feat: integrate analytics and fragment receipt improvements

gateway/internal/inbound/delivery.go

@@ -142,8 +142,13 @@ func pushReceiptWithResult(event DownstreamReceipt, allowRecovery bool) (Downstr
 			when = parsed
 		}
 	}
+	// Every inbound CMPP_SUBMIT fragment receives its own SUBMIT_RESP Msg_Id.
+	// Rebuild that exact client Msg_Id from the fragment's original Sequence_Id;
+	// the live session stores only connection state and must not collapse a long
+	// message back to the first fragment's Msg_Id.
+	receiptMessageID := downstreamReceiptMessageID(event, session)
 	receipt := &cmpp.CmppReceiptPkt{
-		MsgId:          session.gatewayMsgID,
+		MsgId:          receiptMessageID,
 		Stat:           stat,
 		SubmitTime:     when.Format("0601021504"),
 		DoneTime:       when.Format("0601021504"),
@@ -154,10 +159,20 @@ func pushReceiptWithResult(event DownstreamReceipt, allowRecovery bool) (Downstr
 	if err != nil {
 		return DownstreamSendResult{}, err
 	}
-	deliver := downstreamDeliverPacket(session, session.gatewayMsgID, session.srcID, defaultString(event.PhoneNumber, session.phoneNumber), 0, 1, string(receiptBytes))
+	deliver := downstreamDeliverPacket(session, receiptMessageID, session.srcID, defaultString(event.PhoneNumber, session.phoneNumber), 0, 1, string(receiptBytes))
 	return sendDownstream(session, deliver, event.DeliveryID)
 }
 
+func downstreamReceiptMessageID(event DownstreamReceipt, session *downstreamSession) uint64 {
+	if event.SubmitSequenceID != 0 {
+		return messageIDFrom(defaultString(event.SubmitGroupMessageID, event.MessageID), event.SubmitSequenceID)
+	}
+	if session == nil {
+		return 0
+	}
+	return session.gatewayMsgID
+}
+
 func findReceiptSession(messageID string, account string) *downstreamSession {
 	downstreamRegistry.RLock()
 	defer downstreamRegistry.RUnlock()