OpenAI’s new board formally took over on Wednesday and said it would add an observer role for partner Microsoft, capping a dramatic chapter for the artificial-intelligence startup and launching a new phase of difficult decisions.

The new board’s initial three members were decided as part of CEO Sam Altman’s return last week after the previous board abruptly fired him. The replacement directors’ priorities include creating an independent committee to review the events around Altman’s ouster, said Bret Taylor, the board’s chairman.