I'll update this if I find more. For now, this seems to be a partial solution. It's a Gmail add on (except I don't use Gmail) that adds reminders. The options when setting reminders include cancelling it if someone replies, and to remind everyone in the thread. If you combine those two, it seems like — if you use Gmail's web client and have $23/month you're dying to get rid of — a decent way to add the feature. Source: over 1 year ago

Have tampermonkey installed (google), then go to greasyfork (website) I have the link here https://greasyfork.org/en and search up character ai, have fun :)). Source: about 1 year ago

If the above mentioned URL rewriter doesn't work for you (I found it hard to use myself, and never could get the rules figured out), then you could try using https://github.com/janekptacijarabaci/greasemonkey and finding a redirect script here: https://greasyfork.org/en. Source: about 1 year ago

I was thinking more greasemonkey / userscripts. Source: about 1 year ago

Https://greasyfork.org/en is sort of what you're looking for. - Source: Hacker News / over 1 year ago

Then you should rather look for simple userscripts on for example https://greasyfork.org/en then use them or convert to uBO scriptlet syntax (which should be easy). Source: over 1 year ago