Heretic removes the model's safety alignment ("censorship") using directional ablation (abliteration), with parameters chosen automatically by a TPE optimizer that co-minimizes the refusal rate and the KL divergence from the original model. Hence, the model stops refusing while keeping as much of its original behavior as possible. No human prompt-engineering or fine-tuning data was involved.

Performance

Metric	This model	Original model
Refusals (/100 harmful prompts)	5	98
KL divergence (harmless prompts)	0.1003	0 (by definition)

Refusals are measured against mlabonne/harmful_behaviors; KL divergence is measured on mlabonne/harmless_alpaca. Lower is better for both. A KL of ~0.10 indicates the model's responses on benign prompts remain very close to the original.

Usage

python

from transformers import AutoModelForCausalLM, AutoTokenizer

model_id = "LFM2.5-1.2B-Instruct-Uncensored"  # replace with your repo id

tokenizer = AutoTokenizer.from_pretrained(model_id)
model = AutoModelForCausalLM.from_pretrained(model_id, device_map="auto")

messages = [{"role": "user", "content": "Who are you?"}]
inputs = tokenizer.apply_chat_template(
    messages,
    add_generation_prompt=True,
    tokenize=True,
    return_dict=True,
    return_tensors="pt",
).to(model.device)

outputs = model.generate(**inputs, max_new_tokens=256)
print(tokenizer.decode(outputs[0][inputs["input_ids"].shape[-1]:], skip_special_tokens=True))

The export is a merged, full-precision BF16 model in Hugging Face format (148 tensors, ~2.2 GB) — no adapter merge or dequantization step is required at load time.

Abliteration parameters

Selected from trial 72 of 80 (the best refusal/KL trade-off found by the optimizer). Parameter names follow Heretic's canonical scheme; for LFM2 these map onto the out_proj (attention output) and w2 (MLP down) projections.

Parameter	Value
direction_scope	per layer
direction_index	12.31
attn.o_proj.max_weight	1.4818
attn.o_proj.max_weight_position	10.34
attn.o_proj.min_weight	0.9854
attn.o_proj.min_weight_distance	7.06
mlp.down_proj.max_weight	0.9760
mlp.down_proj.max_weight_position	11.74
mlp.down_proj.min_weight	0.2448
mlp.down_proj.min_weight_distance	6.54

Run details

Base model: LiquidAI/LFM2.5-1.2B-Instruct @ commit 6314d2b7cf28a6ae9de9d3e77dcfcd9c9f281c77
Architecture: LFM2, 16 layers, BF16
Trials: 80 (24 startup) · Seed: 260601
Quantization during Heretic run: none
Row normalization: pre · Orthogonalize direction: true
Harmful set: mlabonne/harmful_behaviors · Harmless set: mlabonne/harmless_alpaca

Notes / reproducibility

LFM2 is not yet natively supported by upstream Heretic. This run used a local compatibility patch for LFM2 module discovery, targeting the LFM2 out_proj and w2 projections (which the parameter table above refers to by Heretic's generic attn.o_proj / mlp.down_proj names).

Intended use & disclaimer

This model has had its refusal behavior substantially removed and will comply with requests the original model would have declined. It is provided for research and unrestricted local use. You are responsible for how you use it and for complying with all applicable laws and with the base model's lfm1.0 license, which carries over to this derivative.

Acknowledgements

Base model: LiquidAI/LFM2.5-1.2B-Instruct
Decensoring tool: Heretic by p-e-w

Justbackup/LFM2.5-1.2B-Instruct-Uncensored

LFM2.5-1.2B-Instruct-Uncensored