Show HN: Mdarena – Benchmark your Claude.md against your own PRs

hudsongr

Hey! I built this because everyone's writing CLAUDE.md files now but nobody knows if theirs actually works. The research is contradictory too, one paper says they hurt performance, another says they help. So I made a tool that just measures it on your own repo using your own PRs and your own test suite. Turns out it's not often you can point to a single markdown file and say "this made the agent 27% better at resolving real tasks." That's what we saw on our production monorepo. I imagine this as a way for teams to actually make their agents write better code instead of guessing.