Merge remote-tracking branch 'origin/main' into feat/ks4-destinations

# Conflicts:
#	nextjs-app/__tests__/components/darkThemeSafety.test.ts

nextjs-app/__tests__/lib/analytics.test.ts

@@ -62,3 +62,97 @@ describe('getNavigationSource', () => {
     expect(getNavigationSource()).toBe('direct');
   });
 });
+
+/*
+ * The defect the existing suite could not see.
+ *
+ * Every test above sets document.referrer, which the browser writes only when
+ * a *document* loads. Every internal navigation in this app is an App Router
+ * soft navigation — history.pushState, no new document — so document.referrer
+ * keeps naming whatever opened the tab for the whole session. Verified on
+ * staging: /schools/brentwood → click a school → URL changes to /school/…
+ * and document.referrer is still "".
+ *
+ * So `from` reported 'direct' for essentially every in-app journey, and the
+ * suite passed because it only ever exercised the full-page-load path.
+ */
+function freshAnalytics() {
+  let mod!: typeof import('@/lib/analytics');
+  jest.isolateModules(() => {
+    mod = require('@/lib/analytics');
+  });
+  return mod;
+}
+
+function at(path: string) {
+  window.history.pushState({}, '', path);
+}
+
+describe('getNavigationSource across a soft navigation', () => {
+  afterEach(() => {
+    referrer('');
+    at('/');
+  });
+
+  it('attributes a school view to the place page the user actually came from', () => {
+    const { recordVisitedPath, getNavigationSource: source } = freshAnalytics();
+    at('/schools/brentwood');
+    recordVisitedPath('/schools/brentwood');
+
+    at('/school/115429-brentwood-school');
+    recordVisitedPath('/school/115429-brentwood-school');
+
+    expect(source()).toBe('place');
+  });
+
+  it('does not depend on whether the new path was recorded first', () => {
+    // The trail is written by a layout-level effect and read by a page-level
+    // one. React orders those by tree position, which is not a contract worth
+    // resting a measurement on, so the answer must be the same either way.
+    const { recordVisitedPath, getNavigationSource: source } = freshAnalytics();
+    recordVisitedPath('/rankings');
+    at('/school/115429-brentwood-school');
+
+    expect(source()).toBe('rankings');
+  });
+
+  it('names the previous page, not the current one, when both are schools', () => {
+    const { recordVisitedPath, getNavigationSource: source } = freshAnalytics();
+    at('/school/100010-brecknock-primary-school');
+    recordVisitedPath('/school/100010-brecknock-primary-school');
+
+    at('/school/115429-brentwood-school');
+    recordVisitedPath('/school/115429-brentwood-school');
+
+    expect(source()).toBe('detail');
+  });
+
+  it('looks past a return visit to the page the user came back from', () => {
+    const { recordVisitedPath, getNavigationSource: source } = freshAnalytics();
+    for (const p of ['/schools/brentwood', '/school/115429-brentwood-school',
+                     '/schools/brentwood']) {
+      at(p);
+      recordVisitedPath(p);
+    }
+    expect(source()).toBe('detail');
+  });
+
+  it('falls back to the referrer on a real document load, where it is true', () => {
+    // A fresh module is a fresh document: nothing has been recorded, and
+    // document.referrer is meaningful again.
+    const { getNavigationSource: source } = freshAnalytics();
+    at('/school/115429-brentwood-school');
+    referrer(`${ORIGIN}/schools/barnet`);
+
+    expect(source()).toBe('place');
+  });
+
+  it('still reads an arrival from outside as direct', () => {
+    const { recordVisitedPath, getNavigationSource: source } = freshAnalytics();
+    at('/schools/brentwood');
+    recordVisitedPath('/schools/brentwood');
+    referrer('https://www.google.com/search?q=schools+in+brentwood');
+
+    expect(source()).toBe('direct');
+  });
+});