HOW TO EFFECTIVELY DEBUG WHEN YOU NO LONGER UNDERSTAND THE CODE

Summary from the TLDR Dev newsletter

Three production investigations, a latency regression, a memory leak, and a kernel-level hang, show how to steer coding agents through unfamiliar systems using runtime evidence. The framework separates facts from hypotheses, compares failures with a control, and requires every proposed cause to satisfy all known constraints. Adversarial reviews should seek contradictions, and reproductions must match the real failure's signals before they can be trusted.