smolmachines / smolvm as a sandbox for untrusted Python & JavaScript

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• Simon Willison’s research identifies smolmachines / smolvm as a well-suited sandbox for untrusted Python and JavaScript code, particularly for data transformations, leveraging hardware-isolated VMs for robust security.
• smolvm provides strong isolation through hardware-isolated VMs (Firecracker), with tested features like CPU/RAM limits, no network access, storage quotas, and guest-enforced timeouts, achieving cold starts of 0.6-1.5 seconds and warm executions around 50 ms.
• The research itself was conducted by Claude Fable 5, which demonstrated “relentlessly proactive” problem-solving by autonomously overcoming its own environment’s limitations (lack of /dev/kvm) by executing tests on GitHub Actions runners.