How Frontier Models Train on Outcomes: A History of RL Post-Training

SergioPaniego · x · 2026-08-10

This article serves as complementary material for Hugging Face's "Training an Agent" series, tracing the history of Reinforcement Learning (RL) in post-training to make it more accessible.

Rather than diving deep into specific algorithms like GRPO, the piece takes a historical perspective. It connects concepts from previous classes—such as SFT and distillation—and illustrates how these same ideas appear in the technical reports of frontier AI labs, helping readers grasp the evolution of current training paradigms.

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