test(notifications): the center re-says its rows after a switch, a repeat coalesces by content; e2e helper fails with a cause

The center's rows (title, message, refusal, live button) were never rendered across a language
switch, and nothing held the structural compare that coalescing now needs. The channel-link helper
swallowed whatever ended its poll into a bare false: a link that goes away mid-look now counts as
not hit, and no hittable link fails with the poll's own message.

frontend/e2e/bookmark.spec.ts

@@ -196,7 +196,7 @@ test.describe("a bookmark reopens the view it was taken of", () => {
   test("a channel page's own tab, over the page it was opened from", async ({ page, browser }) => {
     await openApp(page, "/?page=feed");
     await expect(page.getByTestId("video-card").first()).toBeVisible();
-    expect(await clickVisibleChannelLink(page)).toBe(true);
+    await clickVisibleChannelLink(page);
     const title = await page.getByTestId("channel-title").textContent();
     await tab(page, "About").click();
     const fresh = await bookmarked(browser, page);

frontend/e2e/channel.spec.ts

@@ -48,7 +48,7 @@ test.describe("channel view", () => {
     // `.first()` here would grab an overscan card ABOVE the viewport, and Playwright's scroll-into-
     // view would move the feed before navigating, so Back would restore that moved position, not
     // the one under test. (This is what made the test fail while the app was in fact correct.)
-    expect(await clickVisibleChannelLink(page)).toBe(true);
+    await clickVisibleChannelLink(page);
     await expect(page.getByTestId("channel-title")).toBeVisible();
     await page.getByTestId("channel-back").click();
     await expect(page.getByTestId("video-card").first()).toBeVisible();

frontend/e2e/helpers.ts

@@ -33,35 +33,41 @@ export async function gotoPage(page: Page, id: string): Promise<void> {
  * that then asserts on where the feed was. Being inside the viewport is not enough either: a card
  * can sit under the page chrome above the scroller (the update banner, the toolbar band), and the
  * covered click makes Playwright scroll and retry — the same move (webkit failed 3 in 24).
- * So the link must be the element hit at its own centre. Returns false if none found.
- * Looked for again until one is, not once: a fresh load is still settling when the first card shows
- * (the links move down ~55px), and webkit can answer the hit test at a link's new centre with the
- * card under it — every link missed in 1 of 30 runs.
+ * So the link must be the element hit at its own centre; none within the wait fails the test, with
+ * the poll's own message. Looked for again until one is, not once: a fresh load is still settling
+ * when the first card shows (the links move down ~55px), and webkit can answer the hit test at a
+ * link's new centre with the card under it — every link missed in 1 of 30 runs. A link that goes
+ * away mid-look (its evaluate waits for it, or throws) counts as not hit, so the next look runs.
  */
-export async function clickVisibleChannelLink(page: Page): Promise<boolean> {
+export async function clickVisibleChannelLink(page: Page): Promise<void> {
   const links = page.getByTestId("video-card-channel").filter({ visible: true });
   let index = -1;
   const findHittable = async () => {
     const count = await links.count();
     for (let i = 0; i < count; i++) {
-      const hittable = await links.nth(i).evaluate((el) => {
-        const r = el.getBoundingClientRect();
-        const hit = document.elementFromPoint(r.left + r.width / 2, r.top + r.height / 2);
-        return hit !== null && el.contains(hit);
-      });
+      const hittable = await links
+        .nth(i)
+        .evaluate(
+          (el) => {
+            const r = el.getBoundingClientRect();
+            const hit = document.elementFromPoint(r.left + r.width / 2, r.top + r.height / 2);
+            return hit !== null && el.contains(hit);
+          },
+          undefined,
+          { timeout: 1000 },
+        )
+        .catch(() => false);
       if (hittable) return i;
     }
     return -1;
   };
-  try {
-    await expect
-      .poll(async () => (index = await findHittable()), { timeout: 5000 })
-      .toBeGreaterThan(-1);
-  } catch {
-    return false;
-  }
+  await expect
+    .poll(async () => (index = await findHittable()), {
+      message: "a channel link hit at its own centre",
+      timeout: 5000,
+    })
+    .toBeGreaterThan(-1);
   await links.nth(index).click();
-  return true;
 }
 
 /**

frontend/src/lib/notifications.coalesce.dom.test.ts

@@ -0,0 +1,37 @@
+// @vitest-environment jsdom
+//
+// A burst of the same notice is one entry with a count (×N), not a pile of copies. The texts are
+// objects now (what to say, built afresh by every msg() call), so "the same" is the same key and
+// values, never the same object: a compare by reference would let every repeat stack.
+import { afterEach, describe, expect, it } from "vitest";
+import { clearAll, getNotifications, msg, notify, raw } from "./notifications";
+
+afterEach(() => clearAll());
+
+describe("coalescing a repeated notice", () => {
+  it("folds the same key and values into one entry, counted", () => {
+    notify({
+      level: "error",
+      title: msg("errors.title"),
+      message: msg("errors.reason.unreachable"),
+    });
+    notify({
+      level: "error",
+      title: msg("errors.title"),
+      message: msg("errors.reason.unreachable"),
+    });
+    expect(getNotifications().map((n) => n.repeat)).toEqual([2]);
+  });
+
+  it("folds the same server refusal too", () => {
+    notify({ level: "error", message: { detail: { code: "not_found", reason: "view" } } });
+    notify({ level: "error", message: { detail: { code: "not_found", reason: "view" } } });
+    expect(getNotifications().map((n) => n.repeat)).toEqual([2]);
+  });
+
+  it("keeps two notices apart when only a value differs", () => {
+    notify({ message: msg("channels.notify.hidden", { name: raw("One") }) });
+    notify({ message: msg("channels.notify.hidden", { name: raw("Two") }) });
+    expect(getNotifications().map((n) => n.repeat)).toEqual([1, 1]);
+  });
+});

