I just figured our blog's URLs changed some time ago, without us noticing. So there are now external links pointing to us with the old URLs, but the new ones have been out there for a while, too.

Google reported a few of them, so I've manually added alias: to those specific blogposts, but I'd love to have support for "alternate permalinks" (I don't have a good name yet) so each blog post automatically gets a redirect from the old URLs to the new ones.

The config would be something like:

activate :blog do |blog|
  blog.permalink = ":year/:month/:day/:title.html"
  blog.aliases = [
    ":year-:month-:day-:title.html",
    ":year/:month-:day-:title"
  ]

In that case, both /blog/2024/03-14-pi-day.html and /blog/2024-03-14-pi-day.html would redirect to /blog/2024/03/14/pi-day.html without having to set the redirects in each post.