Matchlock is a command-line interface (CLI) tool designed for running AI agents within temporary microVMs. It emphasizes security by incorporating features like network allowlisting and secret injection via a MITM (man-in-the-middle) proxy. This setup ensures that sensitive information never enters the virtual machine. The tool allows users to create a full Linux environment that boots in less than a second, providing isolation and disposability for executing code. When using Matchlock, you can restrict network access by specifying allowed hosts with the `--allow-host` flag and inject secrets into the VM without exposing them. For example, if you need to call an API that requires authentication, Matchlock can inject the real credentials during the request, while the agent only sees placeholder values. Each sandbox operates with a copy-on-write filesystem that disappears after use, maintaining the integrity of the host machine. The CLI works on both Linux with KVM support and macOS on Apple Silicon, making it versatile across platforms. Matchlock also includes Go and Python SDKs, allowing developers to programmatically create and manage sandboxes. In these SDKs, you can set up a sandbox, allow specific hosts, and securely inject secrets before executing commands. This capability is particularly useful for tasks that require internet access without compromising security, such as API calls. The tool's architecture, featuring a policy engine and transparent proxy, enhances its effectiveness in managing network traffic and isolating execution environments.