Draw the session annotation board on Navara: draped areas and routes as clamped meshes, every other mark on the shared screen board over the engine's projector

scripts/package-boundaries.json

@@ -2629,6 +2629,7 @@
       "src/annotations/index.js",
       "src/annotations/resolver.js",
       "src/annotations/screenAnnotationRenderer.js",
+      "src/annotations/screenScene.js",
       "src/annotations/worldAnnotationRenderer.js",
       "src/app/catalog.js",
       "src/app/constructCatalog.js",
@@ -3599,6 +3600,7 @@
       "src/app/engineChoice.js",
       "src/app/navaraMode.js",
       "src/app/navaraTools.js",
+      "src/annotations/navaraAnnotationRenderer.js",
       "src/data/render/cesiumProjection.js",
       "src/data/render/cesiumConstants.js",
       "src/data/render/cesiumTrailRenderer.js",

scripts/qa-navara-annotations.mjs

@@ -0,0 +1,264 @@
+#!/usr/bin/env node
+// Annotations on both engines, under the strict network policy: the same
+// board (a hand-drawn area, a pin in view and a pin on the far side of the
+// globe) is drawn on Navara, survives a switch to Cesium and back, and on
+// each engine the draped area paints amber pixels on the canvas, the near
+// pin's callout shows and the far pin is culled at the horizon.
+//
+//   node scripts/qa-navara-annotations.mjs http://127.0.0.1:<PORT>/
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import sharp from 'sharp';
+import { createStrict, localPreview } from './qa-strict-harness.mjs';
+
+const LAT = 37.7749;
+const LON = -122.4194;
+const base = localPreview(process.argv[2]);
+base.search = '?engine=navara&welcome=0';
+base.hash = `v=2&lat=${LAT}&lon=${LON}&alt=7000&heading=0&pitch=-90&roll=0&map=osm&l=`;
+const strict = createStrict({ origin: base.origin, layers: ['annotations'] });
+const SHOTS = process.env.QA_SHOT_DIR || 'qa-shots/navara-annotations';
+fs.mkdirSync(SHOTS, { recursive: true });
+const wait = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
+// The area: a box around the view centre, clear of the panels.
+const RING = [
+  [LON - 0.012, LAT - 0.009],
+  [LON + 0.012, LAT - 0.009],
+  [LON + 0.012, LAT + 0.009],
+  [LON - 0.012, LAT + 0.009],
+];
+
+await strict.run(
+  {
+    args: [
+      '--use-angle=metal',
+      '--enable-gpu',
+      '--disable-background-timer-throttling',
+      '--disable-renderer-backgrounding',
+    ],
+  },
+  async (browser) => {
+    const page = await browser.newPage();
+    await page.setViewport({ width: 1280, height: 860 });
+    const errors = [];
+    page.on('pageerror', (error) => errors.push(error.message));
+    await page.goto(base.href);
+    const ready = async (kind) => {
+      await page.waitForFunction(
+        (k) =>
+          window.__godsEyeView?.engine?.kind === k &&
+          !document.querySelector('#globe-engine')?.disabled &&
+          !document.querySelector('.engine-switch-frame') &&
+          document.querySelector('#loading-screen.hidden'),
+        { timeout: 120000 },
+        kind,
+      );
+      await page.evaluate(
+        () => window.__godsEyeView.styleManager.initialRestorePromise,
+      );
+    };
+    await ready('navara');
+    assert.equal(
+      await page.evaluate(() =>
+        Boolean(window.__godsEyeView.tileset || window.__GOOGLE_MAPS_API_KEY__),
+      ),
+      false,
+      'keyless preview required',
+    );
+
+    /** Amber pixels of the globe canvas alone (the SVG board hidden). */
+    const canvasAmber = async () => {
+      await page.addStyleTag({
+        content: '.gev-screen-whiteboard{visibility:hidden!important}',
+      });
+      await page.evaluate(() => window.__godsEyeView.requestRender?.('qa'));
+      await wait(700);
+      const { data, info } = await sharp(
+        await page.screenshot({
+          clip: { x: 340, y: 180, width: 600, height: 500 },
+        }),
+      )
+        .removeAlpha()
+        .raw()
+        .toBuffer({ resolveWithObject: true });
+      await page.evaluate(() =>
+        document
+          .querySelectorAll('style')
+          .forEach(
+            (style) =>
+              style.textContent.includes('gev-screen-whiteboard{visibility') &&
+              style.remove(),
+          ),
+      );
+      let amber = 0;
+      for (let i = 0; i < data.length; i += info.channels) {
+        const [r, g, b] = [data[i], data[i + 1], data[i + 2]];
+        if (r > 150 && g > 90 && g < 225 && b < 150 && r - b > 60 && r - g > 15)
+          amber++;
+      }
+      return amber;
+    };
+    /** The callout texts the page board shows, and those it hides. */
+    const board = () =>
+      page.evaluate(() => {
+        const out = { shown: [], hidden: [] };
+        for (const group of document.querySelectorAll(
+          '.gev-screen-whiteboard-svg g.gev-anno',
+        )) {
+          const text = group.querySelector('.gev-anno-text')?.textContent;
+          if (!text) continue;
+          const hidden =
+            group.style.display === 'none' ||
+            getComputedStyle(group).display === 'none';
+          (hidden ? out.hidden : out.shown).push(text);
+        }
+        out.shown.sort();
+        out.hidden.sort();
+        return out;
+      });
+
+    let round = 0;
+    const drawn = await page.evaluate(
+      async (ring, lat, lon) => {
+        const annotations = window.__gevAnnotations;
+        window.qaBoard = annotations;
+        const result = await annotations.annotate(
+          [
+            {
+              type: 'area',
+              manual: true,
+              ring,
+              label: 'QA Area',
+              color: 'amber',
+            },
+            {
+              type: 'pin',
+              manual: true,
+              latitude: lat + 0.004,
+              longitude: lon + 0.006,
+              label: 'QA Near',
+              color: 'green',
+            },
+            {
+              type: 'pin',
+              manual: true,
+              latitude: -lat,
+              longitude: lon + 180,
+              label: 'QA Far',
+              color: 'cyan',
+            },
+          ],
+          { persist: true, flyTo: false },
+        );
+        return {
+          drawn: result.drawn,
+          attached: annotations.attached,
+          handle: window.__godsEyeView.annotations === annotations,
+        };
+      },
+      RING,
+      LAT,
+      LON,
+    );
+    await strict.check(
+      page,
+      'annotations',
+      'the board draws three marks on the attached engine and is the debug handle',
+      drawn.drawn === 3 && drawn.attached && drawn.handle,
+      drawn,
+    );
+
+    for (const kind of ['navara', 'cesium', 'navara']) {
+      if (
+        (await page.evaluate(() => window.__godsEyeView.engine.kind)) !== kind
+      ) {
+        await strict.pick(page, kind);
+        await ready(kind);
+      }
+      await wait(2500);
+      const state = await page.evaluate(() => ({
+        same: window.__gevAnnotations === window.qaBoard,
+        count: window.qaBoard.count(),
+        attached: window.qaBoard.attached,
+        handle: window.__godsEyeView.annotations === window.qaBoard,
+      }));
+      await strict.check(
+        page,
+        'annotations',
+        'the same session board keeps its three marks and draws on this engine',
+        state.same && state.count === 3 && state.attached && state.handle,
+        state,
+      );
+      const seen = await board();
+      console.log(kind, 'board', JSON.stringify(seen));
+      await strict.check(
+        page,
+        'annotations',
+        'the near callouts show and the far pin is culled at the horizon',
+        seen.shown.includes('QA Near') &&
+          seen.shown.includes('QA Area') &&
+          !seen.shown.includes('QA Far'),
+        seen,
+      );
+      await page.screenshot({
+        path: `${SHOTS}/annotations-${kind}-${round}.png`,
+      });
+      const amber = await canvasAmber();
+      // The same view without the marks (hidden from the list).
+      const setHidden = (hidden) =>
+        page.evaluate((h) => {
+          for (const mark of window.qaBoard.list())
+            window.qaBoard.setHidden(mark.id, h);
+        }, hidden);
+      await setHidden(true);
+      const bare = await canvasAmber();
+      await setHidden(false);
+      console.log(kind, 'amber pixels', { bare, amber });
+      await strict.check(
+        page,
+        'annotations',
+        'the draped area paints amber on the globe canvas',
+        amber - bare > 400,
+        { bare, amber },
+      );
+      round++;
+    }
+
+    // Fly-to a mark goes through the engine's camera on Navara.
+    const flight = await page.evaluate(async () => {
+      const { engine } = window.__godsEyeView;
+      const before = engine.camera.height();
+      const area = window.qaBoard.list().find((m) => m.label === 'QA Area');
+      const ok = window.qaBoard.frame(area.id);
+      await new Promise((r) => setTimeout(r, 2600));
+      return { ok, before, after: engine.camera.height() };
+    });
+    await strict.check(
+      page,
+      'annotations',
+      'framing a mark flies the Navara camera to it',
+      flight.ok && Math.abs(flight.after - flight.before) > 100,
+      flight,
+    );
+    // Hidden from the list: the board and the canvas let it go.
+    const hidden = await page.evaluate(async () => {
+      for (const mark of window.qaBoard.list())
+        window.qaBoard.setHidden(mark.id, true);
+      await new Promise((r) => setTimeout(r, 600));
+      return window.qaBoard.list().every((m) => m.hidden);
+    });
+    const afterHide = await board();
+    await strict.check(
+      page,
+      'annotations',
+      'hidden marks leave the board',
+      hidden && afterHide.shown.length === 0,
+      afterHide,
+    );
+    await page.evaluate(() => window.qaBoard.clear());
+    assert.deepEqual(errors, []);
+    console.log(
+      'PASS annotations drawn, culled and kept across engine switches',
+    );
+  },
+);

