A solid reference guide for iOS file protection APIs that covers FileProtectionType options and when files are actually accessible versus encrypted. You'll want this when debugging those annoying "file not accessible" errors after a device locks, or when you need to make the right call between complete protection and allowing background access. It's been around since January 2026 with 945 GitHub stars and 180 installs, which suggests people find it genuinely useful. The skill covers the full range from iOS 4.0 basics through iOS 26 enhancements, and includes practical comparisons between file protection and Keychain approaches. Basically, it's the reference you keep open when implementing secure file storage so you don't have to context switch to Apple's docs constantly.
npx skills add https://github.com/charleswiltgen/axiom --skill axiom-file-protection-ref