Beacon-Seeded Fair-Sampling Deriver

Derives a deterministic, offline-replayable audit sample by HMAC-DRBG (SHA-256) seeded from a caller-pasted public randomness beacon pulse (drand quicknet or NISTIR-8213) combined with an item-manifest hash committed before the pulse round. Emits the selected item indices plus a full per-draw derivation transcript (seed, per-draw HMAC output, candidate index, accept/reject) so an examiner re-derives the identical sample offline from the transcript alone. Verdict DERIVED, or INDETERMINATE when inputs are missing or malformed. The beacon pulse, its round and its randomness are caller-declared inputs: the kernel performs SHA-256/HMAC math only, never fetches a pulse and never verifies the pulse's BLS signature, so a sample is only as trustworthy as the pulse the caller supplied. Committing the item-manifest hash before the pulse round is what makes the selection cherry-pick-proof, and the page teaches that ordering. Extends the assurance and workpaper family; cross-links the shipped art-471 disposition-sampling-frame rather than duplicating it.

Tool URL: https://ainumbers.co/chaingraph/art-583-beacon-seeded-fair-sampling-deriver.html