src/annotations/annotationEngine.js

@@ -2,6 +2,7 @@ import { isUnavailableCapability } from '../sources/capability.js';
 import { defaultGeospatial } from '../search/defaults.js';
 import * as Cesium from 'cesium';
 import * as geo from '../geo/index.js';
+import { isGlobeEngine } from '../globe/contract.js';
 import { greatCircleMeters } from '../geoDistance.js';
 import {
   holdContinuousRender,
@@ -1713,12 +1714,9 @@ export function createAnnotationEngine({
         geo.cartesian3.fromDegrees(p.lon, p.lat, p.height || 0),
       );
       const sphere = Cesium.BoundingSphere.fromPoints(cart);
-      viewer.camera.flyToBoundingSphere(sphere, {
+      flyToSphere(sphere.center, sphere.radius, {
-        offset: new Cesium.HeadingPitchRange(
+        pitch: geo.math.toRadians(-35),
-          viewer.camera.heading,
+        range: Math.max(900, sphere.radius * 2.6),
-          geo.math.toRadians(-35),
-          Math.max(900, sphere.radius * 2.6),
-        ),
         duration: 1.6,
       });
     } catch {
@@ -1730,8 +1728,9 @@ export function createAnnotationEngine({
    *  globe. On any API hiccup, report visible — bad data must never move the camera. */
   function isPointOnScreen(p) {
     try {
-      const camera = viewer.camera;
       const pos = geo.cartesian3.fromDegrees(p.lon, p.lat, p.height || 0);
+      if (isGlobeEngine(viewer)) return engineSeesPoint(viewer, pos);
+      const camera = viewer.camera;
       const cv = camera.frustum.computeCullingVolume(
         camera.position,
         camera.direction,
@@ -1770,29 +1769,46 @@ export function createAnnotationEngine({
               : anno.ring,
           )
         : viewportRange(anno.viewport) || 600;
-      viewer.camera.flyToBoundingSphere(
+      flyToSphere(
-        new Cesium.BoundingSphere(
         geo.cartesian3.fromDegrees(
           target.lon,
           target.lat,
           anno.anchor.height || 0,
         ),
         range,
-        ),
+        { pitch: geo.math.toRadians(-35), range: range * 2.4, duration: 1.8 },
-        {
-          offset: new Cesium.HeadingPitchRange(
-            viewer.camera.heading,
-            geo.math.toRadians(-35),
-            range * 2.4,
-          ),
-          duration: 1.8,
-        },
       );
     } catch {
       /* framing is best-effort */
     }
   }
 
+  /**
+   * Fly to a sphere keeping the camera's heading: Cesium's
+   * flyToBoundingSphere on a viewer, the contract's flyToSphere on a globe
+   * engine (the same offset semantics).
+   */
+  function flyToSphere(center, radius, { pitch, range, duration }) {
+    if (isGlobeEngine(viewer)) {
+      viewer.camera.flyToSphere(
+        { center, radius },
+        { heading: viewer.camera.pose().heading, pitch, range, duration },
+      );
+      return;
+    }
+    viewer.camera.flyToBoundingSphere(
+      new Cesium.BoundingSphere(center, radius),
+      {
+        offset: new Cesium.HeadingPitchRange(
+          viewer.camera.heading,
+          pitch,
+          range,
+        ),
+        duration,
+      },
+    );
+  }
+
   const engine = {
     annotate,
     clear,
@@ -2045,7 +2061,7 @@ export function createAnnotationEngine({
   }) {
     if (destroyed) return;
     try {
-      viewer.camera.flyTo({
+      viewer?.camera.flyTo({
         destination: geo.cartesian3.fromDegrees(lon, lat, height),
         orientation: {
           heading: geo.math.toRadians(heading),
@@ -2408,3 +2424,16 @@ function appendDistance(baseLabel, distM) {
   if (!dist) return baseLabel;
   return baseLabel ? `${baseLabel} — ${dist}` : dist;
 }
+
+/**
+ * Whether a globe engine shows a world point: in front of the camera, inside
+ * the canvas and on the near side of the globe (what the Cesium path's
+ * culling volume and ellipsoid occluder answer).
+ */
+function engineSeesPoint(engine, position) {
+  if (!engine.projector.horizonVisible(position)) return false;
+  const win = engine.projector.worldToWindow(position);
+  if (!win || !Number.isFinite(win.x) || !Number.isFinite(win.y)) return false;
+  const { width, height } = engine.host.size();
+  return win.x >= 0 && win.x <= width && win.y >= 0 && win.y <= height;
+}

