Move satellites, launches and the sky with the world time

Layers whose data has a time of its own follow the page's world clock from
the start; live feeds such as flights, military, vessels and transit stay
live. Launches register the span of the launches loaded, so turning them on
brings up the timeline. Each timed layer registers its coverage once and
reports none while off, telling the clock after each step has settled. The
launch feed keeps its own window, and an orbit ring is drawn again once the
world time has moved far from when it was drawn.

src/data/rocketLaunches.test.mjs

@@ -2,6 +2,7 @@ import test from 'node:test';
 import assert from 'node:assert/strict';
 import * as Cesium from 'cesium';
 import { gstime } from 'satellite.js';
+import { worldClock } from '../time/worldClock.js';
 import { createModel } from '../layers/launches/model.js';
 import rocketLaunchesLayer, {
   _setRocketMissionOverlayHostForTest,
@@ -1228,7 +1229,11 @@ test('real mission build, select, refresh, deselect, disable, and destroy paths
     rocketLaunchesLayer.init(viewer);
     initialized = true;
     await rocketLaunchesLayer.enable();
+    assert.equal(worldClock.coverage(), null, 'nothing loaded, no time to show');
     await rocketLaunchesLayer.update();
+    const at = Date.parse(launchTime);
+    assert.deepEqual(worldClock.coverage(), { start: at, end: at, marks: [at] });
+    assert.equal(worldClock.isSupported(), true, 'loaded launches bring up the timeline');
 
     const entities = dataSources[0].entities.values;
     assert.ok(entities.length >= 7, 'runtime guard requires the populated mission build path');
@@ -1367,6 +1372,7 @@ test('real mission build, select, refresh, deselect, disable, and destroy paths
     assert.equal(deselectedPublication[2][0].protected, false);
 
     await rocketLaunchesLayer.disable();
+    assert.equal(worldClock.coverage(), null, 'off, launches show no time');
     assert.deepEqual(hostCalls.slice(-4), [
       ['clear', ROCKET_MISSION_AMBIENT_OVERLAY_SOURCE_ID],
       ['visible', ROCKET_MISSION_AMBIENT_OVERLAY_SOURCE_ID, false],
@@ -1488,3 +1494,11 @@ test('missing payload details stay unknown without inventing mass or classificat
   const [launch] = normalizeRocketLaunches([{ id: 'missing', pad: { latitude: 1, longitude: 2 }, net: '2026-07-20T10:00:00Z' }], NOW);
   assert.deepEqual(launch.payloads, []);
 });
+
+test('away from live the feed keeps its own window of launches', (t) => {
+  t.after(() => worldClock.goLive());
+  worldClock.seek(Date.now() - 20 * 86_400_000);
+  const net = new Date(Date.now() - 86_400_000).toISOString();
+  const launches = normalizeRocketLaunches([{ id: 'recent', pad: { latitude: 1, longitude: 2 }, net }]);
+  assert.deepEqual(launches.map((launch) => launch.id), ['recent']);
+});