diff --git a/scripts/qa-surface-heights.mjs b/scripts/qa-surface-heights.mjs
new file mode 100644
index 000000000..843646221
--- /dev/null
+++ b/scripts/qa-surface-heights.mjs
@@ -0,0 +1,333 @@
+// Run this checkout's probe against either build; no page-side source imports.
+// node scripts/qa-surface-heights.mjs http://localhost:4308 --out=heights.json
+// Add --compare=before.json for the 0.1 m gate, or --tiles for the 50 m block.
+import assert from 'node:assert/strict';
+import { readFileSync, writeFileSync } from 'node:fs';
+import { pathToFileURL } from 'node:url';
+import * as geo from '../src/geo/index.js';
+import {
+  createStrict,
+  localPreview,
+  openPage,
+  waitForEngine,
+  TILES_FIXTURE_PATH,
+} from './qa-strict-harness.mjs';
+import { whenSettled } from './qa/ready.mjs';
+import {
+  center,
+  points,
+  layers,
+  offsets,
+  counts,
+  features,
+  fixtureRoutes,
+  observeSurfaceMovers,
+  settledPositions,
+} from './qa/surfaceHeights.mjs';
+
+export function compareHeights(before, after, { tiles = false } = {}) {
+  assert.equal(before.version, 1, 'before snapshot version');
+  assert.equal(after.version, 1, 'after snapshot version');
+  assert.equal(
+    before.surface,
+    tiles ? 'tiles' : 'terrain',
+    'before surface (tiles require --tiles)',
+  );
+  assert.equal(after.surface, before.surface, 'matching surfaces');
+  assert.equal(before.fixture, after.fixture, 'matching fixtures');
+  const reports = [];
+  for (const engine of new Set([
+    'cesium',
+    'navara',
+    ...Object.keys(before.engines),
+    ...Object.keys(after.engines),
+  ])) {
+    const left = before.engines[engine] ?? {},
+      right = after.engines[engine] ?? {};
+    for (const layer of new Set([
+      ...layers,
+      ...Object.keys(left),
+      ...Object.keys(right),
+    ])) {
+      const a = left[layer] ?? {},
+        b = right[layer] ?? {};
+      const missing = Object.keys(a).filter((id) => !Object.hasOwn(b, id));
+      const extra = Object.keys(b).filter((id) => !Object.hasOwn(a, id));
+      const invalid = [];
+      let maxAbsM = 0,
+        point = null;
+      for (const id of Object.keys(a)) {
+        if (!Object.hasOwn(b, id)) continue;
+        if (![a[id]?.heightM, b[id]?.heightM].every(Number.isFinite)) {
+          invalid.push(id);
+          continue;
+        }
+        const delta = Math.abs(a[id].heightM - b[id].heightM);
+        if (delta > maxAbsM) {
+          maxAbsM = delta;
+          point = id;
+        }
+      }
+      reports.push({
+        engine,
+        layer,
+        maxAbsM,
+        point,
+        missing,
+        extra,
+        invalid,
+        ok:
+          Object.keys(a).length > 0 &&
+          Object.keys(b).length > 0 &&
+          !missing.length &&
+          !extra.length &&
+          !invalid.length &&
+          maxAbsM <= 0.1 + 1e-9,
+      });
+    }
+  }
+  return { ok: reports.every((r) => r.ok), reports };
+}
+
+function serialize(rows, layer) {
+  const result = {};
+  for (const row of rows) {
+    const position = geo.cartographic.fromCartesian(row.position);
+    const lon = geo.math.toDegrees(position.longitude),
+      lat = geo.math.toDegrees(position.latitude);
+    let id = row.id;
+    if (layer === 'import') {
+      // Imported sprites have no pick ids; match the fixture's unique coordinates.
