audit: annotate all remaining to_vec/memcpy_dtoh — categorized 158 sites
Every to_vec()/memcpy_dtoh across 48 files audited and annotated:
- ~100 false positives: Rust slice .to_vec() (cpu-side, never touches GPU)
- ~25 gpu-exit: legitimate scalar readbacks (loss, grad_norm, epoch state)
- ~20 test-only readbacks: gated by #[cfg(test)] scope
- ~10 cpu-side uploads: .to_vec() before from_vec() GPU upload
- ~3 checkpoint exports: export_to_host at epoch boundary
Annotations use inline comments: // cpu-side, // gpu-exit:, // test-only
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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