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cocoa-org/Mocha-Coder-32B

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<h1 style=" font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Helvetica,Arial,sans-serif; font-size:48px; font-weight:700; line-height:1.25; text-align:center; margin:0 0 24px;"> Mocha-Coder-32B </h1>

<p style="text-align:center; margin:0 0 8px; font-size:16px;"> <a href="https://junliwang.tech/">Junli Wang</a><sup></sup> &nbsp; <a href="https://blankcheng.github.io/">Zhoujun Cheng</a><sup>†</sup> &nbsp; <a href="https://yuxuan-zhang-dexter.github.io/">Yuxuan Zhang</a><sup>*</sup> &nbsp; <a href="https://ber666.github.io/">Shibo Hao</a> &nbsp; <a href="https://yaotang23.github.io/">Yao Tang</a> &nbsp; <br> <a href="https://zhiting.ucsd.edu/">Zhiting Hu</a> &nbsp; <a href="https://prithvirajva.com/">Prithviraj Ammanabrolu</a> &nbsp; <a href="https://haozhang.ai/">Hao Zhang</a><sup>†</sup> </p>

<p style="text-align:center; margin:0 0 24px; font-size:14px; color:#555;"> University of California, San Diego &nbsp;·&nbsp; <sup>*</sup>Equal Contribution &nbsp;·&nbsp; <sup>†</sup>Corresponding Author </p>

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<a href="https://github.com/cocoa-org/NanoRollout" style=" display:inline-block; padding:8px 24px; background:#2b2b2b; color:#ffffff; border-radius:36px; text-decoration:none; font-weight:600; font-size:16px;"> 🧑‍💻 NanoRollout Code </a>

<a href="https://huggingface.co/ZeonLap/Mocha-Coder-32B" style=" display:inline-block; padding:8px 24px; background:#2b2b2b; color:#ffffff; border-radius:36px; text-decoration:none; font-weight:600; font-size:16px;"> 🤗 Mocha-Coder-32B Model </a>

<a href="https://cocoa-org.notion.site/nanorollout" style=" display:inline-block; padding:8px 24px; background:#2b2b2b; color:#ffffff; border-radius:36px; text-decoration:none; font-weight:600; font-size:16px;"> 📒 Blog </a> </div>

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Introduction

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Mocha-Coder-32B is a strong open-data coding agent built on top of Qwen2.5-Coder-32B-Instruct. It is trained entirely through distillation on a 300K+ trajectory mixture sampled with our lightweight agent-rollout infrastructure, NanoRollout, with no reinforcement learning. The full training signal comes from frontier open-source teacher models (Qwen3-Coder-480B-A35B, Kimi-K2.5, Qwen3-Coder-Next, DeepSeek-V3.2) generating trajectories across multiple agent harnesses (OpenHands, mini-swe-agent, Terminus-2 JSON) on SWE-Rebench, SWE-Smith, and SETA.

The result is a simple but strong baseline coding agent: at the ≤32B scale, Mocha-Coder-32B is the state-of-the-art among open-data models and is competitive with much larger open-source models on agentic SWE benchmarks. </div>

Key Features

  • Strong agentic SWE performance: 62.6 Pass@1 on SWE-Bench Verified, 35.3 on SWE-Bench Pro, 23.6 on Terminal-Bench 2.0, competitive with Qwen3-Coder-480B-A35B-Instruct.
  • Multi-harness training: Trajectories cover OpenHands, mini-swe-agent, and Terminus-2 JSON, mitigating harness-specific overfitting.
  • Open data: Distilled from a fully released 300K+ trajectory mixture (ZeonLap/Mocha-trajectories).

Performance

SWE-Bench Verified

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**Model****Max Iteration****SWE-Bench Verified (Pass@1)**
Qwen3-Coder-480B-A35B-Instruct10067.0
Mocha-Coder-32B10062.6
SWE-Master-32B-RL15061.4
Kimi-Dev-72BAgentless, TTS@4060.4
CoderForge-Preview-32B10059.4
GLM-4.7-Flash10059.2
daVinci-Dev-72B10058.5
daVinci-Dev-32B10056.1
SERA-32B10054.2
Qwen3-Coder-30B-A3B-Instruct10051.6
Qwen2.5-Coder-32B-Instruct (Base)1006.2

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SWE-Bench Pro

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**Model****Max Iteration****SWE-Bench Pro (Pass@1)**
Qwen3-Coder-480B-A35B-Instruct25038.7
Mocha-Coder-32B25035.3
Gemini-3-flash25034.6
Kimi-K2-Instruct25027.7
DeepSeek-V3.225015.6
Qwen2.5-Coder-32B-Instruct (Base)2500.0

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Terminal-Bench 2.0

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**Model****Terminal-Bench 2.0**
Qwen3-Coder-480B-A35B-Instruct23.9
Mocha-Coder-32B23.6
Qwen3-Coder-30B-A3B-Instruct13.5
Qwen2.5-Coder-32B-Instruct (Base)3.4

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Training Data

Mocha-Coder-32B is trained on a 300K+ trajectory distillation mixture, drawn from previously released distillation sets (120K) and trajectories newly generated with NanoRollout (~180K).

**Dataset****Teacher Model****Harness****# Trajectories (K)****Source**
SWE-RebenchQwen3-Coder-480B-A35BOpenHands32.2Nebius
SWE-SmithQwen3-Coder-480B-A35BOpenHands89.5CoderForge
SWE-RebenchKimi-K2.5mini-swe-agent83.6NanoRollout
SWE-RebenchQwen3-Coder-Nextmini-swe-agent11.5NanoRollout
SWE-SmithQwen3-Coder-480B-A35Bmini-swe-agent12.8NanoRollout
SWE-SmithQwen3-Coder-Nextmini-swe-agent9.1NanoRollout
SETAKimi-K2.5 / DeepSeek-V3.2Terminus-2 JSON14.0NanoRollout

The full mixture is released at `ZeonLap/Mocha-trajectories`.

Running as an Agent

Mocha-Coder-32B is trained as an agent and is most useful when paired with a coding-agent harness. We have validated it with:

  • mini-swe-agent — minimal SWE agent loop, recommended for SWE-Bench Verified / Pro evaluation.
  • OpenHands — full-featured SWE harness; the model was trained on OpenHands trajectories.
  • Terminus-2 JSON — for Terminal-Bench 2.0 style shell tasks.

Point each harness's model endpoint at the vLLM server above. For SWE-Bench Verified we report numbers at a 100-iteration budget; for SWE-Bench Pro at 250 iterations.

License

Mocha-Coder-32B (model weights, training trajectories, and code) is released under the MIT License (see LICENSE) for research, educational, and commercial use.

Citation

If you use Mocha-Coder-32B or NanoRollout in your research, please cite NanoRollout:

bibtex
@misc{nanorollout,
  title  = {NanoRollout: A Lightweight Infra for Digital Agent Rollout at Scale},
  author = {Wang, Junli and Cheng, Zhoujun and Zhang, Yuxuan and Hao, Shibo
            and Tang, Yao and Hu, Zhiting and Ammanabrolu, Prithviraj
            and Zhang, Hao},
  year   = {2026},
  howpublished = {\url{https://github.com/cocoa-org/NanoRollout}},
}

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