Masoud Pezeshkian, the reformist president-elect of Iran, clocked a narrow win over a hard-line candidate in the Islamic Republic’s election Sunday. But given the long-term priorities of the clerics who are the ultimate source of power in Iran, Pezeshkian will only be able to make limited changes, in certain areas — and any reforms he does successfully make are not guaranteed to last beyond his tenure. Pezeshkian’s victory reveals a few things about both the regime under Supreme Leader...