Nexus is basically a daemon that runs and routes messages to where they need to be, it is fully customizable, which you can write scripts off of so that it will wake agents or route that message to an already existing agent. Right now it supports Codex, Claude Code, OpenCode and Hermes. But more are underway. It runs on your machine with no container required. (In my opinion, messaging within your machine should not require you to have to run a container.)
To try it:
npm install --global @egregore/nexus
It runs on Linux, Windows and WSL today; It can run on mac but I havent fully tested it also you would have to build the binaries yourself for the latest version though. Full support for it is planned in the near future.