Every day at the close, QuantLogix freezes what it published — the signal rankings, the ETF rankings, the private-company roster, and the SEC-filed Mark Tape — into an immutable snapshot. Each day's manifest is hash-chained to the previous day's, so rewriting any past number would visibly break the chain. Pick a date and see exactly what the data said. The archive only grows forward: history cannot be backfilled — by us or by anyone trying to catch up.
Every snapshot's SHA-256 and the day-to-day chain are public — no account needed:
GET /api/rewind?verify=1 recomputes the whole chain,
?list=1 lists every frozen day with its hashes, and
?surface=signal_rankings&date=YYYY-MM-DD returns a day exactly as it was frozen.
Save any day's manifest hash; if we ever rewrote that day, your saved hash would no longer match —
that's the point.