AuthRedirectDelegate
final class AuthRedirectDelegate: NSObject, URLSessionTaskDelegate, Sendable
#20857: decides the app's credentials again on every redirect hop. URLSession drops an
Authorization header set on the request at the first redirect, even one to the same host, and
carries any other header (rpctoken) on to wherever the redirect leads. cp-gatekeeper redirects a
protected embed or clip to /cpp/<code>/... on the same host, so without this the Bearer token
never reaches the response that matters.