Let's discuss sandbox isolation

I disagree with this section about WebAssembly:

> But the practical limitation is language support. You cannot run arbitrary Python scripts in WASM today without compiling the Python interpreter itself to WASM along with all its C extensions. For sandboxing arbitrary code in arbitrary languages, WASM is not yet viable.

There are several versions of the Python interpreter that are compiled to WASM already - Pyodide has one, and WASM is a "Tier 2" supported target for CPython: https://peps.python.org/pep-0011/#tier-2 - unofficial builds here: https://github.com/brettcannon/cpython-wasi-build/releases

Likewise I've experimented with running various JavaScript interpreters compiled to WASM, the most popular of those is probably QuickJS. Here's one of my many demos: https://tools.simonwillison.net/quickjs (I have one for MicroQuickJS too https://tools.simonwillison.net/microquickjs )

So don't rule out WASM as a target for running non-compiled languages, it can work pretty well!

I appreciate the details in this, but I also notice it is very machine-focused. When a user wants to sandbox an AI agent, they don’t just want their local .ssh keys protected. They also want to be able to control access to a lot of off-machine resources - e.g. allowing the agent to read github issues and sometimes also make some kinds of changes.

I also disagree with that.

Wasmer can run now Python server-side without any restrictions (including gevent, SQLAlchemy and native modules!) [1] [2]

Also, cool things are coming on the JS land running on Wasmer :)

[1] https://wasmer.io/posts/greenlet-support-python-wasm

[2] https://wasmer.io/posts/python-on-the-edge-powered-by-webass...

I'm mainly addressing sandboxing by running stuff in Claude Code for web, at which point it's Anthropic's problem if they have a sandbox leak, not mine.

It helps that most of my projects are open source so I don't need to worry about prompt injection code stealing vulnerabilities. That way the worst that can happen would be an attack adding a vulnerability to my code that I don't spot when I review the PR.

And turning off outbound networking should protect against code stealing too... but I allow access to everything because I don't need to worry about code stealing and that way Claude can install things and run benchmarks and generally do all sorts of other useful bits and pieces.

QubesOS was built to give sandboxes kernel isolation via a hypervisor.

It’s not surprising that most people don’t know about it, because QubesOS as a daily driver can be painful. But with some improvements, I think it’s the right way to do it.