sections: 15; label counts: [('Mormon', 7), ('Nephi', 3), ('Moroni', 3), ('Jacob', 2)]
observed blocked LOO acc=0.5508 kappa=0.133 (chunks=118)
null acc: mean=0.2691 sd=0.1304 p95=0.5254 max=0.6610
permutation p-value (acc >= observed): 0.0350
--- cosine-delta robustness (cs=2000, mfw=100) ---
validation  naive acc=0.96 (k=0.95)  blocked acc=0.92 (k=0.89)
narrators   naive acc=0.86 (k=0.73)  blocked acc=0.60 (k=0.25)
null        naive acc=0.80 (k=0.65)  blocked acc=0.25 (k=-0.16)