feat(sdr): local receivers — browser RTL-SDR, Local ADS-B layer and decoder feeds (#732)

Adds a Local ADS-B layer fed by your own receivers: a browser WebUSB
RTL-SDR (with FM listening) and local 1090/978 MHz decoder feeds
(LOCAL_RECEIVER_FEEDS, local and private addresses only). Local aircraft
draw in magenta with class, silhouettes, 3D models, trails and a position
sanity filter; the click card names the band and input that heard them.

Builds on Sameh Khamis's SDR prototype and the initial GEV port by
Mazeyar Moeini Feizabadi (#134); the decoder-feed design follows the
notes on #57. Closes #57.

Co-authored-by: Sameh Khamis <[email protected]>
Co-authored-by: Mazeyar Moeini Feizabadi <[email protected]>

src/data/aircraftClass.js

@@ -438,6 +438,20 @@ export function classifyAircraft({ typeCode, category } = {}) {
   return 'airliner';
 }
 
+/** Readable name of each class, for cards and readouts. */
+export const AIRCRAFT_CLASS_LABELS = Object.freeze({
+  light: 'Light aircraft',
+  glider: 'Glider',
+  turboprop: 'Turboprop',
+  airliner: 'Airliner',
+  widebody: 'Widebody',
+  quadjet: 'Four-engine jet',
+  helicopter: 'Helicopter',
+  fastjet: 'Fast jet',
+  bizjet: 'Business jet',
+  uav: 'Drone',
+});
+
 /** Billboard scale multipliers (skylight GLYPH_SCALE, + fastjet). */
 export const CLASS_SCALE_2D = {
   light: 0.62,

src/data/fixtures/README.md

@@ -7,3 +7,16 @@
   (22,980 bytes). Used by offline decode/source tests and the explicit `qa-traffic --fixtures`
   browser mode — it is a point-in-time congestion snapshot, not a bundled
   data layer, and is never loaded by ordinary application startup. © TomTom.
+- `adsb-austin-frames.txt` — 112 raw Mode S frames (`*<hex>;`, one per line,
+  in receive order) received over Austin, TX, and
+  `adsb-austin-dump1090-aircraft.json` — dump1090-fa's `aircraft.json` decode
+  of the same frames, trimmed to the fields the tests assert on. Used by the
+  Local ADS-B decoder and record-adapter tests; never loaded at runtime.
+- `adsb-austin-capture-timed.json` — a second ~90 s receive over Austin, TX:
+  846 extended squitters from six aircraft (`frames`: `[ms, hex]`), with
+  dump1090-fa's decoded positions and emitter categories for the same
+  interval (`dump1090`: per ICAO `flight`, `category` and `fixes` as
+  `[ms, lat, lon]`). The capture has no per-frame timestamps; each frame's
+  time is interpolated between the frames whose decoded position equals a
+  dump1090 fix, timed as dump1090's `now − seen_pos`. Used by the decoder's
+  category, speed-check and track-accuracy tests; never loaded at runtime.

