Getting a second look at Rose’s room is a welcome opportunity to start talking about it (especially since we weren’t around back when its first appearance, in Rose’s Room appropriately enough). We know it has its limits, but how it functions can only be explained with the broad brush of “Gem magic”.
In Rose’s Room the room starts to act up because it is trying to simulate far more than it has the ability to: the wrong things start appearing, people act and look strange, then finally the scenery goes wrong; it doesn’t have the processing power to keep up with demands, so it cuts corners where it can.
The problem in Open Book is different: rather than ask the room to do too much, Steven asks the room (again unknowingly) to do something it didn’t know how to do.
I don’t want you to just do what I want
The room appears to be programmed to give Steven what he wants: when he tells the room, that he thinks is Connie, that he doesn’t want her just do what he wants, the room has trouble handling it. Its processing power wasn’t being stressed, since everything else continued as normal, but it didn’t know what to do with the fake Connie for quite a while.
When it finally resolves the paradox, that it’s supposed to do what he wants but not just do what he wants, it seems to be in a much more user-friendly fashion than the run-of-the-mill rogue simulation story: rather than become fully self-aware and hostile, it proceeds to help him do what he actually wants (tell Connie the truth) by disregarding his further orders.
Interestingly, the rest of Rose’s room continued to follow Steven’s orders: it was only the Connie construct that defied him. The easy explanation for this is that since he only gave that order to the Connie construct, only orders to it were disregarded. It’s doubtful that he could have gotten around the problem by ordering the room itself to delete or trap the construct, but he was able to summon objects that were meant to slow her pursuit or to attempt to evade her entirely.
The room knew Steven’s private thoughts regarding the ending, just like it knew what color he (apparently incorrectly) thought Lisa’s childhood tunic was. It also disregarded what Connie said her costume would be like in favor of a different costume for the Connie construct, likely based off of his own imagination.
While this fact was obviously important for the emotional climax of Open Book, it has interesting implications for the end of Rose’s Room as well. The secret ending for Golf Quest Mini the room showed him was quite rushed, and many people suspected at the time that the room was only showing Steven what he thought the ending might be. Now there’s even more reason to believe that the room fabricated the ending; Steven might have to play the final dungeon all over again (or we suppose he could always look up the ending on Tube-Tube).