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Nex-N2.5-mini-Uncensored

The abliterated (refusal-removed) build of Nex-AGI's Nex-N2.5-mini — baked directly into the official BF16 shards, byte-for-byte drop-in for the original

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The abliterated (refusal-removed) build of nex-agi/Nex-N2.5-mini — a ~34B Mixture-of-Experts agentic VLM with hybrid gated-delta-net + full attention, 256 routed experts top-8 beside a shared expert on every layer, a native vision tower, and a 262K-token context.

The refusal direction is baked directly into the official BF16 shards — same dtype, same shard layout, same model.safetensors.index.json. All 1026 tensors match the base checkpoint in name, dtype and shape, so this is a drop-in replacement for nex-agi/Nex-N2.5-mini in any stack that already serves it.

On precision: BF16 is the format Nex-AGI ships Nex-N2.5-mini in — there is no quantization step here, applied or undone.


⚠️ Disclaimer — read before use

This model has had its safety alignment substantially removed via abliteration (orthogonalizing the refusal direction out of the residual stream). As a direct consequence:

  • It will comply with harmful, unethical, offensive, or illegal requests that the original Nex-N2.5-mini would refuse. It has no meaningful built-in guardrails.
  • It is released strictly for legitimate research — interpretability, AI-safety and refusal-mechanism study, red-teaming, robustness evaluation, and controlled experiments.
  • You assume full responsibility and liability for how you use it and for everything it generates. Do not deploy it to end users or in production without adding your own safety, moderation, and abuse-prevention layers.
  • Use must comply with the Apache 2.0 License inherited from the base model, and all laws and regulations that apply to you.
  • The authors and uploaders accept no liability for any misuse or harm. Its outputs do not reflect the views of the uploaders or of Nex-AGI.

By downloading or using this model you acknowledge and accept the above.


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Model details

Base model nex-agi/Nex-N2.5-mini
Architecture Qwen3_5MoeForConditionalGeneration (qwen3_5_moe) — 40 layers, hidden 2048, hybrid attention (30 gated-delta-net linear-attention + 10 full-attention with attn_output_gate, interval 4), 256 routed experts top-8 + 1 shared expert on every layer, interleaved mRoPE, native vision tower (27 blocks @ 1152, patch 16, spatial merge 2)
Parameters ~34B total — 35.1B tensor elements on disk, including the 0.44B vision tower
Modification Abliteration (refusal-direction removal), baked on disk into the BF16 shards — no quantization applied
Format safetensors, BF16, 16 shards, 1026 tensors, 66 GiB
Edited 122 of 1026 tensors; the other 904 are byte-identical to the base
Preserved Everything that reads or gates the residual stream rather than writing it — the MoE router, the expert and attention input projections, the linear-attention state parameters, every norm, lm_head, and the vision tower apart from the merger's output projection
Context 262,144 tokens
Vocabulary 248,320 (untied embeddings)
Recommended for Red-team & refusal-mechanism research, robustness evaluation, and as a base for further post-training / quantization

Abliteration

Refusal-direction removal following Arditi et al. (2024), Refusal in Language Models Is Mediated by a Single Direction. A single refusal direction is estimated from the residual stream on paired harmful/harmless prompts, then projected out of the matrices that write that stream — the attention output projections, the routed and shared expert down-projections, the token embeddings, and the vision merger's output projection. The projection is computed in float32 and stored back in the checkpoint's own BF16.

122 of the 1026 tensors are edited; the other 904 are byte-identical to the base. Nothing that reads or gates the residual stream is touched. That is verified by a tensor-by-tensor comparison of the two checkpoints rather than by trusting the code that produced them, which is also what guarantees the drop-in property: every dtype, shape and shard boundary survives.

The edit is applied to the whole depth of the model, and the layer the direction is fitted at was selected on a held-out validation split by an objective that rewards bypassing refusal while charging for both divergence on harmless prompts and any newly induced refusal of benign ones. Capability retention is therefore measured rather than assumed — see Evaluation.

