Upload endpoint for SmugMug’s Library (“All Media”): media uploaded here
isn’t placed in any album/gallery. Not in SmugMug’s public API docs;
discovered from the web uploader. It takes a multipart form (Media,
ByteCount, Sha256Sum, optional Filepath/Title/Caption/
Keywords) and answers 201 with the standard v2 envelope
({"Response":{"Image":{...}},"Code":201}).
Replace the file content of an existing image, identified by its image URI
(e.g. /api/v2/image/<key>). This uploads new bytes onto the existing
image record, keeping its album placement, keywords, and other metadata,
instead of creating a new image (which SmugMug rejects with 409 if an
image with the same filename already exists in the album).
Upload a file to the Library (no album). filepath is sent as the
Filepath field, which SmugMug describes as “the relative path to the
photo or video itself on the uploader’s file system”.