Add Wikidata railway-station reference build pipeline (CC0)

Adds scripts/build-railways.mjs + a `railways` npm script that pulls mainline
railway stations from Wikidata (instance of Q55488) via SPARQL and reshapes them
into the app's reference format (id=QID, name, countryIso2 via P17→P297, lat/lon
via P625), writing public/reference/railways.json with recorded provenance
(source, CC0 licence, retrieval date).

Thresholding keeps it to a few-thousand notable mainline stations: require
coordinates, drop demolished/disused (P576/P5817), and keep only stations with a
Wikipedia sitelink or a UIC/IBNR code (P954); metro/tram are different Wikidata
classes and are already excluded. Aggregator-only — reshapes existing openly-
licensed facts, invents none (Constitution I).

NOTE: query.wikidata.org is blocked by this environment's egress policy (403), so
the fetch must run where Wikidata is reachable (a dev machine or CI); the produced
railways.json is then bundled like cities/airports. Wiring railway stations as a
full place type across the app (search/map/stats/pickers) is a follow-up feature.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014W6tgHRgLEugCsbKC9ccST

Author: davd-gzl

apps/postcards/package.json

@@ -15,6 +15,7 @@
     "test:e2e": "playwright test",
     "format": "prettier --write .",
     "reference": "node scripts/build-reference.mjs",
+    "railways": "node scripts/build-railways.mjs",
     "cap:sync": "cap sync",
     "cap:copy": "cap copy",
     "cap:add:android": "cap add android",

apps/postcards/scripts/build-railways.mjs

@@ -0,0 +1,112 @@
+// Build the bundled RAILWAY STATION reference data from Wikidata (CC0).
+//
+//   public/reference/railways.json   mainline/intercity railway stations
+//
+// WHY Wikidata (CC0): it is the only global source that maps 1:1 onto this app's
+// reference shape — a stable id (QID), a name, a country (P17 → ISO 3166-1 alpha-2
+// via P297) and coordinates (P625) — with NO attribution or share-alike burden.
+// Aggregator-only (Constitution I): this script RESHAPES existing, openly-licensed
+// facts; it invents nothing. Provenance is recorded in the emitted file.
+//
+// THRESHOLDING to a few-thousand MAINLINE set (not hundreds of thousands of
+// tram/metro stops): we take instances of *railway station* (Q55488) EXACTLY — its
+// metro/tram/light-rail siblings are DIFFERENT classes, so they're already excluded
+// — require a coordinate (P625), drop demolished/disused (P5817/P576), and keep only
+// stations notable enough to carry a Wikipedia sitelink OR a UIC/IBNR code (P954).
+// That lands in the low-thousands globally and biases toward significant stations.
+//
+// NOTE: query.wikidata.org must be reachable to run this (it was blocked by the
+// egress policy in the authoring sandbox). Run it where Wikidata is reachable:
+//
+//   node scripts/build-railways.mjs   (from apps/postcards)
+//
+// Then the file is bundled under public/reference/ like cities/airports and loaded
+// through the same reference-data seam.
+
+import { writeFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { dirname, join } from "node:path";
+
+const OUT = join(dirname(fileURLToPath(import.meta.url)), "..", "public", "reference", "railways.json");
+const ENDPOINT = "https://query.wikidata.org/sparql";
+const PAGE = 5000; // rows per request; paginate with LIMIT/OFFSET to avoid timeouts
+const UA = "Postcards-reference-build/1.0 (local-first travel journal; contact via repo)";
+
+// One page of stations. Filters, in order: exactly a railway station (Q55488);
+// has coordinates; not marked demolished/disused; has a country; AND (has ≥1
+// Wikipedia sitelink OR a UIC/IBNR station code P954) as the notability threshold.
+const query = (limit, offset) => `
+SELECT ?station ?stationLabel ?iso2 ?lat ?lon WHERE {
+  ?station wdt:P31 wd:Q55488 ;
+           wdt:P625 ?coord ;
+           wdt:P17 ?country .
+  ?country wdt:P297 ?iso2 .
+  FILTER NOT EXISTS { ?station wdt:P576 ?abolished. }        # dissolved/abolished date
+  FILTER NOT EXISTS { ?station wdt:P5817 wd:Q56556915. }     # state of use = demolished
+  FILTER NOT EXISTS { ?station wdt:P5817 wd:Q45382883. }     # state of use = disused
+  FILTER( EXISTS { ?station wdt:P954 ?uic. }
+          || EXISTS { ?sl schema:about ?station ; schema:isPartOf ?wiki .
+                      FILTER(CONTAINS(STR(?wiki), "wikipedia.org")) } )
+  BIND(geof:latitude(?coord) AS ?lat)
+  BIND(geof:longitude(?coord) AS ?lon)
+  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
+}
+ORDER BY ?station
+LIMIT ${limit} OFFSET ${offset}`;
+
+async function fetchPage(limit, offset) {
+  const url = `${ENDPOINT}?format=json&query=${encodeURIComponent(query(limit, offset))}`;
+  const res = await fetch(url, { headers: { Accept: "application/sparql-results+json", "User-Agent": UA } });
+  if (!res.ok) throw new Error(`Wikidata SPARQL ${res.status} ${res.statusText}`);
+  const json = await res.json();
+  return json.results.bindings;
+}
+
+function main() {
+  return (async () => {
+    // De-dupe by QID (occasional split items) and drop unnamed rows — a place must
+    // carry a label. Coordinates are numbers; ISO2 is upper-cased for the app.
+    const byId = new Map();
+    for (let offset = 0; ; offset += PAGE) {
+      const rows = await fetchPage(PAGE, offset);
+      if (!rows.length) break;
+      for (const r of rows) {
+        const id = r.station.value.replace("http://www.wikidata.org/entity/", "");
+        const name = r.stationLabel?.value?.trim();
+        // Wikidata returns the QID as the label when no English label exists — skip those.
+        if (!name || name === id || byId.has(id)) continue;
+        const iso2 = r.iso2.value.toUpperCase();
+        const lat = Number(r.lat.value);
+        const lon = Number(r.lon.value);
+        if (!/^[A-Z]{2}$/.test(iso2) || !Number.isFinite(lat) || !Number.isFinite(lon)) continue;
+        // subdivisionId is left null for v1: railways contribute to per-COUNTRY
+        // coverage immediately; region (admin-1) assignment via nearest-centroid
+        // against public/reference/subdivisions.json can be layered on later, the
+        // way build-reference.mjs matches city regions geographically.
+        byId.set(id, { id, name, countryIso2: iso2, subdivisionId: null, lat, lon });
+      }
+      process.stderr.write(`  …${byId.size} stations so far\n`);
+      if (rows.length < PAGE) break;
+    }
+
+    const stations = [...byId.values()].sort((a, b) => a.name.localeCompare(b.name));
+    const out = {
+      // Provenance is part of the file (Constitution: named source + license + date).
+      _source: {
+        dataset: "Wikidata railway stations (instance of Q55488)",
+        url: "https://query.wikidata.org/",
+        license: "CC0-1.0",
+        retrieved: new Date().toISOString().slice(0, 10),
+        note: "Mainline stations with coordinates and a Wikipedia sitelink or UIC code; metro/tram excluded.",
+      },
+      stations,
+    };
+    writeFileSync(OUT, JSON.stringify(out));
+    process.stderr.write(`Wrote ${stations.length} railway stations → ${OUT}\n`);
+  })();
+}
+
+main().catch((e) => {
+  process.stderr.write(String(e?.stack || e) + "\n");
+  process.exitCode = 1;
+});