It would be a great evolution if the translation server would accept an extra "begining" parameter for a sentence, to return with one (or N) possible way(s) of ending its translation. As far as I understand the way it's working, I think this could be done by forcing the first tokens in the beam search.. right ?
PS : a bit harder would be to get a predictive post-editing server = knowing a sentence to translate, and an already existing translation with a pointed position in it, in the beam search force all beginning and ending tokens, and let free exploration to fill the pointed position at best. The hard part is certainly to force the ending tokens in the beam search. The first above proposition of predictive translation server would be equivalent to set the pointed position at the end of the translation in this predictive post-editing server.