ACE-Step is a production-grade music generation system that implements a flow-matching diffusion model (ACEStepTransformer2D) with a custom DCAE autoencoder and vocoder. It provides multiple deployment options: a Gradio UI, CLI inference, and FastAPI REST endpoints. The system supports text-to-music, lyrics-conditioned generation, audio-to-audio editing, LoRA fine-tuning, and multilingual lyrics (17+ languages). Architecturally, it extends Hugging Face diffusers with custom attention processors (LiteLA linear attention), schedulers (Euler/Heun/PingPong flow matching), and a Conformer-based lyric encoder. It includes CPU offloading, overlapped decode, and memory optimizations for GPU-constrained environments. While primarily an application, the repository also contains training scripts (PyTorch Lightning) and dataset conversion utilities, reflecting its hybrid research-production nature.