Build Your AgenticOS: The CLAUDE.md Constitution

CLAUDE.md is where your AgenticOS rules live. It governs every session, every agent, every project.

Every layer in the AgenticOS stack is optional except one. You can skip memory if you're comfortable re-establishing context each session. You can skip shapers if you want to write briefs by hand. You can run without a structured agent library and just prompt directly. None of that is fatal.

Skip CLAUDE.md and you have no system at all.

Without it, every session you start from scratch. You re-explain the same anti-patterns. You remind the agent not to skip code review. You re-establish that parallel fan-out is required for independent tasks. You correct the same mistake twice, then three times, because nothing was written down and the agent's behavior resets on the next cold start.

CLAUDE.md is the instruction layer that governs every session. It is where you encode the rules you are tired of repeating.

Here is what it is, where it sits in the priority stack, what belongs inside it versus what doesn't, and how to write a rule that actually holds.