Function aggregate_to_rows 

pub fn aggregate_to_rows(
    lmpg: &Lmpg,
    buckets: &[GroupBucket],
    req: &AggregateRequest,
) -> Result<Vec<Value>, QueryError>

Shape aggregate buckets into flat result rows: group-by dimensions (incl. timeBucket aliases), count/sum outputs, and derived outputs keyed by their output name.

Errors

Propagates storage/engine read errors when opening the snapshot or attaching per-root $collect shapes.