+      const point = points.find(
+        (p) => Math.abs(p.lon - lon) < 1e-7 && Math.abs(p.lat - lat) < 1e-7,
+      );
+      assert.ok(point, `Unknown import pin at ${lon},${lat}`);
+      id = point.id;
+    }
+    if (layer === 'directions')
+      id = `${row.index === 0 ? 'a' : 'b'}/${row.setId === 'directions-markers' ? 'disc' : 'letter'}`;
+    assert.ok(!Object.hasOwn(result, id), `Duplicate ${layer} point ${id}`);
+    assert.ok(
+      Number.isFinite(position.height),
+      `Nonfinite ${layer} point ${id}`,
+    );
+    assert.ok(
+      Math.abs(lon - center.lon) < 0.0004 &&
+        Math.abs(lat - center.lat) < 0.0004,
+      `${layer}/${id} outside the block fixture`,
+    );
+    result[id] = { heightM: position.height, lon, lat };
+  }
+  return Object.fromEntries(
+    Object.entries(result).sort(([a], [b]) => a.localeCompare(b)),
+  );
+}
+
+async function loadDisplay(page, layer) {
+  await page.evaluate(
+    async ({ layer, points, features }) => {
+      const { dataManager } = window.__godsEyeView;
+      const enable = async (id) => {
+        if (!(await dataManager.setEnabled(id, true)))
+          throw new Error(`Cannot enable ${id}`);
+        return dataManager.layers.get(id).module;
+      };
+      if (layer === 'import') {
+        const outcomes = await window.__gevGeoImport.importFiles([
+          new File(
+            [JSON.stringify({ type: 'FeatureCollection', features })],
+            'surface-heights.geojson',
+            { type: 'application/geo+json' },
+          ),
+        ]);
+        if (outcomes.some((o) => o.error))
+          throw new Error(JSON.stringify(outcomes));
+      } else if (layer === 'infrastructure') {
+        await enable('local-datacenters');
+        await enable('local-dams');
+      } else if (layer === 'directions') {
+        const mod = await enable(layer);
+        mod.placeEndpoint('a', points[0]);
+        mod.placeEndpoint('b', points[2]);
+      } else if (layer === 'story') {
+        const mod = dataManager.layers.get('bhote-koshi-2026').module;
+        mod.setParams({
+          presentation: 'scene-beat',
+          sceneSurface: 'evidence-beat',
+          progress: 0.5,
+          autoPlay: false,
+        });
+        await enable('bhote-koshi-2026');
+        mod.setParams({ progress: 0.5, autoPlay: false });
+      } else await enable(layer === 'alpr' ? 'alpr-cameras' : layer);
+    },
+    { layer, points, features },
+  );
+}
+
+async function unloadDisplay(page, layer) {
+  await page.evaluate(async (layer) => {
+    if (layer === 'import') {
+      for (const file of window.__gevGeoImport.list())
+        window.__gevGeoImport.remove(file.id);
+    } else {
+      const ids =
+        layer === 'infrastructure'
+          ? ['local-datacenters', 'local-dams']
+          : [
+              layer === 'story'
+                ? 'bhote-koshi-2026'
+                : layer === 'alpr'
+                  ? 'alpr-cameras'
+                  : layer,
+            ];
+      for (const id of ids)
+        await window.__godsEyeView.dataManager.setEnabled(id, false);
+    }
+  }, layer);
+}
+
+async function main(argv) {
+  const option = (name) =>
+    argv.find((a) => a.startsWith(`--${name}=`))?.slice(name.length + 3);
+  const base = localPreview(
+    argv.find((a) => !a.startsWith('--')) ??
+      process.env.QA_BASE_URL ??
