A developer builds a Lambda function that processes clickstream records from an Amazon Kinesis Data Stream. Traffic is low and sporadic — sometimes only a few records arrive per minute. The current event source mapping invokes the function very frequently with tiny batches, increasing invocation overhead and cost. The team wants Lambda to accumulate records for up to 30 seconds (or until 500 records arrive) before invoking the function. Which event source mapping setting should the developer configure?