Implement a rewrite

A rewrite is riskier than a refactor because behavior is permitted to change — so an unintended change hides exactly where an intended one is allowed. The discipline forces the change onto two provable surfaces: the delta (every behavior meant to change) and the preserved non-delta (everything else). The delta is the contract; anything not on it must survive untouched. This guide adds the rewrite discipline on top of the base implement-task rules. These are conventions the review packet inspects — nothing enforces them at edit time.

Plan the transformation first — the workspace's change plan covers baseline, waves, and rollback; this guide is the execution half. If your task moves no observable behavior, it is a refactor; if only the implementation API moves while behavior holds, it is a migration; if it adds capability that did not exist, it is a feature. Relabel rather than proceed under the wrong discipline.

Rules