Function build_source_pack 

pub fn build_source_pack<W>(
    builder: StreamingPackBuilder<W>,
    source: &impl ObjectSource,
    selected: &State,
    max_objects: usize,
    max_decoded_bytes: u64,
) -> Result<(W, PackStats), HeddleError>
where
    W: Write + Read + Seek + SyncData,

Build an exact selected-source pack without consulting State history, provenance, attachments, or linked spools. Full canonical trees keep private delta bases out of the pack. The caller owns revision authorization and the temporary output directory; discard that directory on failure.

Object bytes stream into the builder one object at a time. Blob header lengths are checked before reading where the source supports that probe. No object repository, CLI, network, or async runtime dependency is required.