If this is in reference to the copyright comment, it doesn't matter -- you're still transmitting/redistributing the content, which is what matters. One way to get around this is to ship the code and have the code execute on the user's machine (i.e. what you're presumably doing with the extension).
Edit: How about the backend just returns pointers to the text (word #x till word #y) and the js just (re)assembles it?
Plus moving it to the client side would free up whatever resources they are currently using to feed summary info to us.
you're still transmitting/redistributing
the content
So they provide a service that includes storing your content in it's entirety.
Has this ever been tested in court?
They are showing a small extract for context OR a summary specified by the publisher.
That’s completely legit and fair use.
Because there is plenty of precedent for this in available APIs and I've never heard of a case claiming this.
Though, just by copying & summarizing with your current implementation, there would be NO ONE to sue you, since you are just grabbing it and displaying it in the browser (sure, depending on the jurisdiction, one may rate this simple step already as some type of copyright issue)
In reality, this will not happen. (Except in North Korea ;-)
My comment regarding copyright was really about grabbing, summarizing and re-distributing it on another webpage, like a news aggregator.
I'm pretty sure this would be covered by fair use.
[1] https://www.theverge.com/platform/amp/2019/6/16/18681225/gen...
When you Google a newspaper article you get a verbatim snippet, same concept.