fix(bot): pre-fetch group metadata + retry sender on libsignal race

First send to a group after pairing fails with libsignal SessionError
"No sessions" because Baileys hasn't yet established encryption sessions
with all participants. Force-fetch group metadata before sendMessage so
Baileys populates its participant map; if the first send still races,
retry once after a 1.5s delay.

apps/bot/src/whatsapp/sender.ts

@@ -5,6 +5,29 @@ export async function sendTextToGroup(
   groupJid: string,
   text: string,
 ): Promise<{ messageId: string | undefined }> {
+  // Force-fetch group metadata so Baileys populates its internal participant
+  // map and triggers libsignal session establishment for any unknown member.
+  // Without this, the first send to a freshly-paired group fails with
+  // "No sessions" from libsignal-node.
+  try {
+    await socket.groupMetadata(groupJid);
+  } catch {
+    // If metadata fetch itself fails we still try the send — sendMessage will
+    // surface a clearer error than the metadata layer.
+  }
+
+  try {
+    const result = await socket.sendMessage(groupJid, { text });
+    return { messageId: result?.key?.id ?? undefined };
+  } catch (err) {
+    // libsignal session establishment can race on the very first send. Retry
+    // once after a brief delay before giving up.
+    const message = (err as Error)?.message ?? "";
+    if (message.includes("No sessions")) {
+      await new Promise((resolve) => setTimeout(resolve, 1500));
       const result = await socket.sendMessage(groupJid, { text });
       return { messageId: result?.key?.id ?? undefined };
     }
+    throw err;
+  }
+}