I built ra to understand how tools like Claude Code and Codex actually work under the hood. It's a single CLI binary where a config file is the agent — change the config, change what the agent does. Same binary runs as a REPL, HTTP server, cron job, or MCP server. Drop a config in your repo and your whole team gets the same agent.
Every line of code, tests, docs was written by AI using Claude Code. The blog post covers the full workflow — what worked, what didn't. If you need a simple, cross-provider agent harness, give it a shot!