diff --git a/AGENTS.md b/AGENTS.md
index 14887dc..6d449e5 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -29,6 +29,7 @@ Build a reliable, maintainable salon booking platform with Django (backend) and
 - Avoid introducing regressions without covering a fix or guardrail.
 - Payment and booking flows must be idempotent and auditable.
 - Phone auth must be rate‑limited and safe from abuse.
+- Every change should be tested before completion; no exceptions.
 
 ## Testing Expectations
 ### Backend