Since 3 body was first published in 2008 and Extremis in 2017, I think you mean to say "I convinced myself that Extremis was the same story as 3 body"... maybe it's irrelevant, but precedence can matter sometimes
Yes, that is what I should have said (and it was also what I was thinking at the time, since it is not uncommon for sci-fi episodes to take plots from other stories. https://www.escapistmagazine.com/star-trek-strange-new-world... is another such example).
