The same weights as AngelSlim/Hy-MT2-1.8B-1.25Bit-GGUF, converted losslessly for MLX: Hy-MT2-1.8B — Tencent's 33-language translation model, in its official 1.25-bit QAT checkpoint (Sherry, ggml type STQ1_0) — running on the Apple-Silicon GPU. The runtime is hy-mt2-mlx: the model ships its own decoder (sherry_model.py, loaded via mlx-lm's model_file hook), so vanilla mlx-lm runs it with zero extra code.

The upstream checkpoint exists only as a GGUF with CPU-only (NEON) kernels in an unmerged llama.cpp PR. This artifact is that checkpoint on the GPU:

path (M2 Pro)	decode	prefill @207 tok	peak mem	weights
llama.cpp CPU, 8 threads (NEON)	98 tok/s	313 tok/s	—	462 MB GGUF
this artifact — MLX 1.31-bit native	136	1020	0.59 GB	455 MB
MLX 2-bit transcode (same weights, via converter)	150	1220	1.09 GB	745 MB

Methodology and full conditions: hy-mt2-mlx docs/benchmarks.md.

Use

bash

pip install mlx-lm

mlx_lm.generate --model kuotient/Hy-MT2-1.8B-1.25Bit-MLX \
  --prompt "Translate the following segment into Korean, without additional explanation.

The quarterly results exceeded expectations, but the team remains cautious."

The chat template (bundled) wraps the prompt in Hy-MT's expected markers. Decode runs a custom Metal GEMV over the packed 1.31-bpw stream; multi-token prefill dequantizes one layer at a time into the stock matmul. Weights stay 1.31 bpw resident. If you prefer maximum speed over the memory savings, convert the source GGUF with hy-mt2-mlx's convert.py instead — the same weights transcode losslessly into MLX's stock affine 2-bit kernels.

What "lossless" means here

Sherry is quantization-aware-trained: the released GGUF is the trained weight grid, so no re-quantization is involved —

all 224 STQ1_0 linear tensors are preserved bit-exact (the sparse-ternary grid travels verbatim and is decoded by the bundled kernel);
the tied embedding (Q6_K in the GGUF) is re-quantized to 6-bit affine — the only approximation, Q6_K-class fidelity;
norms are fp16.

Greedy outputs matched llama.cpp's reference CPU implementation token-for-token (5/5) in the parity suite (scripts/parity.py).

Provenance

Source: AngelSlim/Hy-MT2-1.8B-1.25Bit-GGUF · Hy-MT2-1.8B-1.25Bit.gguf · sha256 cc497fe8f033b52b3b8b00a7669e9661435432f9d4cd43f7ed24400c01507a93
Converter: hy-mt2-mlx python -m sherry_mlx.convert_native --gguf Hy-MT2-1.8B-1.25Bit.gguf --ref <tencent/Hy-MT2-1.8B json files> --out <dir> --embed-bits 6
Config/tokenizer files come from the original tencent/Hy-MT2-1.8B repo.

License & attribution

Apache-2.0, matching both upstream repos. The model, the Sherry quantization scheme (arXiv 2601.07892) and the Hy-MT2 weights (arXiv 2605.22064) are Tencent's (Hunyuan / AngelSlim); the STQ1_0 format reference is llama.cpp PR #22836. This repo only moves those weights to a new backend — see the hy-mt2-mlx NOTICE for full attribution.