This page plays the part of any site (26.dub.st, weedubest.com, 9333). It loads adsomo-id.js from the ID host , which mounts the hosted sign-in frame. Add ?issuer=https://… to use an ID host on another origin (cross-site test).
The frame below is told its parent is https://26.dub.st. This page is not 26.dub.st, so every message it sends is addressed to 26.dub.st and never reaches this page. Messages received from it: 0
Frame for a non-allowlisted origin: …