# Lesson 1 complete: spectrum mostly in, document vs revival not yet

Learner finished lesson 1. Treat as known: same-realm nested detach → `structuredClone()`; intended shared nested refs → shallow copy; large binary ownership → transfer. Missed B (REST `application/json` needs `JSON.stringify` — a document, not a JS clone) and D (domain class + methods + schema version needs a custom serializer). Likely over-applied structured clone as the “correct copy” everywhere. Next ZPD: type matrix (keep / flatten / throw) so “still JS, not a document, not a live class” is visible, then retrieve B and D again.