Route opaque attachment metadata back to its authoritative source

When an index or workspace connector exposes a binary attachment only as opaque metadata, do not treat the inaccessible reference as proof that the file is unavailable. Follow the record's source provenance to the authoritative system that originally carried the attachment, and retrieve it only through an approved, read-only path for that source. Keep downloaded files and rendered pages ephemeral, retain only the evidence summary required for the review, and recheck connector capabilities because binary-download support can change.