Activation Contract

Load this skill when a refactor plan runs at deep depth 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.

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