fix(military): start new contacts at their delayed display position

The military fleet also renders behind real time and projects a fresh contact's first fix back to that delayed time, but its billboard was created at the raw fix. A new contact therefore appeared ahead of where the next fleet tick put it and jumped back. The snapshot renderer now receives the layer's motion and creates the billboard at the dead-reckoned delayed position.

src/layers/military/index.js

@@ -33,6 +33,7 @@ export function createMilitaryFlightLayer({
     militaryRegistry: services.militaryRegistry,
     rendering: parts.rendering,
     tracking: parts.tracking,
+    motion: parts.motion,
     queries: parts.queries,
   });
   parts.ingestion = createIngestion({

src/layers/military/ownership.test.mjs

@@ -113,3 +113,101 @@ test('a normalized source can retain its stale reason without changing standalon
   assert.equal(layer.getStats().error, null);
   assert.equal(layer.getStats().stale, true);
 });
+
+test('a newly seen military contact appears at its delayed position, not ahead of it', async () => {
+  // The military fleet renders RENDER_DELAY_SEC behind real time, so a fresh
+  // contact's first displayed position is its fix projected back to that
+  // delayed time. Creating the billboard at the raw fix drew it ahead until
+  // the next fleet tick jumped it back.
+  const Cesium = await import('cesium');
+  const { RENDER_DELAY_SEC } = await import('./policy.js');
+  // The application's own scene services, as src/app/layers/militaryFlights.js
+  // composes them; only the surface samplers and registry are stubbed.
+  const supplied = {
+    picking: await import('../../data/pickRegistry.js'),
+    sprites: await import('../../data/spriteOrder.js'),
+    trails: await import('../../data/trailRenderer.js'),
+    aircraftPresentation: await import('../../data/tr3bRegistry.js'),
+    camera: await import('../../data/trackedCamera.js'),
+    labels: await import('../../data/detectionDraw.js'),
+    geoid: await import('../../data/geoid.js'),
+    focus: await import('../../data/focusDeemphasis.js'),
+    readout: await import('../../data/trackedReadout.js'),
+    context: await import('../../data/contextStore.js'),
+    render: await import('../../renderGovernor.js'),
+    recession: await import('../../data/aircraftRecession.js'),
+    groundFloor: await import('../../data/groundFloor.js'),
+    groundSnap: await import('../../data/groundSnap.js'),
+    meshFloor: { sampleMeshFloorCells: () => {} },
+    militaryRegistry: { registerMilitaryIcaos: () => {} },
+  };
+  const fixLon = -97.6;
+  const fixLat = 30.3;
+  const speedMps = 200;
+  const fixAgeMs = 2_000;
+  const nowMs = Date.now();
+  const layer = createMilitaryFlightLayer({
+    services: supplied,
+    source: {
+      label: 'Fixture aircraft',
+      async getSnapshot() {
+        return {
+          source: 'Fixture aircraft',
+          complete: true,
+          observedAtMs: nowMs,
+          records: [
+            {
+              id: 'ae0001',
+              latitude: fixLat,
+              longitude: fixLon,
+              onGround: false,
+              baroAltitudeM: 9_000,
+              courseDeg: 90,
+              speedMps,
+              positionTimeMs: nowMs - fixAgeMs,
+              contactTimeMs: nowMs - fixAgeMs,
+            },
+          ],
+        };
+      },
+    },
+  });
+  const added = [];
+  layer.testing._setTrackedMilitaryRefreshStateForTest({
+    icao24: 'seed00',
+    entity: null,
+    meta: { rawLat: 0, rawLon: 0, onGround: false },
+    billboard: {
+      show: false,
+      position: Cesium.Cartesian3.fromDegrees(0, 0, 0),
+    },
+    billboardCollection: {
+      show: false,
+      add(options) {
+        const billboard = { ...options };
+        added.push(billboard);
+        return billboard;
+      },
+      remove() {},
+    },
+    viewer: { camera: { positionCartographic: null }, scene: {} },
+    tracked: false,
+  });
+  await layer.update({ camera: { positionCartographic: null }, scene: {} });
+  const billboard = added.find((entry) => entry.id === 'ae0001');
+  assert.ok(billboard, 'the new contact gets a billboard');
+  const shown = Cesium.Cartographic.fromCartesian(billboard.position);
+  const behindM = Cesium.Cartesian3.distance(
+    Cesium.Cartesian3.fromRadians(shown.longitude, shown.latitude, 0),
+    Cesium.Cartesian3.fromDegrees(fixLon, fixLat, 0),
+  );
+  const expectedM = speedMps * (RENDER_DELAY_SEC - fixAgeMs / 1000);
+  assert.ok(
+    Cesium.Math.toDegrees(shown.longitude) < fixLon,
+    'drawn behind the fix',
+  );
+  assert.ok(
+    Math.abs(behindM - expectedM) < speedMps * 3,
+    `expected about ${Math.round(expectedM)} m behind the fix, got ${Math.round(behindM)} m`,
+  );
+});

src/layers/military/snapshotRenderer.js

@@ -23,6 +23,7 @@ export function createMilitarySnapshotRenderer({
   militaryRegistry,
   rendering,
   tracking,
+  motion,
   queries,
 }) {
   const { warmGroundFloor, cachedGroundFloor, GROUND_FLOOR_LIFT_M } =
@@ -142,8 +143,14 @@ export function createMilitarySnapshotRenderer({
         // Round 5: depth policy is uniform (always depth-test-free, see
         // _groundDepthDistance) — nothing to flip on landing/takeoff.
       } else {
+        // Start where the fleet pass will draw it: the fleet renders behind
+        // real time, so a fresh contact's displayed position is its fix
+        // projected back to that delayed time. Creating it at the raw fix drew
+        // it ahead until the next fleet tick snapped it back.
+        const displayed =
+          motion._deadReckon(icao24, new Cesium.Cartesian3()) || position;
         const bb = flightState._billboardCollection.add({
-          position,
+          position: displayed,
           image: aircraftIcon(rendering._iconKind(icao24, meta.klass)),
           width: isTracked ? 24 : 20,
           height: isTracked ? 24 : 20,