Jeva

NUS research model built for the failure modes letter-readout models inherit: a set-native architecture encodes each candidate independently against an immutable option memory, so representations are request-independent and reusable, decisions are permutation-stable (zero flips under candidate reordering, against 17–23% for comparable open models), sets scale to 2,048 options, and an explicit null probability separates "none of these applies" from uncertainty (98.66% null-detection AUROC). 4B checkpoint and code, Apache 2.0; the paper frames it as System One models from first principles.