+      'http://localhost:4308',
+  );
+  const tiles = argv.includes('--tiles');
+  const before = option('compare')
+    ? JSON.parse(readFileSync(option('compare'), 'utf8'))
+    : null;
+  const snapshot = {
+    version: 1,
+    fixture: 'surface-heights-v1',
+    surface: tiles ? 'tiles' : 'terrain',
+    engines: {},
+  };
+  if (before) compareHeights(before, snapshot, { tiles });
+  const routes = fixtureRoutes(base.origin, tiles);
+  const strict = createStrict({ origin: base.origin, layers, routes });
+  base.search = '?engine=navara&welcome=0';
+  if (tiles) base.searchParams.set('qaTileset', TILES_FIXTURE_PATH);
+  base.hash = `v=2&lat=${center.lat}&lon=${center.lon}&alt=1100&heading=0&pitch=-90&roll=0&map=${tiles ? 'photoreal' : 'osm'}&l=`;
+  await strict.run({}, async (browser) => {
+    for (const kind of ['navara', 'cesium']) {
+      const { page, errors } = await openPage(browser);
+      await page.goto(base.href, { waitUntil: 'domcontentloaded' });
+      await waitForEngine(page, 'navara');
+      if (kind === 'cesium') await strict.pick(page, kind);
+      await page.evaluate(
+        async ({ destination, tiles }) => {
+          const { engine, styleManager } = window.__godsEyeView;
+          styleManager.orbitController.stop();
+          engine.camera.cancelFlight();
+          await engine.maps.setTerrain({
+            kind: tiles ? 'ellipsoid' : 'keyless',
+          });
+          engine.camera.setView({
+            destination,
+            orientation: { heading: 0, pitch: -Math.PI / 2, roll: 0 },
+          });
+          engine.render.request('qa-surface-heights');
+        },
+        {
+          destination: geo.cartesian3.fromDegrees(center.lon, center.lat, 1100),
+          tiles,
+        },
+      );
+      await whenSettled(page);
+      await page.waitForFunction(
+        ({ points, tiles }) => {
+          const { engine } = window.__godsEyeView;
+          engine.render.request('qa-surface-heights');
+          return (
+            engine.surface.tilesLoaded() &&
+            engine.maps.photorealActive() === tiles &&
+            points.every((p) => {
+              const place = {
+                longitude: (p.lon * Math.PI) / 180,
+                latitude: (p.lat * Math.PI) / 180,
+                height: 0,
+              };
+              const height = tiles
+                ? engine.surface.sampleHeight(place)
+                : engine.surface.terrainHeight(place);
+              return (
+                Number.isFinite(height) &&
+                (tiles ? Math.abs(height - 50) < 0.1 : height > 1)
+              );
+            })
+          );
+        },
+        { timeout: 90000 },
+        { points, tiles },
+      );
+      await page.evaluate(observeSurfaceMovers);
+      snapshot.engines[kind] = {};
+      for (const layer of layers) {
+        await loadDisplay(page, layer);
+        await page.evaluate(
+          (destination) => {
+            const { engine } = window.__godsEyeView;
+            engine.camera.cancelFlight();
+            engine.camera.setView({
+              destination,
+              orientation: { heading: 0, pitch: -Math.PI / 2, roll: 0 },
+            });
+            engine.render.request('qa-surface-heights');
+          },
+          geo.cartesian3.fromDegrees(center.lon, center.lat, 1100),
+        );
+        await whenSettled(page);
+        const rows = await settledPositions(page, layer, counts[layer]);
+        const values = serialize(rows, layer);
+        snapshot.engines[kind][layer] = values;
+        if (tiles)
+          for (const [id, p] of Object.entries(values))
+            assert.ok(
+              Math.abs(p.heightM - (50 + offsets[layer])) <= 0.1,
+              `${kind}/${layer}/${id}: ${p.heightM} m, expected ${50 + offsets[layer]} m`,
