Special remote airports + isRemote curation (ISS-097, v0.61.0)

lib/airports.test.ts

@@ -1,5 +1,7 @@
+import { promises as fs } from 'node:fs';
+import path from 'node:path';
 import { describe, expect, it } from 'vitest';
-import { assertUniqueIcaos, filterWorldAirports, parseCsv, toGeoJson, airportsHandler } from './airports';
+import { assertUniqueIcaos, filterWorldAirports, isRemote, parseCsv, toGeoJson, airportsHandler, REMOTE_RADIUS_KM } from './airports';
 
 const HEADER =
   '"id","ident","type","name","latitude_deg","longitude_deg","elevation_ft","continent","iso_country","iso_region","municipality","scheduled_service","icao_code","iata_code","gps_code","local_code","home_link","wikipedia_link","keywords"';
@@ -132,3 +134,61 @@ describe('/api/airports handler', () => {
     expect(await a.json()).toEqual(await b.json());
   });
 });
+
+describe('isRemote (v0.61.0 — ISS-097 special remote airports)', () => {
+  it('synthetic: an isolated point is remote; a neighbour inside the radius is not', () => {
+    // Equator pair: Δlon 8.5° ≈ 945 km (inside REMOTE_RADIUS_KM) vs Δlon 9.5° ≈ 1052 km (outside).
+    const near = [
+      { icao: 'AAA', lat: 0, lon: 0 },
+      { icao: 'BBB', lat: 0, lon: 8.5 },
+    ];
+    expect(isRemote(near, 'AAA')).toBe(false);
+    expect(isRemote(near, 'BBB')).toBe(false);
+
+    const far = [
+      { icao: 'AAA', lat: 0, lon: 0 },
+      { icao: 'CCC', lat: 0, lon: 9.5 },
+    ];
+    expect(isRemote(far, 'AAA')).toBe(true);
+    expect(isRemote(far, 'CCC')).toBe(true);
+
+    // A lone airport has no other member to be near — remote by definition.
+    expect(isRemote([{ icao: 'SOLO', lat: -77.84, lon: 166.91 }], 'SOLO')).toBe(true);
+  });
+
+  it('real coords: Frankfurt↔Amsterdam (~370 km) is not remote; McMurdo vs Christchurch (~3800 km) is', () => {
+    const eu = [
+      { icao: 'EDDF', lat: 50.0376, lon: 8.5622 }, // Frankfurt Main
+      { icao: 'EHAM', lat: 52.3093, lon: 13.3698 }, // Amsterdam Schiphol
+    ];
+    expect(isRemote(eu, 'EDDF')).toBe(false);
+
+    const pacific = [
+      { icao: 'MCDD', lat: -77.8425, lon: 166.9133 }, // McMurdo Station (Antarctica)
+      { icao: 'NZCH', lat: -43.4893, lon: 172.5308 }, // Christchurch
+    ];
+    expect(isRemote(pacific, 'MCDD')).toBe(true);
+    expect(REMOTE_RADIUS_KM).toBe(1000);
+  });
+
+  it('an unknown ICAO is not remote', () => {
+    expect(isRemote([{ icao: 'AAA', lat: 0, lon: 0 }], 'ZZZ')).toBe(false);
+  });
+
+  it('committed dataset curation rule: every non-large row has no large airport within REMOTE_RADIUS_KM', async () => {
+    const text = await fs.readFile(path.join(process.cwd(), 'data', 'airports_world.csv'), 'utf8');
+    const rows = filterWorldAirports(parseCsv(text));
+    expect(rows.length).toBeGreaterThan(0);
+
+    const large = rows.filter((r) => r.type === 'large_airport').map((r) => ({ icao: r.icao_code || r.ident, lat: +r.latitude_deg, lon: +r.longitude_deg }));
+    const nonLarge = rows.filter((r) => r.type !== 'large_airport');
+    // The dataset must actually carry the "special" airports — not just large ones.
+    expect(nonLarge.length).toBeGreaterThan(0);
+
+    for (const r of nonLarge) {
+      const self = { icao: r.icao_code || r.ident, lat: +r.latitude_deg, lon: +r.longitude_deg };
+      // Remote against the kept set: no LARGE airport within REMOTE_RADIUS_KM (the curation rule).
+      expect(isRemote([...large, self], self.icao), `${self.icao} (${r.name}) must be remote`).toBe(true);
+    }
+  });
+});

lib/airports.ts

@@ -1,5 +1,6 @@
 import { promises as fs } from 'node:fs';
 import path from 'node:path';
+import { haversineKm } from './geo';
 
 export type CsvRow = Record<string, string>;
 
@@ -52,15 +53,38 @@ export function parseCsv(text: string): CsvRow[] {
 // The 2026 schema splits "airport" into small/medium/large_airport (older dumps used a
 // single "airport" type + category column) — both spellings are accepted. Heliports are
 // excluded — no fixed-wing transport ops; other types (closed, balloonport, ...) are
-// irrelevant to an airline-ops game. The committed dataset is pre-curated to large_airport
-// only (scripts/build-world-airports.mjs); this check stays as a cheap guard against an
-// uncurated dump being swapped in.
+// irrelevant to an airline-ops game. The committed dataset is pre-curated by
+// scripts/build-world-airports.mjs: every large_airport plus the small/medium/seaplane rows
+// that are REMOTE (see isRemote) — this check stays as a cheap guard against an uncurated
+// dump being swapped in.
 const INCLUDED_TYPES = new Set(['airport', 'small_airport', 'medium_airport', 'large_airport', 'seaplane_base']);
 
 export function filterWorldAirports(rows: CsvRow[]): CsvRow[] {
   return rows.filter((r) => INCLUDED_TYPES.has(r.type));
 }
 
+// v0.61.0 (ISS-097): "special" remote airports — the issue's loneliness test: an airport is
+// remote when no other member of `airports` sits within this radius, so it stands alone in a
+// genuinely empty region (Antarctica, high Arctic, far islands) rather than being one of many.
+export const REMOTE_RADIUS_KM = 1000;
+
+export interface RemoteAirport {
+  icao: string;
+  lat: number;
+  lon: number;
+}
+
+// True when the airport with this ICAO has no OTHER member of `airports` within REMOTE_RADIUS_KM
+// (haversine). Unknown ICACOs are not remote — callers only pass rows they intend to include.
+export function isRemote(airports: readonly RemoteAirport[], icao: string): boolean {
+  const a = airports.find((x) => x.icao === icao);
+  if (!a) return false;
+  for (const b of airports) {
+    if (b.icao !== a.icao && haversineKm(a.lat, a.lon, b.lat, b.lon) <= REMOTE_RADIUS_KM) return false;
+  }
+  return true;
+}
+
 export interface AirportProperties {
   name: string;
   icao: string;