Beacon-Seeded Fair-Sampling Deriver V2

Version 1 of this sampler is a proven, sealed node: it is not edited, and every receipt already issued against it keeps replaying byte-identically. New runs should use this V2 node, which fixes three V1 defects in a new algorithm id:

1. No draw cap. V1 rejected duplicate candidates against a walk capped at 10 × item_count draws; a full sample needs about item_count × H(item_count) draws (coupon collector), so near-full populations above roughly 12,000 items exhausted the cap and failed. V2 walks a partial Fisher-Yates over an index array: every accepted draw selects exactly one remaining item, so exactly sample_size accepted draws are consumed, at any population up to the 1,000,000-item ceiling (a 4 MB index array at maximum).
2. No modulo bias. V1 reduced each 32-bit draw with a raw remainder, which biases selection toward lower indices by up to item_count / 2³². V2 rejects any draw at or above the largest multiple of the remaining window width that fits in 32 bits, so every offset in the window is hit by exactly the same number of raw draws: exact uniformity, proven by integer arithmetic rather than statistics.
3. Validated hex inputs. Both hex inputs must now be exactly 64 lowercase hex characters (no sha256: prefix); anything else is a structured refusal naming the rule. V1 only trimmed them.

The emitted transcript is capped at 50 draws with full draws_used and rejection counts, so artifacts stay bounded at large sample sizes while the whole walk stays reconstructible offline from the declared inputs. For past receipts and replays of earlier samples, keep using ART-583 (version 1).

The fairness of this sample depends entirely on doing these three steps in order, before you touch this page:

1. Fix the population first. Freeze the exact item list to be sampled and hash it (any stable canonical hash of the manifest works; SHA-256 of the sorted item list is typical). Publish or otherwise commit to that item_manifest_hash (exactly 64 lowercase hex characters, no prefix) before the next step.
2. Wait for a beacon pulse you did not choose. Take the NEXT round of a public randomness beacon after your commitment: drand's quicknet chain (a new pulse roughly every 3 seconds, verifiable output published openly) or a NIST NISTIR-8213 randomness beacon pulse. Paste that round's declared randomness value below exactly as published (exactly 64 lowercase hex characters).
3. Derive, don't re-roll. This page derives the sample once, deterministically, from the manifest hash and the pulse. If the result is inconvenient, the correct response is never to re-run with a different pulse: that is the cherry-picking this ceremony exists to prevent.

Precedent: NIST's Interoperable Randomness Beacons project names bias-resistant audit sampling as a beacon application; U.S. election jurisdictions running risk-limiting audits (e.g. Colorado, per the U.S. Election Assistance Commission's RLA guidance) draw ballot samples from a public dice roll or beacon for the identical reason. drand quicknet is treated as the primary beacon here (sub-3-second cadence, no single operator); a NISTIR-8213 pulse serves as a corroborating co-seed when both are available.