Space reconnaissance and heavy stealth drones lobbing heavy supersonic ASCMs(aka ones unable of advanced AI search patterns and with rather limited radar only seeker) deep into contested area?Yes, I think the optimal assets to deal with these types of "guerilla" missile launch units is a combination of space-based surveillance & long endurance stealth drones (GJ-X comes to mind, if we can make a large number of them cheaply). Space based surveillance to see where such units are sailing to, & a stealthy “察打一体" type of long-range UCAV to strike ships with YJ-19 (or some comparable air-launched variant thereof) ideally before they land to minimize munitions expenditures.
This doesn't add up. The only thing such effector is good at is time-sensitive prosecution of larger, more obvious asset; it isn't even a weapon against LSMs (much less smaller distributed assets), it's a weapon to hit LHAs.
But LHAs aren't directly in consideration. And contrary to, no, LSMs aren't front line movers. Not even ships in accessible bluefor backline are of operations. Look for smaller and far more obscure, low individual cost targets, operating short sprints in space ISR windows - either natural or created.