src/data/fixtures/adsb-austin-capture-timed.json

@@ -0,0 +1 @@
+{"receiver":{"latitude":30.27,"longitude":-97.8},"frames":[[10,"8d0d0c07501d0030aa4c0c2140c6"],[80,"8da5b3a758b99408f8dda679bb00"],[150,"8da0b702e1150d0000000004eb56"],[220,"8d0d0c0722594377e37820b79a0d"],[290,"8d0d0c07990c111d483c0c92e5f3"],[360,"8da0b702590d40253c4af26e47d9"],[430,"8da0b70299105d833818018770a8"],[500,"8d0d0c07501bf7da9cd71ab9e124"],[570,"8da5b3a7ea466864013c085e68e2"],[640,"8da3627d58a580665464f23579f2"],[780,"8d0d0c07990c111d483c0c92e5f3"],[850,"8da0b702590d47cf46d60b223463"],[920,"8da0b70299105d83380c015f9ea8"],[990,"8d0d0c07f8200002004ab89cec0b"],[1060,"8da0b702f8122006005ab8b0ce08"],[1130,"8d0d0c07501bf030d84c0b00e5d5"],[1200,"8da5b3a758b9905ff8528e447e65"],[1275,"8d0d0c07990c111d483c0c92e5f3"],[1350,"8da0b702590d5025384afb963e58"],[1425,"8da0b70299105d83300481465660"],[1500,"8da3627d58a5840ef0ef82e7f39f"],[1600,"8d0d0c07501bf030f64c0af8367b"],[1675,"8da5b3a7990da30b30085d4a3fb6"],[1750,"8d0d0c07990c111d483c0b6d35d7"],[1825,"8da5b3a723041333c31c2045cc84"],[1900,"8da0b702590d4025364affe4f100"],[1963,"8da0b70299105c833008010a006e"],[2088,"8dabe7c59915ad0d380456abc760"],[2150,"8dabe7c558af87ce8ccac01d62c7"],[2213,"8d0d0c07501be031124c090e5e08"],[2275,"8d0d0c07e1058a00000000c4d44e"],[2338,"8da3627de106290000000030ef86"],[2400,"8da5b3a758b994091cdd51bae36d"],[2460,"8d0d0c07990c111d483c0c92e5f3"],[2580,"8da0b702590d47cf40d6170e6567"],[2640,"8da0b70299105c83100c01774a47"],[2700,"8d0d0c07501be031244c08456bbe"],[2800,"8da5b3a7990da30b30085d4a3fb6"],[2900,"8da27e81592147de34ccbfe1e71f"],[3000,"8d0d0c07990c111d683c0b2849fe"],[3100,"8da0b702590d57cf3cd61d759697"],[3133,"8da0b70299105c83101081d8ce87"],[3200,"8da5b3a7ea466864013c085e68e2"],[3233,"8d0d0c07501be7db16d7163df6ea"],[3267,"8da3627d991417bb100854ccc1a2"],[3300,"8da27e81592147de3cccc18db35e"],[3333,"8da27e819910390f18080b8ece70"],[3367,"8d0d0c07990c111d683c0cd799da"],[3400,"8da5b3a758b990601e52360713ad"],[3450,"8da0b702f8122006005ab8b0ce08"],[3500,"8d0d0c07f8200002004ab89cec0b"],[3550,"8da0b702590d50252e4b0d6c0eab"],[3600,"8da0b70299105b83101481e9cced"],[3650,"8da5b3a7f82300060049b8e08700"],[3700,"8d0d0c07501be7db32d715b033d5"],[3700,"8da3627d58a580652c64ebca78d9"],[3860,"8da5b3a7990da30b30085eb5d7a4"],[3940,"8d0d0c07990c111d68380b107ffe"],[4020,"8dabe7c59915ad0d380456abc760"],[4100,"8da0b702590d57cf38d625439697"],[4140,"8da0b70299105b83101801a6902d"],[4180,"8d0d0c07501bd031724c05906709"],[4220,"8dabe7c558af87ceb8ca66b4e8a7"],[4260,"8d0d0c07990c111d68380cefafda"],[4300,"8da5b3a758b9906030520dfe8d1c"],[4417,"8d0d0c07501bd031844c05445a49"],[4533,"8da0b702590d57cf36d62b019958"],[4650,"8da0b70299105b83101881a196ed"],[4767,"8da5b3a7990da30b30085d4a3fb6"],[4883,"8d0d0c07990c111d88380b35ff28"],[5000,"8da0b702590d57cf34d62ee5fde5"],[5000,"8da0b70299105b82f01481e7b168"],[5000,"8da0b702e1150d0000000004eb56"],[5000,"8d0d0c07501bd7db74d71347e30c"],[5150,"8da0b70227c74d5462082004597a"],[5300,"8da5b3a758b990604051e7fb7390"],[5333,"8d0d0c0722594377e37820b79a0d"],[5367,"8d0d0c07990c111d88380cca2f0c"],[5400,"8dabe7c558af8024c23ee7c8e962"],[5460,"8dabe7c5f8230006004ab8db4fc2"],[5520,"8da0b702590d5025264b1f025060"],[5580,"8da0b70299105b82f01401e0b7a8"],[5640,"8da5b3a7ea466864013c085e68e2"],[5700,"8d0d0c07501bd031b44c03dc465d"],[5760,"8da5b3a7990da30b30085eb5d7a4"],[5820,"8da0b702f8122006005ab8b0ce08"],[5880,"8d0d0c07990c111d88380b35ff28"],[5940,"8dabe7c59915ad0d300456c56568"],[6000,"8da0b702590d57cf30d6372dc85c"],[6050,"8da0b70299105b82f01401e0b7a8"],[6100,"8d0d0c07501bc031c64c021a765d"],[6250,"8d0d0c07f8200002004ab89cec0b"],[6400,"8dabe7c558af8024d83eba9c7813"],[6500,"8d0d0c07501bc7dbb4d71117af08"],[6600,"8d0d0c07990c111da83c0b48b501"],[6700,"8da5b3a7990da30b30085d4a3fb6"],[6800,"8dabe7c59915ad0d300456c56568"],[6900,"8d0d0c07501bc7dbc8d710a36866"],[7050,"8d0d0c07990c111da83c0cb76525"],[7200,"8da5b3a758b990606451947414a7"],[7300,"8dabe7c558af87cef8c9e42b1cae"],[7360,"8dabe7c5ea428867215c08fe0874"],[7420,"8d0d0c07e1058a00000000c4d44e"],[7540,"8d0d0c07501bc0320a4c005f6240"],[7600,"8d0d0c07990c111da83c0b48b501"],[7660,"8da0b702590d67cf28d645cd6577"],[7720,"8da0b70299105a82f01081dc8da6"],[7780,"8da5b3a7990da30b30085eb5d7a4"],[7840,"8dabe7c59915ad0d300456c56568"],[7900,"8d0d0c07501bb032264bff008fc5"],[7933,"8d0d0c07990c111da83c0cb76525"],[7967,"8da5b3a7ea466864013c085e68e2"],[8000,"8da0b702590d67cf26d6487082aa"],[8150,"8da0b70299105a82d01481a1c78f"],[8300,"8da5b3a758b9906076516b48fcb5"],[8300,"8dabe7c558af8025003e6a60fadf"],[8364,"8da5b3a7f82300060049b8e08700"],[8427,"8da0b702f8122006005ab8b0ce08"],[8491,"8d0d0c07f8200002004ab89cec0b"],[8555,"8d0d0c07990c111dc83c0b87317a"],[8618,"8d0d0c07501bb032444bfe2b5735"],[8682,"8da5b3a7e10d2800000000aefd57"],[8745,"8da0b702590d67cf24d64d94e617"],[8809,"8da0b70299105a82d01481a1c78f"],[8873,"8dabe7c59915ad0d300456c56568"],[8936,"8d0d0c07990c111dc83c0c78e15e"],[9000,"8d0d0c07501bb032564bfeedbba7"],[9200,"8da0b702590d6025164b3fca5cc9"],[9267,"8da0b70299105a82d010019ef74f"],[9333,"8da5b3a758b9940996dc34d66e25"],[9400,"8dabe7c55Line truncated