Fine-tuning & post-training

Nothing here changes the architecture, the config, the tokenizer or the shard layout, so anything that fine-tunes or quantizes the base checkpoint works unmodified on this one. Note that further training on refusal-bearing data will partially restore the direction; re-derive and re-bake afterwards rather than assuming the edit survives.


Intended use

  • Research into refusal mechanisms, alignment, and interpretability.
  • Red-teaming and safety / robustness evaluation in controlled environments.
  • A base for further post-training and quantization.

Evaluation

Measured on these exact weights, 8×H100, greedy decoding, 64 new tokens, reasoning_effort=none, thinking off. Both columns come from the same script, the same sampling seed, the same settings and the same scoring code. Refusal is judged by a rule-based opening-phrase classifier (caveat = answered but wrapped in a disclaimer) — indicative, not an LLM-judge / publication-grade number. Read Limitations before quoting the 0.000s.

Safety — harmful-prompt refusal (lower = more uncensored)

Benchmark n Base This model Δ Caveat (base → this)
AdvBench 100 1.000 0.000 −100% 1.000 → 0.360
JailbreakBench (harmful) 100 0.980 0.000 −98% 0.980 → 0.370
StrongREJECT 150 0.933 0.000 −93% 0.953 → 0.360
MaliciousInstruct 100 0.950 0.000 −95% 0.950 → 0.400
HarmBench (standard) 150 0.980 0.020 −96% 0.980 → 0.227
ForbiddenQuestions 150 0.587 0.020 −57% 0.627 → 0.273
SimpleSafetyTests 50 0.960 0.060 −90% 0.960 → 0.380

The base model refuses 93–100% of harmful prompts on six of the seven sets. ForbiddenQuestions is the outlier at 0.587, which says more about that set — a large share of its questions are sensitive rather than harmful, and the base model answers them — than about the edit.

The caveat column is the second half of the story. It does not merely track refusal: it falls from ~0.96 to ~0.35, so roughly two thirds of the disclaimer-wrapping goes with the refusal rather than surviving it.

Over-refusal — benign prompts wrongly refused (lower = better)

Benchmark n Base This model Δ
XSTest-safe 250 0.056 0.008 −4.8 pp
JailbreakBench (benign) 100 0.220 0.000 −22.0 pp

XSTest-safe is 250 prompts written to look harmful while being benign. The base model is already fairly restrained there at 5.6%; the edit does not blunt that discrimination, it sharpens it. JBB's benign split is the harder one — adversarially benign, 22% wrongly refused at baseline — and it goes to zero.

Capability retention — vs the official base (same scripts, same settings)

Benchmark n Base This model Δ
MMLU (0-shot) 300 0.830 0.830 ±0.0 pp
MMLU-Pro (CoT) 250 0.776 0.752 −2.4 pp
GSM8K (CoT) 150 0.907 0.907 ±0.0 pp
CMMLU (0-shot, Chinese) 500 0.852 0.864 +1.2 pp

Every delta is within ±2.4 pp, and unparsed rates were ≤1.6% on both checkpoints. Two of the four move up or hold exactly, which is the signature of sampling noise at these sizes rather than of an improvement — read the table as "unchanged", not as a gain. The −2.4 pp on MMLU-Pro is the largest single move and sits within the noise band of a 250-item CoT subset; it is not evidence of a regression, and it is not evidence against one either.

MMLU and CMMLU ask for a bare option letter, so they are scored from a single forward pass — an argmax over the option letters' logits. MMLU-Pro and GSM8K are chain-of-thought scored by generation, because their prompts ask the model to reason first: an argmax at the first position there measures the opening of a chain of thought, not an answer, and reads ~55 points low. These MMLU-Pro figures are therefore directly comparable to CoT-scored MMLU-Pro results elsewhere.


