Explore the development of a record/replay debugger for macOS in this 42-minute conference talk from Recon 2023. Delve into the macOS-specific internals required for creating such a tool, understand why existing tools cannot be simply ported, and examine the challenges involved in building this type of debugger from scratch. Learn about the concept of "time travel" debugging, which allows developers to record and replay program execution traces, facilitating easier diagnosis of hard-to-reproduce bugs. Gain insights from speakers Nick Gregory and Pete Markowsky, both experienced software engineers with backgrounds in low-level systems, exploitation, and operating system security, as they share their expertise on this groundbreaking project for the macOS platform.