Every generated leaf <head> preloaded mapbox-gl.js whatever the provider, so code that used the
bare `mapboxgl` global always found one, even on a MapLibre map. Removing that peer (it sends
every visitor's IP to Mapbox under provider=maplibre) turns each such site into an error.
engineFor(map), next to isMapboxMap in useMapProvider.js, asks the map which engine built it:
- useSelectedPin: the selected-pin Marker
- useMapEvents: the pin-fallback and region Popups
- useMapPoster: main already builds the hidden map with the source map's engine (1cbfb3aa);
its choice now goes through this one helper instead of a second inline sniff
- pplr-data-maps: glFor is now this helper; the geocoder awaits ensureEngineScript first
- key-cities: ensureEngineScript('mapbox') before reading the global
Measured with every api.mapbox.com tag stripped from the served leaf (no peer at all for
key-cities), before -> after:
pin select under MapLibre, on cities-internet, country-posters, doxa-research-map and
doxa-simple-map: "reading 'Marker'" -> marker drawn; country-posters region popup: none ->
popup; PPLR search: no input -> suggestions (both engines); key-cities: "mapbox-gl not
loaded" -> map loaded. Mapbox rows unchanged (they passed before and after).
The poster UI could not be driven: PosterDialog never opens in country-posters or
doxa-research-map (they pass props it does not declare and no modelValue/getMap), reported
separately. useMapPoster itself was rendered from a real map with only its engine on the page:
MapLibre "mapboxgl global not found" on the pre-1cbfb3aa library -> a 400x300 PNG with 88 colours.