feat: open Following alerts in changed review (Closes #1317)

tests/e2e/test_mobile_following_release.py

@@ -80,3 +80,34 @@ def test_following_queue_is_phone_usable_at_narrow_viewport(viewport):
         overflow = page.evaluate("document.documentElement.scrollWidth > document.documentElement.clientWidth")
         assert overflow is False
         browser.close()
+
+
+def test_following_alert_route_opens_truthful_empty_state_with_one_refresh():
+    with sync_playwright() as playwright:
+        browser = playwright.chromium.launch(headless=True)
+        page = browser.new_page(viewport={"width": 390, "height": 844})
+        page.set_content((FRONTEND / "index.html").read_text())
+        page.add_style_tag(path=FRONTEND / "dashboard.css")
+        page.add_script_tag(path=FRONTEND / "following.js")
+
+        result = page.evaluate("""async () => {
+          let requests=0;
+          globalThis.fetch=async () => {
+            requests += 1;
+            return {ok:true,json:async () => ({revision:2,items:[]})};
+          };
+          const queue=attachFollowing(() => {});
+          await queue.route();
+          return {requests,open:document.querySelector('#following-sheet').open,
+            status:document.querySelector('#following-status').textContent};
+        }""")
+
+        assert result == {
+            "requests": 1,
+
+            "open": True,
+            "status": "No watched items yet. Watch an issue or pull request from Search to keep it here.",
+        }
+        expect(page.locator("#following-sheet")).to_be_visible()
+        assert page.locator("#close-following").bounding_box()["height"] >= 44
+        browser.close()