ReDefiNER is an open-weight 0.8B model for entity extraction controlled by a plain-English prompt. List the entity types, describe each and add rules about what counts, up to about 10,000 tokens; it returns exact spans with a type and a confidence. The prompt is encoded once and cached, and editing it changes what it finds with no retraining. Built on Qwen3.5-0.8B, it is one 0.77 GB int8 file that runs offline on a CPU. Apache 2.0.