Rationale
Every entry in decisions.md carries the task, the head and the reason, so a decision can be found by the worker who needs it.
Required behaviour
Every recorded decision carries the task, the head and the reason, so the worker who needs it can find it.
Failure behaviour
A violation is a WARN finding under the category records; the command continues and exits as it otherwise would. Under watch it is reported as drift and the command exits 11.
Verification
mj_validate_decisions decides it, dispatched from check, doctor, watch. The behavioural case test/cases/21_decision_question.sh proves it, and CI runs that case.