Erasure

Agents default to adding. This skill is the opposite discipline on every edit: when X becomes Y, finish deleting X and garbage-collect what that change made dead—without breaking behavior.

Scope. Files and symbols the task touches, plus artifacts those edits make obsolete. Do not expand the task to hunt removals. Repo-wide sweeps need an explicit ask.

Swap rule

When X becomes Y, fully deleting X is part of the task unless the user asked to keep it.