src/data/fixtures/adsb-austin-dump1090-aircraft.json

@@ -0,0 +1,53 @@
+{
+  "now": 1790127097.5,
+  "messages": 112,
+  "aircraft": [
+    {
+      "hex": "a15c54",
+      "flight": "SKW3301 ",
+      "alt_baro": 5050,
+      "gs": 287.5,
+      "track": 291.2,
+      "baro_rate": 3072,
+      "seen": 31.5,
+      "messages": 14,
+      "rssi": -28.2
+    },
+    {
+      "hex": "ae5d8a",
+      "flight": "SHINR42 ",
+      "lat": 30.269662,
+      "lon": -97.793262,
+      "alt_baro": 1600,
+      "gs": 129.9,
+      "track": 330.5,
+      "baro_rate": 64,
+      "seen": 30.5,
+      "seen_pos": 34.6,
+      "messages": 74,
+      "rssi": -30.0
+    },
+    {
+      "hex": "a3c775",
+      "lat": 30.360625,
+      "lon": -97.919659,
+      "alt_baro": 34000,
+      "gs": 434.4,
+      "track": 283.7,
+      "baro_rate": 0,
+      "seen": 38.2,
+      "seen_pos": 43.4,
+      "messages": 20,
+      "rssi": -30.5
+    },
+    {
+      "hex": "a46e6a",
+      "gs": 319.8,
+      "track": 351.2,
+      "baro_rate": 2688,
+      "seen": 32.0,
+      "messages": 4,
+      "rssi": -37.1
+    }
+  ]
+}

src/data/fixtures/adsb-austin-frames.txt

@@ -0,0 +1,112 @@
+*8da46e6a99143227b0ac21405d5c;
+*8da46e6aea428858015c080bb810;
+*5da46e6ae86d20;
+*8da3c775990da70d180457361e57;
+*8dae5d8aea00085ee53e004546c3;
+*8dae5d8a580d77d658d63e32c82f;
+*5dae5d8a54a93d;
+*8da3c77558af803cce430dad950f;
+*200015b8f3156e;
+*02e615b82df0c7;
+*02e615b82df0c7;
+*8da3c775990da70d180458c9be1f;
+*8dae5d8a99a4400e70088202ff80;
+*5dae5d8a54a93d;
+*200015b8f3156e;
+*200015b8f3156e;
+*8dae5d8a580d702c844b24b6523e;
+*8dae5d8af80300020049bc1cd8f3;
+*200015b8f3156e;
+*20000197d80069;
+*5dae5d8a54a93d;
+*020001970f9c90;
+*8dae5d8a580d77d688d63170d088;
+*8da3c77558af87e6a0cdf2c8bbf8;
+*8dae5d8aea00085ee53e004546c3;
+*8dae5d8a274c824e4b4ca06f9608;
+*5dae5d8a54a93d;
+*8dae5d8a99a4400e700c823ac980;
+*020001970f9c90;
+*5da15c54111a4b;
+*8dae5d8a580d77d6a0d62aa4760f;
+*5da3c7758f35d4;
+*8dae5d8aea00085ee53e004546c3;
+*8dae5d8a99a4410e500c827cbf67;
+*8da15c54581b8019e24c96ebec6d;
+*8dae5d8a580d77d6ccd61fccec2f;
+*5dae5d8a54a93d;
+*8dae5d8a99a4410e500c827cbf67;
+*8dae5d8a580d77d6d8d61cd91129;
+*8dae5d8a99a4410e500c827cbf67;
+*8dae5d8a580d77d6e2d619cbefa5;
+*8dae5d8af80300020049bc1cd8f3;
+*20000197d80069;
+*80000197580d77d6e8d6172cc0e3;
+*8dae5d8a580d702d044b0189a64f;
+*020001970f9c90;
+*8dae5d8a99a4410e500882448967;
+*8dae5d8a580d77d6fad6128791c3;
+*5dae5d8a54a93d;
+*8dae5d8a99a4410e500882448967;
+*020001970f9c90;
+*8da15c54581bc01a424c2f038351;
+*8dae5d8ae1080800000000e6168f;
+*8da3c77558af87e730ccd3243e2f;
+*8dae5d8a580d87d728d6051c99a8;
+*5dae5d8a54a93d;
+*8dae5d8aea00085ee53e004546c3;
+*8dae5d8a99a4410e500882448967;
+*8dae5d8a580d802d584aea9aed46;
+*5da15c54111a4b;
+*8dae5d8a99a4410e500c827cbf67;
+*2000019827a021;
+*8dae5d8af80300020049bc1cd8f3;
+*8dae5d8a580d87d754d5f94050dd;
+*8dae5d8a99a4410e500c827cbf67;
+*5dae5d8a54a93d;
+*8dae5d8a99a4410e500c827cbf67;
+*02000198f03cd8;
+*8dae5d8a580d87d76ed5f252fa10;
+*8dae5d8aea00085ee53e004546c3;
+*8da15c5499150a0df0ac0d713d8d;
+*200015b8f3156e;
+*8da3c775990da70d100458a71c17;
+*8dae5d8a580d87d778d5ef5c1b0d;
+*8dae5d8a99a4410e500882448967;
+*5dae5d8a54a93d;
+*02818393027eb0;
+*5da3c7758f35d5;
+*5da3c7758f35d5;
+*5da3c7758f35d4;
+*200015b8f3156e;
+*8dae5d8a580d87d782d5ec2e3d53;
+*8da15c54ea178858015e88a53d08;
+*5dae5d8a54a93d;
+*8dae5d8a99a4410e500882448967;
+*02000198f03cd8;
+*8dae5d8ae1080800000000e6168f;
+*200015b8f3156e;
+*8dae5d8a580d802db04ad2d09e9c;
+*02e195b8f5cd24;
+*8da15c5499150b0db0b40d687b11;
+*8dae5d8aea00085ee53e004546c3;
+*8dae5d8a99a4410e500882448967;
+*8dae5d8a580d802dc64accee13e8;
+*2000019827a021;
+*8dae5d8a99a4410e500881bb6175;
+*8dae5d8a580d802ddc4ac5b9d917;
+*8dae5d8af80300020049bc1cd8f3;
+*80000198580d87d7cad5d9283036;
+*02000198f03cd8;
+*5da15c54111a4b;
+*8dae5d8a580d87d7ecd5d0a28b94;
+*8dae5d8a99a4410e500881bb6175;
+*8da15c54234cb5f3cf0c6055934a;
+*5dae5d8a54a93d;
+*8da15c5499150d0d50c40e1a396a;
+*8da15c5499150d0d30c40ed5bd11;
+*5da15c54111a4b;
+*5da46e6ae86d29;
+*8da15c54581f201b484af27089b0;
+*02000198f03cd8;
+*5dae5d8a54a93d;

