Sandbox runtimes deprecated in favor of versioned container images (universal, node, python, ubuntu, arch) pinned or rolling via tags, defaulting to Ubuntu with Node 24, Python 3.14, and preinstalled coding agents.
Summary
Eliminates custom image builds for most workloads and guarantees automatic security patches nightly while maintaining reproducibility via digest pinning. Shifts from Amazon Linux to Ubuntu aligns local dev environments with broader industry standard.
Why it matters
Eliminates custom image builds for most workloads and guarantees automatic security patches nightly while maintaining reproducibility via digest pinning. Shifts from Amazon Linux to Ubuntu aligns local dev environments with broader industry standard.
Implementation verdict
Replaces the deprecated `runtime` property with `image` property; existing code still works but should migrate. Requires SDK version 3+. Ready now—no breaking changes for existing sandboxes, but new projects should adopt managed images immediately to get automatic updates and smaller footprint.
Sources
Dev Signal
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