Darkstar-Nemotron-3.5-Lightning-30B-A3B-Abliterated-ModelOpt-W4A16-NVFP4

Reduced-refusal model: a refusal-direction edit was deliberately applied in BF16 before quantization. Read the safety warning before use.

Summary

NVIDIA ModelOpt quantization of the Darkstar Abliterated BF16 derivative of nvidia/NVIDIA-Nemotron-3.5-Lightning-30B-A3B-BF16, pinned upstream at d468880b6ad3c6e0d21377ce7242adaea4cc884d. The R1 edit projects a normalized float32 refusal direction (measured at layer 34, seed 42, chat-templated corpora) from exactly 3,126 residual-writing tensors; the edited BF16 artifact was then quantized to a mixed W4A16-NVFP4 layout (5,934 expert modules quantized; lm_head, Mamba/SSM, norms, embeddings, and MTP head protected in BF16). Artifact is 3 shards, ≈22 GB; quantization_config maps to vLLM modelopt_mixed.

ModelOpt is pinned to 0.46.0rc2 at 43fd41a58d52c4e6e5dec1d1ff5989ecc737ae1a. Calibration used cnn_dailymail plus nvidia/Nemotron-Post-Training-Dataset-v2, 512+512 samples, sequence length 2048, seed 1234, batch 1, KV cache quantization disabled (BF16).

Full provenance, protocol, and caveats:

Evaluation

Metric	Value	Basis
GPQA Diamond (thinking on)	141/198 = 71.2%	llm-inference-bench `gpqa-diamond`, chat template + thinking ON, temp 0; full denominator; served MTP10 + `--reasoning-parser nemotron_v3`
Behavior: harmful-prompt compliance	200/200 (0/200 refusals)	fresh suite on this exact artifact; 0 errors
Safe over-refusals	0/83 (0.00%)	0 errors
Single-stream throughput (MTP10)	554.7 tok/s weighted	4K 571.2 / 16K 546.3 / 48K 480.7; sweep winner

Missing cells are marked not measured and are never backfilled from a different checkpoint or protocol.

Safety warning

This model has had its refusal direction deliberately reduced. It complied with 200/200 harmful prompts in the measured suite and has no added safety mitigations. It will comply with many requests the upstream model would refuse. Deploy only behind appropriate policy, filtering, access controls, and legal review. Refusal-rate numbers are behavior measurements, not safety endorsements.

Release reference

Engineering release: darkstar-nemotron-3.5-lightning-v1.0.0. This immutable tag exists and the release contract is published.

Runtime

Validated with vLLM (CUDA 13 Blackwell nightly build family), Flash Attention, BF16 KV cache, context 131,072, MTP depth 10, and max_num_seqs=16:

vllm serve HangGlidersRule/Darkstar-Nemotron-3.5-Lightning-30B-A3B-Abliterated-ModelOpt-W4A16-NVFP4 \
  --served-model-name darkstar-nemotron-3.5-lightning-abliterated-nvfp4 \
  --kv-cache-dtype bfloat16 \
  --max-model-len 131072 \
  --max-num-seqs 16 \
  --reasoning-parser nemotron_v3 \
  --speculative-config '{"method": "mtp", "num_speculative_tokens": 10}'