cargo runs tests with cwd = crate dir, so the bare relative default
data/tinystories-valid-3mb.txt didn't resolve. Anchor it to the repo root via
CARGO_MANIFEST_DIR so the test runs out of the box (still overridable with
XTRAIN_CORPUS).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The loss trajectory already matched torch.optim.AdamW (worst relerr ~2e-4),
but the float64 torch reference diverged per-weight from the f32 GPU training
after the model memorised the batch (flat region: weights underdetermined,
loss identical). Fixes: run the torch reference in float32 (match engine
precision), shorten to 10 steps (weights still well-determined), and compare
final params with an allclose-style rtol+atol metric (a pure relative metric is
misleading on near-zero weights).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Acceptance tests (GPU-gated not(no_cuda), run on dash5):
- adamw_parity_dump.rs + adamw_parity.py: build the tiny model with fixed init,
run N AdamW steps on a fixed batch, dump the loss trajectory + final params;
the Python side rebuilds the identical model and runs torch.optim.AdamW with
matched lr/wd/betas/eps, comparing trajectory + final params within rtol.
- checkpoint_roundtrip.rs: train a few steps, save, load into a fresh model with
a DIFFERENT init, assert identical logits/loss on a fixed input.
- real_training.rs (#[ignore], --release): train on TinyStories for a bounded
budget; assert loss drops substantially and print greedy samples.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