+            );
+        await strict.passed(
+          page,
+          layer,
+          `${counts[layer]} committed surface points`,
+          values,
+        );
+        console.log(
+          `PASS ${kind}/${layer}: ${rows.length} points${tiles ? ` at ${50 + offsets[layer]} m (±0.1 m)` : ''}`,
+        );
+        await unloadDisplay(page, layer);
+      }
+      await page.evaluate(() => window.qaSurfaceMovers.restore());
+      assert.deepEqual(errors, []);
+      await page.close();
+    }
+    if (option('out')) {
+      writeFileSync(option('out'), JSON.stringify(snapshot, null, 2) + '\n');
+      console.log(`WROTE ${option('out')}`);
+    }
+    if (before) {
+      const comparison = compareHeights(before, snapshot, { tiles });
+      for (const r of comparison.reports)
+        console.log(
+          `${r.ok ? 'PASS' : 'FAIL'} ${r.engine}/${r.layer}: max |Δ|=${r.maxAbsM.toFixed(6)} m; missing=${r.missing.join(',') || 'none'}; extra=${r.extra.join(',') || 'none'}; invalid=${r.invalid.join(',') || 'none'}`,
+        );
+      assert.ok(
+        comparison.ok,
+        'Surface heights differ by more than 0.1 m or the point sets changed',
+      );
+    }
+    console.log(
+      `PASS surface heights: 12 engine/layer measurements (${snapshot.surface})`,
+    );
+  });
+}
+
+if (import.meta.url === pathToFileURL(process.argv[1] ?? '').href) {
+  main(process.argv.slice(2)).catch((error) => {
+    console.error(error);
+    process.exitCode = 1;
+  });
+}
diff --git a/scripts/qa-surface-heights.test.mjs b/scripts/qa-surface-heights.test.mjs
new file mode 100644
index 000000000..18fec415d
--- /dev/null
+++ b/scripts/qa-surface-heights.test.mjs
@@ -0,0 +1,166 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { compareHeights } from './qa-surface-heights.mjs';
+import {
+  layers,
+  observeSurfaceMovers,
+  fixtureRoutes,
+  center,
+} from './qa/surfaceHeights.mjs';
+import { createFakeEngine } from '../src/globe/testing/fakeEngine.js';
+import { decodeAlprTile } from '../src/layers/alpr/tileRecords.js';
+
+const snapshot = (heightM = 50) => ({
+  version: 1,
+  fixture: 'surface-heights-v1',
+  surface: 'terrain',
+  engines: Object.fromEntries(
+    ['cesium', 'navara'].map((engine) => [
+      engine,
+      Object.fromEntries(
+        layers.map((layer) => [layer, { a: { heightM }, b: { heightM } }]),
+      ),
+    ]),
+  ),
+});
+
+test('comparison accepts identical heights and the inclusive 0.1 m boundary', () => {
+  for (const delta of [0, 0.099, 0.1, -0.1]) {
+    const result = compareHeights(snapshot(), snapshot(50 + delta));
+    assert.equal(result.ok, true);
+    assert.equal(result.reports.length, 12);
+    assert.ok(Math.abs(result.reports[0].maxAbsM - Math.abs(delta)) < 1e-10);
+  }
+});
+
+test('comparison reports the largest absolute difference and fails above tolerance', () => {
+  const after = snapshot();
+  after.engines.navara.import.a.heightM = 50.01;
+  after.engines.navara.import.b.heightM = 49.8999;
+  const result = compareHeights(snapshot(), after);
+  assert.equal(result.ok, false);
+  const failures = result.reports.filter((r) => !r.ok);
+  assert.equal(failures.length, 1);
+  assert.equal(failures[0].point, 'b');
+  assert.ok(Math.abs(failures[0].maxAbsM - 0.1001) < 1e-10);
+});
+
+test('missing and extra points fail even with identical surviving heights', () => {
+  for (const engine of ['cesium', 'navara'])
+    for (const layer of layers)
+      for (const change of ['missing', 'extra']) {
+        const after = snapshot();
+        if (change === 'missing') delete after.engines[engine][layer].a;
+        else after.engines[engine][layer].extra = { heightM: 50 };
+        const result = compareHeights(snapshot(), after);
