feat: add /og contextual share-image route

src/routes/index.ts

@@ -4,6 +4,7 @@ import rss from './rss';
 import alerts from './alerts';
 import redirector from './redirector';
 import devcards from './devcards';
+import shareImages from './shareImages';
 import privateRoutes from './private';
 import whoami from './whoami';
 import notifications from './notifications';
@@ -49,6 +50,7 @@ export default async function (fastify: FastifyInstance): Promise<void> {
   fastify.register(redirector, { prefix: '/r' });
   fastify.register(emailTracking, { prefix: '/em/t' });
   fastify.register(devcards, { prefix: '/devcards' });
+  fastify.register(shareImages, { prefix: '/og' });
   if (process.env.ENABLE_PRIVATE_ROUTES === 'true') {
     fastify.register(privateRoutes, { prefix: '/p' });
   }

src/routes/shareImages.ts

@@ -0,0 +1,54 @@
+import { FastifyInstance, FastifyReply } from 'fastify';
+import { retryFetch } from '../integrations/retry';
+import { WEBAPP_MAGIC_IMAGE_PREFIX } from '../config';
+
+// Contextual Open Graph share images. Mirrors the devcard v2 approach: render a
+// real webapp page and screenshot it via the scraper — no Satori. Each type
+// maps to /image-generator/share/<type>/<id> on the webapp, captured at the
+// `#screenshot_wrapper` element (sized to 1200×630 by the page).
+const ALLOWED_TYPES = new Set([
+  'posts',
+  'comments',
+  'sources',
+  'squads',
+  'profile',
+  'tags',
+  'invite',
+  'plus',
+]);
+
+export default async function (fastify: FastifyInstance): Promise<void> {
+  fastify.get<{
+    Params: { type: string; name: string };
+    Querystring: { userid?: string };
+  }>('/:type/:name', async (req, res): Promise<FastifyReply> => {
+    const { type } = req.params;
+    const [id, format] = req.params.name.split('.');
+
+    if (!ALLOWED_TYPES.has(type) || format !== 'png' || !id) {
+      return res.status(404).send();
+    }
+
+    const url = new URL(
+      `${WEBAPP_MAGIC_IMAGE_PREFIX}/share/${type}/${encodeURIComponent(id)}`,
+      process.env.COMMENTS_PREFIX,
+    );
+    // Forward the sharer for post-share attribution ("{name} shared").
+    if (req.query?.userid) {
+      url.searchParams.set('userid', req.query.userid);
+    }
+
+    const response = await retryFetch(`${process.env.SCRAPER_URL}/screenshot`, {
+      method: 'POST',
+      body: JSON.stringify({ url, selector: '#screenshot_wrapper' }),
+      headers: { 'content-type': 'application/json' },
+    });
+
+    return res
+      .type(response.headers.get('content-type')!)
+      .header('cross-origin-opener-policy', 'cross-origin')
+      .header('cross-origin-resource-policy', 'cross-origin')
+      .header('cache-control', 'public, max-age=3600, s-maxage=3600')
+      .send(await response.buffer());
+  });
+}