Many Terraform discussions focus on variables, workspaces, or deployment pipelines. The larger question is what actually prevents a mistake from reaching production.
Environment separation is a boundary design problem.
AWS accounts, root modules, state files, and workspaces all provide different levels of isolation. They do not offer the same protection, and understanding those differences is important when designing infrastructure at scale.
In this lesson, we examine how Terraform environments are separated, why state acts as infrastructure memory, and how stronger boundaries reduce blast radius when changes go wrong.