AnswerTab was a Chrome extension. That extension was retired, and the pages describing it — the right-click menu, the hotkey, the knowledge map, the bring-your-own-key tier — were describing software that no longer ran. They came down rather than be left up to be believed.
What replaced it is built and working. Open something you are reading, select any phrase, and the explanation opens where the words are. Then keep asking: the follow-up is answered in the same place, and the paragraph underneath never moves.
What it commits to
And what it does not do yet
.txt / .md files, and
Chrome's built-in PDF viewer will not run an extension. That is the biggest gap.The argument, in full
Two working papers set out why the docked panel and the spotlight overlay do not solve this, and what the rebuild had to commit to: The Panel Is Also a Tab and The Second Question.