Upload a photo or video to a connected account and get back what you attach to a post. Send it as multipart form-data with a single file field. Works for Fansly, OnlyFans and 4based. Fansly returns {media_id, account_media_id, mime, size} (put account_media_id in a post's attachments). OnlyFans returns {platform, media_type, mime, size, md5, media_file} (put media_file as one item of the post's mediaFiles; it is single-use, post it promptly). Billed as a write.

4based is different: there is no separate upload-then-attach step, the upload itself publishes the post immediately and this returns the created post object directly. Optional extra multipart fields: categories (comma-separated, default media/image or media/video by mime type), description, price (0 or 300+, a standalone PPV price — ignored if is_subscription_item is also set, 4based never prices subscription-included content separately), is_subscription_item (true/false), tag (comma-separated), private (true/false), to_be_posted_at (ISO 8601, schedules instead of publishing now). Set reel=true for a free 4based video up to 120 seconds; incompatible price/privacy/schedule fields are rejected.