Separate rollout activation gates from preparation dependencies

General delivery-method inference, observed 2026-09-09: an observation window should gate activation, not automatically postpone all preparation for the next phase. While shadow traffic accumulates, prepare disabled suppression code, reader tests, staging fixtures, reconciliation, and the explicit promotion decision; revise them if evidence changes. Predeclare duration, sample, failure conditions, and completion criteria so additional monitoring does not silently become a new completion gate. Distinguish core rollout completion from optional flag retirement and unrelated hardening. This is a scheduling recommendation, not permission to bypass validation or deployment approval, and not an estimate of human labor.