diff --git a/AGENTS.md b/AGENTS.md
index 3cdde89f..50b54a41 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -163,6 +163,7 @@ After pushing, verify in the browser:
 - No build step, no transpilation — write ES2020 for server, ES5/6 for frontend (broad browser support)
 
 ## What NOT to Do
+- **Don't check in private information** — no names, API keys, tokens, passwords, IP addresses, personal data, or any identifying information. This is a PUBLIC repo.
 - Don't add npm dependencies without asking
 - Don't create a build step
 - Don't add framework abstractions (React, Vue, etc.)