The signs of Imamate and being God’s representative are the power to heal incurable diseases, which we are referring to here
Muhammad bin Yusuf narrates, I got an illness that the doctors were disappointed to cure.
I wrote a letter to Imam Mahdi (may Allah bless her and grant her peace) and asked her for healing.
In response, he wrote: “Albasak Allah Al-Afiya; May God clothe you with the garment of health”, it was not long before I was cured and when the doctors were informed about this story, they said: “This healing and health is definitely from God (1) (2)”.
Of course, after the advent of Imam Mahdi (A.S.), the healing of the sick continues by him
In a narration from Imam Hussain (a.s.) it is stated that no blind, sick or painful person will remain on earth (at the time of his appearance) unless God removes his pain.
From the above narration, it can be understood that after his appearance, Imam Mahdi (A.S.) heals the terminally ill, the blind, and other patients.
source:
(1) Kelini, Muhammad bin Yaqub, Usul Kafi, vol. 1, p. 519
(2) Kelini, Muhammad bin Yaqub, Usul Kafi, vol.1, p.332.
(3) Bahar al-Anwar, vol. 53, p. 62)
Andishe Qom site, taken from the article “Examining the Miracles of Imam Zaman”
Wiki jurisprudence
National center for answering religious questions