# Track closed at decision playbook (issue #12)

Learner finished lesson 4 (decision playbook) with all quiz answers correct. Can run the four gates — job, wire, truth, ship risks — to defend or reject `BroadcastChannel` in a design review (vs SharedWorker, sessionStorage, SW clients, storage-event bus). Mission success criteria from issue #12 are met at lesson-first depth (external primaries optional). Keep `reference/decision-playbook.html` + `integration-checklist.html` + `core-api.html` for real reviews. No further lessons planned unless a new gap appears (e.g. deeper two-tab lab, polyfill/long-tail Safari deep dive).