ACI-039: An Instrument Must Say What It Did Not Look At

Thesis

A gate has three outcomes (pass, fail and declined to answer), and an agent-built check characteristically reports a confident verdict over rows it never opened. Give refusal its own exit code and wording, make an empty population refuse, print what was examined beside what was walked, and give "unknown" its own value; prove that something runs each guard, and re-derive a green from its evidence, never from its marker. An exit code belongs to its callers: enumerate them before you change one, and keep an escape path that does not run through the gate.