validating-blast-radius

Map change impact radius by tracing what breaks when modifying functions, types, or APIs to quantify migration effort before proposing changes. Use when: (1) proposing to change function signatures, rename exports, or modify public APIs before checking what calls them, (2) a change is characterized as safe without verifying how many callers exist and where they are, (3) shared types or components are about to be modified without analyzing type propagation to distant code, (4) a proposed change lacks a list of specific files and locations that would be affected.