Provenance · Audit ledger
Cryptographic audit ledger
Every change to the dataset is committed to an append-only, SHA-256 hash-chained log. Each dated entry hashes the entire published dataset and links to the previous entry's head, so altering any past figure — or the order in which we recorded it — breaks every entry after it. Priority of discovery becomes something you can verify, not just trust.
- Chain length
- 77
- Tracking since
- June 2026
- Last entry
- 2026-09-05
- Integrity
- ✓ verified
Current head
The head digest commits to all history before it. Quote it to pin the dataset's exact state on 2026-09-05.
edcd05afbe940416007592eff45ce18b96186364cd397e59b1cc371cf06e2f68 Verify it yourself
- Download the chain: /data/ledger.jsonl (one JSON entry per line:
d, n, filesHash, prevHash, headHash). - For each entry, recompute
headHash = SHA256(prevHash + ":" + filesHash + ":" + d + ":" + n)and confirm it matches, and that eachprevHashequals the previous entry'sheadHash(the first isGENESIS). - To check the data itself, recompute
filesHash: SHA-256 each file underdata/products,data/sections,data/catalogplusdata/price-history.jsonl, join aspath:shalines sorted, and SHA-256 the result. The build script isscripts/build-ledger.mjs.
- The chain (NDJSON)
- Price Index — how the data is verified and how large the moat is.
- Corrections log — every fix, dated.