What makes an AI audit log actually defensible

Plenty of tools log AI usage. Far fewer produce a record that would survive scrutiny from an auditor or opposing counsel. The gap is in the details.

Append-only has to mean append-only

If immutability is enforced in application middleware, it can be bypassed by anyone who can deploy code. A defensible record enforces append-only at the database itself — revoking update and delete, or using triggers — so 'no one can quietly change history' is a property of the system, not a convention.

Completeness is the guarantee

Every prompt must produce exactly one record — including the ones that errored or were blocked. A log with gaps invites the question 'what else is missing?' Wardary writes one immutable row per prompt, no exceptions, and treats that completeness as the core compliance guarantee.

The value of an audit log is inversely proportional to how easily it can be altered.