OptionalkindApp category for icon/filtering, e.g. "game".
OptionallabelHuman label for the action, e.g. "Dice game".
OptionalmetadataFree-form row data, shallow-merged across the group's resolvers (first-writer-wins).
OptionaloutcomeResolver-declared outcome for the group, e.g. "failed", "refunded" — an opaque machine token for the app to map to its own copy or icon, not display text.
The non-id, non-amount part of a GroupMembership.