qvalue_stats_reduce and qvalue_divergence_check used bf16() identity wrappers on native f32 data — legacy from the bf16 era. These wrappers can cause subtle precision differences across GPU architectures. Replaced with native fminf/fmaxf/__shfl_xor_sync. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>