d22 + 6000 iter + bs=1M + warmdown=0.85 + muonclip τ=100
- CORE 0.2646 in 88.2 min (matches Run 6 quality, 10.9% faster wall-clock)
- val_bpb 0.7241
Both warmdown=0.85 and muonclip individually regress at d22; together they
synergize. MuonClip is the only code addition — 66 LOC across optim.py +
gpt.py + base_train.py, default OFF preserves Run 6 behavior bit-identical.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
