Stage 6c — Network Service Adapter

This chapter records the original single-primary-connection stage. The current simultaneous-transport snapshot is documented in Stage 6e.

Why this stage exists

Stage 6 had battery, volume, and brightness done. Network is next, and unlike volume/brightness it has a real, near-universal D-Bus service to key off — NetworkManager — same shape as UPower for battery.

Before designing anything, the actual property names and types were checked live against the FP5’s NetworkManager over D-Bus (busctl --system ...), since guessing D-Bus API details from memory is exactly what turned out wrong for zbus’s feature flags in stage 6a:

org.freedesktop.NetworkManager at /org/freedesktop/NetworkManager exposes PrimaryConnection (an object path, "/" when there is none) and PrimaryConnectionType (a string — "802-11-wireless" was the live value on the FP5’s wifi connection).
A wifi signal percentage takes a real walk: the ActiveConnection object’s Devices → that Device’s org.freedesktop.NetworkManager.Device.Wireless.ActiveAccessPoint → that AccessPoint’s Strength, a y (byte, 0–100) — confirmed 68 live, no scaling needed unlike UPower’s f64 percentage.
The FP5 also runs ModemManager (cellular capability exists), but pulling in cellular signal detail was scoped out of this stage, the same kind of cut stage 6b made for audio/brightness detail. Any primary connection type other than wifi/wired (including gsm/cdma) just reports as generically connected.

New crate: `patin-service-network`

Named by domain (network), not mechanism, since a future cellular addition via ModemManager would still belong under the same domain rather than forcing a rename.

#![allow(unused)]
fn main() {
pub enum NetworkSnapshot {
    Disconnected,
    Wired,
    Wifi { percentage: u8 },
    Other,
}
}

Provider::poll returns Option<NetworkSnapshot>, but unlike battery, None here means only “NetworkManager unreachable over D-Bus” — being reachable but disconnected is a real reading (Some(NetworkSnapshot::Disconnected)), not folded into None. This matches how BatterySnapshot always carries a real charging reading rather than conflating “no data” with “off”.

The wifi signal walk (wifi_strength) is a small private helper using ? short-circuiting across the three D-Bus hops; if any hop fails despite the connection type saying wireless (an edge case), it degrades to NetworkSnapshot::Other rather than panicking or failing the whole poll.

Cargo.toml reuses the exact same zbus = "=5.18.0" pin and feature list as patin-service-upower — already resolved in stage 6a, no new research needed. It compiled clean on the first try, which is what checking the live D-Bus API first was for.

Demo integration

examples/demo_bar/services.rs gained a fourth provider field and a format_network function ("NET 55%" for wifi, "NET ETH" for wired, "NET OFF" disconnected, "NET UP" otherwise). StatusSnapshot gained a network: Option<String> field.

examples/demo_bar/scene.rs needed the same mechanical extension the other three fields already had — a fourth optional row slot, joining only when Some, plus its damage-tracking branch in set_status and its Text draw command — the one part of this stage that touched scene.rs (6a/6b were additive only). Root Cargo.toml gained patin-service-network under [workspace] members and [dev-dependencies].

Verification

Verified on 30 July 2026:

$ cargo build -p patin-service-network
Finished, no errors (compiled clean on the first try)

$ cargo fmt --all -- --check
(no output after one auto-fix to a too-long line)

$ cargo test --workspace --all-targets
11 tests across 5 crates, all passed, including
  patin-service-network: 1 (poll_without_a_system_bus_returns_none)

$ cargo clippy --workspace --all-targets --all-features -- -D warnings
Finished, no warnings

$ cargo run --example demo_bar (timeout 5s, this sandbox: no NetworkManager)
demo_bar: status providers: battery=unavailable, volume=VOL MUTE, brightness=BRI 71%, network=unavailable
patin: connected; waiting for the compositor to configure the bar

Confirmed independently with busctl --system list | grep -i networkmanager that NetworkManager is genuinely absent here, so unavailable is the adapter degrading correctly.

$ mdbook build
 INFO Book building has started
 INFO Running the html backend
 INFO HTML book written to `/home/vdzee/proj/patin/book`

$ git diff --check
(no output, exit 0)

FP5 end-to-end confirmation

Same round-trip as 6a/6b: working tree copied over with tar piped over SSH, built natively (fast — zbus already cached), installed, and relaunched as a transient systemd user unit per the fp5-test-device memory:

demo_bar: status providers: battery=BAT 64%, volume=VOL 8%, brightness=BRI 40%, network=NET 69%
patin: connected; waiting for the compositor to configure the bar

NET 69% is close to the 68 read directly from the access point’s Strength property during the initial busctl probe (signal strength drifts slightly between reads) — the adapter reads the FP5’s real wifi connection correctly end to end.

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