src/data/lifecycle.js

@@ -16,6 +16,8 @@ const VALID_LAYER_SERIALIZATION_DISPOSITIONS = new Set([
   'enabled-only',
   'enabled+options',
   'enabled+mirrored-options',
+  // Registered but never serialized (for example hardware-local layers).
+  'local-only',
 ]);
 
 function isAbortError(error) {

src/data/localReceiversProxy.test.mjs

@@ -0,0 +1,459 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import {
+  LOCAL_RECEIVERS_ROUTE,
+  createLocalReceiversHandler,
+  localReceiversProxy,
+  parseLocalReceiverFeeds,
+} from '../../server/providers/local-receivers.js';
+import { localProviderPlugins } from '../../server/providers/local.js';
+
+const FIXTURE = readFileSync(
+  new URL('./fixtures/adsb-austin-dump1090-aircraft.json', import.meta.url),
+  'utf8',
+);
+const FIXTURE_NOW_MS = JSON.parse(FIXTURE).now * 1000;
+const FEED_1090 = 'http://localhost:8080/data/aircraft.json';
+const FEED_978 = 'http://127.0.0.1:8978/data/aircraft.json';
+
+function quietLogger() {
+  const lines = [];
+  return {
+    lines,
+    warn: (line) => lines.push(line),
+    info: (line) => lines.push(line),
+  };
+}
+
+function respond(status = 200, body = FIXTURE, headers = {}) {
+  return new Response(body, {
+    status,
+    headers: { 'content-type': 'application/json', ...headers },
+  });
+}
+
+async function call(handler, method = 'GET') {
+  const res = {
+    writeHead(status, headers) {
+      Object.assign(this, { status, headers });
+    },
+    end(body) {
+      this.body = body;
+    },
+  };
+  await handler.handle({ url: '/', method }, res);
+  return { ...res, json: JSON.parse(res.body) };
+}
+
+test('LOCAL_RECEIVER_FEEDS accepts local http(s) aircraft.json feeds per band', () => {
+  const { configured, feeds } = parseLocalReceiverFeeds(
+    ` 1090=${FEED_1090} , 978=http://skyaware.local/skyaware978/data/aircraft.json,1090=https://192.168.1.20:8443/tar1090/data/aircraft.json`,
+  );
+  assert.equal(configured, true);
+  assert.deepEqual(
+    feeds.map(({ band, label, url }) => ({ band, label, url })),
+    [
+      { band: '1090', label: '1090 MHz #1', url: FEED_1090 },
+      {
+        band: '978',
+        label: '978 MHz UAT',
+        url: 'http://skyaware.local:80/skyaware978/data/aircraft.json',
+      },
+      {
+        band: '1090',
+        label: '1090 MHz #2',
+        url: 'https://192.168.1.20:8443/tar1090/data/aircraft.json',
+      },
+    ],
+  );
+  assert.deepEqual(parseLocalReceiverFeeds(undefined), {
+    configured: false,
+    feeds: [],
+  });
+  assert.equal(parseLocalReceiverFeeds(' , ').configured, false);
+});
+
+test('LOCAL_RECEIVER_FEEDS rejects public, link-local and named hosts, bad paths and bands', () => {
+  const cases = {
+    '1090=http://8.8.8.8/data/aircraft.json': 'host must be',
+    '1090=http://169.254.169.254/latest/aircraft.json': 'host must be',
+    '1090=http://example.com/data/aircraft.json': 'host must be',
+    '1090=http://[::1]:8080/data/aircraft.json': 'host must be',
+    '1090=http://localhost:8080/data/receiver.json': 'path must end',
+    '1090=http://localhost:8080/data/aircraft.json.bak': 'path must end',
+    '1090=http://localhost:8080/data/aircraft.json?x=1': 'query',
+    '1090=http://user:pw@localhost:8080/data/aircraft.json': 'credentials',
+    '1090=ftp://localhost/data/aircraft.json': 'scheme',
+    '1090=not a url': 'not a valid URL',
+    '868=http://localhost:8080/data/aircraft.json': 'band must be',
+    'http://localhost:8080/data/aircraft.json': 'expected band=url',
+  };
+  for (const [entry, reason] of Object.entries(cases)) {
+    const [feed] = parseLocalReceiverFeeds(entry).feeds;
+    assert.equal(feed.url, undefined, `${entry} must not be fetchable`);
+    assert.match(feed.reason, new RegExp(reason), entry);
+  }
+  const [badBand] = parseLocalReceiverFeeds(
+    '868=http://localhost/aircraft.json',
+  ).feeds;
+  assert.equal(badBand.band, null);
+  assert.equal(badBand.label, 'entry 1');
+});
+
+test('an unconfigured route answers 200 without fetching anything', async (t) => {
+  t.mock.method(globalThis, 'fetch', () => {
+    throw Error('must not fetch');
+  });
+  const handler = createLocalReceiversHandler({
