GpxStore#save now calls geojson() itself right after writing the
file, so the (potentially tens-of-seconds, for a large POI export)
conversion cost is paid during the upload — covered by the frontend's
existing "Uploading…" status — instead of on whichever checkbox
toggle happens to be first, which otherwise reads as a silent hang
indistinguishable from broken. An unparseable file still saves fine;
the error just surfaces on first view same as before.
randy
dd272ffb8a