docs(readme): document distro install path and demote NixOS to optional aside

README.md

@@ -9,33 +9,6 @@ No existing SomaFM client is used: the station list, playlists, song history,
 audio control, spectrum visualiser and MPRIS service are all implemented here from
 the public SomaFM endpoints and open protocols.
 
-```
-▄▀▀▀ ▄▀▀▄ █▄ ▄█ ▄▀▀▄           SOMA FM RADIO                     14:32:07
-▀▀▀▄ █  █ █ █ █ █▀▀█           LISTENER SUPPORTED              Sat 15 Nov
-▄▄▄▀ ▀▄▄▀ █   █ █  █           SAN FRANCISCO                     vol  70%
-● PLAYING   Groove Salad  ·  Jens Buchert — Rauschebart
-┌ STATIONS ───────────────┐┌ ON AIR ────────────────────────────────────┐
-│ ★ ▶ Groove Salad   1.9k ││  ▄▄▄▄▄▄▄▄  ▄▄▄▄▄▄▄▄  GROOVE SALAD ● PLAYING│
-│   ▶ Drone Zone      812 ││  ▀▀▀▀▀▀▀▀  ▀▀▀▀▀▀▀▀  A nicely chilled plate│
-│     Secret Agent    420 ││                                            │
-│     Indie Pop Rocks 901 ││  NOW PLAYING  12s ago                      │
-│     …                   ││  Jens Buchert                              │
-│                         ││  Rauschebart                               │
-│                         ││  Gravity    dj Rusty Hodge                 │
-│                         ││  ♪ 1.9k listeners · mp3 · 128k             │
-│                         ││                                            │
-│                         ││  LAST PLAYED                               │
-│                         ││  14:29  Alex Cortiz — Room 505             │
-│                         ││  14:24  Tosca — Amber November             │
-└─────────────────────────┘└────────────────────────────────────────────┘
-┌ SPECTRUM · MIRROR · SYNC ─────────────────────────────────────────────┐
-│                   ▁▃▅▇█▇▅▃▁        ▂▄▆█▆▄▂                            │
-│        ▁▂▄▆██████████████████▆▄▂▁▂▄▆█████████▆▄▂▁                     │
-│        ▀▄▂▁▂▄▆██████████████████▆▄▂▁▂▄▆█████████▆▄▂▁                  │
-└───────────────────────────────────────────────────────────────────────┘
-space pause · ↑↓ station · enter tune · +/- vol · f ★ · / filter · ? help
-```
-
 ## Features
 
 - **Live spectrum analyser** — 72 log-spaced bands with peak caps, a moving
@@ -71,41 +44,77 @@ space pause · ↑↓ station · enter tune · +/- vol · f ★ · / filter · ?
 
 ## Requirements
 
-Python **3.10+**, plus the tools below. This is a minimum, not a pin: there
+`somafm-tui` is a normal Python application: there is nothing to compile and
-is no `.python-version`, and `uv` can install a compatible interpreter if your
+no distro-specific packaging. It runs on any Linux distribution with Python
-distro ships something older. `shell.nix` provides everything inside an
+**3.10+** and a few command-line audio tools on `$PATH`.
-**FHS environment** (needed because uv installs manylinux wheels such as
-NumPy, which expect `libstdc++.so.6` in the standard FHS paths):
 
-| tool     | why                                                     |
+| tool | why |
-| -------- | ------------------------------------------------------- |
+| ---- | --- |
-| python3  | runtime (CPython 3.10 or newer; no exact version pin)   |
+| `python3` | runtime (3.10 or newer; no exact version pin) |
-| uv       | installs **all** Python dependencies (see `pyproject.toml`) |
+| [`uv`](https://docs.astral.sh/uv/) | creates the venv and installs every Python dependency from `uv.lock` |
-| mpv      | playback + JSON IPC control                              |
+| `mpv` | playback and JSON IPC control |
-| ffmpeg   | muted stream decode (fallback analyser)                  |
+| `ffmpeg` | muted stream decode for the fallback analyser |
-| pulseaudio | `parec`/`pactl` for the synced monitor capture (works with PipeWire) |
+| `parec` / `pactl` | synced monitor capture for the spectrum (`pulseaudio-utils`; works with PipeWire) |
-| dbus     | session bus for MPRIS (`playerctl` included for testing) |
+| D-Bus session bus | MPRIS desktop media integration (`playerctl` is handy for testing) |
+
+Install these with your package manager. Names are usually:
+
+```bash
+# Debian / Ubuntu
+sudo apt install python3 mpv ffmpeg pulseaudio-utils dbus playerctl
+
+# Fedora (enable RPM Fusion for ffmpeg if needed)
+sudo dnf install python3 mpv ffmpeg pulseaudio-utils dbus-tools playerctl
+
+# Arch / Manjaro
+sudo pacman -S python mpv ffmpeg libpulse dbus playerctl
+
+# openSUSE
+sudo zypper install python3 mpv ffmpeg pulseaudio-utils dbus-1-tools playerctl
+```
+
+For other distributions, install the equivalents. On a headless machine you
+can skip the audio/D-Bus tools and use `--no-audio` for a UI-only demo, though
+the synced spectrum needs `parec`/`pactl`.
+
+Install `uv` once with the official installer:
+
+```bash
+curl -LsSf https://astral.sh/uv/install.sh | sh
+```
+
+`pipx install uv`, `brew install uv`, or a distro package also work. If your
+distro's Python is older than 3.10, let uv manage one: `uv python install 3.12`.
 
