Fail-open governance assumes safety by default. Fail-closed governance assumes risk by default. In agentic systems with irreversible state mutation, only one of these assumptions survives production.
Fail-open governance assumes safety by default and proceeds when authority is ambiguous. Fail-closed governance assumes risk by default and refuses. The labels suggest a temperament — permissive versus cautious — but in agentic systems with irreversible state mutation, only one of the two assumptions survives contact with production.
A system that proceeds under ambiguity has already chosen speed over governance, and the cost is paid at the one boundary that cannot be undone. Production AI requires default-deny behavior at every mutation boundary: ambiguity halts, it does not pass.