fix(feed): a live search whose first page failed offers Retry where trying again can help

Search YouTube again with the same term read the failure from the cache and sent nothing, so a busy or unreachable YouTube left the search on its error until the term changed. The first page's failure is now the error state with Retry, offered only where a retry can answer (not the day's cap, the feature turned off or the shared budget).

frontend/src/modules/feed/Feed.tsx

@@ -624,7 +624,16 @@ export default function Feed({
         {ytQuery.isLoading ? (
           <div className="py-16 text-center text-muted">{t("feed.yt.searching")}</div>
         ) : ytError && !ytItems.length ? (
-          <div className="py-16 text-center text-muted max-w-md mx-auto">{ytError}</div>
+          // A first page that failed is said as the error it is, with Retry where trying again can
+          // help (YouTube busy or unreachable): Search YouTube again with the same term reads the
+          // failure from the cache and sends nothing.
+          <StateMessage
+            tone="error"
+            className="max-w-md mx-auto"
+            onRetry={ytFinal ? undefined : () => void ytQuery.refetch()}
+          >
+            {ytError}
+          </StateMessage>
         ) : ytItems.length === 0 ? (
           <div className="py-16 text-center text-muted">{t("feed.yt.noResults")}</div>
         ) : (

frontend/src/modules/feed/Feed.ytLoadMore.dom.test.tsx

@@ -146,6 +146,38 @@ describe("Feed — a live search's Load more that fails", () => {
   });
 });
 
+describe("Feed — a live search whose first page fails", () => {
+  // Search YouTube again with the same term reads the cached failure: Retry is the way to ask again.
+  it("offers Retry where trying again can help, and reads the page on it", async () => {
+    const search = vi
+      .spyOn(api, "searchYoutube")
+      .mockRejectedValueOnce(
+        new HttpError(429, "Too many searches", { code: "refused", reason: "search_busy" }),
+      )
+      .mockResolvedValueOnce({ items: [hit("a")], next_cursor: null, source: "scrape" } as never);
+    mount();
+    expect(await screen.findByText("Too many searches")).toBeTruthy();
+    fireEvent.click(screen.getByRole("button", { name: "common.retry" }));
+    await waitFor(() =>
+      expect(screen.getByRole("list", { name: "results" }).textContent).toBe("hit a (new)"),
+    );
+    expect(search).toHaveBeenCalledTimes(2);
+  });
+
+  it("offers no Retry after a refusal a retry cannot answer", async () => {
+    vi.spyOn(api, "searchYoutube").mockRejectedValue(
+      new HttpError(429, "Today's limit", {
+        code: "refused",
+        reason: "search_daily_limit",
+        limit: 2,
+      }),
+    );
+    mount();
+    expect(await screen.findByText("Today's limit")).toBeTruthy();
+    expect(screen.queryByRole("button", { name: "common.retry" })).toBeNull();
+  });
+});
+
 describe("Feed — a live search's Load more on its way", () => {
   // Marked in this session, then changed back elsewhere: a search read after the mark carries the
   // server's word.