The picture is uploaded to rupload.facebook.com/messenger_image/<entity> through
MessengerMediaUpload, the one owner of a media upload's wire (the header set
the foreign host needs, the entity headers and the owner's error mapping). The
photo posts without a slot, as a messenger_image upload does, and its entity
name is the app's <upload id>_0_<signed tail>.
The broadcast is the one the app sends from the gallery picker
(direct-message-photo 099): the form's own field order, attachment_fbid the
uploaded media's id, and the three fields the picker's send carries
(is_duplicate_attachment, meta_gallery_media_info, allow_full_aspect_ratio).
Send a new photo from a gallery.
The picture is uploaded to
rupload.facebook.com/messenger_image/<entity>throughMessengerMediaUpload, the one owner of a media upload's wire (the header set the foreign host needs, the entity headers and the owner's error mapping). The photo posts without a slot, as amessenger_imageupload does, and its entity name is the app's<upload id>_0_<signed tail>.The broadcast is the one the app sends from the gallery picker (
direct-message-photo099): the form's own field order,attachment_fbidthe uploaded media's id, and the three fields the picker's send carries (is_duplicate_attachment,meta_gallery_media_info,allow_full_aspect_ratio).