diff --git a/README.md b/README.md
index ac4883e1..d1d828be 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,14 @@
 
 Soroban smart contracts for the Callora API marketplace: prepaid vault (USDC) and balance deduction for pay-per-call settlement.
 
+## API stability snapshots
+
+Client-facing contract error code numbers are treated as part of each
+contract's public API. The checkpoint contract freezes its
+`CheckpointError` discriminants with a focused snapshot test in
+`contracts/checkpoint/tests/err_stab.rs` so accidental renumbering is caught
+by diff.
+
 [![CI](https://github.com/CalloraOrg/Callora-Contracts/actions/workflows/ci.yml/badge.svg)](https://github.com/CalloraOrg/Callora-Contracts/actions/workflows/ci.yml)
 [![Coverage](https://github.com/CalloraOrg/Callora-Contracts/actions/workflows/coverage.yml/badge.svg)](https://github.com/CalloraOrg/Callora-Contracts/actions/workflows/coverage.yml)
 
diff --git a/contracts/allowlist/tests/auth.rs b/contracts/allowlist/tests/auth.rs
index cff3452e..93c375a1 100644
--- a/contracts/allowlist/tests/auth.rs
+++ b/contracts/allowlist/tests/auth.rs
@@ -34,6 +34,7 @@ use soroban_sdk::{token, Address, Env, IntoVal, Vec};
 
 use callora_vault::{CalloraVault, CalloraVaultClient};
 
+
 // ---------------------------------------------------------------------------
 // Helpers
 // ---------------------------------------------------------------------------