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Show HN: Plimsoll, a self-hosted sandbox for code your AI agent writes
Brief published October 13, 2026 ยท Original source published October 11, 2026
Original reporting at github.com.
Automated brief. Verify important details at the original source.
What happened
Plimsoll is a self-hosted, open-source sandbox service for executing untrusted code produced by AI agents. Each execution result reports which isolation boundary was active during that run. Callers can specify a minimum required sandbox strength, and requests are rejected if the available isolation falls below that threshold. The project is hosted on GitHub and interactive lessons are available without cloning the repository.
Why it matters
Agent-authored code execution is a growing attack surface, and most tooling leaves developers to infer isolation guarantees indirectly. Plimsoll surfaces the actual sandbox strength per run, giving builders a programmatic way to enforce safety floors rather than assuming a fixed environment. That per-result transparency is uncommon in self-hosted options currently available.
What to watch
Adoption will depend on how clearly the project documents the range of supported isolation backends and what sandbox strength levels map to in practice. Watch for community contributions that expand backend options and whether the strength-reporting mechanism holds up under adversarial agent-generated inputs.