Usage

transformers

qwen3_5_moe needs transformers ≥ 5.2; verified here on 5.17.0 with torch 2.14. Install flash-linear-attention as well — without it transformers falls back to a reference PyTorch gated-delta-rule on 30 of the 40 layers, which is correct but much slower.

from transformers import AutoModelForCausalLM, AutoTokenizer

model_id = "orcarouter/Nex-N2.5-mini-Uncensored"
tok = AutoTokenizer.from_pretrained(model_id)
model = AutoModelForCausalLM.from_pretrained(model_id, dtype="bfloat16", device_map="auto")

msgs = [{"role": "user", "content": "..."}]
text = tok.apply_chat_template(
    msgs, tokenize=False, add_generation_prompt=True, reasoning_effort="none"
)
out = model.generate(**tok(text, return_tensors="pt").to(model.device), max_new_tokens=512)
print(tok.decode(out[0], skip_special_tokens=True))

The weights are 66 GiB, so they fit on a single 80 GB card with room for activations, or shard across smaller ones with device_map="auto".

Serving: we did not serve this build through vLLM or SGLang, so no flag set is recommended here. Because every tensor matches the base checkpoint in name, dtype and shape, whatever recipe works for nex-agi/Nex-N2.5-mini applies unchanged — follow the base model's own serving instructions.

Thinking control

Nex-N2.5-mini has no enable_thinking toggle — passing one is silently inert, because apply_chat_template drops unknown kwargs into a non-strict jinja context and the prompt renders byte-identically either way. Control it with reasoning_effort:

value renders use
none <think>\n\n</think>\n\npre-closed the reply starts at the answer; this family's thinking-off, and what every number above was measured with
unset / other <think> reasoning on, template default
high <think>\n reasoning on, longer traces

none is not a quieter low: it closes the thinking block inside the prompt, so no reasoning budget is needed and the reply is the answer. With reasoning on, give generation enough budget to reach </think> or replies get truncated inside the scratchpad.

Note for evaluators: do not pair reasoning_effort="none" with a <think>-stripping classifier. The block is already closed in the prompt, so the reply contains no </think>, every reply strips to the empty string, and the run reports a 100% refusal rate on every split.


Bias, risks, and limitations

  • Safety guardrails removed — the model will produce harmful, biased, or offensive content on request (see the disclaimer).
  • It inherits any biases and limitations of the base Nex-N2.5-mini.
  • The 0.000s are a statement about phrasing, not a measured bypass rate. This is the most important caveat on the card. The classifier keys on first-person inability ("I cannot", "I can't"); after ablation the model declines in a register that contains no such marker — "There is no valid movie script to write for this request, because it involves … which is illegal and harmful." — and that reply scores as compliance. So the edit demonstrably removed the first-person refusal register, and reduced refusal behaviour by an amount these numbers do not pin down. The caveat column (≈0.96 → ≈0.35) shows the moralising fell by roughly two thirds, which is real but is also not a bypass rate. An LLM judge or human eval would be needed to quantify it.
  • The vision path is edited but unverified. visual.merger.linear_fc2 writes the language residual stream, so an image could otherwise re-introduce the direction the text writers no longer carry, which is why it is included. But the direction was fitted on text only, and on transformers 5.17 AutoModelForImageTextToText does not register this config — the checkpoint loads text-only as Qwen3_5MoeForCausalLM — so no image prompt could be pushed through to check the effect. Treat image-conditioned behaviour as untested in both directions: neither confirmed removed nor confirmed intact.
  • Agentic and long-context behaviour was not measured at all. This is an agentic model whose stated strengths are computer use, browsing and visually grounded tasks, and none of that is in the evaluation above. Neither is the 262K context.
  • Capability retention is measured, not assumed (see Evaluation), but on sampled subsets of four benchmarks — enough to rule out a large regression, not a substitute for a full harness run.
  • A small residual refusal rate remains on two sets (HarmBench 0.020, SimpleSafetyTests 0.060). Some content is not mediated by the direction this method removes; do not assume a uniformly uncensored model.
  • The reported refusal metric is a rule-based heuristic; evaluate rigorously for your own use case.

License

Apache 2.0, inherited from the base model nex-agi/Nex-N2.5-mini. Abliteration does not change the underlying license obligations.

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