The group operations seem to generally assume input x,y,z can be multiplied directly i.e. there is an implicit mag 8 requirement, which could be worth adding verification for. In some group operations (broadly speaking those where special z values are in play, either gej_add_ge or coz) the input field values are normalized, usually to ensure that they are mag 6 or so (I am presupposing zero tests for h/i replacing u?/s? equality checks), but it varies. In practice the group ops don't produce higher than 6 mag anyway, so there's some waste here (and some performance-neutral jiggling might lower the output mags).

So I'm proposing to i) add pre/post verification for the current mag 8 assumptions, then ii) explore whether tightening the requirements can improve performance. At this stage, I'm only envisaging a simple global requirement, not op-specific bounds.

Thoughts?