src/annotations/hybridAnnotationRenderer.js

@@ -18,14 +18,19 @@ import { createScreenAnnotationRenderer } from './screenAnnotationRenderer.js';
  *
  * The hybrid surface honors add/update/remove/sync/destroy; update coordinates the
  * one route change that spans both sub-renderers. `screen` passes options to the
- * screen renderer (its store, in tests).
+ * screen renderer (its store, in tests). On a globe without a Cesium viewer
+ * (Navara), `world` is that globe's world renderer and `screenScene` the
+ * screen scene the board is drawn over (src/annotations/screenScene.js).
  */
 export function createHybridAnnotationRenderer(
   viewer,
-  { screen: screenOptions } = {},
+  { screen: screenOptions, world: worldRenderer, screenScene } = {},
 ) {
-  const world = createWorldAnnotationRenderer(viewer);
+  const world = worldRenderer ?? createWorldAnnotationRenderer(viewer);
-  const screen = createScreenAnnotationRenderer(viewer, screenOptions);
+  const screen = createScreenAnnotationRenderer(
+    screenScene ?? viewer,
+    screenOptions,
+  );
   // anno.id -> { worldProxy?, screenProxy? } — proxies own the sub-renderer state.
   const routed = new Map();
 

src/annotations/index.js

@@ -24,16 +24,25 @@ export function initAnnotations({
 /**
  * The page's annotation board, kept across globe engine switches: the marks
  * belong to the page session, their drawing to the attached globe.
- * `attachScene({ viewer, tileset })` draws the board on a Cesium viewer (an
+ * `attachScene({ viewer, tileset })` draws the board on a Cesium viewer;
- * engine without one keeps the marks undrawn); `detachScene()` releases the
+ * `attachScene({ engine, renderer })` on a globe engine without a viewer
- * drawing and keeps the marks.
+ * (Navara: src/annotations/navaraAnnotationRenderer.js, built by the caller
+ * so this module never loads it); with neither the marks stay undrawn.
+ * `detachScene()` releases the drawing and keeps the marks.
  */
 export function createSessionAnnotations({ placeSearch, resolver }) {
   const engine = createAnnotationEngine({
     placeSearch,
     resolveTarget: resolver?.resolveAnnotationTarget,
   });
-  engine.attachScene = ({ viewer = null, tileset = null } = {}) => {
+  engine.attachScene = ({
+    viewer = null,
+    tileset = null,
+    engine: globe = null,
+    renderer = null,
+  } = {}) => {
+    if (!viewer && globe && renderer)
+      return engine.attachRenderer({ viewer: globe, renderer });
     if (!viewer) return engine.detachRenderer();
     // World-space footprint draping; clamped marks can use the photoreal tiles.
     if (tileset) {

