prevent writing battery json when there has been no change, filter out devices with unknown state

Helpers/Battery.qml

@@ -21,7 +21,7 @@ Singleton {
 	readonly property bool ready: UPower.displayDevice.ready
 	readonly property real timeToEmpty: UPower.displayDevice.timeToEmpty
 	readonly property real timeToFull: UPower.displayDevice.timeToFull
-	readonly property list<UPowerDevice> upowerDevices: UPower.devices.values
+	readonly property list<UPowerDevice> upowerDevices: UPower.devices.values.filter(d => d.state !== UPowerDeviceState.Unknown)
 
 	function getColors(percentage: real, state: string): var {
 		if (state === "charging" || state === "full" || state === "recharging")

cli/src/zshell/subcommands/battery.py

@@ -229,11 +229,15 @@ def daemon(
 
 	typer.echo(f"Polling every {interval}s, writing to {out}")
 
+	last_payload = None
 	try:
 		while running:
 			try:
 				results = poll_once()
-				_write_json_atomic(out, results)
+				payload = [asdict(r) for r in results]
+				if payload != last_payload:
+					_write_json_atomic(out, results)
+					last_payload = payload
 			except RuntimeError as e:
 				typer.echo(f"error: {e}", err=True)
 				raise typer.Exit(code=1) from None