1. Persona Scoping File
A markdown document loaded at session start to scope WHO the agent is. Sets voice, expertise lens, hard constraints, anti-patterns it flags. It has no execution life of its own — it is text loaded into a context window.
INDUSTRY TERMS: “agent file”, “subagent definition”, “mode”, “AGENTS.md”.
WHEN TO USE: any time a body of work benefits from a stable lens (a domain expert, a reviewer voice, an arbitrator persona).
KEY PROPERTY: orthogonal to threads. A persona is loaded INTO a thread. A thread is not a persona. Conflating the two is the most common error in this domain.
See also
Section titled “See also”- Child-Thread Spawn — the runtime that personas are loaded into.
- Module Entrypoint — the unit of REUSE; can compose with personas.
- Per-harness paths and frontmatter for persona files: Harness setup.