Built **tmux-player-ctl.py**, a single-file, pure-Python TUI that pops up inside tmux and gives you full keyboard control over any MPRIS media player (spotifyd, mpv, mpd, VLC, Chrome, Firefox, etc.) using `playerctl`.


When starting to write it I considered various options like bash, rust, go, etc... but Python was the most suitable for what this needed to do and where it needed to go (most Linux distros have python already).


What worked well on from the Python side:

- Heavy but careful use of the `subprocess` module — both synchronous calls and asynchronous background processes (I run a metadata follower subprocess that pushes real-time updates without blocking the TUI).
- **380+ tests** covering metadata parsing round-trips, player state management, UI ANSI/Unicode width craziness, optimistic UI updates + rollback, signal handling, and full integration flows with real `playerctl` commands.
- Clean architecture with dataclasses, clear separation between config, player abstraction, metadata tracking, and the display layer.
- Signal handling (SIGINT/SIGTERM) so the subprocesses and tmux popup shut down cleanly.
- Zero external Python library dependencies beyond the stdlib.

It’s intentionally tiny and fast: launches in a compact tmux popup (`-w72 -h12`), shows live track info + progress bar + color-coded volume, supports seek, shuffle, loop modes, and Tab to switch between running players.

Typical one-liner:
```bash
tmux display-popup -B -w72 -h12 -E "tmux-player-ctl.py"
```


GitHub: https://github.com/kesor/tmux-player-ctl


I’d especially love feedback from people who regularly wrangle `subprocess`, build CLI/TUI tools, or obsess over testing: any patterns I missed, better ways to handle long-running playerctl followers, or testing gotchas you’ve run into? Especially if you have tips on how to deal with ambiguous-width emoji symbols that have different widths in different fonts.

tmux-player-ctl.py - a controller for MPRIS media players (spotifyd, mpv, mpd, vlc, chrome, ...)