Anyway, the idea is not to put a Xunlai agent in Pre-Searing, but instead put an NPC in that would only accept items. You wouldn't be able take things out. But wait! When you do put things into this NPC window, they "hold" the items for you through time, namely the two years between Pre- and Post-Searing.
Who here has seen Back to the Future? *imagines hundred of hands being raised* OK, at the end of the second movie, Marty sees the Delereon hit by lightning right? Doc ends up back in the Wild West, 1885. Remember the Western Union guy that shows up with a letter from Doc Brown? That's my idea! That letter was given to Western Union with the explicit instructions to deliver it to Marty "at this exact location, at this exact minute, November 12, 1955.
An NPC could either approach you, or you just walk up to him/her, and they'd say "Excuse me, but I have some things from you. Things that were... I mean are supposed to be given to you after exactly two years and eighty-seven days, at this location, by well... someone of your acquaintance."
A character in Pre-Searing would put stuff into this holdings NPC in Pre, and another character would take them out in Post. It would just work like a one-way valve to prevent Pre-Searing characters from receiving high-end items from the future. The slot limit could be set at ten slots, half the number in a Xunlai vault box.
