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Status Providers

Battery, volume, brightness, and network are each an optional, opt-in toolkit crate implementing patin::service::Provider (see Architecture), not code inside the patin library or a demo-only fixture. examples/demo_bar/services.rs composes battery, volume, and network into one StatusSnapshot for its row layout — that composition, and the row’s dynamic membership/damage behavior, remains the demo’s own job. A missing provider does not prevent the example from starting.

Battery

crates/patin-service-upower’s BatteryProvider (see Stage 6a) reads UPower’s synthetic DisplayDevice over D-Bus — the aggregate device UPower maintains specifically for status bars — via zbus’s blocking API, fetching the Percentage and State properties. It does not depend on battery names such as BAT0 or on a hardware model. A missing system bus or UPower service returns None.

The demo renders the percentage as the fill level of a battery outline. Low battery uses a warning color and charging uses the Patin accent; no percentage or name is drawn.

Volume

Linux audio systems do not expose one universal standard D-Bus volume interface, so crates/patin-service-volume’s VolumeProvider (see Stage 6b) shells out instead:

  1. wpctl get-volume @DEFAULT_AUDIO_SINK@;
  2. pactl get-sink-volume @DEFAULT_SINK@ plus get-sink-mute.

This supports a native PipeWire default sink and the common PulseAudio compatibility service. Failure of both commands returns None. The demo maps the percentage to zero through three sound bars; mute replaces them with a warning-colored strike.

Brightness

There is no portable D-Bus property to read the current backlight level (systemd-logind only exposes a SetBrightness method, not a readable one), so crates/patin-service-brightness’s BacklightProvider reads Linux’s documented /sys/class/backlight ABI directly: it discovers entries, reads brightness and max_brightness, and returns a percentage. It does not assume a driver or panel name. A missing or invalid backlight entry returns None. The adapter remains available to other compositions, but the current demo bar deliberately does not instantiate it.

Network

crates/patin-service-network’s NetworkProvider (see Stage 6e) reads every active NetworkManager connection over D-Bus. A wifi connection additionally walks ActiveConnection.Devices → Device.Wireless.ActiveAccessPoint → AccessPoint.Strength for a signal percentage; ethernet sets the independent wired field.

The same provider discovers modem objects through ModemManager’s standard ObjectManager interface. A registered modem contributes its independent SignalQuality percentage. This represents simultaneous wifi and SIM service without treating VPN or loopback connections as physical transports.

The demo draws a wifi fan, a linked-node icon for wired, and cellular strength bars. Only active/registered transport icons receive slots.

Polling

The demo’s Shell::update polls its three providers once per platform update. Unchanged values produce no redraw; changed values damage only their component. A provider’s snapshot appearing or disappearing changes row membership and damages the full bar.

examples/demo_bar/services.rs preserves the adapters’ structured snapshot types instead of formatting strings. examples/demo_bar/scene.rs owns all icon choices and builds them from existing Fill and RoundedFill commands, so neither the toolkit nor service crates prescribe a visual style or require an icon font.

All four adapters are poll-based today, reusing the same once-per-second tick. A future push-only service (notifications, media) will need a way to wake the platform event loop from a background thread between ticks — that plumbing does not exist yet.