The spec
Two files define who your agent is.
You write personaxis.md, the quantitative source: who the agent is across ten layers, with values and ranges. It compiles to PERSONA.md, the document your agent actually reads, which holds character steady across models and long sessions and can self-improve over time. One source, portable across every model, versionable, and auditable when it matters.
Two files
The behavioral layer is the most important part of an AI system, and it has never had a complete standard.
personaxis.md
The source you write: YAML frontmatter across ten layers, each with values and ranges, plus a Markdown body. It lives in .personaxis/, versioned with your repo.
PERSONA.md
What compile produces from it: a self-contained Markdown document your agent reads to know who it is. It is committed next to personaxis.md; edit either side and the CLI keeps them in sync.
MIT licensed, published on GitHub. The standard is open; Personaxis builds the tooling around it.
Ten dimensions
Each maps to a layer in personaxis.md. Together they define an AI Persona completely.
identity:
Who the agent is
character:
Values and principles
personality:
Style and temperament
values_and_drives:
Goals and value hierarchy
affect:
Functional affective state
cognition:
How it reasons
memory:
What persists across sessions
metacognition:
Self-model and meta-awareness
reflexive_self_regulation:
Principled refusals and limits
persona:
How it presents itself
How it works
Write
Run personaxis init and fill in each layer of your AI Persona.
Validate
The CLI checks your spec against the schema and flags missing or contradictory fields.
Compile
Compile to PERSONA.md for Claude Code, or the equivalent for Codex. One source, every tool.
Version
Version each release and push it. Signed, diffable, and pullable from any machine or team.
Fits your stack
PERSONA.md completes the triangle. It does not replace the standards you already use.
AGENTS.md
What your agent does in the repo
SKILL.md
What your agent can do
PERSONA.md
Who your agent is
Why we built it.
Five beliefs about AI agents, character drift, and why the spec was missing.