For seven days, the Islamic Republic will pause. The coffin of Ali Khamenei — Supreme Leader of Iran since 1989, the longest-serving ruler in the country's post-revolutionary history — has been prepared for a state funeral that authorities say will be among the largest ever held in Tehran. Streets that once bore the weight of millions mourning Ayatollah Khomeini are expected to fill again, this time for the man Khomeini himself designated as his heir. Khamenei's 35-year tenure defined the contours of modern Iran in ways that will take years to fully measure.

He presided over four American presidencies, two Israeli military campaigns against Iranian proxies, the suppression of the Green Movement in 2009, and the brutal crackdown on nationwide protests in 2022. He steered the country through crippling international sanctions while simultaneously advancing a nuclear programme that brought it to the threshold of weapons capability. Whether that combination amounted to resilience or recklessness remains a matter of fierce debate, both inside Iran and across the capitals of Europe and Asia. The immediate question is succession.

Iran's constitution assigns the selection of a new Supreme Leader to the Assembly of Experts, an 88-member clerical body that has rarely been tested in quite this way.