Documented all findings from the training step performance session:
- Shared memory race was real but not the NaN source (racecheck: 0 hazards)
- NaN is non-deterministic numerical instability, NOT a concurrency bug
- Suspected math bug in gradient budget allocation during MSE warmup
- Investigation plan: GPU NaN detection kernels, gradient audit, git bisect
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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