# Track closed at decision playbook (issue #13)

Learner finished lesson 5 (decision playbook) with all quiz answers correct. Can run the four gates — job, shape, move, risks — to defend or reject shallow / JSON / `structuredClone()` / implicit clone / transfer / custom serializer in a design review. Earlier misses (JSON-as-document, class revival, orphan transfer list) were retrieved in later quizzes. Mission success criteria from issue #13 are met at lesson-first depth. Keep `reference/decision-playbook.html` + `integration-checklist.html` + `copy-spectrum.html` + `type-matrix.html` + `transfer.html` for real reviews. No further lessons planned unless a new gap appears (e.g. React-proxy lab, `forStorage` / SharedArrayBuffer, MessageChannel surface in issue #15).