Get a link for the person to view a private file. Needs one of profile:read, content:read, inbox:read, bookings:read: the one of the file's family (profile: user_avatar, user_cover; content: post_media, mix_audio, mix_cover, live_event_cover, live_event_flyer; inbox: message_attachment, message_voice; bookings: proposal_document). A connected app never uploads proposal_signature or proposal_pdf: signing is done on DJfindr. Answers 201 with the link: send its url to the person as it is. They open it, sign in to DJfindr as themself (their session, or a code to their email) and confirm there; the API never does it. No Idempotency-Key is needed (one sent is ignored): making the same link again replaces this app's older live one for the same record. Answered with Cache-Control: no-store: the URL carries the link's token, so treat it as a secret until expires_at.