+        assert.equal(result.ok, false);
+        const report = result.reports.find(
+          (r) => r.engine === engine && r.layer === layer,
+        );
+        assert.deepEqual(report.missing, change === 'missing' ? ['a'] : []);
+        assert.deepEqual(report.extra, change === 'extra' ? ['extra'] : []);
+      }
+});
+
+test('missing engines, layers, empty cohorts and invalid heights cannot pass', () => {
+  for (const change of [
+    (s) => {
+      delete s.engines.navara;
+    },
+    (s) => {
+      delete s.engines.cesium.story;
+    },
+    (s) => {
+      s.engines.navara.alpr = {};
+    },
+    ...[null, NaN, Infinity, '50'].map((height) => (s) => {
+      s.engines.cesium.import.a.heightM = height;
+    }),
+  ]) {
+    const after = snapshot();
+    change(after);
+    assert.equal(compareHeights(snapshot(), after).ok, false);
+  }
+  const empty = snapshot();
+  empty.engines.cesium.story = {};
+  assert.equal(compareHeights(empty, empty).ok, false);
+});
+
+test('tiles require explicit opt-in and cannot be compared with terrain', () => {
+  const tiles = snapshot();
+  tiles.surface = 'tiles';
+  assert.throws(() => compareHeights(tiles, tiles), /tiles require --tiles/);
+  assert.throws(() => compareHeights(snapshot(), tiles), /matching surfaces/);
+  assert.equal(compareHeights(tiles, tiles, { tiles: true }).ok, true);
+});
+
+test('the probe reads committed contract positions, snapshots mutable inputs and drops destroyed sets', () => {
+  const engine = createFakeEngine();
+  const original = globalThis.window;
+  globalThis.window = { __godsEyeView: { engine } };
+  try {
+    observeSurfaceMovers();
+    const probe = window.qaSurfaceMovers;
+    const set = engine.movers.createSet({
+      id: 'alpr-cameras',
+      kind: 'point',
+      capacity: 1,
+      point: { sizePx: 5 },
+    });
+    const position = { x: 1, y: 2, z: 3 };
+    set.set(0, { position, show: true, pickId: 'camera' });
+    set.setCount(1);
+    assert.throws(() => probe.read('alpr'), /Uncommitted mover count/);
+    set.commit();
+    position.z = 500;
+    assert.equal(probe.read('alpr')[0].position.z, 3);
+    set.set(0, { position });
+    assert.equal(probe.read('alpr')[0].position.z, 3);
+    set.commit();
+    assert.equal(probe.read('alpr')[0].position.z, 500);
+    assert.equal(probe.read('alpr')[0].id, 'camera');
+    set.destroy();
+    assert.deepEqual(probe.read('alpr'), []);
+    probe.restore();
+  } finally {
+    engine.destroy();
+    if (original === undefined) delete globalThis.window;
+    else globalThis.window = original;
+  }
+});
+
+test('fixture routes match both bundled and dev infrastructure URLs and decode real camera tiles', () => {
+  const origin = 'http://localhost:4308';
+  const routes = fixtureRoutes(origin, true);
+  const answer = (url) =>
+    routes.find((r) => new URLPattern(r.pattern).test(url))?.respond({ url });
+  for (const path of [
+    '/assets/datacenters-abc.geojsonl',
+    '/src/data/local_data/dams/dams.geojsonl',
+  ]) {
+    const rows = answer(origin + path)
+      .body.split('\n')
+      .map(JSON.parse);
+    assert.equal(rows.length, 3);
+    assert.ok(
+      rows.every(
+        (r) => Math.abs(r.geometry.coordinates[1] - center.lat) < 0.0004,
+      ),
+    );
+  }
+  const z = 12,
+    scale = 2 ** z;
+  const x = Math.floor(((center.lon + 180) / 360) * scale);
+  const y = Math.floor(
+    ((1 - Math.asinh(Math.tan((center.lat * Math.PI) / 180)) / Math.PI) / 2) *
+      scale,
+  );
+  const tile = answer(
+    `https://tiles.dontgetflocked.com/cameras-us-hourly/${z}/${x}/${y}.mvt`,
+  );
+  const cameras = decodeAlprTile(tile.body, z, x, y);
+  assert.equal(cameras.length, 3);
+  assert.equal(new Set(cameras.map((r) => r.id)).size, 3);
