func (c *CatalogClient) DataAccess(req proto.Message) (grpc.BidiStreamingClient[pb.DataAccessRequest, pb.DataAccessResponse], error) {
    c.streamInitOnce.Do(func() {
        ctx := c.ctx
        if c.hmacConfig != nil {
            var err error
            ctx, err = c.prepareHMACContext(c.ctx, req)
            if err != nil {
                c.streamInitErr = fmt.Errorf("failed to prepare HMAC context: %w", err)
                return
            }
        }

        stream, err := c.protoClient.DataAccess(ctx)
        if err != nil {
            c.streamInitErr = err
            return
        }
        c.cachedStream = stream
    })

    return c.cachedStream, c.streamInitErr
}

// Initialize KMS client once
func (c *CatalogClient) getKMSClient(ctx context.Context) (kmsClient, error) {
    c.kmsClientOnce.Do(func() {
        cfg, err := config.LoadDefaultConfig(ctx, config.WithRegion(c.hmacConfig.KeyRegion))
        if err != nil {
            c.kmsClientErr = fmt.Errorf("failed to load AWS config: %w", err)
            return
        }
        c.kmsClient = kms.NewFromConfig(cfg)
    })
    return c.kmsClient, c.kmsClientErr
}