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Simon Willison Ships 'micropython-wasm' — A Self-Hostable WASM Sandbox for Running Untrusted Agent Code, Locks GPT-5.5 Inside and Dares It to Escape
On June 6 Willison released an alpha package (micropython-wasm) that runs untrusted Python inside a 362KB WebAssembly binary with enforced memory, CPU, and file/network limits — the safe-code-execution primitive he's chased for years — and wired it into a Datasette Agent plugin (datasette-agent-micropython). He locked GPT-5.5 xhigh inside the sandbox and challenged it to break out; so far it hasn't. For builders shipping agents that execute model-generated code, this is a practical, container-free sandbox pattern you can self-host rather than renting cloud VMs.
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