What problem does it solve? Aligning language models with human preferences requires navigating multiple post-training methods, dataset formats, and hyperparameter choices. This Skill provides complete, working workflows for supervised fine-tuning, preference alignment, reward modeling, and online reinforcement learning with HuggingFace TRL. ## Core Features & Use Cases - Full RLHF Pipeline: Step-by-step checklists for SFT, reward model training, and RLOO reinforcement learning, with both Python and CLI examples. - Preference Alignment with DPO: Train on chosen/rejected pairs without a reward model, including 10+ loss variants (IPO, hinge, robust, APO) with recommended hyperparameters. - Memory-Efficient GRPO: Deep guidance on reward function design, mode collapse detection, multi-stage training, and a production-ready training template. - Use Case: Fine-tune Qwen2.5-1.5B-Instruct on GSM8K math problems using GRPO with correctness and format reward functions, LoRA adapters, and 8-bit optimization on a single GPU. ## Quick Start Ask the agent to fine-tune a Qwen model with DPO on a preference dataset using TRL and save the aligned model.