There are some dynamic irt models that model the
transition from one time point to another as a first-order Markov process, allowing different sets of questions in each time point (suitable for, for example, models of parliamentary voting). One example is Martin and Quinn's model in Dynamic Ideal Point Estimation via Markov Chain Monte Carlo for the U.S. Supreme Court, 1953-1999. That model is available in MCMCpack, but only for the one-dimensional case. I wonder whether it is possible to estimate such models in mirt (and thus allowing for several item types, which would be amazing).