The default Subgroup set an allocation implies: one subgroup per allocated
group (mix) bus, at unity master, un-muted, with no members yet and folding into main.
This is the bridge from "the allocation declares N group buses" to the routing model —
the engine / UI seed their subgroup layer from this, and the operator then assigns input
channels into each and sets its fader / mute / main fold-back.
The default Subgroup set an allocation implies: one subgroup per allocated group (
mix) bus, at unity master, un-muted, with no members yet and folding into main. This is the bridge from "the allocation declares N group buses" to the routing model — the engine / UI seed their subgroup layer from this, and the operator then assigns input channels into each and sets its fader / mute / main fold-back.