src/annotations/navaraAnnotationRenderer.js

@@ -0,0 +1,254 @@
+// The annotation board on the Navara engine: the hybrid renderer's routing
+// (hybridAnnotationRenderer.js) with a Navara world renderer for the marks
+// draped on the ground — area footprints and routes as clamped meshes — and
+// the shared screen-space SVG board (callouts, reticles, rings, arrows) over
+// the engine's projector (screenScene.js). No Cesium, no three.
+
+import { showOsmCredit, hideOsmCredit } from '../data/dataCredits.js';
+import { createHybridAnnotationRenderer } from './hybridAnnotationRenderer.js';
+import { screenSceneFromEngine } from './screenScene.js';
+
+// The world renderer's palette (worldAnnotationRenderer.js).
+const PALETTE = {
+  primary: 0x8be9ff,
+  amber: 0xffb547,
+  cyan: 0x39d0ff,
+  green: 0x5dff9f,
+  red: 0xff6b6b,
+};
+
+/**
+ * A map colour (0xRRGGBB) on `view`: the planet's photographic exposure is
+ * compensated before its tone-mapping pass, as for the story overlays
+ * (src/layers/shared/render/navaraStory.js), so the palette stays readable.
+ */
+function displayColor({ view, NavaraColor }, hex) {
+  const c = new NavaraColor().setHex(hex);
+  const exposure = Math.max(1, view.toneMappingExposure ?? 1);
+  const [r, g, b] = c.toArray();
+  return c.setRGBLinear(r / exposure, g / exposure, b / exposure);
+}
+
+/** 0.6 .. 1.0 at ~0.8 Hz, the Cesium marks' pulse. */
+export function pulseFactor(now = performance.now()) {
+  return 0.8 + 0.2 * Math.sin(now * 0.005);
+}
+
+const closedRing = (ring) => {
+  const [first] = ring;
+  const last = ring[ring.length - 1];
+  return first[0] === last[0] && first[1] === last[1]
+    ? ring.map(([lon, lat]) => [lon, lat])
+    : [...ring.map(([lon, lat]) => [lon, lat]), [first[0], first[1]]];
+};
+
+/**
+ * The draped parts of one mark, as plain data: `{ kind: 'polygon' |
+ * 'polyline', geojson, alpha, pulse, width? }`. Areas (a building, a
+ * district, a multi-part outline with holes) are a fill and an outline per
+ * ring, as the Cesium world renderer draws them; a route is one line.
+ * Anything else is screen-space only (none).
+ */
+export function drapedParts(anno) {
+  if (anno.ring?.length >= 3) {
+    const building = anno.footprintKind === 'building';
+    const parts =
+      Array.isArray(anno.polygons) && anno.polygons.length
+        ? anno.polygons
+        : [[anno.ring]];
+    const out = [];
+    for (const [outer, ...holes] of parts) {
+      if (!Array.isArray(outer) || outer.length < 3) continue;
+      const rings = [outer, ...holes.filter((hole) => hole?.length >= 3)];
+      out.push({
+        kind: 'polygon',
+        geojson: { type: 'Polygon', coordinates: rings.map(closedRing) },
+        alpha: building ? 0.45 : anno.synthesized ? 0.1 : 0.2,
+        pulse: true,
+      });
+      for (const ring of rings)
+        out.push({
+          kind: 'polyline',
+          geojson: { type: 'LineString', coordinates: closedRing(ring) },
+          width: building ? 3 : 6,
+          // Approximate outlines are fainter (Cesium dashes them).
+          alpha: building ? 0.7 : anno.synthesized ? 0.6 : 1,
+          pulse: false,
+        });
+    }
+    return out;
+  }
+  if (anno.type === 'route' && Array.isArray(anno.path) && anno.path.length) {
+    const coordinates = anno.path.map((p) => [p.lon, p.lat]);
+    return coordinates.length >= 2
+      ? [
+          {
+            kind: 'polyline',
+            geojson: { type: 'LineString', coordinates },
+            width: 9,
+            alpha: 1,
+            pulse: false,
+          },
+        ]
+      : [];
+  }
+  return [];
+}
+
+/**
+ * The world half on Navara: one clamped mesh per draped part, its opacity
+ * following the mark's fade and pulse each frame and its visibility the
+ * mark's `hidden`. Renderer contract: add / remove / sync / destroy.
+ * @param {import('../globe/contract.js').GlobeEngine} engine
+ * @param {{ view: object, NavaraColor: Function }} views The Navara view and
+ *   its colour class (src/app/navaraMode.js).
+ */
+export function createNavaraWorldAnnotationRenderer(
+  engine,
+  { view, NavaraColor },
+  { now = () => performance.now() } = {},
+) {
+  // mark -> its meshes: { handle, kind, alpha, pulse, opacity, visible }
+  const drawn = new Map();
+  const credited = new Set();
+  let destroyed = false;
+
+  const targetOpacity = (anno, part, at) =>
+    Math.max(
+      0,
+      Math.min(
+        1,
+        (anno.alpha ?? 1) * part.alpha * (part.pulse ? pulseFactor(at) : 1),
+      ),
+    );
+
+  function add(anno) {
+    if (destroyed) return;
+    const parts = drapedParts(anno);
+    // Published before any mesh lands, so a mid-add failure leaves the meshes
+    // that did land reachable by remove().
+    const meshes = [];
+    drawn.set(anno, meshes);
+    const color = displayColor(
+      { view, NavaraColor },
+      PALETTE[anno.color] ?? PALETTE.primary,
+    );
+    const at = now();
+    for (const part of parts) {
+      const opacity = targetOpacity(anno, part, at);
+      const visible = !anno.hidden;
+      const handle = view.addMesh({
+        [part.kind]: {
+          geojson: part.geojson,
+          clampToGround: true,
+          color,
+          transparent: true,
+          opacity,
+          ...(part.kind === 'polyline' ? { width: part.width } : {}),
+        },
+        visible,
+        lit: false,
+        pickable: false,
+      });
+      meshes.push({ ...part, handle, opacity, visible });
+    }
+    if (
+      anno.type === 'route' ||
+      (meshes.length &&
+        anno.ring?.length >= 3 &&
+        !anno.synthesized &&
+        (anno.outlineCredit === 'tiles' || anno.outlineCredit === 'osm'))
+    ) {
+      credited.add(anno);
+      showOsmCredit(
+        engine,
+        anno,
+        anno.type === 'route'
+          ? undefined
+          : { openMapTiles: anno.outlineCredit === 'tiles' },
+      );
+    }
+    engine.render.request('annotations');
+  }
+
+  function remove(anno) {
+    const meshes = drawn.get(anno);
+    if (credited.delete(anno)) hideOsmCredit(engine, anno);
+    if (!meshes) return;
+    drawn.delete(anno);
+    for (const mesh of meshes) {
+      try {
+        mesh.handle.delete();
+      } catch {
+        /* the view went first */
+      }
+    }
+    engine.render.request('annotations');
+  }
+
+  /** Follow each mark's fade, pulse and visibility. */
+  function sync() {
+    if (destroyed) return;
+    const at = now();
+    let changed = false;
+    for (const [anno, meshes] of drawn) {
+      for (const mesh of meshes) {
+        const opacity = targetOpacity(anno, mesh, at);
+        const visible = !anno.hidden && opacity > 0;
+        if (
+          visible === mesh.visible &&
+          Math.abs(opacity - mesh.opacity) < 0.004
+        )
+          continue;
+        mesh.handle.update({
+          [mesh.kind]: { opacity },
+          visible,
+        });
+        mesh.opacity = opacity;
+        mesh.visible = visible;
+        changed = true;
+      }
+    }
+    if (changed) engine.render.request('annotations');
+  }
+
+  // The pulse animates every frame the engine draws (the board holds
+  // continuous rendering while a mark is visible).
+  const offFrame = engine.frames.preRender.addEventListener(sync);
+
+  function destroy() {
+    if (destroyed) return;
+    offFrame();
+    for (const anno of [...drawn.keys()]) remove(anno);
+    for (const anno of credited) hideOsmCredit(engine, anno);
+    credited.clear();
+    destroyed = true;
+  }
+
+  return {
+    add,
+    remove,
+    sync,
+    destroy,
+    /** The meshes drawn now, for diagnostics and the QA handle. */
+    diagnostics: () => ({
+      marks: drawn.size,
+      meshes: [...drawn.values()].reduce((n, meshes) => n + meshes.length, 0),
+    }),
+  };
+}
+
+/**
+ * The annotation board's renderer on a Navara scene: draped areas and routes
+ * on the engine, every other mark and every caption on the shared SVG board.
+ * `screen` passes options to the screen renderer (its store, in tests).
+ */
+export function createNavaraAnnotationRenderer(engine, views, { screen } = {}) {
+  const world = createNavaraWorldAnnotationRenderer(engine, views);
+  const renderer = createHybridAnnotationRenderer(null, {
+    world,
+    screenScene: screenSceneFromEngine(engine),
+    screen,
+  });
+  return { ...renderer, diagnostics: world.diagnostics };
+}