+    feedsValue: undefined,
+    logger: quietLogger(),
+  });
+  const res = await call(handler);
+  assert.equal(res.status, 200);
+  assert.deepEqual(res.json, { configured: false, feeds: [], records: [] });
+});
+
+test('construction mounts the route once and neither parses nor fetches', (t) => {
+  t.mock.method(globalThis, 'fetch', () => {
+    throw Error('construction must not fetch');
+  });
+  const plugins = localProviderPlugins();
+  assert.equal(
+    plugins.filter((plugin) => plugin.name === 'local-receivers-proxy').length,
+    1,
+  );
+  const routes = [];
+  localReceiversProxy({
+    feedsValue: '',
+    logger: quietLogger(),
+  }).configureServer({ middlewares: { use: (route) => routes.push(route) } });
+  assert.deepEqual(routes, [LOCAL_RECEIVERS_ROUTE]);
+});
+
+test('live feeds are read in parallel and labelled with their band', async () => {
+  const calls = [];
+  const handler = createLocalReceiversHandler({
+    feedsValue: `1090=${FEED_1090},978=${FEED_978}`,
+    now: () => FIXTURE_NOW_MS + 2_000,
+    logger: quietLogger(),
+    fetchImpl: async (url, options) => {
+      calls.push({ url, redirect: options.redirect });
+      return respond();
+    },
+  });
+  const { status, json } = await call(handler);
+  assert.equal(status, 200);
+  assert.deepEqual(
+    calls.sort((a, b) => (a.url < b.url ? 1 : -1)),
+    [
+      { url: FEED_1090, redirect: 'manual' },
+      { url: FEED_978, redirect: 'manual' },
+    ],
+  );
+  assert.equal(json.configured, true);
+  assert.deepEqual(json.feeds, [
+    {
+      band: '1090',
+      label: '1090 MHz',
+      status: 'live',
+      aircraft: 4,
+      ageMs: 2_000,
+    },
+    {
+      band: '978',
+      label: '978 MHz UAT',
+      status: 'live',
+      aircraft: 4,
+      ageMs: 2_000,
+    },
+  ]);
+  assert.equal(json.records.length, 8);
+  const shinr = json.records.filter((record) => record.icao === 'ae5d8a');
+  assert.deepEqual(
+    shinr.map(({ band, source }) => ({ band, source })),
+    [
+      { band: '1090', source: 'feed' },
+      { band: '978', source: 'feed' },
+    ],
+  );
+  // Ages are anchored at the feed's own `now`.
+  assert.equal(shinr[0].lastPositionAt, FIXTURE_NOW_MS - 34_600);
+  assert.equal(shinr[0].lat, 30.269662);
+});
+
+test('a feed whose own now is over 10 s old is stale; failures are unreachable', async () => {
+  const logger = quietLogger();
+  const handler = createLocalReceiversHandler({
+    feedsValue: [
+      `1090=${FEED_1090}`,
+      `978=${FEED_978}`,
+      '1090=http://10.0.0.5/redirect/aircraft.json',
+      '1090=http://10.0.0.6/big/aircraft.json',
+      '1090=http://10.0.0.7/error/aircraft.json',
+      '978=http://10.0.0.8/garbage/aircraft.json',
+      '1090=http://8.8.8.8/aircraft.json',
+    ].join(','),
+    now: () => FIXTURE_NOW_MS + 10_001,
+    logger,
+    maxBytes: 4_096,
+    fetchImpl: async (url) => {
+      if (url === FEED_978) throw new TypeError('connect ECONNREFUSED secret');
+      if (url.includes('/redirect/'))
+        return respond(302, '', { location: 'http://169.254.169.254/' });
+      if (url.includes('/big/'))
+        return respond(200, `{"aircraft":[${' '.repeat(5_000)}]}`);
+      if (url.includes('/error/'))
+        return respond(500, 'upstream internal detail');
+      if (url.includes('/garbage/')) return respond(200, '<html>');
+      if (url.includes('8.8.8.8')) throw Error('invalid feed was fetched');
+      return respond();
+    },
+  });
+  const { json, body } = await call(handler);
+  assert.deepEqual(
+    json.feeds.map(({ band, status }) => `${band} ${status}`),
+    [
+      '1090 stale',
+      '978 unreachable',
+      '1090 unreachable',
+      '1090 unreachable',
+      '1090 unreachable',
+      '978 unreachable',
+      '1090 invalid',
+    ],
+  );
+  assert.equal(json.feeds[0].ageMs, 10_001);
+  assert.equal(json.records.length, 4, 'stale feed records still flow');
+  for (const secret of ['ECONNREFUSED', 'secret', 'internal detail', '169.254'])
+    assert.equal(body.includes(secret), false, `${secret} leaked`);
+  assert.equal(
+    body.includes('10.0.0'),
+    false,
+    'feed addresses stay server-side',
