pub fn pack_record(
spec: &ExpertRecordSpec,
stride: u64,
header: &ExpertRecordHeader,
projs: &[ProjData<'_>; 3],
) -> Result<Vec<u8>>Expand description
2026-09-25: Build one stride-byte record: the header at offset 0, each
projection’s bytes at the spec’s offsets, zeros elsewhere. Fails when
stride is below spec.raw_bytes() or a projection’s lengths differ from
the spec.