diff --git a/AGENTS.md b/AGENTS.md
index 474fe6e7f..add9d5040 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -13,6 +13,7 @@
 - **Ruby Version**: Manage Ruby via `rbenv` and install the version listed in `.ruby-version` (e.g., `rbenv install $(cat .ruby-version)`)
 - **rbenv setup**: Before running any `bundle` or `rspec` commands, init rbenv in your shell (`eval "$(rbenv init -)"`) so the correct Ruby/Bundler versions are used
 - Always prefer `bundle exec` for Ruby CLI tasks (rspec, rake, rubocop, etc.)
+- **Test env**: Specs should run without `.env`. If present, temporarily rename it (e.g., `.env` -> `.env.bak`) while running specs and restore afterward.
 
 ## Code Style