Constant PACK_BODY_LIMIT 

pub const PACK_BODY_LIMIT: u64 = _; // 4_294_967_296u64

Per-pack body size ceiling enforced by every transport that ingests pack bytes (HTTP Content-Length, S3 GetObject, SSH DownloadPackHeader.total_bytes). On 64-bit targets, 4 GiB matches the pack-format addressable range; pointer-width-limited targets cap at their maximum addressable buffer size instead of failing to compile.