A SET drawn from a closed vocabulary — canonically ordered and deduplicated.
The field is a set, not a list: "which recall-safe scopes are on this channel" has no order an
operator can observe, so two clients that toggled the same scopes in a different order must
produce the SAME wire body — otherwise the convergence law (two clients given the same history
are byte-identical) fails on a difference nobody made. The decode re-emits in the vocabulary's
declared order and drops repeats, so the canonical spelling is a property of the CODEC rather
than of every caller's discipline.
An unknown member is REFUSED, never dropped, for the reason enumMap refuses one: a
member the desk silently discards reads back as applied, and the operator learns their spelling
was wrong only when the thing it was meant to protect is overwritten.
A SET drawn from a closed vocabulary — canonically ordered and deduplicated.
The field is a set, not a list: "which recall-safe scopes are on this channel" has no order an operator can observe, so two clients that toggled the same scopes in a different order must produce the SAME wire body — otherwise the convergence law (two clients given the same history are byte-identical) fails on a difference nobody made. The decode re-emits in the vocabulary's declared order and drops repeats, so the canonical spelling is a property of the CODEC rather than of every caller's discipline.
An unknown member is REFUSED, never dropped, for the reason enumMap refuses one: a member the desk silently discards reads back as applied, and the operator learns their spelling was wrong only when the thing it was meant to protect is overwritten.