OpenRLHF is a production-oriented distributed RLHF/RL training framework for large language models, not a research notebook collection. The codebase implements a full training stack: SFT, reward modeling, DPO/IPO/cDPO, and RL algorithms including PPO, REINFORCE++, GRPO, RLOO, Dr.GRPO, and FlashREINFORCE. Its architecture combines Ray for distributed actor orchestration and placement groups, vLLM for high-throughput rollout generation, DeepSpeed ZeRO for model training, and HuggingFace Transformers for model handling. The primary entry points are CLIs under openrlhf/cli, with train_ppo_ray.py as the main RL launcher; these accept a large set of hierarchically parsed dotted flags that control training, rollout, reward, vLLM, and DeepSpeed behavior. The repository is genuinely hybrid in spirit because it trains research-scale models and reproduces academic methods, but its dominant character is application/framework: it ships packaging, Dockerfiles, CLI entry points, unit tests, and versioned releases. The design emphasizes a token-in-token-out agent abstraction that unifies single-turn and multi-turn RLHF, plus sync and async training modes, a hybrid engine that colocates training and generation on shared GPUs, and VLM support. Distributed checkpointing, LoRA/QLoRA, packing, dynamic batch sizing, importance sampling corrections, and KL-estimator variants are all present in the code, not merely in the README. Craftsmanship is strong. The code separates concerns across cli/, trainer/, models/, datasets/, and utils/, and includes several genuinely reusable patterns such as a self-contained math answer grader, a flat-to-hierarchical argparse config converter, a typed RL experience dataclass, and distributed loss-normalization utilities. The test suite exercises loss estimators, trainer control flow, experience batching, and agent behavior with mocked heavy dependencies, which is a pragmatic way to test GPU-bound code on CPU. The main weaknesses are operational rather than architectural: dependencies are extremely tightly pinned (deepspeed==0.19.6, transformers==5.15.0, ray==2.55.0, vllm==0.29.0), and the code monkey-patches upstream internals and relies on version-specific behaviors. This makes upgrades brittle, and the CI pipeline builds wheels without running the test suite. Overall, this is a mature, actively maintained framework with high reusability for engineers building LLM alignment pipelines, though it demands GPU infrastructure and careful dependency alignment.