landAndRoads

fun landAndRoads(roadLayerId: String = "road-motorway", roadMaskId: String? = "road-motorway::mask", roadStrokeThickness: Double? = null, mode: StencilMaskCombineMode = StencilMaskCombineMode.ALL): LayerMaskSpec

JS docs “countries + motorways” example: built-in land ∩ visible motorway lines.

"countries" resolves to built-in OSM land (not a fill countries::mask layer).
roadLayerId is an existing line layer or a com.xweather.mapsgl.weather.LayerCode (e.g. road-motorway).