Rationale
Every noun is a concept a worker has to learn and a surface that can drift; the design stays small on purpose, and docs/CONCEPTS.md is the whole vocabulary.
Required behaviour
The tool gains no agents, personas, roles, tiers or registries beyond the vocabulary it has.
Failure behaviour
No command decides this rule; a reviewer does, and a change that violates it is not merged. Where a behavioural case covers part of it, that case is named below.
Verification
Review. test/cases/28_no_hardcoded_values.sh checks that every term in docs/CONCEPTS.md is one the tool uses.