Thanks! I totally fell for the “crosspost” label—I didn’t realize Lemmy just uses that term to mean “posts with the same link.”

The merged crossposts feature we have planned is actually exactly what you’re asking for then, since that’s what Lemmy means by a crosspost.

Do you have an example of a post where lemmy-ui does this? I’d love to look into how they implement it but I can’t find an example of the feature in action.

Mlem dev here.

This feature, as suggested, presents a fundamental technical problem: frontend clients load posts a page at a time, and so are only aware of the posts you’ve already scrolled past and the ~20-50 posts ahead in the feed. It’s therefore not possible to find all posts with the same URL and aggregate their comments into a single chain under the first occurrence of the URL, at least not without loading infeasible amounts of data ahead of time.

We do have a merged crossposts feature planned, which achieves the same basic functionality but using the backend crosspost data rather than absolute URLs; our comments view also currently shows the list of crossposts and indicates the number of comments on each one.

Alternatively, a filter that only shows posts with comments

That’s a good idea, we’ll add it to a future build.

Mlem has this feature planned–we have a clear path towards implementation, but there’s a lot of groundwork and design to do first so it probably won’t be delivered for at least several months.