fix(power-widget): Power widget charging icon/label stuck after unplugging AC

[heyssh]

Fix: Power widget charging icon/label stuck after unplugging AC

Problem

In the Power bar-widget, when the charger cable was unplugged, the
battery icon and the status label (Charging) would not update —
they stayed stuck in the charging state indefinitely, even though the
system itself (upower --monitor) correctly reported the AC-unplug
event instantly.

Root cause

Two separate issues, found and fixed in sequence:

1. Unreliable reactivity source. The icon/label were originally
   read via plain JS functions (batteryIcon(), modeLabel()) called
   directly inside QML Text bindings. This made their re-evaluation
   depend on QML's automatic dependency tracking working transitively
   across function calls into an imported .js module — a pattern
   that isn't guaranteed to be as reliable as a plain readonly property binding.

2. Wrong UPower source property (the real cause). Charging state
   was derived from UPower.onBattery — a global, aggregate property
   on the UPower daemon. This property is known to lag or fail to
   notify promptly on some hardware. This is a well-documented pitfall
   in other UPower consumers (e.g. an equivalent bug was reported and
   fixed in cosmic-applets, where the fix was to switch from the
   global on_battery flag to the per-device state property).

   The correct, reliable source is the per-device state
   (UPowerDevice.state, e.g. UPowerDeviceState.Discharging /
   Charging / FullyCharged / PendingCharge), which is what
   upower --monitor itself reads and reports instantly.

Fix

• Replaced the two JS functions with readonly property bindings
  (batteryIconText, modeLabelText) so the icon/label are
  guaranteed to re-evaluate on every relevant property change.
• Changed discharging (and by extension charging) to be computed
  from UPowerDevice.state === UPowerDeviceState.Discharging instead
  of the global UPower.onBattery flag.

Known remaining behavior (not a bug)

There can still be a short delay (typically a couple of seconds)
between the physical plug/unplug event and the widget updating. This
comes from the underlying kernel → upowerd → DBus signal chain
(embedded-controller/ACPI reporting latency), which is outside the
widget's control and is consistent with the delay seen in
upower --monitor itself and in other desktop environments (GNOME,
KDE, etc.).

Testing

• Verified with udevadm monitor --udev --subsystem-match=power_supply
  and upower -i <device> --monitor that the underlying system
  reports the state change, and confirmed the widget now reflects it
  (icon + label) without requiring the panel to be open.

[Copilot]

Pull request overview

This PR fixes the Power panel widget getting stuck showing the charging icon/label after AC unplug events by switching charge detection from the global UPower.onBattery flag to the per-device UPower.displayDevice.state, and by moving icon/label computation into readonly property bindings to improve QML reactivity.

Tip

If you aren't ready for review, convert to a draft PR.
Click "Convert to draft" or run gh pr ready --undo.
Click "Ready for review" or run gh pr ready to reengage.

Changes:

• Replace batteryIcon() / modeLabel() QML functions with readonly property bindings (batteryIconText, modeLabelText).
• Compute discharging from UPower.displayDevice.state instead of UPower.onBattery.
• Update consumers to use the new bound properties for icon/label rendering.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.