diff --git a/AGENTS.md b/AGENTS.md
index ae48362..fc4af2c 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -106,6 +106,17 @@ TEST; if not, ship it!
 
 ## Code
 
+### Principles
+
+Every change is held to these four, in this order — simplest thing that
+works, written once, built only when needed, behaving as promised:
+
+| Principle | Meaning                                                                                                                                                         |
+| --------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| **KISS**  | Keep it simple. Prefer the plain solution over the clever one; complexity must earn its keep with a need the simple version can't meet.                         |
+| **DRY**   | Don't repeat yourself. A rule two places must agree on is written once and shared — duplication is where the copies drift apart.                                |
+| **YAGNI** | You aren't gonna need it. Build for the requirement in front of you, not the one imagined; speculative machinery is deleted-on-sight, not kept just in case.    |
+
 ### Naming
 
 Descriptive names everywhere. Short names are fine for local variables