I use live bookmarks in Firefox, so I have a tick next to the items I have looked at, just something like that, or some sort of visual indication.
The comment count thing was more a thing I like on other sites, so like on ArsTech I can see if there are more comments from where I last read (which is handy to go and see if there are more cool discussions going on) but yea maybe would hammer the API a bit too much - unless limited to just 'new 'or 'ask' or something
At the simplest level LocalStorage or equivalent keyed on the submission id with a prior comment count to be compared with the new comment count would be sufficient. If it had a time of hast check as well, highlighting new comments would also be easy.
I'm not sure about other people, but thise are really the two things I care about most when trying to keep up with a discussion (are there new comments, and which are they).
1. The alt+h hotkey will be probably be replaced by "?". That should fix this.
2.1 That's a pretty cool idea. Would you want the "mark as read" part to happen automatically or manually?
2.2 Showing new/unread comments is also a cool idea but it will increase the amount of requests to the HN api. However I'm gonna look into it.
Wrapping it in a Tauri might be cool, because I actually wanted to try that. But I think the first step would be to make it a PWA, so you can install it without downloading anything.
Thank you for the feeback!