Optional RSS/Atom feed for microblogging use case (follow-up to #6243)

Check before submitting

• I searched existing issues and did not find a duplicate

What problem would this solve?

I'm actively using it as a personal microblog. I noticed RSS support was removed in #6243. The reasoning (limited configurability, an unused frontend entry point, ongoing maintenance for a feature that didn't fit the core focus) makes sense to me.

For a microblogging use case, though, a feed is a pretty central feature: it lets readers subscribe to my public memos in their RSS reader without having to actively visit the site.

What would you like to happen?

Rather than bringing back the old, unconfigurable feed system, a lightweight, opt-in feed could work well.

• One feed per public profile (/u/:username/feed.xml or similar), only for users who explicitly enable it.

• A minimal implementation: just title/content/timestamp/link, with no server-side HTML rendering needed (which was a big part of the original maintenance burden).

• (Alternatively: official API documentation/an example showing how to generate a feed from the existing API yourself, in case a native feature isn't desired.)

Additional context

No response