Adds a remote image (by url), no AI. as:"reference" (default) = a reusable reference asset whose id goes into reference_asset_ids; as:"timeline" = a photo in a project's timeline (needs project_id); as:"product" = that project's product photos. metadata = your own fields (max 4 KB), returned on every read. The answer's versions lists other versions of the same picture already in the library (larger, smaller, same size): tell the user. Counts against storage.