dash5-verified gate numbers: accum=N bit-close to N× big batch (loss 8.5e-8 / grad 3.8e-5), accum=1 bit-identical (0.0), DDP+accum matches single-GPU (5.7e-7), memory flat (same effective batch 64: 27.7GB big → 7.2GB accum, −74%), xserv closed loop md5-identical + token-identical. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>