Defines an abstract base class for NFC protocol support with standardized render and unlock helper interfaces. Enables clean separation of protocol-specific logic from application/UI code. Demonstrates dependency inversion principle where high-level application logic depends on abstractions rather than concrete protocol implementations. Multiple protocols (ISO14443, Felica, EMV, etc.) implement this interface, making it highly reusable across different NFC applications.

Implements a dynamic list-based UI component for building settings and configuration screens. Features standardized alloc/free lifecycle, callback-driven interactions, and separation of visual presentation from data model. Used consistently across power settings, clock settings, input settings, and other configuration applications. Eliminates boilerplate for creating settings screens while providing consistent user experience and validation patterns.

Provides a scene-based navigation framework using macro-driven scene definition and standardized enter/event/exit handlers. Enables consistent application flow across all modules (NFC, Sub-GHz, Infrared, etc.) with automatic view switching and resource management. The pattern reduces boilerplate for screen navigation while ensuring proper cleanup and initialization. Demonstrates effective use of macros to create maintainable, standardized application structure.

Defines a unified storage API that abstracts internal and external storage mechanisms with automatic fallback. Features clean error handling, versioned storage support, and seamless SD card/internal storage switching. Used throughout the firmware for settings persistence, application data, and file operations. Demonstrates excellent API design that hides implementation complexity while providing reliable storage semantics.

Implements versioned persistent storage for structured data with automatic migration support. Solves the common problem of settings schema evolution while maintaining backward compatibility. Used by power settings, input services, Bluetooth settings, and other subsystems requiring persistent configuration. Shows foresight in handling data evolution without breaking existing user configurations.

Provides a sequenced feedback system for LED, vibration, and sound notifications. Enables consistent user feedback across applications through simple API calls. Used in NFC operations, Sub-GHz transactions, power events, and system alerts. Demonstrates attention to user experience in embedded systems where feedback channels are limited but critical for usability.

Core event loop implementation providing timers, flags, and message queues for embedded real-time systems. Forms the foundation for inter-component communication throughout the firmware. Demonstrates skill in creating lightweight, efficient primitives suitable for resource-constrained environments while maintaining flexibility for complex application logic.