Verified live on brick against real cached extracts: a plain Geofabrik
PBF's ways only carry bare node references, not coordinates, so
locations_on_ways on the final `cat -f opl` had nothing to embed —
every way came out as e.g. n123xy, empty x/y, and every relation got
dropped for having no usable geometry (0 routes for Macedonia).
osmium add-locations-to-ways between the tags-filter and cat steps
resolves those references first. Re-verified after the fix: 45 routes
for Macedonia, 3009 for Slovakia, with real colour/ref/operator/
distance (326 red, 782 yellow, 510 blue, 902 green KST-style routes).