Intercom emphasizes the importance of "heartbeat metrics" as a critical tool for assessing system reliability, especially given the complexity of modern platforms and the need for immediate customer impact detection. These metrics provide a direct indication of whether a product is fulfilling its core function, offering a clear and fast signal when customer experiences are affected, thus enabling swift action before customers even report issues. At Intercom, the central heartbeat metrics include the rate of new messages and replies, reflecting the system's ability to support essential communication functions. These metrics not only inform the company's service level agreements (SLAs) by defining what constitutes downtime but also guide automated responses to incidents, such as rolling back recent code changes when issues are detected. By tracking these vital signs, Intercom ensures that its systems remain aligned with customer needs, fostering trust and accountability.