Index: src/routes/posts.js
===================================================================
--- src/routes/posts.js	(revision 667fb411773ddfae0500a3a6b0e9807d8d999e43)
+++ src/routes/posts.js	(revision dc41bef1bc3ebefe5d5dc1cfd1be3316e09cfc26)
@@ -1122,4 +1122,7 @@
     const _apBase = (process.env.PUBLIC_BASE_URL || `${req.protocol}://${req.get('host')}`).replace(/\/+$/, '');
     fediverse = ActivityPubService.getInteractions(post.id, _apBase, site);
+    // Stale-while-revalidate: render from cache now; refresh the remote thread in the
+    // background (TTL-gated, non-blocking) so undelivered replies-to-replies fill in next view.
+    if (res.locals.apEnabled !== false) ActivityPubService.maybeCrawlThread(post.id);
   } catch { /* non-fatal */ }
   // Owner/admin of this site may reply back to a fediverse interaction.