On the one hand, you're right: those commit messages are proof positive that the security is not perfect. On the other hand, the threat model is that most threats from AI agents stem from human inattention, and that agents powered by hyperscaler models are unlikely to be overtly malicious without an outside attacker.

There are some known limitations of the security model, and they are limitations that I can accept. But I do believe that yolo-cage provides security in depth, and that the security it provides is greater than what is achieved through permission prompts that pop up during agent turns in Claude Code.

Then I was talking to a security engineer at my company, who pointed out that a VM would make him feel better about the whole thing anyway. And it occurred to me: if I packaged it as a VM, then I'd get both isolation and determinism. It would be easier to install and easier to debug.

So that's why I decided to go with a Vagrant-based installation. The obvious downside is that it's harder now to integrate it with external systems or to use the full power of whatever environment you deploy it in.

> I want to be direct: containers are not a sufficient security boundary for hostile code. They can be hardened, and that matters. But they still share the host kernel. The failure modes I see most often are misconfiguration and kernel/runtime bugs — plus a third one that shows up in AI systems: policy leakage.

¹ https://www.luiscardoso.dev/blog/sandboxes-for-ai

What's my role here? Over the past year, it's become clear to me that there are really two distinct activities to the business of software development. The first is the articulation of a process by which an intent gets actualized into an automation. The second is the translation of that intent into instructions that a machine can follow. I'm pretty sure only the first one is actually engineering. The second is, in some sense, mechanical. It reminds me of the relationship between an architect and a draftsperson.

I have been much freer to think about engineering and objectives since handing off the coding to the machine. There was an Ars Technica article on this the other day that really nails the way I've been experiencing this: https://arstechnica.com/information-technology/2026/01/10-th...

Why do I trust the finished product if I don't trust the environment? This one feels a little more straightforward: it's for the same reason that construction workers wear hard hats in environments that will eventually be safe for children. The process of building things involves dangerous tools and exposed surfaces. I need the guardrails while I'm building, even though I'm confident in what I've built.

Wait, do you also think there are no guardrails in a production system that would fundamentally alter the security posture of a system rather than on a single laptop with a single developer would engender.

Wait, do you not believe all the AI companies aren't also trying to develop (have developed) their own sandboxing solutions?

Wait, did you even bother to think about what you were writing before you decided to write it?

I think it's the convergence of two things. First, the agents themselves make it easier to get exactly what you want; and second, the OEM solutions to these things really, really aren't good enough. CC Cloud and Codex are sort of like this, except they're opaque and locked down, and they work for you or they don't.

It reminds me a fair bit of 3D printer modding, but with higher stakes.

https://www.anthropic.com/research/small-samples-poison

(A small number of samples can poison LLMs of any size) to save clicks to read the headline

The way I think of it is, coding agents are power tools. They can be incredibly useful, but can also wreak a lot of havoc. Anthropic (et al) is marketing them to beginners and inevitably someone is going to lose their fingers.

As far as lock-in, though, that's been much less of a problem. It's insanely easy to switch because these tools are largely interchangeable. Yes, this project is currently built around Claude code, but that's probably a one-hour spike away from flexibility.

I actually think the _lack_ of lock-in is the single biggest threat to the hyperscalers. The technology can be perfectly transformative and still not profitable, especially given the current business model. I have Qwen models running on my Mac Studio that give frontier models a run for their money on many tasks. And I literally bought this hardware in a shopping mall.

That said, I have not yet started playing with MCP servers. I suspect that they are completely broken inside yolo-cage right now, as they almost certainly get stopped by the proxy.

Anthropic is trying to earn developer trust; they have a strong incentive to make sure that private keys and other details that the agent sees do not leak into the training data. But the agent itself is just a glorified autocomplete, and it can get confused and do stupid stuff. So I put it in a transparent prison that it can see out of but can't leave.

That definitely helps with the main failure modes I was worrying about, but it's just one layer. You definitely want to make sure that your production secrets are in an external vault (Hashicorp Vault, Google Secret Store, GitHub secrets, etc) that the agent can't access.

The things that agent is seeing should be dev secrets that maybe could be used as the start of a sophisticated exploit, but not the end of it. There's no such thing as perfect security, only very low probabilities of breach. Adding systems that are very annoying to breach and have little offer when you do greatly lowers the odds.

For Claude specifically, there are two places where it tracks state:

~/.claude.json -- contains a bunch of identity stuff and something about oauth

~/claude/ -- also contains something about oauth, plus conversation history, etc

If they're not _both_ present and well-formed, then it forces you back through the auth flow. On an ordinary desktop setup, that's transparent. But if you want to sandbox each thread, then sharing just the token requires a level of involvement that feels icky, even if the purpose is TOS-compliant.

I have my own Docker image for similar purpose, which is for multiple agent providers. Works great so far.