--- broker.original
+++ M11-cursor
@@ -6488,7 +6488,7 @@
             `SELECT m.seq FROM messages m JOIN message_threads mt ON mt.message=m.id WHERE m.id=? AND m.business=? AND mt.thread IN (${placeholders})`,
             identifier(a.after), s.business, ...tids,
           )?.seq;
-          if (after === undefined) fail('message-not-found');
+          if (after === undefined) after = 0;
         }
         // At most one row per instance joins a group; one lookahead row completes the last page.
         const rows = this.#store.all(