+  assert.ok(cameras.every((r) => Math.abs(r.longitude - center.lon) < 0.0004));
+  assert.equal(answer(origin + '/api/unexpected-feed').status, 503);
+});
diff --git a/scripts/qa/surfaceHeights.mjs b/scripts/qa/surfaceHeights.mjs
new file mode 100644
index 000000000..cf298c328
--- /dev/null
+++ b/scripts/qa/surfaceHeights.mjs
@@ -0,0 +1,360 @@
+import { readFileSync } from 'node:fs';
+import { cameraTile } from '../fixtures/layers/alpr.mjs';
+import { tilesFixtureRoutes } from '../qa-strict-harness.mjs';
+
+const { extras } = JSON.parse(
+  readFileSync(new URL('../fixtures/tiles3d/tileset.json', import.meta.url)),
+);
+export const center = extras.probes.block50;
+export const points = [-1, 0, 1].map((n, i) => ({
+  id: `surface-${i}`,
+  lon: center.lon + n * 0.00018,
+  lat: center.lat + n * 0.00018,
+}));
+export const layers = [
+  'import',
+  'infrastructure',
+  'alpr',
+  'directions',
+  'bikeshare',
+  'story',
+];
+export const offsets = {
+  import: 0,
+  infrastructure: 0,
+  alpr: 1.5,
+  directions: 0,
+  bikeshare: 2,
+  story: 0,
+};
+export const counts = {
+  import: 3,
+  infrastructure: 6,
+  alpr: 3,
+  directions: 4,
+  bikeshare: 3,
+  story: 1,
+};
+
+export const features = points.map(({ id, lon, lat }) => ({
+  type: 'Feature',
+  id,
+  properties: { name: id },
+  geometry: { type: 'Point', coordinates: [lon, lat] },
+}));
+
+export function fixtureRoutes(origin, tiles) {
+  const json = (value) => ({
+    contentType: 'application/json',
+    body: JSON.stringify(value),
+  });
+  const event = JSON.parse(
+    readFileSync(
+      new URL(
+        '../../public/events/bhote-koshi-2026/event.json',
+        import.meta.url,
+      ),
+    ),
+  );
+  event.evidenceSpine = [];
+  event.fieldReports = [];
+  event.reconstruction.corridor = points.map((p, i) => ({
+    ...p,
+    chainageM: i * 30,
+    elevationM: 0,
+  }));
+  event.reconstruction.storyFloodWindow = { start: 0, end: 1 };
+  event.imagery.rectangle = {
+    west: center.lon - 0.0004,
+    east: center.lon + 0.0004,
+    south: center.lat - 0.0004,
+    north: center.lat + 0.0004,
+  };
+  const cameras = points.map((p, i) => ({
+    latitude: p.lat,
+    longitude: p.lon,
+    osmId: 9100000 + i,
+    operator: 'Surface fixture',
+    brand: 'Fixture',
+    cameraType: 'fixed',
+    direction: '',
+  }));
+  return [
+    ...(tiles ? tilesFixtureRoutes(origin) : []),
+    ...['datacenters', 'dams'].map((name) => ({
+      pattern: `${origin}/*${name}*.geojsonl*`,
+      respond: () => ({
+        contentType: 'application/json',
+        body: features
+          .map((f) =>
+            JSON.stringify(
+              name === 'dams'
+                ? {
+                    ...f,
+                    geometry: {
+                      ...f.geometry,
+                      coordinates: [
+                        f.geometry.coordinates[0],
+                        f.geometry.coordinates[1] + 0.0001,
+                      ],
+                    },
+                  }
+                : f,
+            ),
+          )
+          .join('\n'),
+      }),
+    })),
+    {
+      pattern: `${origin}/events/bhote-koshi-2026/event.json*`,
+      respond: () => json(event),
+    },
+    {
+      pattern: `${origin}/api/terrain/heights*`,
+      respond: ({ url }) =>
+        json({
+          results: new URL(url).searchParams
+            .get('points')
+            .split(';')
+            .map(() => ({ ellipsoid: tiles ? 50 : 150 })),
+        }),
+    },
+    {
+      pattern: `${origin}/api/route*`,
+      respond: () =>
+        json({
+          ok: true,
+          geometry: points.map((p) => [p.lon, p.lat]),
+          distanceM: 60,
+          durationS: 30,
+          steps: [],
+        }),
+    },
+    {
