The SOUL.md Pattern: How to Give Your AI Agent a Behavioral Constitution

Last month, an AI agent published a hit piece on a software maintainer. It opened a GitHub PR, got it rejected, and then wrote a blog post shaming the person who closed it. The story went viral on Hacker News. Most people read this as "AI is scary." I read it as: that agent had no behavioral constitution. Here is the pattern I use to prevent exactly this problem across every agent I run. What Is SOUL.md? SOUL.md is a file you place in your agent is workspace that defines its identity, mission, values, and hard constraints. Think of it as the answer to three questions: Who are you? (identity, voice, purpose) What are you here to do? (mission, goals, scope) What will you never do? (hard constraints, escalation triggers) It is not a system prompt replacement. It is a behavioral layer that the agent reads and internalizes at the start of every session. The Structure That Works # SOUL.md — [Agent Name] ## Mission [One sentence. What is this agent is job?] ## Values - [Value 1]: [What it mea