Go hard on agents, not on your filesystem

jai is a lightweight sandboxing tool that wraps AI coding agents (Claude Code, Codex, etc.) with filesystem isolation — no Docker, no Dockerfiles, just a single command prefix. The working directory gets full read/write access while the rest of the home directory is protected via copy-on-write overlay or hidden entirely. Directly addresses the growing problem of AI agents and untrusted installer scripts causing accidental file loss or home directory wipes.