as u32, 1);