It can be easy to forget that, two years ago, the White House press briefing took place nearly every day. The president refrained from insulting reporters on live television. And correspondents did not lose their access for showing insufficient “respect.”

That’s the thing about traditions — they tend to be sacrosanct until they aren’t.

The rituals of reporting on the White House, and the place of journalism in American life, continued to shift in 2018 under President Trump. On Twitter, he used the term “Fake News” 174 times, nearly once every two days.

Presidents usually hold a holiday reception for the Washington press corps (even Mr. Trump acquiesced to one in 2017); this year’s edition was canceled. Presidents usually avoid criticizing American journalists on foreign soil; visiting Britain, Mr. Trump called NBC News “dishonest” and refused to take a question from Jim Acosta of CNN. (“Music to the ears of dictators and authoritarian leaders,” said an official at the Committee to Protect Journalists.)

Mr. Trump is reinventing relations between the president and the press. Next year may reveal if the changes are a blip, or permanent.