Seal binds an exact UTF-8 content SHA-256 digest and expiry to a HALOWERK Ed2551...
https://agent.halowerk.com/v1/artifact-receiptOverview
Seal binds an exact UTF-8 content SHA-256 digest and expiry to a HALOWERK Ed25519 signature; verify checks signature, expiry and optional exact content. The service public key is included. This attests digest receipt only, not truth, legal timestamp, identity or ownership. Keep the receipt to verify offline; content is not retained by this module.