ethos noun — Merriam-Webster: “The distinguishing character, sentiment, moral nature, or guiding beliefs of a person, group, or institution.”
Navigator™ agents carry ETHOS.md files — not system prompts, guardrails, constitutions, or principles. The distinction matters.
System prompts issue instructions for a session. Guardrails block specific outputs. Constitutions declare values. Principles state guidelines. All of these tell an agent what to do, what to avoid, or what to stand for.
Ethos is different. In Webster’s own terms, it is the distinguishing character of an entity — not what it is told, but what it is. An agent that carries an ETHOS.md has internalized the guiding beliefs that govern how it acts when no instruction, guardrail, or declared principle covers the situation.
You can write a constitution in an afternoon. You cannot shortcut character.
That is why Navigator is built this way.