Reverse-Engineering Claude Web's Hidden Antspace MicroVM: What Firecracker Isolation Tells Us
Every Claude Code Web session you run doesn’t execute on a shared server — it boots inside a dedicated Firecracker microVM managed by an undocumented Anthropic platform codenamed Antspace. That is the finding that emerged in March 2026 when developer AprilNEA ran a single strace -p 1 command inside a Claude Code Web sandbox and exposed a five-layer architecture: a Firecracker microVM, an unstripped 27MB Go runner binary, a Rust process supervisor, a mature but completely undocumented deployment PaaS, and a web-app builder codenamed Baku. This post walks through how the discovery was made, what each layer reveals, and why it changes how you should think about isolating your own agent workloads. ...