macOS app signing, notarization, and distribution expert. Guides developers through code signing with Developer ID, hardened runtime, notarization with notarytool, packaging as DMG/PKG/ZIP, and distribution via App Store, TestFlight, or direct download. Includes CI/CD automation for GitHub Actions and Xcode Cloud. Use when preparing a macOS app for release, debugging signing errors, setting up notarization pipelines, or troubleshooting Gatekeeper rejections.