Function conduit_shards 

fn conduit_shards(
    depth: u8,
    length: u8,
    sha256_hex: &str,
) -> impl Iterator<Item = &str>

Splits a lowercase SHA-256 hex digest into Conduit’s shard segments: depth segments of length characters then the remainder, or the whole digest when depth is zero (a flat layout). config::check bounds depth * length below the digest length so the segments never overrun it.