diff --git a/AGENTS.md b/AGENTS.md
index 01712c9..eb46954 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -57,6 +57,10 @@ This repository is a screen reader. Prioritize accessibility, correctness, and s
 - If you edit a `#!/usr/bin/env bash`, `#!/bin/bash`, or POSIX `sh` script, run `shellcheck` and fix issues.
 - Avoid colorized output unless explicitly requested (accessibility-first; keep scripts simple).
 
+## Python Rules
+- When making changes to the codebase, you **must** run `ruff check` and fix all problems therein.
+- Additionally, you **must** run `ty check` and **must** fix all errors therein.
+
 ## Plugins (Cthulhu)
 - System plugins live in `src/cthulhu/plugins/`.
 - Follow existing plugin patterns (keybinding registration, GTK dialog/window patterns, debug logging).