HybridAgent-HybridSFT-v1

• Paper: Hybrid Reasoning Agents
• Code: togethercomputer/HybridAgent

Overview

Each trajectory interleaves text reasoning, latent-mode spans and tool calls (Python interpreter and web search) with their tool observations. The format matches what the hybrid agent generates at inference time. This version was used to train the released HybridAgent checkpoints. HybridAgent-HybridSFT-v2 is also available.

Data Format

{
  "id": "0",
  "system": "<system prompt of the hybrid trajectory format>",
  "question": "...",
  "num_rounds": 2,
  "rounds": [
    {
      "assistant": "<think>...<latent>pseudo-text of the latent span</latent>...</think><python>...</python>",
      "tool": "python",
      "tool_result": "<result>...</result>"
    },
    {
      "assistant": "<think>...</think><answer>\\boxed{...}</answer>",
      "tool": null,
      "tool_result": null
    }
  ]
}

Fields

Field	Description
id	Trajectory ID
system	System prompt that defines the hybrid trajectory format
question	Input question
num_rounds	Number of rounds in the trajectory
rounds	List of rounds; each round has the fields below
rounds[].assistant	Model output for the round (reasoning, latent spans, and a tool call or final answer)
rounds[].tool	Tool called in the round: python, search, or null for the final round
rounds[].tool_result	Tool observation wrapped in <result>...</result>, or null for the final round

Latent Spans

<latent>...</latent> marks the spans the agent reasons through in latent mode. The text inside each span is the supervision target for that span.

Usage

Load the dataset

from datasets import load_dataset

ds = load_dataset("togethercomputer/HybridAgent-HybridSFT-v1", split="train")

Train with HybridSFT

git clone https://github.com/togethercomputer/HybridAgent.git && cd HybridAgent
MODEL=Qwen/Qwen3-8B-Base \
DATA=togethercomputer/HybridAgent-HybridSFT-v1 \
OUT=outputs/hybrid_sft \
bash scripts/run_hybrid_sft.sh all

Citation

@article{zou2026hybrid,
  title   = {Hybrid Reasoning Agents},
  author  = {Zou, Jiaru and Qi, Yunzhe and Chen, Sirui and Bianchi, Federico and Zhu, Shang and
             Lu, Pan and He, Jingrui and Zou, James},
  journal = {arXiv preprint arXiv:XXXX.XXXXX},
  year    = {2026}
}