In the first case it simply fails to subscribe, in the second it adds a suscription entry to an empty https://danluu.com/atom/index.xml URL.
P.S. Where should I be reporting bugs? While in general I like the UX choices and find the implementation of POSSE in micro.blog very nice, I struggle to recommend it to ordinary people (i.e. not FOSS nerds) because the whole thing lacks QA.
I checked that feed and I think the main problem is that the posts are all older than a couple years. Inkwell focuses on recent posts. The UI will usually only show posts from the last week, although it can show older posts when selecting a specific blog.
Also it is a big feed and will perform better if it was a lot smaller.
That danluu.com/atom/index.xml URL is showing up because it’s referenced in the feed. I think Inkwell is discovering it by accident, so that is something I can fix, but the feed is also probably wrong.
To be clear, I haven’t faced a situation where a URL that points to an actual XML file is saved with no entries appearing, so this is not just a misapprehension on my part of how the UI works.
The only feed URL that is saved is the one that returns 404 danluu.com/atom/index.xml .
So I suppose the primary difference in behavior between the Liferea RSS client (that imports the feed successfully) and Inkwell, is that Liferea uses the URL provided directly (https://danluu.com/atom.xml) while Inkwell attempts to read the one from within the <atom:link> tag, as you noted.
I gather since there’s multiple things wrong with this feed, there’s no obvious fix.
I see that, if i try to import https://danluu.com/atom/index.xml directly, it refuses to be saved because apparently Inkwell tries to validate and gets a 404.
Perhaps it would be safer for Inkwell to save the same URL that it validates (i.e. https://danluu.com/atom.xml) or, alternatively, to also validate the URL found inside the <atom:link> tag prior to saving it.