One feature I've wanted since forever is a full text search engine of only stuff I've previously seen before. I've spent hours typing in various search queries

One feature I've wanted since forever is a full text search engine of only stuff I've previously seen before. I've spent hours typing in various search queries for an article I'm sure I read 3 years ago but am fuzzy on the details of. Doesn't seem too hard to do technologically and would solve a real problem in my life.