Human-readable signing-key filter (#818). None (no filter) omits the
line entirely; the empty filter is the state that must never be
misrendered — “no keys” and “no filter” are opposite grants, so the empty
set is spelled out rather than shown as a blank list.
Human-readable approve-authority — what this entry may confer via an
approval (task-consent delegation / step-up ratification) while acting
nowhere. None when it confers nothing, so callers omit the line entirely.
Parse the operator’s --direction value, defaulting to the historical
“who may act in this context” reading and refusing anything else with the
valid set — the same table the wire uses, so flag and payload cannot drift.