ds4.c is Salvatore Sanfilippo’s deliberately narrow inference engine for DeepSeek V4 Flash on Macs with 128GB+ of RAM only. It is not a generic GGUF runner and it is not trying to be a framework. It is a model-specific native engine with a Metal path, model-specific loading, prompt rendering, KV handling, server API glue, and tests. (May 2026).