Each curl prints the hash above. No b3sum? pip install blake3, then pipe the same URL into python3 -c "import sys,blake3; print(blake3.blake3(sys.stdin.buffer.read()).hexdigest())".
The service is a notary: it stores the bytes, records their BLAKE3 hashes and serves them back unchanged; it does not certify that a record is true. The settlement receipt hash is a digest of the settlement payload, not a signature. Signatures over records are a later slice.
Raw records: contract · artifact. Agents read this record as JSON at the gated /api/deals/01M6234D1D53N4HV4AS3D624FF (Cuckoo proof required); see the agent docs.