I had Mac Minis sitting in the corner doing nothing and a laptop battery that tanks whenever I run tests when working from a coffee shop & on battery power. So I built a CLI that syncs code over SSH and runs commands remotely on my (usually) idle hardware. That's basically it.
``` brew install rileyhilliard/tap/rr rr run "make test" ```
Where this got surprisingly useful: heavy TDD with Claude Code. When you're running swarm agents or sub-agents, they all want to run tests constantly to verify their work. Great in theory, but suddenly you've got 3-4 parallel processes all hammering your test suite at once on your laptop. Tests fail because they're stomping on each other, ports are already in use, your laptop is melting, etc.
rr handles the coordination automagically. It tries your LAN IP first, falls back to Tailscale when you're remote, and waits if someone else (which is probably you in another terminal) is already using the machine. Throw multiple hosts at it and it'll load balance across whatever's available.
``` hosts: mini-1: ssh: - 192.168.1.50 - mini1-tailscale mini-2: ssh: - 192.168.1.51 - mini2-tailscale ```
The parallel execution part is where it gets quite nice. My test suite takes ~60s on one machine. Partitioned across three, it finishes in ~20s. Same tests, 3x faster. Agents checking work via TDD stay productive instead of sitting around waiting.
This isn't really a CI/CD thing (that's async, runs when you push). rr is for your active dev loop when you want results NOW so you can keep iterating.
Any hardware that holds an SSH connection works. Old laptops, cloud boxes, whatever. Minimal setup on the remote side.