feat(tools): count aircraft in an area by airline

OpenSky, the default civil feed, reports no operator, so group_by: operator
said "no operator reported". aircraft_in_area now also takes
group_by: 'airline', read from the ICAO designator in each callsign: three
letters followed by a flight number that starts with a digit (SWA1234,
UAL12A). Registrations used as callsigns (N123AB) count as unknown. Rows are
unchanged; the designator is derived for the breakdown only.

Live, Texas: "785 aircraft ...; most by airline: AAL (89), SWA (65), UAL (52);
283 unknown."

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/tools/queries/aviation.js

@@ -36,11 +36,29 @@ const MILITARY_SCHEMA = Object.freeze({
 });
 const MAX_TRACK_POINTS = 200;
 const GROUP_LABELS = Object.freeze({
+  airline: 'airline',
   operator: 'operator',
   origin_country: 'country',
   type_code: 'type',
 });
 
+/**
+ * The ICAO airline designator a callsign flies under: three letters, then a
+ * flight number that starts with a digit (SWA1234, UAL12A, BAW1). Registrations
+ * used as callsigns (N123AB, GABCD) have no designator.
+ */
+export function airlineDesignator(callsign) {
+  const match = /^([A-Z]{3})\d[0-9A-Z]{0,4}$/.exec(
+    String(callsign ?? '')
+      .trim()
+      .toUpperCase(),
+  );
+  return match ? match[1] : null;
+}
+
+const groupValue = (field) =>
+  field === 'airline' ? (row) => airlineDesignator(row.callsign) : undefined;
+
 const round = (value, digits) =>
   Number.isFinite(value) ? Number(value.toFixed(digits)) : null;
 
@@ -91,7 +109,8 @@ export const aircraftInArea = defineTool({
   description:
     'Aircraft currently reported inside an area, nearest the center first. ' +
     'Optionally military aircraft only, airborne only, or within an altitude band. ' +
-    'group_by counts every matched aircraft by operator, country or type, and ' +
+    'group_by counts every matched aircraft by airline (the ICAO designator ' +
+    'in its callsign), operator, country or type, and ' +
     'stats summarizes airborne altitude and speed; both cover all matches, not ' +
     'just the rows returned.',
   inputSchema: {
@@ -151,7 +170,9 @@ export const aircraftInArea = defineTool({
       ...(regional ? [`regional feed: ${snapshot.coverage}`] : []),
       ...(snapshot.freshness === 'stale' ? ['data may be stale'] : []),
     ];
-    const groups = args.group_by ? breakdown(rows, args.group_by) : null;
+    const groups = args.group_by
+      ? breakdown(rows, args.group_by, groupValue(args.group_by))
+      : null;
     return {
       summary:
         `${rows.length} ${kind} in ${area.label}` +

src/tools/queries/aviation.test.mjs

@@ -1,6 +1,7 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
 import { composeCatalog, coreTools } from '../index.js';
+import { airlineDesignator } from './aviation.js';
 import { LiveSourceError } from '../../sources/live/contract.js';
 
 const record = (id, latitude, longitude, extra = {}) => ({
@@ -504,3 +505,43 @@ test('altitude bands require a reported altitude from normalized OpenSky records
   });
   assert.equal(minimum.data.total, 3);
 });
+
+test('an airline designator is read from an ICAO flight callsign only', () => {
+  for (const [callsign, designator] of [
+    ['SWA1234', 'SWA'],
+    ['ual12a', 'UAL'],
+    [' BAW1 ', 'BAW'],
+    ['RCH123', 'RCH'],
+    ['N123AB', null],
+    ['GABCD', null],
+    ['SWA', null],
+    ['SWAX123', null],
+    ['', null],
+    [null, null],
+  ])
+    assert.equal(airlineDesignator(callsign), designator, String(callsign));
+});
+
+test('aircraft in an area can be counted by airline from their callsigns', async () => {
+  const fleet = [
+    record('a1', 37.6, -122.3, { callsign: 'SWA100' }),
+    record('a2', 37.61, -122.3, { callsign: 'SWA2' }),
+    record('a3', 37.62, -122.3, { callsign: 'UAL9' }),
+    record('a4', 37.63, -122.3, { callsign: 'N123AB' }),
+  ];
+  const catalog = composeCatalog({
+    tools: coreTools,
+    services: { aircraft: feed(fleet) },
+  });
+  const result = await catalog.call('aircraft_in_area', {
+    area: bay,
+    group_by: 'airline',
+  });
+  assert.equal(
+    result.summary,
+    '4 aircraft in 60 km around 37.600, -122.300; most by airline: SWA (2), UAL (1); 1 unknown.',
+  );
+  assert.equal(result.data.breakdown.field, 'airline');
+  // Rows are unchanged: the designator is derived, not added to each row.
+  assert.equal('airline' in result.data.rows[0], false);
+});