OpenThinkerAgent-8B-RL

OpenThinkerAgent-8B-RL

OpenThoughts-Agent is an open-source effort to curate the best datasets for training agents. Our release includes datasets, models and our research codebase.

OpenThinkerAgent-8B-RL is the final, RL-trained 8B agentic checkpoint of the OpenThoughts-Agent SFT→RL recipe. Starting from the cold-start SFT base OpenThinkerAgent-8B-ColdStartSFTForRL, it is further trained with on-policy reinforcement learning on the OpenThoughts-Agent-RL-5K task set. This checkpoint corresponds to RL step 45.

Architecture note. Although the upstream lineage carries a GLM-4.7 label (which refers to the teacher used for the cold-start SFT trajectories, not the student), this model is a Qwen3-8B. Its config.json reports model_type: qwen3, architectures: ["Qwen3ForCausalLM"], 36 layers, hidden size 4096, 32 attention heads / 8 KV heads, and a 40,960-token context — i.e. standard Qwen3-8B.

• Homepage: https://www.openthoughts.ai/blog/agent
• Repository: https://github.com/open-thoughts/OpenThoughts-Agent

Model details

• Base (pre-RL) model: OpenThinkerAgent-8B-ColdStartSFTForRL (itself an SFT of Qwen/Qwen3-8B)
• Architecture: Qwen3 (Qwen3ForCausalLM), 36 layers, hidden size 4096, 32 attention heads, 8 KV heads, RoPE θ = 1e6
• Context length: 40,960 tokens (max position embeddings); RL rollouts used a 32,768-token serving window
• Vocabulary: 151,936 tokens
• Precision: bf16
• Checkpoint: RL step 45

The SFT → RL recipe

1. OpenThoughts-Agent-SFT-ColdStartForRL-10K — cold-start SFT trajectories.
2. OpenThinkerAgent-8B-ColdStartSFTForRL — Qwen3-8B after cold-start SFT (the pre-RL base).
3. OpenThoughts-Agent-RL-5K — the 5,000 on-policy RL tasks.
4. OpenThinkerAgent-8B-RL — this model, the final RL'd checkpoint (step 45).

Training data

• Cold-start SFT: OpenThoughts-Agent-SFT-ColdStartForRL-10K (9,437 task/trajectory pairs).
• RL tasks: OpenThoughts-Agent-RL-5K (5,000 pymethods2test-large tasks); the policy rolls out against each task in a Daytona sandbox and is rewarded by the task's test verifier.

Training procedure

On-policy RL with the OpenThoughts-Agent codebase (SkyRL), recorded in the run config shipped with this repo (swesmith-fixthink-pymethods2test_rl_config.json):

• Algorithm: RLOO-n advantage estimator (advantage_estimator=rloo_n), no KL loss (use_kl_loss=false, kl_loss_coef=0.0)
• PPO clip: eps_clip_low/high = 0.2, loss reduction = token_mean
• Optimizer: AdamW, learning_rate 5e-6, weight_decay 0.0, betas (0.9, 0.999)
• Batch: train_batch_size 64, policy_mini_batch_size 64
• Rollouts: vLLM backend, 8 samples per prompt, sampling temperature 0.7 / top_p 0.95 / top_k 20, max generate length 4096, served at 32,768-token context
• Harness: terminus-2 agent in Daytona sandboxes; interleaved thinking enabled
• Strategy: FSDP2; HF checkpoint exported every 5 RL steps; this artifact is step 45

Intended uses & limitations

This is an agentic coding model: it is designed to operate as a tool-using agent in the terminus-2 harness (issuing shell commands / edits and reasoning over terminal output) to solve software-engineering tasks. It inherits Qwen3-8B's general capabilities plus agentic behaviour from cold-start SFT and the RL stage. Limitations: outputs (including shell commands) may be incorrect or unsafe and should be executed only in sandboxed environments with review; the RL stage optimized for the pymethods2test/SWE-Smith-style task distribution and may generalize unevenly to other domains.

Evaluation: No verified agentic-benchmark numbers are published for this specific 8B RL checkpoint in the source artifact; evaluation results are TBD. (The flagship OpenThinkerAgent-32B card reports the project's benchmark suite for the 32B SFT line.)

Links

• 🌐 OpenThoughts-Agent project page
• 💻 OpenThoughts-Agent GitHub repository
• 📚 OpenThinker-Agent collection
• 🤖 Pre-RL base model: OpenThinkerAgent-8B-ColdStartSFTForRL
• 🧠 RL tasks: OpenThoughts-Agent-RL-5K
• 🧠 Cold-start SFT dataset: OpenThoughts-Agent-SFT-ColdStartForRL-10K

Citation

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@misc{openthoughts-agent,
  author = {Team, OpenThoughts-Agent},
  title = {{OpenThoughts-Agent: Data Recipes for Agentic Models}},
  howpublished = {https://www.openthoughts.ai/blog/agent},
  year = {2026}
}