Model Summary
Table with columns: Item, Value| Item | Value |
|---|
| Parameters | ~501M |
| Architecture | 24-layer decoder, hidden 1280, GQA 4:1 (20Q / 5KV) |
| Context length | 4096 tokens |
| Vocab size | 65536 (BPE) |
| FFN | SwiGLU, d_ffn=3456 |
| Position encoding | RoPE (θ=5×10⁵) |
| Training stages | Pretrain → SFT → DAPO RL |
| Best RL method | DAPO (Direct Advantage Policy Optimization) |
Benchmark Results
Evaluated on HumanEval, HumanEval+, MBPP, MBPP+ with n=8, temperature=0.2, top_p=0.95, sandbox execution.
Macro average (this checkpoint)
Table with columns: Metric, Score| Metric | Score |
|---|
| pass@1 | 37.6% |
| pass@4 | 43.6% |
| pass@8 | 46.6% |
Per-dataset pass@1
Table with columns: Dataset, pass@1| Dataset | pass@1 |
|---|
| HumanEval+ | 34.1% |
| HumanEval | 36.1% |
| MBPP | 42.1% |
| MBPP+ | 38.3% |
Comparison vs Qwen2.5-0.5B-Instruct (pass@1 macro)
Table with columns: Model, Macro pass@1| Model | Macro pass@1 |
|---|
| Qwen2.5-0.5B-Instruct | 36.7% |
| Walkie-Code-0.5B (this) | 38.4% (+1.7 pp) |
Full training pipeline (macro pass@1)
Table with columns: Stage, pass@1, pass@8| Stage | pass@1 | pass@8 |
|---|
| SFT | 33.7% | 41.4% |
| DAPO (this checkpoint) | 37.6% | 46.6% |
Training Details
Pretraining (~17B tokens, code-heavy ~70%)
- The Stack v2 Python, StarCoder Python Edu, FineWeb Edu, FineMath, OPC Annealing
- Two-stage WSD schedule (main 89% + anneal 11%)
- Muon + AdamW mixed optimizer, FlashAttention-2
SFT
- KodCode-V1-SFT-R1 (~246k samples), DeepSeek-R1 generated solutions
- Instruct/complete Python function generation, ~2.6 epochs
RL (DAPO)
- KodCode-V1-RL (~12k filtered samples)
- Online rollout with code sandbox rewards (pass/fail)
- Dynamic group filtering + clipped policy gradient (ε_l=0.2, ε_h=0.28)
Usage
from transformers import AutoModelForCausalLM, AutoTokenizerimport torch model_id = "Henry665/Walkie-Code-0.5B" tokenizer = AutoTokenizer.from_pretrained(model_id, trust_remote_code=True)model = AutoModelForCausalLM.from_pretrained( model_id, torch_dtype=torch.bfloat16, device_map="auto", trust_remote_code=True,) prompt = "user: Write a Python function to check if a number is prime.\nassistant:"inputs = tokenizer(prompt, return_tensors="pt").to(model.device)outputs = model.generate(**inputs, max_new_tokens=256, temperature=0.2, top_p=0.95)print(tokenizer.decode(outputs[0], skip_special_tokens=True))
vLLM
vllm serve Henry665/Walkie-Code-0.5B --dtype auto --max-model-len 4096
Training used a simple dialog template:
user: <instruction>assistant: <python code>
For code benchmarks, plain user: / assistant: text prompts are recommended.
Limitations
- Specialized for Python code generation; general chat / multilingual ability is limited.
- Small scale (0.5B); not competitive with much larger models on broad reasoning.
- Exported as Qwen3-compatible config for tooling — verify behavior matches Walkie training setup.
- Benchmark scores depend on prompt template, sandbox, and sampling settings.
Citation & Links
- Project: LLM Walk-Through
- Architecture: RMSNorm, RoPE, GQA, SwiGLU, QK-Norm, Muon optimizer
- RL method: DAPO (dynamic filtering + clipped surrogate)
@misc{walkie-code-0.5b, title={Walkie-Code-0.5B: A Modular 0.5B Python Code LLM}, author={LLM Walk-Through Team}, year={2026}, howpublished={\url{https://huggingface.co/Henry665/Walkie-Code-0.5B}}}
License
Apache 2.0