 Terminal image rendering uses [Pillow](https://python-pillow.org/) and is
 implemented directly (Kitty TGP + iTerm2 OSC 1337) — no terminal probing.
 
 ## Run
 
-```bash
+From the repository root, sync the environment and start the app:
-nix-shell            # enters the FHS dev shell
-uv sync
-uv run somafm-tui
-```
-
-If you used an older `shell.nix` before, recreate the venv once so it picks up
-the Nix-provided Python:
 
 ```bash
-rm -rf .venv && uv sync
+uv sync              # create .venv and install exactly what uv.lock pins
+uv run somafm-tui    # run inside that environment
 ```
 
-> FHS shell.nix files do not support `nix-shell --run "..."`. Enter the shell
+You do **not** need to activate the venv. `uv run` uses `.venv` automatically,
-> interactively and run commands there.
+and re-syncs it first if `pyproject.toml` or `uv.lock` changed. If you prefer a
+traditional shell, run `source .venv/bin/activate` and then `somafm-tui`.
+
+### Keeping the uv environment in sync
+
+`uv sync` is the command to remember. It is incremental, safe to re-run, and
+should be run after pulling changes, switching branches, or editing
+`pyproject.toml`:
+
+```bash
+uv sync                  # make .venv match uv.lock
+uv sync --frozen         # strict: fail if uv.lock is out of date, never rewrite it
+uv lock --upgrade        # refresh uv.lock to the newest allowed versions
+uv sync --upgrade        # upgrade dependencies and sync .venv in one step
+rm -rf .venv && uv sync  # last resort if the venv was built by an older Python
+```
 
 Useful flags:
 
@@ -195,14 +204,6 @@ containers, …) MPRIS is skipped and the status bar shows `mpris off`.
 
 ## Notes / troubleshooting
 
-- **NixOS: `libstdc++.so.6: cannot open shared object file`** — this is NumPy's
-  manylinux wheel looking for the C++ runtime. `shell.nix` now uses
-  `pkgs.buildFHSEnv` and installs `stdenv.cc.cc.lib`, so `nix-shell` puts you in
-  an FHS root where the wheel loads. If the error persists, your `.venv` was
-  built against a different Python: `rm -rf .venv && uv sync`.
-- **`bwrap: No permissions to create a new namespace`** — FHS shells need
-  unprivileged user namespaces. They are enabled by default on NixOS; inside a
-  locked-down container you may need to run the app on the host instead.
 - **Artwork shows the mosaic?** Real images are auto-enabled for Kitty,
   iTerm2 and WezTerm. Force a protocol with `SOMAFM_IMAGES=tgp` (Kitty/TGP) or
   `SOMAFM_IMAGES=iterm2` (iTerm2/WezTerm); `SOMAFM_IMAGES=0` forces the ANSI
@@ -210,9 +211,10 @@ containers, …) MPRIS is skipped and the status bar shows `mpris off`.
   `set -g allow-passthrough on`); iTerm2/WezTerm inside tmux default to the
   mosaic. Images are cached under `~/.cache/somafm-tui/artwork`.
 - **Clock shows UTC?** The clock and song history use the system zone from
-  `/etc/localtime`; a non-UTC `TZ` overrides it. `nix-shell` can inherit a
+  `/etc/localtime`; a non-UTC `TZ` overrides it. A container or dev shell can
-  build-time `TZ=UTC`, which the app deliberately ignores. In a container, bind
+  inherit a build-time `TZ=UTC`, which the app deliberately ignores; bind the
-  the host's `/etc/localtime` or set e.g. `TZ=Europe/Berlin`.
+  host's `/etc/localtime` or set e.g. `TZ=Europe/Berlin` in the shell that
+  launches the app.
 - **MPRIS says off/error?** No session bus. Run from your desktop session
   (the shell profile picks up `$XDG_RUNTIME_DIR/bus`). `dbus-run-session -- uv
   run somafm-tui` starts a private bus for testing, but desktop widgets won't
@@ -238,6 +240,28 @@ containers, …) MPRIS is skipped and the status bar shows `mpris off`.
   demo).
 - SomaFM is listener-supported: if you enjoy it, [donate](https://somafm.com/support/).
 
+## NixOS (optional aside)
+
+None of the above needs Nix. If you *are* on NixOS, `shell.nix` wraps the same
+`uv sync` / `uv run` workflow in an FHS environment, because uv installs
+manylinux wheels such as NumPy that expect `libstdc++.so.6` in the usual
+`/usr/lib` paths:
+
+```bash
+nix-shell            # enter the FHS dev shell
+uv sync
+uv run somafm-tui
+```
+
+- If you see `libstdc++.so.6: cannot open shared object file`, make sure you
+  are inside `nix-shell`, then recreate the venv once with
+  `rm -rf .venv && uv sync`.
+- `nix-shell --run "..."` does not work with FHS `shell.nix` files; enter the
+  shell interactively and run commands there.
+- FHS shells need unprivileged user namespaces. `bwrap: No permissions to
+  create a new namespace` means they are disabled (for example in a locked-down
+  container); run the app on the host instead.
+
 ## Licence
 
 WTFPL — Do What The Fuck You Want To Public License, Version 2. See