It had been a long pandemic for Twitter’s research team. Tasked with solving some of the platform’s toughest problems around harassment, extremism, and disinformation, staffers absconded to Napa Valley in November 2021 for a company retreat. Despite a tumultuous change in leadership — Jack Dorsey had recently stepped down, appointing former chief technology officer Parag Agrawal to take his place — the group felt unified, even hopeful. After months of fighting bad actors online,…