Nex-N2.5-mini oQ4 (MLX)

oQ4 (streaming) MLX conversion of nex-agi/Nex-N2.5-mini, a 35B-parameter Mixture-of-Exerts (MoE) agentic model with 3B active parameters.

Upstream model: Nex-N2.5-mini by Nex-AGI (Shanghai Innovation Institute), released under Apache 2.0.

Conversion: Quantized to MLX format using Hermes Agent with oMLX (streaming oQ4). Sensitivity-driven mixed-precision with per-layer bit allocation.

Architecture

Property Value
Type Qwen3.5 MoE (Hybrid Attention)
Total params 35B
Active params 3B (8 routed + 1 shared expert)
Layers 40
Experts 256
Context length 262K tokens
Hidden size 2048

Quickstart

pip install -U mlx-lm

# Generate
python3 -m mlx_lm.generate \
  --model hermitdave/Nex-N2.5-mini-oQ4 \
  --prompt "Explain why long-context evaluation is difficult." \
  --max-tokens 512 --temp 1.0 --top-p 0.95

# Chat (with reasoning)
python3 -m mlx_lm.chat --model hermitdave/Nex-N2.5-mini-oQ4

Via OpenAI-compatible server

omlx serve hermitdave/Nex-N2.5-mini-oQ4 --port 8000
from openai import OpenAI

client = OpenAI(base_url="http://localhost:8000/v1", api_key="EMPTY")
response = client.chat.completions.create(
    model="hermitdave/Nex-N2.5-mini-oQ4",
    messages=[{"role": "user", "content": "Explain quantum entanglement."}],
    extra_body={"chat_template_kwargs": {"reasoning_effort": "high"}},
)
print("Reasoning:", getattr(response.choices[0].message, "reasoning_content", None))
print("Answer:", response.choices[0].message.content)

Reasoning Modes

Use reasoning_effort to control thinking behavior:

reasoning_effort Mode Behavior
"none" Non-thinking Respond directly without reasoning trace
"medium" (default) Adaptive thinking Model decides whether/how much to think
"high" Thinking Always enable thinking before responding

Conversion Details

  • Method: oQ4 (streaming) via oMLX
  • Bits-per-weight: ~4.6 (mixed precision, sensitivity-driven)
  • Router protection: MoE router gates preserved at 8-bit
  • lm_head: 8-bit
  • Output size: 19 GB (27% of bf16 source)
  • Validated: ✅ Smoke test passed (coherent generation, EOS functional)

Performance

Upstream Benchmarks (Nex-N2.5-mini, bf16)

Benchmark Score
Terminal-Bench 2.1 73.4
SWE-Bench Pro 43.8
AutomationBench v1.0.6 32.3
Toolathlon Verified 54.6
BrowseComp 83.4
OSWorld-Verified 71.2
WebArena-Verified 63.4

See Nex-N2.5 announcement for full evaluation details.

Deployment

  • Minimum RAM: 24 GB (for 19 GB model + inference overhead)
  • Recommended: Apple Silicon M1 Max or better
  • Context: 262K tokens native, extensible to 1M

Known Limitations

  • MTP disabled: Source config claims MTP (mtp_num_hidden_layers: 1) but checkpoint has no mtp.* weights — speculative decoding via MTP unavailable
  • Hybrid attention: Fine generation speed, slower long-context prefill (recurrent state layers)

License

Apache 2.0 (same as upstream). See Nex-N2.5 license.

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