YOLOv8n detector for the Microscopy Bacilli Localization And Counting quest (Shipd.ai / Project Eris). Single class bacillus, trained imgsz=640 on 1632x1224 stained fields (epoch-48, val mAP50 ~0.69). Validated recipe: conf=0.25, iou(NMS)=0.45. Box encoding: normalized xyxy conf x_min y_min x_max y_max.