Step 3B. Embedded mode (iframe in your UI)

The objective

The same handoff as A, but Launch Pad renders inside your product's UI in an iframe, with its own navigation hidden and a partner theme applied - to your user it reads as one application. The launch code signs in your user (the account step 2 created for them, not your service account), and it works even though browsers partition iframe storage, because the code rides in the URL and is exchanged for a session on arrival.