Function validate_source_artifacts 

pub fn validate_source_artifacts(
    directory: TempDir,
    opening: &PublishContentOpen,
    originals: PublicationOriginals,
) -> Result<ValidatedSourceArtifacts, Error>

Call on a bounded disk worker after the complete upload. The directory must contain only the uploaded source.pack and source.idx; validation never falls back to objects already installed in a shared store. Dropping either the input on failure or the result on cancellation removes its scratch.