> The sandbox runs inside WebAssembly with WASI for a minimal syscall interface. WASM provides memory isolation by design—linear memory is bounds-checked, and there's no way to escape to the host address space. The wasmtime runtime we use is built with defense-in-depth and has been formally verified for memory safety.
> On top of WASM isolation, every tool call goes through capability validation: [...]
> The design draws from capability-based security as implemented in systems like seL4—access is explicitly granted, not implicitly available. Agents don't get ambient authority just because they're running in your process.
agentvm looks very cool! They are taking a different approach - full Linux VM emulated in WASM. It's very impressive technically.
We differentiate from agentvm by being lightweight (~11 MB Wasm binary, compared to 173 MB for agentvm). Though there is still a lot we can learn from agentvm, thank you for sharing their project.
Thank you! When I started working on agentvm my original goal was similar to yours, build a kind of Mingw or Cygwin for WASM. However, I quickly learned that this wouldn't really be feasible with reasonable amounts of time/token spend, mostly due to issues like having to find a way to make fork work, etc. I am no expert for WASM or Linux system programming, but it's been a lot of fun working on this stuff. I hope that the WASI standard and runtimes become more mature, as I feel that WASM sandboxes make a lot of sense in environments where containers are not an option.
> Don't there need to be per- CPU/RAM/GPU quotas per WASM scope/tab? Or is preventing DOS with WASM out of scope for browsers?
> IIRC, it's possible to check resource utilization in e.g. a browser Task Manager, but there's no way to do `nice` or `docker --cpu-quota` or `systemd-nspawn --cpu-affinity` to prevent one or more WASM tabs from DOS'ing a workstation with non-costed operations.
Thanks for sharing the context! The fork problem is gnarly. Makes sense that full Linux emulation was the path forward for your use case.
Agreed on WASI maturity. We're hoping the component model lands in a stable form soon. Would love to see the ecosystem converge so these approaches can interoperate.
> Security model
> The sandbox runs inside WebAssembly with WASI for a minimal syscall interface. WASM provides memory isolation by design—linear memory is bounds-checked, and there's no way to escape to the host address space. The wasmtime runtime we use is built with defense-in-depth and has been formally verified for memory safety.
> On top of WASM isolation, every tool call goes through capability validation: [...]
> The design draws from capability-based security as implemented in systems like seL4—access is explicitly granted, not implicitly available. Agents don't get ambient authority just because they're running in your process.