This is the comprehensive data persistence skill you'd reach for anytime you're touching databases, storage, or serialization in Swift. It covers the full stack: SwiftData, Core Data, GRDB, SQLiteData, CloudKit sync, iCloud Drive, Codable, and Keychain. The decision tree is genuinely helpful for navigating between frameworks, and the automated auditors catch real production disasters like unsafe migrations and thread confinement violations. Particularly strong on migration safety across all database layers, which is where most apps eventually burn themselves. If you're storing anything more complex than UserDefaults, this has the reference you need. The cross-references to axiom-security for encryption and keychain work keep the scope clean.
npx skills add https://github.com/charleswiltgen/axiom --skill axiom-data