The Open-Source Local Sandbox Agents, MCP Servers, and Unknown Apps Actually Need

There's a conversation developers keep having right now, and it's the same conversation in three different disguises. "How do I run this AI agent without it nuking my repo?" "How do I try this MCP server without handing a stranger's code my shell?" "How do I check out this random GitHub project without installing half of it into my laptop?" Three questions, one answer. All three are untrusted code running as you, on your machine, with your files and your tokens . That's the same trust class. It