Refusals: refuse

refuse stops the action and speaks a phrase. The conditional form refuse when <condition>: <key> refuses only when its condition holds, as the mittens line above shows. The bare form refuses always, for things that are simply never allowed:

  on taking it
    refuse all-thorns
  end on

The named key resolves entity-scoped first (ADR-231): a phrase all-thorns: override in the refusing entity's own create block wins over a story-wide all-thorns, and a bare key renders on standard actions just as it does on story-defined ones. The key is a single kebab-case word; dots are illegal (ADR-254).

Refusing on a negated condition (refuse when not …) is flagged (analysis.negated-requirement): that is a requirement in disguise, and must says it better.