galaxy-coder-reasoner-v1

Galaxy Nexus Coder-Reasoner v1

A QLoRA fine-tune of Qwen3.5-9B-DeepSeek-V4-Flash for agentic coding + reasoning.

Model Details

Training Data

This adapter was trained on a curated mix of DeepSeek-R1 chain-of-thought reasoning traces from the open-r1/Mixture-of-Thoughts dataset:

• Code subset (3,000 sampled): DeepSeek-R1 reasoning traces on competitive programming problems (Python + C++), sourced from CodeForces
• Math subset (2,000 sampled): DeepSeek-R1 reasoning traces on mathematical problems

After length filtering (≤8192 tokens), 2,893 examples were used for training.

Why This Model

The base model (Qwen3.5-9B-DeepSeek-V4-Flash) is already a reasoning model distilled from DeepSeek-V4. We fine-tuned it further to:

1. Specialize for agentic coding — AWS, Terraform, Docker, Kubernetes, Linux, Python
2. Reinforce step-by-step reasoning before code generation
3. Align to the Galaxy Nexus system prompt for consistent agent behavior

Training Results

Loss decreased 43% over 100 steps, with token accuracy climbing from 73.8% to ~84%.

Benchmark Results

Base model (Qwen3.5-9B-DeepSeek-V4-Flash) scored 10/11 (91%) on our agentic-coding benchmark suite covering Python, Docker, Terraform, Kubernetes, Linux, and reasoning tasks.

Serving with SGLang

# Serve base + adapter via SGLang multi-LoRA
python3 -m sglang.launch_server \
  --model-path Qwen3.5-9B-DeepSeek-V4-Flash \
  --enable-lora \
  --max-lora-rank 16 \
  --lora-paths gnx-coder=/path/to/galaxy-coder-reasoner-v1 \
  --quantization fp8 \
  --kv-cache-dtype fp8 \
  --trust-remote-code \
  --mem-fraction-static 0.88

Then call the adapter:

import openai
client = openai.OpenAI(base_url="http://localhost:8000/v1", api_key="...")
response = client.chat.completions.create(
    model="gnx-coder",  # ← use the adapter name
    messages=[{"role": "user", "content": "Write a Terraform S3 bucket with versioning"}]
)

Limitations

• 1 epoch only — trained for 100 steps (~1.7 epochs of the dataset). More training would improve quality.
• Sequence length 2048 — some long reasoning traces were truncated. Future versions will use 4096+.
• No RLHF/DPO — pure SFT. Future versions will add preference optimization.
• Qwen3.5 hybrid architecture — training is slower than standard attention models due to new, unoptimized kernels.

Citation

@misc{galaxynexus_coder_reasoner_v1,
  title={Galaxy Nexus Coder-Reasoner v1: QLoRA Fine-tune of Qwen3.5-9B for Agentic Coding},
  author={Galaxy Nexus AI},
  year={2026},
  url={https://huggingface.co/GalaxyNexus/galaxy-coder-reasoner-v1}
}

License

Apache 2.0 — commercial use permitted.