For custom badges, awarded manually (by hand or the API), it seems like it might often be nice to be able to have the “reason” posted be an off-site URL. Or, really, arbitarary markdown or html, which might be a link.
But currently, that’s forbidden with External or invalid discourse link is not allowed in badge reason
.
Is this limitation for a practical reason? It doesn’t seem like a security issue, since you need an admin user to grant the badge anyway.