Cap /app/<name> meta descriptions at 150 characters (#3698)

The app shell fed the row's full description into <meta name=
"description">, og:description and twitter:description. Long
descriptions now collapse whitespace and cut at a word boundary with an
ellipsis, never exceeding 150 characters.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

src/backend/controllers/homepage/HomepageController.test.ts

@@ -278,6 +278,47 @@ describe('HomepageController GET /app/:name', () => {
         expect(html).toContain('Cool App');
     });
 
+    it('caps description, og:description and twitter:description at 150 chars', async () => {
+        const { userId } = await makeUser();
+        const name = `long-${Math.random().toString(36).slice(2, 10)}`;
+        const longDescription =
+            'This drawing app has brushes, layers, filters and more. '.repeat(
+                8,
+            );
+        await server.stores.app.create(
+            {
+                name,
+                title: 'Wordy App',
+                description: longDescription,
+                index_url: `https://example.com/${name}/`,
+            },
+            { ownerUserId: userId },
+        );
+
+        const { res, captured } = makeRes();
+        await callRoute(
+            'get',
+            '/app/:name',
+            makeReq({ params: { name }, path: `/app/${name}` }),
+            res,
+        );
+
+        const html = String(captured.body);
+        for (const tag of [
+            'name="description"',
+            'property="og:description"',
+            'name="twitter:description"',
+        ]) {
+            const match = new RegExp(`${tag} content="([^"]*)"`).exec(html);
+            expect(match, `no ${tag} tag`).toBeTruthy();
+            const content = match![1];
+            expect(content.length).toBeLessThanOrEqual(150);
+            expect(content.endsWith('…')).toBe(true);
+            // Cut at a word boundary, not mid-word.
+            expect(longDescription).toContain(content.slice(0, -1));
+        }
+    });
+
     it('does not leak a private app index_url or owner id to an anonymous visitor', async () => {
         const { userId } = await makeUser();
         const name = `priv-${Math.random().toString(36).slice(2, 10)}`;

src/backend/controllers/homepage/HomepageController.ts

@@ -28,6 +28,23 @@ import type {
     LaunchOptions,
 } from '../../services/homepage/PuterHomepageService';
 
+/** Longest description/og:description/twitter:description on `/app/<name>`. */
+export const APP_META_DESCRIPTION_MAX = 150;
+
+/**
+ * App descriptions can run long; search snippets and social cards want a
+ * short blurb. Collapses whitespace, then cuts at a word boundary with an
+ * ellipsis so the result never exceeds `APP_META_DESCRIPTION_MAX`.
+ */
+export function appMetaDescription(text: string): string {
+    const clean = text.replace(/\s+/g, ' ').trim();
+    if (clean.length <= APP_META_DESCRIPTION_MAX) return clean;
+    const head = clean.slice(0, APP_META_DESCRIPTION_MAX - 1);
+    const wordEnd = head.lastIndexOf(' ');
+    const cut = wordEnd > 0 ? head.slice(0, wordEnd) : head;
+    return `${cut.replace(/[\s,;:.!?…—-]+$/, '')}…`;
+}
+
 /**
  * Routes that render the Puter GUI shell, plus a catch-all static fallback
  * under `<gui_assets_root>/src` for non-dist/src paths (images, fonts, lib
@@ -114,10 +131,15 @@ export class HomepageController extends PuterController {
                 // through the apps driver before launching, and that read is
                 // where the entitlement gate and hosted-backing guard run.
                 const clientApp = toAppShellView(app);
+                // Feeds <meta name="description">, og:description and
+                // twitter:description; scrapers truncate long blurbs anyway.
+                const description = appMetaDescription(
+                    String(app.description ?? ''),
+                );
                 await sendShell(req, res, {
                     title: String(app.title ?? name),
-                    description: String(app.description ?? ''),
-                    short_description: String(app.description ?? ''),
+                    description,
+                    short_description: description,
                     icon: typeof app.icon === 'string' ? app.icon : undefined,
                     social_media_image:
                         typeof metadata.social_image === 'string'