Data export and restore

In an app with no server, the export file is the only copy of a user's data that can outlive the phone, and restore is the only recovery path they can invoke themselves. Both are dangerous in opposite directions: a lossy export silently becomes someone's backup, and a half-applied restore destroys the very database it was meant to protect. This skill governs the portable artifacts; the on-device VACUUM INTO snapshot and WAL rules belong to persistence-drift.

Depth lives in references/formats-and-encoding.md (CSV/JSON/PDF mechanics) and references/restore-and-merge-policy.md (validation ladder, merge strategies).

Non-negotiable rules