metadata: do not generate previews for hidden groups
=/ members
~(wyt in (members:grp rid))
=/ =metadatum:store
- %- need
- %+ mate (peek-metadatum %groups rid)
- (peek-metadatum %graph rid)
+ (need (peek-metadatum %groups rid))
[rid channels members channel-count metadatum]
::
++ channels
