# Phase Gate Checklist
At each phase boundary, Codex must verify:
- [ ] source-of-truth ownership unchanged or explicitly updated;
- [ ] no duplicate codec/profile/shape types;
- [ ] no hidden fallback;
- [ ] no silent shape coercion;
- [ ] no app integration;
- [ ] no governor/runtime authority added;
- [ ] receipts exist for material operations;
- [ ] exact fallback remains available;
- [ ] tests were added/updated for new behavior;
- [ ] validation outputs recorded;
- [ ] rollback path remains clear.