Hazmat: a Go tool that runs Claude Code, Codex, OpenCode and Cursor Agent under a separate macOS user with a kernel sandbox and pf firewall — TLA+ verified

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Help Net Security covered Hazmat (Aug 17, 2026), an open-source containment layer for coding agents that gives each agent its own macOS user account, kernel-enforced sandbox, firewall, DNS blocklist and automatic pre-session backup, printing the session's write paths, read-only paths and network reach before launch. The premise is that an agent launched normally runs as you and can read every SSH key and cloud credential in your home directory. The GitHub repo (dredozubov/hazmat) is small — 128 stars, created March 27, 2026 — so this is early tooling, but it is the clearest answer yet to the 'agent runs with my full identity' problem.