What problem does it solve? Non-trivial work done by hand is slow, inconsistent, and impossible for a reviewer to re-verify without redoing it. This Skill enforces a working principle: for any non-trivial edits, migrations, analyses, or checks, build the tool that does or proves the work so the result is a rerunnable artifact. ## Core Features & Use Cases - Lever-First Pattern: Do the first unit by hand to learn the recipe, then build a codemod, script, or generator and prove it by diffing against the hand-done version. - Deterministic Over Fan-Out: Prefer a single deterministic script that processes every unit in one pass instead of delegating hand-applied changes to subagents. - Delegate Skill Contracts: When fan-out is necessary, write the recipe, verification contract, and do-not-touch fences as a skill outside the delegates' write scope. - Use Case: When migrating hundreds of files to a new API, write a codemod, rerun it on the first migrated file, diff against the manual version, and commit the codemod alongside the changes. ## Quick Start Apply the build-the-lever principle to this migration by writing a rerunnable codemod instead of editing each file by hand.
