fix: emit $pageview on popstate for anonymous sessions

src/main.tsx

@@ -172,8 +172,15 @@ function Root() {
 // no-ops without a configured token; sends only allowlisted custom events
 // through the same-origin /rly proxy. The initial sanitized $pageview
 // emits once the SDK is ready; client-side route changes emit from
-// useRoute, deduped on pathname.
-void initAnalytics().then(() => capturePageview()).catch(() => {});
+// useRoute, deduped on pathname. The boot-level popstate listener covers
+// back/forward for anonymous sessions too (useRoute only mounts inside the
+// authenticated App) — pathname dedupe collapses the overlap.
+void initAnalytics()
+  .then(() => {
+    capturePageview();
+    window.addEventListener('popstate', () => capturePageview());
+  })
+  .catch(() => {});
 
 createRoot(document.getElementById("root")!).render(
   <StrictMode>

test/posthog-analytics.test.mjs

@@ -509,7 +509,10 @@ test('facade dedupes pageviews and gates on the public host', () => {
 
 test('pageview wiring: boot emit once, route changes and popstate covered', () => {
   const main = src('src/main.tsx');
-  assert.match(main, /initAnalytics\(\)\.then\(\(\) => capturePageview\(\)\)/);
+  assert.match(main, /initAnalytics\(\)[\s\S]*?capturePageview\(\)/);
+  // boot-level popstate covers back/forward even before the authenticated
+  // App mounts; useRoute's own listener dedupes against it on pathname.
+  assert.match(main, /addEventListener\('popstate',[\s\S]*?capturePageview\(\)/);
   const pages = src('src/pages.ts');
   // navigate + popstate each emit — dedup in capturePageview collapses
   // same-path repeats (StrictMode, hash/range-only history entries).