Every crash point is pre-determined by a SHA-256 hash chain built when the reactor boots: chain[k] = SHA256(chain[k−1]). Rounds consume the chain backwards, so SHA256(round.hash) always equals the previous round's already-published hash — the server physically cannot alter an outcome after the fact. The terminal hash (commitment to the whole run) is printed at boot.

The crash point is a pure function of the round hash: hmac = HMAC_SHA256(key = SALT, msg = hash_bytes); if the first 32 bits of hmac mod 33 = 0 → x1.00 (instant bust, ~3% house edge); otherwise with h = first 52 bits: crash = floor((100·2⁵² − h)/(2⁵² − h))/100, capped at x500. The ✔ badge means your browser re-computed both the chain link and the crash point via WebCrypto and they match. Chain regenerates on every server restart (demo runs in memory).