While using multiple agents, including Claude Code and Codex, I ran into a problem: the same principles (in CLAUDE.md, AGENTS.md, and other files) ended up spread across at least two places.

I had trouble finding accounts of how others had handled this problem, so I'm sharing my approach.

Written by a human (roughly 80% human, 20% AI). translated into English with AI help.

Background: The Need for a Single Source of Truth for Instructions

At work, we currently maintain instructions at several scopes: project-level instructions (committed to GitHub), user-level global instructions on my machine, and local project-level instructions.…