The deadline was nine hours out. My co-author was in another timezone, editing the same main.tex I had open. We were passing the file back and forth over a shared drive like it was 2020. At some point we both hit save. A results section disappeared, and neither of us could say with confidence which copy was the real one. That night didn't make me want to start a company. It made me want to throw my laptop in a river. It's also why we built LetX — a free, real-time collaborative LaTeX ed...