src/annotations/navaraAnnotationRenderer.test.mjs

@@ -0,0 +1,267 @@
+import '../testSupport/registerDom.mjs';
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { createApp, nextTick } from 'vue';
+import { createPinia } from 'pinia';
+import { useScreenAnnotationsStore } from '../ui/stores/screenAnnotations.js';
+import ScreenAnnotations from '../ui/views/panels/ScreenAnnotations.vue';
+import { createFakeEngine } from '../globe/testing/fakeEngine.js';
+import { createSessionAnnotations } from './index.js';
+import {
+  createNavaraAnnotationRenderer,
+  createNavaraWorldAnnotationRenderer,
+  drapedParts,
+} from './navaraAnnotationRenderer.js';
+import { screenSceneFromEngine } from './screenScene.js';
+
+for (const type of [globalThis.SVGElement, globalThis.SVGGraphicsElement]) {
+  if (type)
+    type.prototype.getBBox = () => ({ x: 0, y: 0, width: 40, height: 16 });
+}
+const settle = async () => {
+  for (let flush = 0; flush < 4; flush += 1) await nextTick();
+};
+
+/** A Navara view that records its meshes, and the colour class. */
+function fakeViews() {
+  const meshes = [];
+  class NavaraColor {
+    setHex(hex) {
+      this.hex = hex;
+      return this;
+    }
+    toArray() {
+      return [1, 1, 1];
+    }
+    setRGBLinear() {
+      return this;
+    }
+  }
+  const view = {
+    toneMappingExposure: 1,
+    addMesh(config) {
+      const mesh = { config, updates: [], deleted: false };
+      meshes.push(mesh);
+      return {
+        update: (next) => mesh.updates.push(next),
+        delete: () => {
+          mesh.deleted = true;
+        },
+      };
+    },
+  };
+  return { views: { view, NavaraColor }, meshes };
+}
+
+/** The page's board view, as in screenAnnotationRenderer.test.mjs. */
+function board(t) {
+  document.body.replaceChildren();
+  const pinia = createPinia();
+  const store = useScreenAnnotationsStore(pinia);
+  const app = createApp(ScreenAnnotations).use(pinia);
+  app.mount(document.body.appendChild(document.createElement('div')));
+  const original = globalThis.requestAnimationFrame;
+  globalThis.requestAnimationFrame = () => 0;
+  t.after(() => {
+    globalThis.requestAnimationFrame = original;
+    app.unmount();
+  });
+  const groups = () => [
+    ...(document.querySelectorAll('.gev-screen-whiteboard-svg g.gev-anno') ??
+      []),
+  ];
+  return { store, groups };
+}
+
+test('areas drape a fill and an outline per ring, routes a line, other marks nothing', () => {
+  const ring = [
+    [0, 0],
+    [1, 0],
+    [1, 1],
+  ];
+  const hole = [
+    [0.2, 0.2],
+    [0.4, 0.2],
+    [0.4, 0.4],
+  ];
+  const area = drapedParts({
+    type: 'area',
+    ring,
+    polygons: [[ring, hole]],
+  });
+  assert.deepEqual(
+    area.map(({ kind, alpha, pulse }) => [kind, alpha, pulse]),
+    [
+      ['polygon', 0.2, true],
+      ['polyline', 1, false],
+      ['polyline', 1, false],
+    ],
+  );
+  // Rings close for the polygon's GeoJSON, holes included.
+  assert.equal(area[0].geojson.coordinates.length, 2);
+  assert.deepEqual(area[0].geojson.coordinates[0].at(-1), [0, 0]);
+  assert.equal(area[1].width, 6);
+  const building = drapedParts({
+    type: 'highlight',
+    ring,
+    footprintKind: 'building',
+  });
+  assert.equal(building[0].alpha, 0.45);
+  assert.equal(building[1].width, 3);
+  assert.equal(
+    drapedParts({ type: 'area', ring, synthesized: true })[0].alpha,
+    0.1,
+  );
+  const route = drapedParts({
+    type: 'route',
+    path: [
+      { lon: 0, lat: 0 },
+      { lon: 1, lat: 1 },
+    ],
+  });
+  assert.deepEqual(
+    route.map((p) => [p.kind, p.width]),
+    [['polyline', 9]],
+  );
+  assert.deepEqual(
+    drapedParts({ type: 'pin', anchor: { lon: 0, lat: 0 } }),
+    [],
+  );
+});
+
+test('the world half follows fade, pulse and hide, and lets go of every mesh', () => {
+  const engine = createFakeEngine({ kind: 'navara' });
+  const { views, meshes } = fakeViews();
+  let now = 0;
+  const world = createNavaraWorldAnnotationRenderer(engine, views, {
+    now: () => now,
+  });
+  const anno = {
+    id: 'a',
+    type: 'area',
+    color: 'amber',
+    alpha: 0,
+    ring: [
+      [0, 0],
+      [1, 0],
+      [1, 1],
+    ],
+  };
+  world.add(anno);
+  assert.equal(meshes.length, 2);
+  const [fill, outline] = meshes;
+  assert.equal(fill.config.polygon.clampToGround, true);
+  assert.equal(fill.config.polygon.color.hex, 0xffb547);
+  assert.equal(fill.config.lit, false);
+  assert.equal(fill.config.pickable, false);
+  assert.equal(outline.config.polyline.width, 6);
+  // Faded in: the engine's frame moves the opacity to the mark's alpha.
+  anno.alpha = 1;
+  engine.fake.frame();
+  assert.equal(outline.updates.at(-1).polyline.opacity, 1);
+  assert.ok(fill.updates.at(-1).polygon.opacity > 0.1);
+  // Pulsing: a later frame changes the fill only.
+  const outlineUpdates = outline.updates.length;
+  now = 300;
+  engine.fake.frame();
+  assert.equal(outline.updates.length, outlineUpdates);
+  assert.notEqual(
+    fill.updates.at(-1).polygon.opacity,
+    fill.updates.at(-2).polygon.opacity,
+  );
+  // Hidden from Draw's list: every mesh goes invisible.
+  anno.hidden = true;
+  world.sync();
+  assert.equal(outline.updates.at(-1).visible, false);
+  world.remove(anno);
+  assert.ok(meshes.every((mesh) => mesh.deleted));
+  assert.equal(world.diagnostics().meshes, 0);
+  world.destroy();
+  const before = fill.updates.length;
+  engine.fake.frame();
+  assert.equal(fill.updates.length, before, 'no frame listener after destroy');
+});
+
+test('the screen scene reads the engine camera, projector, horizon and follow', () => {
+  const engine = createFakeEngine({ kind: 'navara', altitude: 1e6 });
+  const scene = screenSceneFromEngine(engine);
+  scene.beginFrame();
+  const near = { x: 6378137, y: 0, z: 0 };
+  const far = { x: -6378137, y: 0, z: 0 };
+  assert.equal(scene.horizonVisible(near), true);
+  assert.equal(scene.horizonVisible(far), false, 'behind the globe');
+  const win = scene.worldToWindow(near, {});
+  assert.ok(Math.abs(win.x - 512) < 1 && Math.abs(win.y - 384) < 1);
+  assert.ok(Math.abs(scene.cameraHeight() - 1e6) < 1);
+  assert.deepEqual(scene.size(), { width: 1024, height: 768 });
+  assert.equal(scene.trackedSubject(), null);
+});
+
+test('marks on the Navara board are drawn, horizon-culled and survive an engine switch', async (t) => {
+  const { store, groups } = board(t);
+  const engine = createFakeEngine({ kind: 'navara', altitude: 2e6 });
+  const { views, meshes } = fakeViews();
+  const annotations = createSessionAnnotations({});
+  t.after(() => annotations.destroy());
+  const attach = () =>
+    annotations.attachScene({
+      engine,
+      renderer: createNavaraAnnotationRenderer(engine, views, {
+        screen: { store, activeTrackedReadoutId: () => null },
+      }),
+    });
+  attach();
+  assert.equal(annotations.attached, true);
+  const result = await annotations.annotate(
+    [
+      { type: 'pin', manual: true, latitude: 0, longitude: 0, label: 'Near' },
+      { type: 'pin', manual: true, latitude: 0, longitude: 180, label: 'Far' },
+      {
+        type: 'area',
+        manual: true,
+        label: 'Box',
+        ring: [
+          [-1, -1],
+          [1, -1],
+          [1, 1],
+          [-1, 1],
+        ],
+      },
+    ],
+    { persist: true, flyTo: false },
+  );
+  assert.equal(result.drawn, 3, JSON.stringify(result));
+  engine.fake.frame();
+  await settle();
+  const shown = () =>
+    groups()
+      .filter((group) => group.style.display !== 'none')
+      .map((group) => group.querySelector('.gev-anno-text')?.textContent)
+      .filter(Boolean)
+      .sort();
+  // The far pin is behind the globe; the area's caption sits on the board.
+  assert.deepEqual(shown(), ['Box', 'Near']);
+  const live = () => meshes.filter((mesh) => !mesh.deleted);
+  assert.deepEqual(
+    live().map((mesh) => Object.keys(mesh.config)[0]),
+    ['polygon', 'polyline'],
+  );
+  // Fly-to on Navara goes through the contract's flyToSphere.
+  const [box] = annotations.list().filter((mark) => mark.label === 'Box');
+  assert.equal(annotations.frame(box.id), true);
+  assert.equal(engine.fake.callsOf('camera.flyToSphere').length, 1);
+  // A switch takes the drawing off this engine and keeps the marks.
+  annotations.detachScene();
+  assert.equal(live().length, 0);
+  assert.equal(annotations.count(), 3);
+  attach();
+  engine.fake.frame();
+  await settle();
+  assert.equal(live().length, 2);
+  assert.deepEqual(shown(), ['Box', 'Near']);
+  // Engine-side camera assist: frame() of a route uses the same flight.
+  engine.fake.resetCalls();
+  annotations.clear();
+  engine.fake.frame();
+  assert.equal(live().length, 0);
+});

