feat(api): add phone number registration endpoint and update related logic

pkg/whatsapp/manager.go

@@ -51,7 +51,10 @@ func (m *Manager) Connect(ctx context.Context, cfg config.WhatsAppConfig) error
 	// Factory pattern based on type
 	switch cfg.Type {
 	case "business-api":
-		client, err = businessapi.NewClient(cfg, m.eventBus, m.mediaConfig)
+		onWABAResolved := func(accountID, wabaID string) {
+			m.updateWABAInConfig(accountID, wabaID)
+		}
+		client, err = businessapi.NewClient(cfg, m.eventBus, m.mediaConfig, onWABAResolved)
 	case "whatsmeow", "":
 		// Create callback for phone number updates
 		onPhoneUpdate := func(accountID, phoneNumber string) {
@@ -187,6 +190,32 @@ func (m *Manager) GetClient(id string) (Client, bool) {
 	return client, exists
 }
 
+// updateWABAInConfig stores the resolved WABA ID back into the in-memory config and syncs to DB/file
+func (m *Manager) updateWABAInConfig(accountID, wabaID string) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	for i := range m.config.WhatsApp {
+		if m.config.WhatsApp[i].ID == accountID {
+			if m.config.WhatsApp[i].BusinessAPI == nil {
+				return
+			}
+			if m.config.WhatsApp[i].BusinessAPI.WABAId == wabaID {
+				return // already up to date
+			}
+			m.config.WhatsApp[i].BusinessAPI.WABAId = wabaID
+			logging.Info("Updated WABA ID in config", "account_id", accountID, "waba_id", wabaID)
+
+			if m.onConfigUpdate != nil {
+				if err := m.onConfigUpdate(m.config); err != nil {
+					logging.Error("Failed to save config after WABA ID update", "account_id", accountID, "error", err)
+				}
+			}
+			break
+		}
+	}
+}
+
 // updatePhoneNumberInConfig updates the phone number for an account in config and saves it
 func (m *Manager) updatePhoneNumberInConfig(accountID, phoneNumber string) {
 	m.mu.Lock()