Read-Mostly: Letting AI Assistants Run Real Slurm Jobs Safely

Between 1 October 2026, when the specification and first release were written, and 27 October I built ursa-bifrost, a Model Context Protocol (MCP) server and command-line tool (CLI) that lets AI assistants work on Ursa Major, UC Riverside Research Computing's Slurm cluster on Google Cloud. It reached v0.10.1 in 42 tagged releases. Assistants can read what a researcher could read about their own jobs. They can change state only through a two-step submit that is capped, bound to the exact plan, and logged. By design there is no shell tool. The main lesson is about testing. A mutation script switches off each of 219 safety guards in turn and requires some test to fail, so each guard is known to be needed. An outside review found three approval checks that existed, passed every test and were wrong. Live tests found a worse bug: a confirm token five processes could redeem at once. Real use so far is one person, me, plus programs running as me. On 28 October I forked the code as ClusterWand, a public tool that runs over a person's own SSH login. Field Notes technical report. Web edition: https://charles-forsyth.github.io/papers/2026-10-29-read-mostly-ai-on-slurm.html. This record holds the PDF (ACM sigconf, PDF/A-2b) and the LaTeX source.