What are prop firm rules and what does rule guard do?

The limits you must not breach, and a live check that warns you as you approach one rather than after you have broken it.

The rule guard watches your daily loss limit, your trailing drawdown and your contract cap, and warns you while you can still do something about it. It is offered during onboarding and configured under Settings → Prop firm rules.

This is the one settings page where being approximately right is not good enough. A drawdown figure that is close but wrong is a rule you will breach while the app tells you that you are fine.