# NVIDIA Releases Polar, a Token-Faithful Rollout Framework for GRPO Training Across Codex, Claude Code, and Qwen Code

> Source: <https://www.marktechpost.com/2026/05/27/nvidia-releases-polar-a-token-faithful-rollout-framework-for-grpo-training-across-codex-claude-code-and-qwen-code/>
> Published: 2026-05-27 17:09:38+00:00

NVIDIA researchers have introduced Polar, a rollout framework that trains language agents using reinforcement learning without modifying their agent harnesses. Polar places a model API proxy between the harness and the inference server, capturing token-level interactions and reconstructing trainer-ready trajectories. Using GRPO on a Qwen3.5-4B base model, Polar improves SWE-Bench Verified pass@1 by 22.6 points under the Codex harness, 4.8 points under Claude Code, and 6.2 points under Pi. The framework is registered as a NeMo Gym environment and released under the ProRL Agent Server repository.

The post [NVIDIA Releases Polar, a Token-Faithful Rollout Framework for GRPO Training Across Codex, Claude Code, and Qwen Code](https://www.marktechpost.com/2026/05/27/nvidia-releases-polar-a-token-faithful-rollout-framework-for-grpo-training-across-codex-claude-code-and-qwen-code/) appeared first on [MarkTechPost](https://www.marktechpost.com).