Use SendTaskSuccess with an AWS SDK

    /// <summary>
    /// Indicate that the Step Functions task, indicated by the
    /// task token, has completed successfully.
    /// </summary>
    /// <param name="taskToken">Identifies the task.</param>
    /// <param name="taskResponse">The response received from executing the task.</param>
    /// <returns>A Boolean value indicating the success of the action.</returns>
    public async Task<bool> SendTaskSuccessAsync(string taskToken, string taskResponse)
    {
        var response = await _amazonStepFunctions.SendTaskSuccessAsync(new SendTaskSuccessRequest
        { TaskToken = taskToken, Output = taskResponse });

        return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
    }

    public static void sendTaskSuccess(SfnClient sfnClient, String token, String json) {
        try {
            SendTaskSuccessRequest successRequest = SendTaskSuccessRequest.builder()
                    .taskToken(token)
                    .output(json)
                    .build();

            sfnClient.sendTaskSuccess(successRequest);

        } catch (SfnException e) {
            System.err.println(e.awsErrorDetails().errorMessage());
            System.exit(1);
        }
    }

suspend fun sendTaskSuccess(
    token: String?,
    json: String?,
) {
    val successRequest =
        SendTaskSuccessRequest {
            taskToken = token
            output = json
        }
    SfnClient { region = "us-east-1" }.use { sfnClient ->
        sfnClient.sendTaskSuccess(successRequest)
    }
}

class Activity:
    """Encapsulates Step Function activity actions."""

    def __init__(self, stepfunctions_client):
        """
        :param stepfunctions_client: A Boto3 Step Functions client.
        """
        self.stepfunctions_client = stepfunctions_client


    def send_task_success(self, task_token, task_response):
        """
        Sends a success response to a waiting activity step. A state machine with an
        activity step waits for the activity to get task data and then respond with
        either success or failure before it resumes processing.

        :param task_token: The token associated with the task. This is included in the
                           response to the get_activity_task action and must be sent
                           without modification.
        :param task_response: The response data from the activity. This data is
                              received and processed by the state machine.
        """
        try:
            self.stepfunctions_client.send_task_success(
                taskToken=task_token, output=task_response
            )
        except ClientError as err:
            logger.error(
                "Couldn't send task success. Here's why: %s: %s",
                err.response["Error"]["Code"],
                err.response["Error"]["Message"],
            )
            raise