Comment by cortesi
I have a tiny, relevant weekend project:
https://github.com/cortesi/agentsmd
This is a command-line tool that lets you generate your AGENTS.md and CLAUDE.md files from common sources. So, for instance, if you have Rust-specific guidance for models, you can define it once, and then automatically include it in any project that contains Rust based on the `lang()` language matcher.
This is one of those small tools I now use many times a day to maintain and update ubiquitous agents files. Maybe other folks will find it useful too.
We are going the opposite way, putting instructions in md files and putting instructions in the Claude.md file when it should read those instructions.