As-salamu 'alaykum I asked my teacher, Mufti Sayyid Ghulam Mustafa Aqil Bukhari (hafidhahullah), about this question. He said that if you have no clue, you will only need to complete your qasr prayer, as this is what is obligatory on you. Even if you find out later that the imam was muqim, you will not have to repeat the prayer. Allah Hafiz Ibn Amin
Asalaamualaikum please click on the following link.... http://library.faizaneattar.net/English/Islamic_Books/03/30/Index.htm the booklet is called 'The Travellers Prayer' which is written by Ameer-e-Ahlesunnath Moulana Muhammad Ilyas Attar Qadiri Razavi... more detail could be found in this booklet... Insha ALLAH Azzawajal Jazak ALLAH Wasalaam Sohaib
if i join the jama'ah late (masbuq?), and am not sure whether the imam was muqeem or musafir and i myself am musafir, and the imam ends the prayer, for example, during my 1st rakah, do i pray 3 more rakahs or one more?