- Who it helps
- Developers researching bounded execution for agent-generated code.
- Availability
- The October 1 prerelease and release notes are public. The notes describe Python compatibility and bundled guest runtimes; this sweep did not install the package.
What the release adds
The release exposes guest execution and resource-limit interfaces. Its lightweight WASI layer documents no filesystem or network access. Registered host callbacks remain an important part of the boundary a developer must understand.
What a useful test would establish
For an evaluation, first define allowed outputs and denial cases. A harmless arithmetic task should return its result; a deliberate infinite loop should terminate at the configured limit. Save the environment and result for each case. This is a proposed test plan. The implementation has not been run here.
What you can do
- Inspect the prerelease documentation and its security assumptions before choosing it as an execution component. Compare a small permitted task and a resource-limit failure in an isolated evaluation environment. Open reference ↗
Where the evidence stops
No package or security boundary was tested. A prerelease and its author-reported test coverage do not certify containment for arbitrary untrusted programs.
Sources read. Primary material was read on October 18, 2026. The external software, account workflow and reported results were not independently executed.
Sources & further reading
GitHub · implementation
pwasm 0.2a0 prerelease ↗
Selected for its direct evidence about this subject, its access conditions or a specific practical limitation.
Simon Willison · page checked 2026-10-18 · Published 2026-10-01
Coverage note: Primary evidence is available. Independent demonstrations and current cross-platform discussion are incomplete in this bounded sample.
The record over time (1)
Dated source checks and published explanations. An observation date can differ from the original release date.
The pwasm 0.2a0 prerelease adds bundled WebAssembly versions of MicroPython and JavaScript engines, with documented controls for memory and execution limits.