{"service":"nhdplus-hr-proxy for SnapBasin","usage":"/?bbox=<3857 bbox>&bboxSR=3857&size=256,256&imageSR=3857&format=png32&transparent=true&layers=show:3,4,7,8,9&dpi=96&f=image","upstream":"https://hydro.nationalmap.gov/arcgis/rest/services/NHDPlus_HR/MapServer/export","version":"v1.2 (2026-08-06) bounded-retry + concurrency gate","behavior":"edge-cache 2592000s (PER-COLO); server-side retry x2 @ 8000ms each on 5xx/429; max 6 concurrent upstream calls (queue wait 10000ms); failures never cached; CORS *"}