Fix Discover catalog dropdown going empty on Movie/Series switch

discover.catalogs held whatever type the last fetch returned, so
switching content type raced the async refetch: the auto-select
effect could latch onto a stale catalog key from the previous type,
which then matched nothing once the real catalogs arrived. Filter
catalogs by the current contentType at the source so a mismatched
entry can never be selected.

Adds a Vitest + RTL harness (none existed) to drive the real
DiscoverScreen through the exact race condition.

package.json

@@ -5,6 +5,7 @@
   "type": "module",
   "scripts": {
     "dev": "vite",
+    "test": "vitest run",
     "typecheck": "node scripts/gen-core-methods.mjs && tsc --noEmit",
     "build": "node scripts/gen-core-methods.mjs && tsc && vite build",
     "check": "npm run build && cd src-tauri && cargo check",
@@ -29,11 +30,16 @@
   },
   "devDependencies": {
     "@tauri-apps/cli": "^2",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
+    "@testing-library/user-event": "^14.6.1",
     "@types/react": "^19.2.17",
     "@types/react-dom": "^19.2.3",
     "@vitejs/plugin-react": "^6.0.3",
     "esbuild": "^0.28.1",
+    "jsdom": "^29.1.1",
     "typescript": "^6.0.3",
-    "vite": "^8.1.1"
+    "vite": "^8.1.1",
+    "vitest": "^4.1.10"
   }
 }

src/screens/DiscoverScreen.race.test.tsx

@@ -0,0 +1,102 @@
+import React, { useState } from 'react';
+import { describe, it, expect } from 'vitest';
+import { render, screen, waitFor, within } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { DiscoverScreen } from './DiscoverScreen';
+import type { AppState, DiscoverCatalog } from '../core/types';
+
+const MOVIE_CATALOGS: DiscoverCatalog[] = [
+  { key: 'cinemeta-movie-top', label: 'Cinemeta: Popular', type: 'movie', extras: [] },
+];
+
+const SERIES_CATALOGS: DiscoverCatalog[] = [
+  { key: 'cinemeta-series-top', label: 'Cinemeta: Popular', type: 'series', extras: [] },
+];
+
+function baseState(): AppState {
+  return {
+    navigation: { route: 'discover' },
+    home: {} as AppState['home'],
+    detail: {} as AppState['detail'],
+    search: {} as AppState['search'],
+    player: {} as AppState['player'],
+    library: {} as AppState['library'],
+    discover: { catalogs: MOVIE_CATALOGS, results: [], isLoading: false, catalogsLoading: false },
+    addons: {
+      installed: [{
+        manifest: { catalogs: [{ type: 'movie' }, { type: 'series' }] },
+      }] as unknown as AppState['addons']['installed'],
+    },
+    settings: {},
+  } as unknown as AppState;
+}
+
+function Harness({ catalogFetchDelayMs }: { catalogFetchDelayMs: number }) {
+  const [state, setState] = useState<AppState>(baseState());
+
+  const onDispatch = (actionJson: string) => {
+    const action = JSON.parse(actionJson) as { type: string; contentType?: string };
+    if (action.type === 'discoverCatalogFiltersRequested') {
+      const forType = action.contentType;
+      setTimeout(() => {
+        setState((prev) => ({
+          ...prev,
+          discover: {
+            ...prev.discover,
+            catalogs: forType === 'series' ? SERIES_CATALOGS : MOVIE_CATALOGS,
+          },
+        }));
+      }, catalogFetchDelayMs);
+    }
+  };
+
+  return (
+    <DiscoverScreen
+      state={state}
+      onDispatch={onDispatch}
+      onNavigateDetail={() => {}}
+      onBack={() => {}}
+    />
+  );
+}
+
+function openPopoverMenu() {
+  return document.body.querySelector('.ui-popover') as HTMLElement;
+}
+
+async function switchToSeries(user: ReturnType<typeof userEvent.setup>) {
+  const typeDropdown = screen.getByText('Movie').closest('button')!;
+  await user.click(typeDropdown);
+  const menu = openPopoverMenu();
+  await user.click(within(menu).getByText('Series'));
+}
+
+describe('DiscoverScreen: switching content type', () => {
+  it('shows the series catalog once the async catalog fetch resolves, never leaving the dropdown stuck empty', async () => {
+    const user = userEvent.setup();
+    render(<Harness catalogFetchDelayMs={50} />);
+
+    await switchToSeries(user);
+
+    await waitFor(() => {
+      expect(screen.getByText('Cinemeta: Popular')).toBeInTheDocument();
+    });
+
+    const catalogDropdown = screen.getByText('Cinemeta: Popular').closest('button')!;
+    await user.click(catalogDropdown);
+    const menu = openPopoverMenu();
+    expect(within(menu).getByText('Cinemeta: Popular')).toBeInTheDocument();
+  });
+
+  it('never lets a stale movie catalog key survive the switch to Series (the actual bug)', async () => {
+    const user = userEvent.setup();
+    render(<Harness catalogFetchDelayMs={10} />);
+
+    await switchToSeries(user);
+
+    await waitFor(() => {
+      expect(screen.queryByText('No content found')).not.toBeInTheDocument();
+    });
+    expect(screen.getByText('Cinemeta: Popular')).toBeInTheDocument();
+  });
+});

src/screens/DiscoverScreen.tsx

@@ -44,7 +44,7 @@ function DiscoverScreenInner({ state, onDispatch, onNavigateDetail, initialGenre
   const isGridScrollingRef = useRef(false);
   const scrollIdleTimerRef = useRef<number | null>(null);
   const hoveredMetaRef = useRef<Meta | null>(null);
-  const catalogs = (discover.catalogs ?? []) as DiscoverCatalog[];
+  const catalogs = ((discover.catalogs ?? []) as DiscoverCatalog[]).filter((catalog) => catalog.type === contentType);
   const selectedCatalog = catalogs.find((catalog) => catalog.key === selectedCatalogKey) ?? null;
   const selectedExtra = selectedCatalog?.extras?.[0] ?? null;
   const key = cacheKey(selectedCatalog?.key ?? null, selectedExtra?.name ?? null, extraValue);

src/test/setup.ts

@@ -0,0 +1,9 @@
+import '@testing-library/jest-dom/vitest';
+
+class ResizeObserverStub {
+  observe() {}
+  unobserve() {}
+  disconnect() {}
+}
+
+window.ResizeObserver = ResizeObserverStub;

vitest.config.ts

@@ -0,0 +1,11 @@
+import { defineConfig } from 'vite';
+import react from '@vitejs/plugin-react';
+
+export default defineConfig({
+  plugins: [react()],
+  test: {
+    environment: 'jsdom',
+    globals: true,
+    setupFiles: ['./src/test/setup.ts'],
+  },
+});