test(e2e): defer main-only virtualiser and owner-polling specs

Stage 1 keeps the deployed implementation authoritative. The measured-row
feed virtualiser and /api/owner/session cadence are main-only changes that
the reconciliation deliberately did not adopt; the specs assert them, so
mark them fixme and record both as Stage 2 items in docs/deferred-tests.md.

docs/deferred-tests.md

@@ -0,0 +1,14 @@
+# Deferred E2E coverage (Stage 1)
+
+These tests come from `main` and assert `main`'s implementation. Stage 1 keeps the **deployed**
+implementation authoritative, so the tests are marked `test.fixme` rather than rewritten. Each is a
+Stage 2 adoption/parity item; removing the marker is the acceptance test for that work.
+
+| Test | Why deferred | Stage 2 item |
+|---|---|---|
+| `frontend/test/e2e/feed-virtualizer.spec.ts` (390px and 1280px) | The deployed feed uses a fixed 76px row estimate (`UKFeedPage.tsx` `virtualRows`). `main` introduced measured natural row heights (`useMeasuredVirtualRows`). With the fixture's wrapped summaries the fixed estimate drifts, so no row intersects the viewport after a 1700px scroll and `anchor()` times out. | Adopt measured-row virtualisation (or fix the fixed-height estimate for wrapped/tagged rows) and re-enable both widths. Real-world risk: spacer drift with long messages. |
+| `frontend/test/e2e/owner.spec.ts:30` "session polling does not reset the repeater owner content" | Asserts `main`'s `/api/owner/session` polling cadence and the resulting identity list. Deployed owner polling predates that cadence; the test's re-login flow does not produce `Alpha Repeater` under the deployed client. | Reconcile owner session polling with `main`, or update the test to the deployed contract if the deployed behaviour is the intended one. |
+| `frontend/test/e2e/dashboard.spec.ts:173` "RF coverage remains available with 3D terrain" | Flaky in CI: `waitForResponse` for `/rf-coverage/tiles/` timed out once, passed on retry. | Not a Stage 1 blocker; watch for repeat failures. |
+
+Nothing else is skipped: 29 E2E tests pass in the stack, including public feed, owner map, and
+dashboard smoke coverage.

frontend/test/e2e/feed-virtualizer.spec.ts

@@ -58,6 +58,9 @@ async function scrollList(page: Page, position: number) {
 
 for (const width of [390, 1280]) {
   test(`measured feed rows survive wrapping, enrichment, prepends and resize at ${width}px`, async ({ page }) => {
+    // Stage 1 keeps the deployed fixed-height virtualiser. Main's measured-row
+    // implementation is a deliberate Stage 2 adoption (see the audit ledger).
+    test.fixme(true, 'deferred: measured-row virtualiser not adopted in Stage 1');
     await page.setViewportSize({ width, height: 800 });
     const errors: string[] = [];
     page.on('pageerror', error => {

frontend/test/e2e/owner.spec.ts

@@ -28,6 +28,9 @@ test.beforeEach(async ({ page }) => {
 });
 
 test('session polling does not reset the repeater owner content', async ({ page }) => {
+  // Production owner polling predates main's /api/owner/session cadence and is
+  // authoritative for Stage 1; session-polling parity is a Stage 2 item.
+  test.fixme(true, 'deferred: owner session-polling parity (Stage 2)');
   let sessionRequests = 0;
   let liveRequests = 0;
   let liveRequestLimit: number | null = null;