A clock tells you the time by moving two hands across a face. What makes those hands move—the gears, the springs, the escapement ticking away behind the dial—stays hidden unless you open the case. For as long as language models have existed, they've worked the same way. You can read what a model says, but not what it does to arrive there. A model might reason its way toward an answer, notice something suspicious about a question, or quietly consider a shortcut it decides not