For G7 leaders, immense global challenges weigh on agenda overshadowed by Trump

Open this photo in gallery: U.S. President Donald Trump withdrew from a joint statement by tweet at 2018’s Charlevoix summit.Doug Mills/The New York Times/The New York Times News Service The last time Canada hosted a G7 summit, Tristen Naylor gained access as an unusual spectator. He was embedded as an academic observing the summit management office that oversaw the 2018 events at Charlevoix, Que. It was, he recalls, a marvel of organization, governed by a 132-page event "bible." "It's page after page of minute-by-minute play-by-play on how the summit runs, with schematics and diagrams of every room setup, who stands…