Interface BusSnapshotJson

This bus's discrete-channel FORMAT (#176, 2026-09-08-lcr-mains.md). Absent ⇒ 'stereo', matching every bus that predates this field — a phase-1 addition, not a stereo:boolean migration (that field is untouched; this one is new and wins when present). main/group only; the field is meaningless on every other bus kind and simply never appears there.

A subgroup's group→main send level: scales the whole group's contribution to the main mix on top of its master fader. Absent ⇒ unity. Persisted alongside toMain.

Member input channels feeding this bus (membership only; gains live on the sends).

For a mix-minus (N−1) bus: its excluded channels (the rest auto-send post-fader ON). Present only on a mix-minus bus. Persisting the N−1 intent (the exclude set) — not just the expanded send list — lets a reloaded bus keep auto-maintaining its all-on-except-excluded behaviour as channels come and go.

The bus balance (−1..1), from the engine strip that owns it. Absent ⇒ centre.

Whether this bus carries distinct L/R (a stereo bus). Persisted so a stereo bus round-trips: a reload re-creates it stereo and a reconnecting client renders it as stereo (with L/R metering). Absent ⇒ the default for its kind (defaultBusStereo).

For a subgroup (mix) bus: whether it folds back into the main mix. A classic sub-group feeds main (true); a stem / standalone group does not (false). Absent ⇒ the default for a sub-group (it feeds main — see subgroupFeedsMain). Persisted so a reload restores whether the group reaches main.