Auditable from day one is a different product, not a later feature
Most platforms add an audit trail when a customer asks for one. By then the shape of the data has already decided what can be proven.
Not your policies. The specific loan, the specific signature, and the specific document the borrower saw.
Lenders preparing for an examination often over-invest in the policy binder and under-invest in the ability to produce a single file. The binder establishes intent. The file establishes what happened. An examination is mostly about the second.
Notice that four of the five are per-loan artifacts, and the fifth is a property of your system rather than a document you can write.
It is rarely "do you have a signature". It is "what did the borrower see". A signature attached to a document you cannot reproduce is close to worthless, because the dispute is almost never about whether they signed. It is about whether they understood what they were signing.
Answering that requires a fingerprint of the exact document presented, stored at the moment of signature, so the copy you produce later can be proven identical.
The dispute is not "did they sign". It is "did they know". Only one of those is answerable from a signature block.
One artifact per loan that contains all of it: each signature with its time, its network address, its authentication method, and the fingerprint of what was presented; the merchant's standing on that date; every event in sequence; and any dispute and how it was closed.
Generated from the live record rather than stored, so it cannot have drifted from the data. If it is assembled by hand from four systems the week the notice arrives, you are not answering the question — you are constructing an answer, and the construction is itself a finding.
Test yourself the way an examiner will: pick a closed loan at random and produce the complete file in an hour, without asking anyone for help.
Pick a closed project. We will show you the document you would hand a regulator. If it does not answer the question, nothing else matters.