@BeAware Yeah, I'm pretty sure everything dies if I heck up the mastodon subdomain, but from a frontend perspective it looks like the user side of things will work / is working without the additional redirect?
All the federation is still happening on the subdomain, but I'm wondering if there's a hidden snag of the users using the frontend on the main is-a.horse domain?
Federation hasn't broken (yet?) with the main domain pointing directly at mastodon for the users, so I'm hopeful.