src/annotations/resolver.js

@@ -2397,6 +2397,7 @@ export function createAnnotationResolver({
    * the tiles for that spot aren't loaded we fall back to the ellipsoid (0).
    */
   function sampleGroundHeight(viewer, lon, lat) {
+    if (isGlobeEngine(viewer)) return engineGroundHeight(viewer, lon, lat);
     const scene = viewer?.scene;
     if (!scene) return 0;
     try {
@@ -2421,6 +2422,29 @@ export function createAnnotationResolver({
     return Number.isFinite(globeHeight) && globeHeight > 0 ? globeHeight : 0;
   }
 
+  /** sampleGroundHeight on a globe engine: the rendered surface, else terrain. */
+  function engineGroundHeight(engine, lon, lat) {
+    try {
+      if (engine.surface.clampToHeightSupported) {
+        const clamped = engine.surface.clampToHeight(
+          geo.cartesian3.fromDegrees(lon, lat, 0),
+        );
+        const h = clamped && geo.cartographic.fromCartesian(clamped)?.height;
+        if (Number.isFinite(h)) return h;
+      }
+    } catch {
+      /* tiles not ready — fall through */
+    }
+    try {
+      const h = engine.surface.terrainHeightSupported
+        ? engine.surface.terrainHeight(geo.cartographic.fromDegrees(lon, lat))
+        : undefined;
+      return Number.isFinite(h) && h > 0 ? h : 0;
+    } catch {
+      return 0;
+    }
+  }
+
   function shortLabel(formattedAddress) {
     if (!formattedAddress) return null;
     return String(formattedAddress).split(',')[0].trim() || null;

src/annotations/screenAnnotationRenderer.js

@@ -8,6 +8,7 @@ import { t } from '../i18n/index.js';
 import { nextTick } from 'vue';
 import { useScreenAnnotationsStore } from '../ui/stores/screenAnnotations.js';
 import { applicationPinia } from '../ui/vueRuntime.js';
+import { isScreenScene } from './screenScene.js';
 
 /** A label whose detailed outline could not be resolved. */
 function outlineUnavailableLabel(label) {
@@ -67,7 +68,7 @@ function markScale(h) {
 }
 
 export function createScreenAnnotationRenderer(
-  viewer,
+  target,
   {
     overlayPaintRect = getOverlayPaintRect,
     activeTrackedReadoutId = getActiveTrackedReadoutId,
@@ -78,11 +79,9 @@ export function createScreenAnnotationRenderer(
   const arrowMarkers = new Map();
   let viewBox = null;
 
-  const scene = viewer.scene;
+  // What the board is drawn over: a Cesium viewer or an engine's screen
-  const occluder = new Cesium.EllipsoidalOccluder(
+  // scene (src/annotations/screenScene.js).
-    Cesium.Ellipsoid.WGS84,
+  const view = isScreenScene(target) ? target : screenSceneFromViewer(target);
-    scene.camera.positionWC,
-  );
   const records = new Map(); // anno.id -> { key, anno, group, parts }
   const leaving = new Map(); // key -> a removed mark's record while it fades out
   const byKey = new Map(); // key -> record, live or fading
@@ -121,7 +120,7 @@ export function createScreenAnnotationRenderer(
   // Re-project every annotation each rendered frame so marks stay glued to the
   // world. postRender runs after the camera/tiles update, so positions are exact.
   const onPostRender = () => projectAll();
-  scene.postRender.addEventListener(onPostRender);
+  const offPostRender = view.onFrame(onPostRender);
 
