Redirect to a short-lived signed URL for the archived UBL (SBDH-wrapped) of one of
your documents, by its document_id (the id returned when you reported it — invoice
or credit note). Before discovery/preparation, return the immutable accepted
UBL directly from durable storage (HTTP 200); archived documents redirect (302).

Stays available after the taxpayer is deregistered: the filing is a record it must be
able to produce long after it stops filing.