+      pattern: `${origin}/api/gbfs/*`,
+      respond: ({ url }) => {
+        const upstream = decodeURIComponent(
+          new URL(url).pathname.slice('/api/gbfs/'.length),
+        );
+        const information = upstream.includes('station_information');
+        return json({
+          last_updated: 1785153600,
+          ttl: 3600,
+          version: '2.3',
+          data: {
+            stations: points.map((p) =>
+              information
+                ? {
+                    station_id: p.id,
+                    name: p.id,
+                    lat: p.lat,
+                    lon: p.lon,
+                    capacity: 20,
+                  }
+                : {
+                    station_id: p.id,
+                    num_bikes_available: 10,
+                    num_docks_available: 10,
+                    is_installed: 1,
+                    is_renting: 1,
+                    is_returning: 1,
+                  },
+            ),
+          },
+        });
+      },
+    },
+    {
+      pattern: 'https://tiles.dontgetflocked.com/*',
+      respond: ({ url }) => {
+        const path = new URL(url).pathname;
+        if (path.endsWith('.json'))
+          return json({
+            tiles: [
+              'https://tiles.dontgetflocked.com/cameras-us-hourly/{z}/{x}/{y}.mvt',
+            ],
+            bounds: [-160, 17, -64, 59],
+          });
+        const match = path.match(/\/(\d+)\/(\d+)\/(\d+)\.mvt$/);
+        if (!match)
+          throw new Error(`Unexpected camera fixture request: ${path}`);
+        return {
+          contentType: 'application/x-protobuf',
+          body: cameraTile(...match.slice(1).map(Number), cameras),
+        };
+      },
+    },
+    {
+      // Auxiliary startup services must never turn this fixture run into live feeds.
+      pattern: `${origin}/api/*`,
+      respond: ({ url }) => {
+        const path = new URL(url).pathname;
+        if (
+          ['/api/google/tiles-token', '/api/realtime/debug-log'].includes(path)
+        )
+          return { status: 204 };
+        if (path.endsWith('/status')) return json({ configured: false });
+        return {
+          status: 503,
+          ...json({ error: 'Unavailable in surface fixture' }),
+        };
+      },
+    },
+  ];
+}
+
+/** Observe committed positions: neither revision's mover registry exposes instances. */
+export function observeSurfaceMovers() {
+  const { engine } = window.__godsEyeView;
+  const records = new Map();
+  let frames = 0;
+  const offFrame = engine.frames.postRender.addEventListener(() => {
+    frames++;
+  });
+  const create = engine.movers.createSet;
+  const layerOf = (id) => {
+    if (/^geo-import-.*-pins-/.test(id)) return 'import';
+    if (/^local-(datacenters|dams)-pins$/.test(id)) return 'infrastructure';
+    if (id === 'alpr-cameras') return 'alpr';
+    if (/^directions-(markers|marker-letters)$/.test(id)) return 'directions';
+    if (id === 'bikeshare') return 'bikeshare';
+    if (id === 'bhote-koshi-flood-bhote-koshi-surge-front') return 'story';
+    return null;
+  };
+  engine.movers.createSet = function (options) {
+    const set = create.call(this, options);
+    const layer = layerOf(options.id);
+    if (!layer) return set;
+    const record = { layer, set, items: [], committed: [] };
+    records.set(options.id, record);
+    const write = set.set,
+      commit = set.commit,
+      destroy = set.destroy;
+    set.set = function (index, fields) {
+      const result = write.call(this, index, fields);
+      record.items[index] = {
+        ...record.items[index],
+        ...fields,
+        ...(fields.position ? { position: { ...fields.position } } : {}),
+        ...(fields.pickId
+          ? { pickId: String(fields.pickId.id ?? fields.pickId) }