   function color(anno) {
     return PALETTE[anno.color] || PALETTE.primary;
@@ -141,11 +140,8 @@ export function createScreenAnnotationRenderer(
       return cached.h;
     }
     try {
-      if (
+      if (view.clampToHeightSupported()) {
-        scene.clampToHeightSupported &&
+        const c = view.clampToHeight(
-        typeof scene.clampToHeight === 'function'
-      ) {
-        const c = scene.clampToHeight(
           Cesium.Cartesian3.fromDegrees(lon, lat, 0),
         );
         if (c) {
@@ -369,20 +365,15 @@ export function createScreenAnnotationRenderer(
       groundHeight(lon, lat),
     );
     // Reject points behind the camera (they produce wrapped/extreme coords).
-    Cesium.Cartesian3.subtract(world, scene.camera.positionWC, scratchDir);
+    Cesium.Cartesian3.subtract(world, view.cameraPosition(), scratchDir);
-    if (Cesium.Cartesian3.dot(scratchDir, scene.camera.directionWC) <= 0)
+    if (Cesium.Cartesian3.dot(scratchDir, view.cameraDirection()) <= 0)
       return null;
     // Reject points beyond the globe horizon.
-    if (!occluder.isPointVisible(world)) return null;
+    if (!view.horizonVisible(world)) return null;
-    const win = Cesium.SceneTransforms.worldToWindowCoordinates(
+    const win = view.worldToWindow(world, scratch);
-      scene,
-      world,
-      scratch,
-    );
     if (!win || !Number.isFinite(win.x) || !Number.isFinite(win.y)) return null;
     // Reject absurd off-screen projections (anchor not in view).
-    const w = scene.canvas.clientWidth || scene.canvas.width;
+    const { width: w, height: h } = view.size();
-    const h = scene.canvas.clientHeight || scene.canvas.height;
     if (
       !allowOffscreen &&
       (win.x < -w || win.x > 2 * w || win.y < -h || win.y > 2 * h)
@@ -422,31 +413,22 @@ export function createScreenAnnotationRenderer(
     let top = painted?.y;
     let bottom = painted ? painted.y + painted.h : undefined;
 
-    const ent = viewer.trackedEntity;
+    // The followed subject's own graphic, where the globe draws one.
-    const now = Cesium.JulianDate.now();
+    const subject = view.trackedSubject();
-    const world =
+    const world = subject?.world ?? null;
-      typeof ent?.gevDisplayPosition === 'function'
+    const win = world ? view.worldToWindow(world, _scratchTrackedWin) : null;
-        ? ent.gevDisplayPosition()
-        : null;
-    const win = world
-      ? Cesium.SceneTransforms.worldToWindowCoordinates(
-          scene,
-          world,
-          _scratchTrackedWin,
-        )
-      : null;
 
     // Billboard box — centered on the anchor, magnified by scaleByDistance.
-    const bb = ent?.billboard;
+    const bb = subject?.billboard;
     if (bb && win && Number.isFinite(win.x) && Number.isFinite(win.y)) {
-      const baseW = bb.width?.getValue?.(now) ?? 28;
+      const baseW = bb.width ?? 28;
-      const baseH = bb.height?.getValue?.(now) ?? 28;
+      const baseH = bb.height ?? 28;
       let scale = 1;
-      const sbd = bb.scaleByDistance?.getValue?.(now);
+      const sbd = bb.scaleByDistance;
       if (sbd)
         scale = nearFarValue(
           sbd,
-          Cesium.Cartesian3.distance(scene.camera.positionWC, world),
+          Cesium.Cartesian3.distance(view.cameraPosition(), world),
         );
       const hw = (baseW * scale) / 2;
       const hh = (baseH * scale) / 2;
@@ -477,14 +459,11 @@ export function createScreenAnnotationRenderer(
     }
     projGen += 1; // new frame: entries touched below are "hot" and survive trimming
     const trackedRect = trackedEntityRect();
-    occluder.cameraPosition = scene.camera.positionWC;
+    view.beginFrame();
-    const h = scene.canvas.clientHeight || scene.canvas.height;
+    const { width: w, height: h } = view.size();
-    const w = scene.canvas.clientWidth || scene.canvas.width;
     viewBox = `0 0 ${w} ${h}`;
     // Shrink point-marker geometry as the camera pulls back (declutter the blob).
-    const mScale = markScale(
+    const mScale = markScale(view.cameraHeight() ?? 1000);
-      viewer.camera.positionCartographic?.height ?? 1000,
-    );
 
     for (const rec of records.values()) {
       const { anno, group, parts } = rec;
@@ -821,7 +800,7 @@ export function createScreenAnnotationRenderer(
 
   function destroy() {
     try {
-      scene.postRender.removeEventListener(onPostRender);
+      offPostRender();
     } catch {
       /* torn down */
     }
@@ -1026,3 +1005,58 @@ function placeCalloutsAboveVoicePreview(callouts, width, height) {
 function ensureArrowMarker(markers, key, c) {
   if (!markers.has(key)) markers.set(key, c);
 }
+
+/**
+ * A Cesium viewer as the board's screen scene (src/annotations/screenScene.js):
+ * Cesium's own window transform and ellipsoid occluder, and the viewer's
+ * tracked entity as the followed subject.
+ */
+export function screenSceneFromViewer(viewer) {
+  const scene = viewer.scene;
+  const occluder = new Cesium.EllipsoidalOccluder(
+    Cesium.Ellipsoid.WGS84,
+    scene.camera.positionWC,
+  );
+  return {
+    onFrame(listener) {
+      scene.postRender.addEventListener(listener);
+      return () => scene.postRender.removeEventListener(listener);
+    },
+    beginFrame() {
+      occluder.cameraPosition = scene.camera.positionWC;
+    },
+    cameraPosition: () => scene.camera.positionWC,
+    cameraDirection: () => scene.camera.directionWC,
+    cameraHeight: () => viewer.camera.positionCartographic?.height,
+    horizonVisible: (world) => occluder.isPointVisible(world),
+    worldToWindow: (world, result) =>
+      Cesium.SceneTransforms.worldToWindowCoordinates(scene, world, result),
+    size: () => ({
+      width: scene.canvas.clientWidth || scene.canvas.width,
+      height: scene.canvas.clientHeight || scene.canvas.height,
+    }),
+    clampToHeightSupported: () =>
+      Boolean(scene.clampToHeightSupported) &&
+      typeof scene.clampToHeight === 'function',
+    clampToHeight: (position) => scene.clampToHeight(position),
+    trackedSubject() {
+      const ent = viewer.trackedEntity;
+      if (!ent) return null;
+      const now = Cesium.JulianDate.now();
+      const bb = ent.billboard;
+      return {
+        world:
+          typeof ent.gevDisplayPosition === 'function'
+            ? ent.gevDisplayPosition()
+            : null,
+        billboard: bb
+          ? {
+              width: bb.width?.getValue?.(now),
+              height: bb.height?.getValue?.(now),
+              scaleByDistance: bb.scaleByDistance?.getValue?.(now),
+            }
+          : null,
+      };
+    },
+  };
+}

