Behavior specs for Kagan, one folder per feature. kagan-supervision-board/ covers the whole plugin today.

1. requirements.md — what must be true. EARS-style acceptance criteria with stable numbers (R1–R18); code and tests trace to these. When documents disagree, this one wins.
2. design.md — how it's built: architecture constraints, the metadata model, and the key flows, each traced to the requirements it satisfies.
3. mental-model.md — why it exists: intent, anti-goals, and ideas already evaluated and rejected. Judge new feature proposals against this before writing requirements.

mental-model.md → the Map in AGENTS.md → src/domain/task/metadata.ts → src/server.ts.

A behavior change lands with matching requirements.md, design.md, docs/, and README updates in the same change — cite the requirement numbers (e.g. R9.16) it adds or alters. Implementation task breakdowns are working artifacts: keep them in .plans/ (gitignored), never committed here.