The sandbox (macOS).
nd7 run claude and nd7 run codex start the agent, and every program it launches, inside one sandbox. The rules: the agent may write only inside your project, the temporary folder and its own state directory, ~/.claude or ~/.codex. It may read everywhere except your keys and credentials. It may make HTTPS connections and nothing else. The operating system enforces these rules, so neither the model nor a compromised package can loosen them from inside.