characterization-test-scopinglisted

## Activation Contract Load this skill when a refactor plan runs at high/critical risk or when scoping work around characterization coverage, seams, and the test safety net. ## Hard Rules - Prefer characterization coverage before structural change. - Prioritize seam creation only when it reduces containment or rollback risk. - Keep executable work behavior-preserving; move redesigns and behavior changes to follow-up. - Require rollback-friendly increments and explicit containment rationale. - Tests must precede structural refactoring. - Keep characterization tests in a dedicated test class/file per unit (per `code-conventions`); they are a permanent regression net and never mix with intent-revealing unit tests. ## Decision Gates | Signal | Action | |---|---| | No tests or unclear behavior | Put characterization coverage first | | Hard-to-isolate dependency or long procedure | Recommend seams that improve testability or rollback safety | | Proposed work changes behavior or public API | Move it to follow-up | ## Execution Steps 1. Identify current behavior that must be locked down first. 2. List the smallest characterization slices that reduce regression risk fastest. 3. Highlight seam opportunities that enable isolation, fakes, or safer rollback. 4. Prefer backlog items that can be validated incrementally. 5. Keep speculative cleanup and redesign out of executable refactor-plan backlog. ## Effect Reasoning Choose what to characterize by tracing effects forward from eac