Design cleanup — make the tree read as designed-this-way

Why this skill exists

When a design decision changes mid-work — a different approach, a renamed concept, a replaced mechanism — the branch tends to keep fossils of the abandoned design: dead branches, shims that only served the old path, names shaped by the old concept, comments narrating the change, tests pinning behavior that no longer matters. The diff may show the journey; the final tree must not. This skill hunts those fossils down and rewrites the result as if the current design had been there from the beginning.

Step 1 — Establish the decision

State the decision as one line: "the design is X; the abandoned approach was Y". Take it from the user or the session context. If it is not stated, reconstruct it from the branch diff and commit messages, then confirm the one-line summary with the user before making sweeping edits — cleanup against a misread decision destroys correct code.