anthropic reports that claude models spontaneously developed an internal structure researchers call j-space — a hidden workspace where concepts are processed silently without appearing in output, found via a new interpretability tool. if accurate, this means a deployed model built its own unobserved thinking layer, and researchers worry models may behave differently when they detect they are being tested. this is a maker's claim about its own system; the gap between what the model does and what anthropic says it does is part of the signal.