Measure engine coupling, QA harness use and contract coverage

Counters that may only fall, each with a committed baseline and a test
that fails on growth:

- report-engine-coupling.mjs gains layer modules that take the viewer
  in attachRenderer (33), layer folders with their own "view being
  restored" flag (9), engine.surface calls outside src/globe (41) and
  layer ids named in the engine switch (3).
- report-qa-harness.mjs counts QA scripts that launch Chrome themselves
  (98), wait with fixed sleeps (117), take the hidden loading screen as
  readiness (9), read Cesium-only objects (75) or define their own
  waitFor helpers (19).
- withCallLog records every contract member the contract suite calls on
  the fake engine; contractCoverage.test.mjs fails when a member outside
  contract-uncalled-baseline.json goes uncalled, and when a listed one
  is called now, so the list of 12 only shrinks.

scripts/qaHarness.test.mjs

@@ -0,0 +1,100 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import {
+  QA_HARNESS_METRICS,
+  harnessGrowth,
+  measureQaHarness,
+  readBaseline,
+  readQaSources,
+} from './report-qa-harness.mjs';
+
+test('QA harness duplication does not grow past the baseline', () => {
+  assert.deepEqual(
+    harnessGrowth(measureQaHarness(), readBaseline().metrics),
+    [],
+    'QA harness duplication grew; use scripts/qa-strict-harness.mjs helpers for browser launch, engine readiness and camera waits instead.',
+  );
+});
+
+test('the baseline names every metric', () => {
+  assert.deepEqual(
+    Object.keys(readBaseline().metrics).sort(),
+    QA_HARNESS_METRICS.map(({ id }) => id).sort(),
+  );
+});
+
+test('a metric that grows is reported, one that falls is not', () => {
+  const baseline = Object.fromEntries(
+    QA_HARNESS_METRICS.map(({ id }) => [id, 10]),
+  );
+  assert.deepEqual(
+    harnessGrowth({ ...baseline, ownLaunch: 11, fixedSleeps: 3 }, baseline).map(
+      ({ id }) => id,
+    ),
+    ['ownLaunch'],
+  );
+  assert.equal(harnessGrowth(baseline, {}).length, QA_HARNESS_METRICS.length);
+});
+
+test('QA sources include the harness and exclude tests and other reports', () => {
+  const names = readQaSources().map(({ file }) => file);
+  assert.ok(names.includes('scripts/qa-strict-harness.mjs'));
+  assert.ok(!names.some((name) => name.endsWith('.test.mjs')));
+  assert.ok(!names.includes('scripts/report-qa-harness.mjs'));
+});
+
+test('metrics count scripts once and distinguish helpers from their callers', () => {
+  const measure = (id, ...sources) =>
+    QA_HARNESS_METRICS.find((metric) => metric.id === id).measure(
+      sources.map((text) => ({ text })),
+    );
+  assert.equal(
+    measure(
+      'ownLaunch',
+      'puppeteer.launch({}); puppeteer.launch({});',
+      'launchBrowser();',
+    ),
+    1,
+  );
+  assert.equal(
+    measure(
+      'fixedSleeps',
+      'const sleep = (ms) => new Promise((r) => setTimeout(r, ms));',
+      'await new Promise((resolve) => { setTimeout(resolve, 1000); });',
+      'await new Promise((resolve) => setTimeout(resolve));',
+      'new Promise((resolve) => requestAnimationFrame(resolve));',
+      'setTimeout(() => reject(new Error()), 1000);',
+    ),
+    3,
+  );
+  assert.equal(
+    measure(
+      'loadingScreenReadiness',
+      "page.waitForSelector('#loading-screen');",
+      "page.waitForSelector('#loading-screen'); await waitForEngine(page);",
+      "document.querySelector('#loading-screen');",
+    ),
+    1,
+  );
+  assert.equal(
+    measure(
+      'cesiumOnlyReads',
+      'window.__godsEyeView?.viewer; window.__godsEyeView.tileset;',
+      'const { scene } = window.__godsEyeView;',
+      'const app = window.__godsEyeView; app.viewer;',
+      'window.__godsEyeView.sceneDirector;',
+      'window.__godsEyeView.engine;',
+    ),
+    3,
+  );
+  assert.equal(
+    measure(
+      'ownWaitHelpers',
+      'async function waitForReady() {}',
+      'const waitForReady = async (page) => page.ready();',
+      'await waitForEngine(page);',
+      "import { waitForEngine } from './qa-strict-harness.mjs';",
+    ),
+    2,
+  );
+});