Function decide 

pub fn decide(class: Class, mode: Mode) -> Decision

Map a class to a decision for the given mode (Tier-1, rules-only).

Security spine: catastrophic is never Allow. In attended mode dangerous and ambiguous commands are held; in unattended mode catastrophic is a hard auto-deny and ambiguous defaults to the safe side (deny) until the Phase-2 model can score it — and the model may then only add caution.