+  );
+  assert.ok(
+    logger.lines.some((line) =>
+      /LOCAL_RECEIVER_FEEDS feed-7 .* rejected: host must be/.test(line),
+    ),
+  );
+  assert.ok(logger.lines.some((line) => /REDIRECT_REFUSED/.test(line)));
+  assert.ok(logger.lines.some((line) => /RESPONSE_TOO_LARGE/.test(line)));
+});
+
+test('a feed that exceeds the timeout is unreachable', async () => {
+  const handler = createLocalReceiversHandler({
+    feedsValue: `1090=${FEED_1090}`,
+    logger: quietLogger(),
+    timeoutMs: 5,
+    fetchImpl: (url, { signal }) =>
+      new Promise((resolve, reject) => {
+        signal.addEventListener('abort', () =>
+          reject(Object.assign(new Error('aborted'), { name: 'AbortError' })),
+        );
+      }),
+  });
+  const { json } = await call(handler);
+  assert.equal(json.feeds[0].status, 'unreachable');
+});
+
+test('requests within a second share one read of every feed', async () => {
+  let clock = FIXTURE_NOW_MS;
+  let fetches = 0;
+  const handler = createLocalReceiversHandler({
+    feedsValue: `1090=${FEED_1090}`,
+    now: () => clock,
+    logger: quietLogger(),
+    fetchImpl: async () => {
+      fetches += 1;
+      return respond();
+    },
+  });
+  await Promise.all([call(handler), call(handler), call(handler)]);
+  assert.equal(fetches, 1, 'concurrent requests are single-flight');
+  clock += 500;
+  await call(handler);
+  assert.equal(fetches, 1, 'cached for about a second');
+  clock += 1_000;
+  await call(handler);
+  assert.equal(fetches, 2);
+  const res = await call(handler, 'POST');
+  assert.equal(res.status, 405);
+});
+
+test('a feed name is resolved, every address checked, and the connection pinned to it', async () => {
+  const lookups = [];
+  const answers = {
+    'good.local': [{ address: '10.0.0.9', family: 4 }],
+    'public.local': [{ address: '93.184.216.34', family: 4 }],
+    'linklocal.local': [{ address: '169.254.169.254', family: 4 }],
+    'mixed.local': [
+      { address: '192.168.1.4', family: 4 },
+      { address: '8.8.8.8', family: 4 },
+    ],
+  };
+  const fetched = [];
+  const logger = quietLogger();
+  const handler = createLocalReceiversHandler({
+    feedsValue: [
+      '1090=http://good.local:8080/data/aircraft.json',
+      '1090=http://public.local:8080/data/aircraft.json',
+      '978=http://linklocal.local/data/aircraft.json',
+      '978=http://mixed.local/data/aircraft.json',
+      `1090=${FEED_978}`,
+    ].join(','),
+    now: () => FIXTURE_NOW_MS,
+    logger,
+    lookupImpl: async (hostname, options) => {
+      lookups.push({ hostname, all: options?.all });
+      return answers[hostname];
+    },
+    fetchImpl: async (url, options) => {
+      fetched.push({ url, lookup: options.lookup });
+      return respond();
+    },
+  });
+  const { json } = await call(handler);
+  assert.deepEqual(
+    json.feeds.map(({ status }) => status),
+    ['live', 'unreachable', 'unreachable', 'unreachable', 'live'],
+  );
+  assert.deepEqual(
+    lookups.map(({ hostname }) => hostname).sort(),
+    ['good.local', 'linklocal.local', 'mixed.local', 'public.local'],
+    'IP literals are not resolved',
+  );
+  assert.ok(
+    lookups.every(({ all }) => all === true),
+    'every address',
+  );
+  assert.deepEqual(
+    fetched.map(({ url }) => url).sort(),
+    [FEED_978, 'http://good.local:8080/data/aircraft.json'],
+    'a name resolving outside loopback/RFC1918 is never contacted',
+  );
+  // The connection resolves only to the validated address, whatever the
+  // resolver would answer later.
+  answers['good.local'] = [{ address: '93.184.216.34', family: 4 }];
+  const pinned = fetched.find(({ url }) => url.includes('good.local')).lookup;
+  assert.equal(typeof pinned, 'function');
+  const one = await new Promise((resolve) =>
+    pinned('good.local', {}, (error, address, family) =>
+      resolve({ error, address, family }),
+    ),
+  );
+  assert.deepEqual(one, { error: null, address: '10.0.0.9', family: 4 });
+  const all = await new Promise((resolve) =>
+    pinned('good.local', { all: true }, (error, addresses) =>
+      resolve(addresses),
+    ),
+  );
+  assert.deepEqual(all, [{ address: '10.0.0.9', family: 4 }]);
