fix(bot): explicit assertSessions before group send

groupMetadata alone wasn't enough — Baileys won't establish individual
libsignal sessions lazily during sendMessage, so the first send to a
freshly-paired group fails per-participant. Cast to the internal
assertSessions(jids, force=true) and call it on every participant before
attempting to send.

apps/bot/src/whatsapp/sender.ts

@@ -1,19 +1,33 @@
 import type { WASocket } from "@whiskeysockets/baileys";
 
+// Internal Baileys method used to fetch pre-key bundles and establish individual
+// libsignal sessions for a list of JIDs. Not part of the public type, but it's
+// the only way to avoid "No sessions" on the first group send after pairing.
+type SocketWithAssertSessions = WASocket & {
+  assertSessions?: (jids: string[], force: boolean) => Promise<boolean>;
+};
+
+async function ensureSessionsForGroup(socket: WASocket, groupJid: string): Promise<void> {
+  const metadata = await socket.groupMetadata(groupJid);
+  const participantJids = metadata.participants.map((p) => p.id);
+  const internal = socket as SocketWithAssertSessions;
+  if (typeof internal.assertSessions === "function") {
+    await internal.assertSessions(participantJids, true);
+  }
+}
+
 export async function sendTextToGroup(
   socket: WASocket,
   groupJid: string,
   text: string,
 ): Promise<{ messageId: string | undefined }> {
-  // Force-fetch group metadata so Baileys populates its internal participant
+  // Establish individual signal sessions with every participant before sending
-  // map and triggers libsignal session establishment for any unknown member.
+  // — group sends fan out per participant and need a per-participant session,
-  // Without this, the first send to a freshly-paired group fails with
+  // but Baileys won't establish them lazily inside sendMessage.
-  // "No sessions" from libsignal-node.
   try {
-    await socket.groupMetadata(groupJid);
+    await ensureSessionsForGroup(socket, groupJid);
   } catch {
-    // If metadata fetch itself fails we still try the send — sendMessage will
+    // Non-fatal: fall through and let sendMessage surface its error
-    // surface a clearer error than the metadata layer.
   }
 
   try {
@@ -24,7 +38,12 @@ export async function sendTextToGroup(
     // 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));
+      await new Promise((resolve) => setTimeout(resolve, 2000));
+      try {
+        await ensureSessionsForGroup(socket, groupJid);
+      } catch {
+        // ignore
+      }
       const result = await socket.sendMessage(groupJid, { text });
       return { messageId: result?.key?.id ?? undefined };
     }