Changing One Prompt Can Affect 50 Others — I Built a Prompt Dependency Graph to Find What Needs Retesting

Changing a single shared prompt can create an unpredictable "blast radius," making it difficult to know which of the many downstream prompts now require re-testing. A prompt dependency graph solves this by mapping these complex relationships to identify the exact set of components that need re-evaluation. This approach distinguishes between all "reachable" components and the smaller "candidate" set that truly depends on the edited section, significantly narrowing the scope of required testing. By applying principles from software engineering, this dependency tracking provides a structural answer to what needs re-verification, preventing costly downstream failures.