Claude Wrote a Cosmology Solver in Days — Patterns a Game Dev Wants to Steal

Original research at Anthropic Research . Code on GitHub . More posts at radarlog.kr . TL;DR Anthropic's "Long-running Claude" research shows a workflow where you give an agent a goal and walk away for days. The headline — a cosmology solver built in days — isn't the point. The scaffolding is: CLAUDE.md, CHANGELOG.md, test oracles, and the Ralph loop. I've been using CLAUDE.md already. The rest? Not yet. Here's how I'm planning to bolt them onto my own projects. The research in 30 seconds Anthropic researcher Siddharth Mishra-Sharma handed Claude Opus 4.6 a task outside his own domain: implementing a cosmological Boltzmann solver in JAX. A Boltzmann solver predicts the statistical properties of the CMB (Cosmic Microwave Background) — the afterglow of the Big Bang. This is the kind of code domain experts spend months to years building. A non-expert gave minimal steering. Days later, sub-percent accuracy against the reference implementation. The impressive part isn't Claude's brain. It's