Hi! I've built an app: https://beatbattle.app/ I offer my users vanity subdomain urls which work great: https://infatuation.beatbattle.app/ I also offer the ability to map a custom domain which functionally works, but since it's on a different domain then, the session is unavailable: https://fiesta.rodeo/ How could I work around this? To offer a bit of clarity, the way the domain mapping works is they just use a cname to point at their custom subdomain. I figure if I let them sign in under the custom domain and had the referral url set properly on whatever oauth service's end, that'd work well, but the issue then is that I'd have to dynamically add allowed redirect urls to the oauth provider which isn't always possible.