Evidence artifacts
The proof file is not the signed PDF.
OctoDoc seals and returns the signed PDF today. The terminal proof file is a separate, richer archive you download from your account once assembly completes.
Today
The sealed PDF carries the current result.
One signature covers every byte you approved. Change anything later and the signature breaks. Anyone can check that in a normal PDF reader, offline, with no account.
Returned now
Every party can return to the sealed PDF from their account, download the request-time evidence archive, and download the terminal proof file once the worker has finished assembling it.
Verify it
The archive carries its own checking guide.
The terminal proof file packages the seal, the chained ledger, independent time evidence, trust material, and an offline verification guide.
Keep the distinction
One artifact is signed. The other explains the record around it.
Changing the evidence bundle must never change the signed PDF. The proof file therefore stays outside the signed byte range.