

Only way I know to do this, is to just regularly check the comment and post feeds, loading more pages until you get content you’ve already ingested.
This is how @saucechan@ani.social works. It also responds to mentions using notifications, but mentions in post bodies don’t create notifications, so the work-around was necessary.
If you didn’t know, there is a comment feed endpoint, which will contain new comments from all posts, without requiring you to check every post for new comments. It’s not used by most clients, but it’s available in the default webUI, and hence the API.
You can make it a little simpler, by only loading the subscribed feed, and making sure you sub to the relevant communities on the bot account.
Either of those are only options for someone who runs an instance.
I agree running things the other way around would be better, but monitoring about a dozen communities, I get away with a call every 5 minutes, and it almost never needs to load a second page. That is not significant afaik.
How would it miss stuff? You’d always use “new” sort and load pages until you run into content from the last update. Stuff from the last page appearing again because new content moved the content along, shouldn’t stop you from loading another page, and any new content will be caught in the next update.