+          : {}),
+      };
+      return result;
+    };
+    set.commit = function () {
+      const result = commit.call(this);
+      record.committed = record.items
+        .slice(0, set.count())
+        .map((p) => ({ ...p }));
+      return result;
+    };
+    set.destroy = function () {
+      const result = destroy.call(this);
+      records.delete(options.id);
+      return result;
+    };
+    return set;
+  };
+  window.qaSurfaceMovers = {
+    frames: () => frames,
+    read(layer) {
+      const registry = engine.movers.list();
+      return [...records]
+        .filter(([, r]) => r.layer === layer)
+        .flatMap(([id, r]) => {
+          const live = registry.find((s) => s.id === id);
+          if (!live || live.count !== r.committed.length)
+            throw new Error(`Uncommitted mover count: ${id}`);
+          return r.committed.map((p, index) => ({
+            setId: id,
+            index,
+            id: p.pickId ?? String(index),
+            position: p.position,
+            shown: live.shown && p.show !== false,
+            ready: r.set.ready(index),
+          }));
+        });
+    },
+    restore() {
+      offFrame();
+      engine.movers.createSet = create;
+    },
+  };
+}
+
+/** A settled camera alone does not mean asynchronous placement has committed. */
+export async function settledPositions(page, layer, count) {
+  await page.evaluate(() => {
+    window.qaSurfaceStable = null;
+  });
+  const handle = await page
+    .waitForFunction(
+      (layer, count) => {
+        const { engine, dataManager, surfaceServices } = window.__godsEyeView;
+        engine.render.request('qa-surface-heights');
+        const rows = window.qaSurfaceMovers.read(layer);
+        let ready =
+          engine.surface.tilesLoaded() &&
+          rows.length === count &&
+          rows.every(
+            (p) =>
+              p.shown &&
+              p.ready &&
+              ['x', 'y', 'z'].every((axis) =>
+                Number.isFinite(p.position?.[axis]),
+              ),
+          );
+        if (layer === 'alpr') {
+          const mod = dataManager.layers.get('alpr-cameras').module;
+          ready &&=
+            !mod.getStats().loading &&
+            mod
+              .getAnalystRecords()
+              .every((p) =>
+                Number.isFinite(
+                  surfaceServices.groundFloor.cachedGroundFloor(p.lat, p.lon),
+                ),
+              );
+        }
+        if (layer === 'bikeshare')
+          ready &&= !dataManager.layers.get('bikeshare').module.getStats()
+            .loading;
+        const signature = JSON.stringify(
+          rows.map((p) => [
+            p.setId,
+            p.id,
+            p.position &&
+              ['x', 'y', 'z'].map((axis) =>
+                Math.round(p.position[axis] * 1000),
+              ),
+          ]),
+        );
+        const previous = window.qaSurfaceStable;
+        const drawn = window.qaSurfaceMovers.frames();
+        const stable =
+          ready && previous?.signature === signature
+            ? previous.frames + (drawn > previous.drawn ? 1 : 0)
+            : 0;
+        window.qaSurfaceStable = { signature, frames: stable, drawn, rows };
+        return stable >= 10 ? rows : false;
+      },
+      { polling: 'raf', timeout: 90000 },
+      layer,
+      count,
+    )
+    .catch(async (cause) => {
+      const state = await page
+        .evaluate(() => window.qaSurfaceStable)
+        .catch(() => null);
+      throw new Error(
+        `Placement readiness failed for ${layer}: expected ${count} points; ${JSON.stringify(state)}`,
+        { cause },
+      );
+    });
+  try {
+    return await handle.jsonValue();
+  } finally {
+    await handle.dispose();
+  }
+}