Structural checks are the first gate
The intake checks strictly ordered timestamps, duplicates, finite values and consistent OHLC ranges. It never silently sorts or deletes a row. A reverse-ordered provider file can be normalized only with an explicit transformation recorded beside the new snapshot.
What a hash proves
A SHA-256 hash lets two runs identify the same bytes. It does not prove that a price is correct, a universe is unbiased or a licence permits publication. Those questions belong to separate evidence fields.
Know the unknowns
Corporate actions, exchange calendars, delisted instruments, missing sessions and feed changes require deeper audits. QuantProp retains unknown status until those checks are performed; it does not upgrade incomplete data because a strategy looks profitable.