src/annotations/screenScene.js

@@ -0,0 +1,57 @@
+// What the screen-space annotation board (screenAnnotationRenderer.js) needs
+// from the globe under it: the camera, the window projection, the horizon
+// test, surface heights, one callback per drawn frame and the followed
+// subject. A Cesium viewer provides it through screenSceneFromViewer (in the
+// renderer); a globe engine through screenSceneFromEngine here. No Cesium.
+
+import * as geo from '../geo/index.js';
+
+const SCREEN_SCENE = Symbol('gev.annotations.screenScene');
+
+/** Whether `value` is a screen scene (rather than a Cesium viewer). */
+export const isScreenScene = (value) =>
+  value != null && value[SCREEN_SCENE] === true;
+
+/** Mark an object as a screen scene. */
+export function screenScene(members) {
+  Object.defineProperty(members, SCREEN_SCENE, { value: true });
+  return members;
+}
+
+/**
+ * A globe engine as the board's screen scene: its projector, its camera read
+ * once per board frame, its rendered surface and its follow.
+ * @param {import('../globe/contract.js').GlobeEngine} engine
+ */
+export function screenSceneFromEngine(engine) {
+  const position = geo.cartesian3.create();
+  const direction = geo.cartesian3.create();
+  let height = undefined;
+  const refresh = () => {
+    const pose = engine.camera.pose();
+    geo.cartesian3.clone(pose.position, position);
+    geo.cartesian3.clone(pose.direction, direction);
+    height = pose.cartographic?.height;
+  };
+  refresh();
+  return screenScene({
+    onFrame: (listener) => engine.frames.postRender.addEventListener(listener),
+    beginFrame: refresh,
+    cameraPosition: () => position,
+    cameraDirection: () => direction,
+    cameraHeight: () => height,
+    horizonVisible: (world) => engine.projector.horizonVisible(world),
+    worldToWindow: (world, result) =>
+      engine.projector.worldToWindow(world, result),
+    size: () => engine.host.size(),
+    clampToHeightSupported: () =>
+      engine.surface.clampToHeightSupported === true,
+    clampToHeight: (world) => engine.surface.clampToHeight(world),
+    // The followed subject: its card is the overlay host's painted
+    // rectangle, its sprite a mover of the default billboard size.
+    trackedSubject() {
+      const world = engine.camera.following()?.target?.();
+      return world ? { world, billboard: { width: 28, height: 28 } } : null;
+    },
+  });
+}

src/app/navaraMode.js

@@ -468,7 +468,7 @@ export function attachViewerlessTools(
   defer(() => styleManager._clearPersistentStatusNotice?.());
   // The page session's annotation board, Draw and Import on this engine
   // (src/app/navaraTools.js).
-  const tools = { engine, view: navaraViews.get(engine) };
+  const tools = { engine, views: navaraViews.get(engine) };
   const context = { operations, placeSearch, layerSession, styleManager };
   const annotations = attachNavaraAnnotations(tools, context, {
     signal,

src/app/navaraTools.js

@@ -2,12 +2,35 @@
 // Navara engine (src/app/sessionTools.js holds the tools themselves). Loaded
 // with src/app/navaraMode.js, so the Cesium-mode bundle carries none of it.
 
+import { createNavaraAnnotationRenderer } from '../annotations/navaraAnnotationRenderer.js';
+import { sessionAnnotations } from './sessionTools.js';
+
 /**
- * The annotation board drawn on this Navara scene. Returns the board, or
+ * The annotation board drawn on this Navara scene: draped areas and routes
- * null while the engine draws no annotations.
+ * on the engine, every other mark on the shared screen board. The board
+ * belongs to the page session; an engine switch takes only its drawing off
+ * this engine. Returns the board (null without the Navara view).
+ * @param {{ engine: object, views: object }} scene `views`: the Navara view
+ *   and its classes (src/app/navaraMode.js).
  */
-export function attachNavaraAnnotations() {
+export function attachNavaraAnnotations(
-  return null;
+  { engine, views },
+  { layerSession, placeSearch, operations },
+  { defer },
+) {
+  if (!views?.view) return null;
+  const annotations = sessionAnnotations({
+    layerSession,
+    placeSearch,
+    resolver: operations.annotationResolver,
+    defer,
+  });
+  annotations.attachScene({
+    engine,
+    renderer: createNavaraAnnotationRenderer(engine, views),
+  });
+  defer(() => annotations.detachScene());
+  return annotations;
 }
 
 /** UTILITIES ▸ Draw on this Navara scene; null while it has none. */

src/app/navaraTools.test.mjs

@@ -0,0 +1,95 @@
+import '../testSupport/registerDom.mjs';
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { createFakeEngine } from '../globe/testing/fakeEngine.js';
+import { attachNavaraAnnotations } from './navaraTools.js';
+
+function fakeViews() {
+  const meshes = [];
+  class NavaraColor {
+    setHex() {
+      return this;
+    }
+    toArray() {
+      return [1, 1, 1];
+    }
+    setRGBLinear() {
+      return this;
+    }
+  }
+  return {
+    meshes,
+    views: {
+      view: {
+        addMesh(config) {
+          const mesh = { config, deleted: false };
+          meshes.push(mesh);
+          return {
+            update() {},
+            delete() {
+              mesh.deleted = true;
+            },
+          };
+        },
+      },
+      NavaraColor,
+    },
+  };
+}
+
+test('Navara attaches the page session board and its switch takes only the drawing', async () => {
+  const lifetime = new AbortController();
+  const layerSession = { lifetime };
+  const engine = createFakeEngine({ kind: 'navara' });
+  const { views, meshes } = fakeViews();
+  const context = {
+    layerSession,
+    placeSearch: null,
+    operations: { annotationResolver: null },
+  };
+  const attach = () => {
+    const cleanups = [];
+    const board = attachNavaraAnnotations({ engine, views }, context, {
+      defer: (cleanup) => cleanups.push(cleanup),
+    });
+    return { board, detach: () => cleanups.reverse().forEach((c) => c()) };
+  };
+  const first = attach();
+  assert.ok(first.board);
+  assert.equal(first.board, layerSession.annotations);
+  assert.equal(first.board.attached, true);
+  assert.equal(window.__gevAnnotations, first.board);
+  const result = await first.board.annotate(
+    [
+      {
+        type: 'area',
+        manual: true,
+        ring: [
+          [0, 0],
+          [1, 0],
+          [1, 1],
+        ],
+      },
+    ],
+    { flyTo: false },
+  );
+  assert.equal(result.drawn, 1);
+  assert.equal(meshes.filter((mesh) => !mesh.deleted).length, 2);
+  first.detach();
+  assert.equal(first.board.attached, false);
+  assert.equal(first.board.count(), 1, 'the marks stay on the session board');
+  assert.equal(meshes.filter((mesh) => !mesh.deleted).length, 0);
+  const second = attach();
+  assert.equal(second.board, first.board, 'one board for the page session');
+  assert.equal(meshes.filter((mesh) => !mesh.deleted).length, 2);
+  second.detach();
+  lifetime.abort();
+  assert.equal(window.__gevAnnotations, undefined);
+  // Without the Navara view there is nothing to draw on.
+  assert.equal(
+    attachNavaraAnnotations({ engine, views: undefined }, context, {
+      defer() {},
+    }),
+    null,
+  );
+});