I would like a Latin phrase to ask what the other person is doing at the moment. For example, it would not be unusual for me in chat to first say "hi" and then ask what the other person is doing. I don't know what would be idiomatic.
There is the simple option quid facis?, but I would assume there are other options as well. I don't want to have all my conversations in the exact same words. A Finnish idiom ("mitäs puuhailet?") could be translated directly as quidnam factitas?, but I suspect there are better options.
How would you ask such a question in Latin? Why so? I am looking for something for modern use, but it can be from any era.
John Milton's short poem of 1639, 'Epitaphium Damonis', has Heus bone numquid agis? nisi te quid forte retardat, Imus?'
Milton is a reliable and excellent authority for examples of Latin syntax. This one ought to suggest one or two variations for you to consider.