Stage
S0 — monolingual only. 12B tokens, Chinese/English 50:50, 45,149 steps.
No parallel or instruction data at any point.
What to expect
This is a 13B-token model. For scale: Qwen3-0.6B-Base saw 36T tokens —
about 2,700x more. Treat the numbers below as what that budget buys, not as a
competitive result.
Table with columns: WMT22 5-shot, BLEU, COMET| WMT22 5-shot | BLEU | COMET |
|---|
| zh->en | 0.54 | 0.4638 |
| en->zh | 3.97 | 0.5872 |
Few-shot translation is essentially zero, and that is the finding. The
model ignores the in-context examples entirely — on zh->en it does not even
switch output language. Language modelling was learned; in-context learning
was not. 12B monolingual tokens is not enough for ICL to emerge at 0.5B.
Its value is as (a) the control for S1, and (b) a starting point for
mid-training / SFT.
Tokenizer
The tokenizer is a compiled C++ extension, not loadable by
AutoTokenizer. The release ships tokenizer.py and example_load.py:
pip install git+https://github.com/Ismantic/PieceTokenizer
python example_load.py
The model code (model.py, checkpoint.py) is bundled too — the package
depends only on torch plus the tokenizer extension, not on transformers.
Training
Full pipeline, data mixes and every design decision (including the mistakes)
are documented in https://github.com/Ismantic/Summer. Notably
docs/WHY.md records why fp32 master weights are mandatory, why the learning
rate schedule is WSD rather than cosine, and what the vocabulary swap cost.
License
Apache-2.0. Training corpora are public datasets (FineWeb-Edu, Cosmopedia,
CCI3-HQ, SkyPile, WMT19, OPUS-100 and others; see data/source.py upstream).
Please observe their respective licenses.