Compliance audit from KV history

The auditor asks the question every regulated company dreads: who changed customer 4729's risk tier on March 14, and what did it change from?

Normally this is a panic: find the right log shipper, hope retention covered the date, parse a million lines, hope the change was logged. Instead, you GET kv/customer:4729:risk/history. You see the row: timestamp, prior value, new value, the request token that wrote it.

Every PUT to the KV store is recorded. Every change preserves the prior version. You did not configure this: it's how the storage works. You can pull a snapshot of the entire customer record as it was on the date in question, hand it to the auditor, and move on.

When your storage layer remembers, your audit story stops being a process and becomes a query.

The audit log isn't a feature you bolt on. It's a property of the storage.