+  assert.ok(logger.lines.some((line) => /FORBIDDEN_ADDRESS/.test(line)));
+});
+
+test('the default transport connects to the validated address, not a re-resolution', async (t) => {
+  const { createServer } = await import('node:http');
+  const server = createServer((req, res) => {
+    res.writeHead(200, { 'content-type': 'application/json' });
+    res.end(JSON.stringify({ now: FIXTURE_NOW_MS / 1000, aircraft: [] }));
+  });
+  await new Promise((resolve) => server.listen(0, '127.0.0.1', resolve));
+  t.after(() => server.close());
+  const { port } = server.address();
+  // `receiver-pin-test.local` has no real DNS entry: only the pinned lookup
+  // can reach the loopback server.
+  const handler = createLocalReceiversHandler({
+    feedsValue: `1090=http://receiver-pin-test.local:${port}/data/aircraft.json`,
+    now: () => FIXTURE_NOW_MS,
+    logger: quietLogger(),
+    lookupImpl: async () => [{ address: '127.0.0.1', family: 4 }],
+  });
+  const { json } = await call(handler);
+  assert.equal(json.feeds[0].status, 'live');
+});
+
+test('null-body statuses (204, 205, 304) from a named feed are a clean feed error, never an uncaught exception', async (t) => {
+  const { createServer } = await import('node:http');
+  const server = createServer((req, res) => {
+    const status = Number(req.url.split('/')[1]);
+    res.writeHead(status, { 'content-type': 'application/json' });
+    res.end();
+  });
+  await new Promise((resolve) => server.listen(0, '127.0.0.1', resolve));
+  t.after(() => server.close());
+  const { port } = server.address();
+  const uncaught = [];
+  const onUncaught = (error) => uncaught.push(error);
+  process.on('uncaughtException', onUncaught);
+  t.after(() => process.off('uncaughtException', onUncaught));
+  const handler = createLocalReceiversHandler({
+    feedsValue: [204, 205, 304]
+      .map(
+        (status) =>
+          `1090=http://receiver-null-body.local:${port}/${status}/aircraft.json`,
+      )
+      .join(','),
+    now: () => FIXTURE_NOW_MS,
+    logger: quietLogger(),
+    timeoutMs: 300,
+    lookupImpl: async () => [{ address: '127.0.0.1', family: 4 }],
+  });
+  const { status, json } = await call(handler);
+  // Let any exception thrown inside the response callback surface.
+  await new Promise((resolve) => setTimeout(resolve, 20));
+  assert.deepEqual(uncaught, [], 'no uncaught exception');
+  assert.equal(status, 200);
+  assert.deepEqual(
+    json.feeds.map((feed) => feed.status),
+    ['unreachable', 'unreachable', 'unreachable'],
+  );
+});
+
+test('a stalled DNS lookup fails its feed at the deadline without holding other feeds or later polls', async () => {
+  let clock = FIXTURE_NOW_MS;
+  const lookups = [
+    // Never answers.
+    () => new Promise(() => {}),
+    // Answers only after the deadline: the late answer is ignored.
+    () =>
+      new Promise((resolve) =>
+        setTimeout(() => resolve([{ address: '127.0.0.1', family: 4 }]), 80),
+      ),
+  ];
+  const fetched = [];
+  const handler = createLocalReceiversHandler({
+    feedsValue: `1090=http://stalled.local/data/aircraft.json,978=${FEED_978}`,
+    now: () => clock,
+    logger: quietLogger(),
+    timeoutMs: 20,
+    lookupImpl: () => lookups.shift()(),
+    fetchImpl: async (url) => {
+      fetched.push(url);
+      return respond();
+    },
+  });
+  const within = (promise) =>
+    Promise.race([
+      promise,
+      new Promise((resolve) => setTimeout(() => resolve('timed out'), 60)),
+    ]);
+  const first = await within(call(handler));
+  assert.notEqual(first, 'timed out', 'the snapshot is not held by DNS');
+  assert.deepEqual(
+    first.json.feeds.map((feed) => feed.status),
+    ['unreachable', 'live'],
+  );
+  clock += 2_000;
+  const second = await within(call(handler));
+  assert.notEqual(second, 'timed out', 'a later poll is not held either');
+  assert.deepEqual(
+    second.json.feeds.map((feed) => feed.status),
+    ['unreachable', 'live'],
+  );
+  await new Promise((resolve) => setTimeout(resolve, 120));
+  assert.ok(
+    fetched.every((url) => !url.includes('stalled.local')),
+    'a late DNS answer is never fetched',
+  );
+});

