Adaptive Budget Allocator

ABA increased mixed-outcome ratio and reduced uniform-fail ratio, with modest increases in leaves and wall-clock time. ABA triggers only for uniform-outcome trees when predicted rescue probability exceeds 0.5. ABA uses prompt and tree summaries to predict whether a high-temperature extension will create another outcome category. ABA performance degraded under distribution shift, but retraining every 100 steps restored ROC-AUC and lift. ABA handles uniform-outcome trees after the initial tree construction phase.