Tangentially, I've been investigating the last few days on how to setup a separate Linux box as an agent "playground". I got a mac mini to use as my own personal driver and now my Linux box is free, so I want to have a local setup where I keep my personal machine a bit stricter while giving near free-reign for agents on the Linux machine.
It is like a locally-hosted version of these commercial projects. But I'm doing it ad-hoc. This seems like a space that should be filled by open source. What are the options that exist now? I have pro plans for both Codex and Claude Code and enough credits to run a couple instances of each. I want to control them from the mac mini over a tailnet. What options exists now?
Agent Substrate from google if you wanna go hardcore, although it adds quite a bit of complexity and management that you probably don't want if it's just a personal setup - https://github.com/agent-substrate/substrate
Docker with tailnet is probably good enough for your usecase.
https://pleasedonotescape.com/
I recommend "byre" from that list, because I built it. You can inject credentials you want into it, but it can't touch the host. I run all my coding harnesses inside it. At the end of the day, it's a flexible and reusable way of spinning up Docker containers designed for agents.
Use smolvm, support for tailscale in each VM.
https://github.com/smol-machines/smolvm