frontend/src/modules/notifications/NotificationsPanel.language.dom.test.tsx

@@ -0,0 +1,106 @@
+// @vitest-environment jsdom
+//
+// The notification center says this browser's notices in the reader's language of the moment: a
+// row raised in English reads Hungarian after a switch, its title, its message, a server refusal
+// and the button of a notice still live. The real i18n, not the key passthrough the other panel
+// tests use.
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { act, cleanup, render, screen } from "@testing-library/react";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import i18n from "../../i18n";
+import { api, type AppNotification } from "../../lib/api";
+import type { Notification as ClientNotif } from "../../lib/notifications";
+
+const h = vi.hoisted(() => ({ client: [] as unknown[] }));
+
+vi.mock("../../components/ui/confirmContext", () => ({ useConfirm: () => vi.fn() }));
+vi.mock("../../lib/notifications", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("../../lib/notifications")>()),
+  subscribe: () => () => {},
+  getNotifications: () => h.client,
+  getUnreadCount: () => 0,
+  markAllRead: () => {},
+}));
+vi.mock("../../features/navigation/navigationContext", () => ({
+  useNavigationActions: () => ({ setPage: vi.fn() }),
+}));
+vi.mock("../files/filesContext", () => ({ useFilesActions: () => ({ openFile: vi.fn() }) }));
+vi.mock("../channels/channelsContext", () => ({
+  useChannelsActions: () => ({ focusChannel: vi.fn() }),
+}));
+vi.mock("../feed/feedFiltersContext", () => ({
+  useFeedFilters: () => ({}),
+  useFeedFiltersActions: () => ({ setFilters: vi.fn() }),
+}));
+vi.mock("../../components/ui/PageShell", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("../../components/ui/PageShell")>()),
+  PageToolbar: ({ children }: { children: React.ReactNode }) => <>{children}</>,
+}));
+
+import NotificationsPanel from "./NotificationsPanel";
+import { msg } from "../../lib/notifications";
+
+beforeEach(async () => {
+  await i18n.changeLanguage("en");
+  vi.spyOn(api, "notifications").mockResolvedValue({
+    items: [] as AppNotification[],
+    total: 0,
+  });
+});
+afterEach(async () => {
+  cleanup();
+  vi.restoreAllMocks();
+  await i18n.changeLanguage("en");
+});
+
+const notice = (id: number, extra: Partial<ClientNotif>) =>
+  ({
+    id,
+    level: "info",
+    message: msg("common.copy.done"),
+    requiresInteraction: false,
+    ts: Date.now() - 60_000,
+    read: false,
+    dismissed: false,
+    transient: false,
+    repeat: 1,
+    ...extra,
+  }) as unknown as ClientNotif;
+
+function mount() {
+  render(
+    <QueryClientProvider client={new QueryClient()}>
+      <main>
+        <NotificationsPanel />
+      </main>
+    </QueryClientProvider>,
+  );
+}
+
+describe("NotificationsPanel · the reader's language", () => {
+  it("says a row's title, message, refusal and live button again after a switch", async () => {
+    h.client = [
+      notice(1, {
+        title: msg("views.actionFailed"),
+        message: { detail: { code: "not_found", reason: "view" } },
+        level: "error",
+      }),
+      notice(2, { action: { label: msg("common.undo"), onClick: () => {} } }),
+    ];
+    mount();
+    const en = i18n.getFixedT("en");
+    const hu = i18n.getFixedT("hu");
+    expect(await screen.findByText(en("views.actionFailed"))).toBeTruthy();
+    expect(screen.getByText("This view doesn't exist any more")).toBeTruthy();
+    expect(screen.getByText(en("common.copy.done"))).toBeTruthy();
+    expect(screen.getByRole("button", { name: en("common.undo") })).toBeTruthy();
+
+    await act(async () => void (await i18n.changeLanguage("hu")));
+
+    expect(screen.getByText(hu("views.actionFailed"))).toBeTruthy();
+    expect(screen.getByText("Ez a nézet már nem létezik")).toBeTruthy();
+    expect(screen.getByText(hu("common.copy.done"))).toBeTruthy();
+    expect(screen.getByRole("button", { name: hu("common.undo") })).toBeTruthy();
+    expect(screen.queryByText(en("views.actionFailed"))).toBeNull();
+  });
+});