Implements a configuration system with typed ConfigItem objects, validation functions, and JSON persistence. Each config item supports type checking, range validation, custom check functions, and temporary overrides. The singleton _Config class provides attribute-style access and automatic saving. This module is self-contained and could be extracted as a reusable configuration library for any CLI application.

Defines BasePlayer and CmdPlayer abstract classes that provide a clean interface for implementing different media players. Handles playback flow (play, next, previous, stop), stream selection, progress display, MPRIS metadata updates, and error handling. The CmdPlayer subclass manages subprocess-based players with argument generation and status parsing. This abstraction allows easy addition of new players (see players/mpv.py, players/mplayer.py, players/vlc.py) and demonstrates good separation of concerns.

Provides a @command decorator that registers functions as CLI commands with associated regex patterns and tab-completion hints. Commands are stored as namedtuples in a global list and matched against user input in the main loop. This pattern enables clean separation of command logic and easy extensibility. The decorator also integrates with a CommandCompleter for readline tab completion. This module is a lightweight command routing framework that could be reused in other CLI applications.