src/data/modelEligibility.js

@@ -0,0 +1,45 @@
+/**
+ * Shared 3D-model eligibility for the aircraft layers.
+ *
+ * Eligibility is by DISTANCE (the mode's add/keep band) with ON-SCREEN
+ * PRIORITY under the cap, in four visible-first passes so the slots are spent
+ * on what the operator can see:
+ *  1. KEEP on-screen contacts that already have a model (hysteresis for
+ *     visible planes);
+ *  2. ADD on-screen new contacts inside the add radius, nearest first;
+ *  3. KEEP off-screen contacts that already have a model;
+ *  4. ADD off-screen new contacts inside the add radius with leftover slots.
+ * KEEP is split by frustum so an off-screen retained model can never starve
+ * an on-screen contact that wants one.
+ *
+ * Portable: no Cesium, DOM or layer state.
+ */
+
+/**
+ * @param {Array<[string, number, boolean]>} candidates `[id, distanceSq,
+ *   onScreen]` for every contact inside the KEEP radius, sorted nearest first.
+ * @param {object} options
+ * @param {number} options.cap Maximum number of eligible contacts.
+ * @param {number} options.addDistSq Squared ADD radius (m²).
+ * @param {(id: string) => boolean} options.isModeled Whether the contact
+ *   already has a model (live, not merely pending).
+ * @returns {Set<string>} Contacts that may hold a model this tick.
+ */
+export function selectModelEligible(candidates, { cap, addDistSq, isModeled }) {
+  const eligible = new Set();
+  const passes = [
+    (onScreen, modeled) => onScreen && modeled,
+    (onScreen, modeled, inAdd) => onScreen && inAdd,
+    (onScreen, modeled) => !onScreen && modeled,
+    (onScreen, modeled, inAdd) => !onScreen && inAdd,
+  ];
+  for (const admit of passes) {
+    for (const [id, distanceSq, onScreen] of candidates) {
+      if (eligible.size >= cap) return eligible;
+      if (eligible.has(id)) continue;
+      if (admit(onScreen, isModeled(id), distanceSq <= addDistSq))
+        eligible.add(id);
+    }
+  }
+  return eligible;
+}

src/data/modelEligibility.test.mjs

@@ -0,0 +1,48 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import { selectModelEligible } from './modelEligibility.js';
+
+const ADD_SQ = 100 * 100;
+
+test('visible contacts win the cap before off-screen retained models', () => {
+  // Nearest first: an off-screen retained model, then two on-screen contacts.
+  const candidates = [
+    ['off-kept', 10, false],
+    ['on-new', 20, true],
+    ['on-kept', 30, true],
+  ];
+  const modeled = new Set(['off-kept', 'on-kept']);
+  const eligible = selectModelEligible(candidates, {
+    cap: 2,
+    addDistSq: ADD_SQ,
+    isModeled: (id) => modeled.has(id),
+  });
+  assert.deepEqual([...eligible], ['on-kept', 'on-new']);
+});
+
+test('retained models keep their slot beyond the add radius; new ones do not', () => {
+  const candidates = [
+    ['near-new', 50, true],
+    ['far-kept', ADD_SQ + 1, true],
+    ['far-new', ADD_SQ + 2, true],
+    ['off-new', 60, false],
+  ];
+  const eligible = selectModelEligible(candidates, {
+    cap: 10,
+    addDistSq: ADD_SQ,
+    isModeled: (id) => id === 'far-kept',
+  });
+  assert.deepEqual([...eligible], ['far-kept', 'near-new', 'off-new']);
+});
+
+test('an empty cap admits nothing', () => {
+  assert.equal(
+    selectModelEligible([['a', 1, true]], {
+      cap: 0,
+      addDistSq: ADD_SQ,
+      isModeled: () => true,
+    }).size,
+    0,
+  );
+});

src/data/tr3bRegistry.test.mjs

@@ -415,8 +415,10 @@ test('a converted contact never consumes a 3D model CAP SLOT', async () => {
     assert.match(loop, /keepDistSq/, `${name}: matched the model-eligibility loop`);
     assert.match(loop, /if \(isTr3b\(icao\)\) continue;/,
       `${name}: converted contacts are dropped BEFORE entering the capped candidate list`);
-    // ...and the cap really is applied to that list, so a dropped candidate is a freed slot.
-    assert.match(source, /modelEligible\.size >= cap/,
+    // ...and the cap really is applied to that list, so a dropped candidate is a
+    // freed slot. The four-pass selection itself is the shared
+    // selectModelEligible (behavior-tested in modelEligibility.test.mjs).
+    assert.match(source, /modelEligible\s*=\s*selectModelEligible\(\s*cand,\s*\{\s*cap,/,
       `${name}: the cap bounds the candidate-derived eligible set`);
   }
 });

src/data/trackedReadout.js

@@ -222,6 +222,7 @@ export function getActiveTrackedReadoutId() {
 const READOUT_CONTEXT_LAYERS = new Set([
   'military-installations',
   'alpr-cameras',
+  'local-adsb',
 ]);
 
 /**