perf: split stats app bundles by route

stats/src/lib/app-lazy-loading.test.ts

@@ -0,0 +1,38 @@
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import path from 'node:path';
+import test from 'node:test';
+import { fileURLToPath } from 'node:url';
+
+const APP_PATH = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '../App.tsx');
+
+test('App lazy-loads non-overview tabs and detail surfaces behind Suspense boundaries', () => {
+  const source = fs.readFileSync(APP_PATH, 'utf8');
+
+  assert.match(source, /\bSuspense\b/, 'expected Suspense boundary in App');
+  assert.match(source, /lazy\(\(\) =>\s*import\('\.\/components\/anime\/AnimeTab'\)/);
+  assert.match(source, /lazy\(\(\) =>\s*import\('\.\/components\/trends\/TrendsTab'\)/);
+  assert.match(source, /lazy\(\(\) =>\s*import\('\.\/components\/vocabulary\/VocabularyTab'\)/);
+  assert.match(source, /lazy\(\(\) =>\s*import\('\.\/components\/sessions\/SessionsTab'\)/);
+  assert.match(source, /lazy\(\(\) =>\s*import\('\.\/components\/library\/MediaDetailView'\)/);
+  assert.match(source, /lazy\(\(\) =>\s*import\('\.\/components\/vocabulary\/WordDetailPanel'\)/);
+
+  assert.doesNotMatch(source, /import \{ AnimeTab \} from '\.\/components\/anime\/AnimeTab';/);
+  assert.doesNotMatch(source, /import \{ TrendsTab \} from '\.\/components\/trends\/TrendsTab';/);
+  assert.doesNotMatch(
+    source,
+    /import \{ VocabularyTab \} from '\.\/components\/vocabulary\/VocabularyTab';/,
+  );
+  assert.doesNotMatch(
+    source,
+    /import \{ SessionsTab \} from '\.\/components\/sessions\/SessionsTab';/,
+  );
+  assert.doesNotMatch(
+    source,
+    /import \{ MediaDetailView \} from '\.\/components\/library\/MediaDetailView';/,
+  );
+  assert.doesNotMatch(
+    source,
+    /import \{ WordDetailPanel \} from '\.\/components\/vocabulary\/WordDetailPanel';/,
+  );
+});