feat(desktop): read gamepad battery from power_supply

BluetoothRow only read BluetoothDevice.battery, which is BlueZ's
org.bluez.Battery1. A gamepad never publishes that interface: a Sony pad
exposes its charge as a kernel power_supply instead, so the percentage never
appeared.

Read every power_supply whose name ends in a MAC on a 30s timer while
anything is connected, keyed by address. BlueZ still wins when it has a
value.

3 files changed, 81 insertions, 2 deletions

diff --git a/desktop/modules/bluetooth/BluetoothModule.qml b/desktop/modules/bluetooth/BluetoothModule.qml
index 4fd600f..6c4f587 100644
--- a/desktop/modules/bluetooth/BluetoothModule.qml
+++ b/desktop/modules/bluetooth/BluetoothModule.qml
@@ -33,6 +33,61 @@ Module {
 
     readonly property bool anyConnected: connectedDevices.length > 0
 
+    // Battery for devices BlueZ does not publish through org.bluez.Battery1.
+    // Gamepads are the case: the Sony pads expose their charge as a kernel
+    // power_supply rather than a BlueZ interface, so BluetoothDevice.battery
+    // reads nothing for them. The DualSense driver names the supply
+    // "ps-controller-battery-<mac>"; the parser takes any supply whose name
+    // ends in a MAC, so the separator ("-" here, "_" under hid-sony) and the
+    // driver do not matter. This map is keyed by lowercase MAC and holds 0-100.
+    property var batteryPct: ({})
+    function batteryFor(address) {
+        if (!address) return null;
+        const v = mod.batteryPct[address.toLowerCase()];
+        return v === undefined ? null : v;
+    }
+
+    function refreshBatteries() {
+        batProc.running = false;
+        batProc.running = true;
+    }
+
+    // Reads every power_supply once. A supply earns a line only when its name
+    // ends in "xx:xx:xx:xx:xx:xx", which excludes the system battery (BAT0)
+    // and AC adapter while catching the controller batteries. The MAC is the
+    // trailing 17 characters; the separator before it is not assumed.
+    property Process batProc: Process {
+        command: ["sh", "-c",
+            "for d in /sys/class/power_supply/*; do n=${d##*/}; " +
+            "case $n in *??:??:??:??:??:??) " +
+            "[ -r \"$d/capacity\" ] && printf '%s %s\\n' \"$n\" \"$(cat \"$d/capacity\")\";; " +
+            "esac; done"]
+        stdout: StdioCollector {
+            onStreamFinished: {
+                const map = {};
+                for (const line of text.trim().split("\n")) {
+                    const i = line.lastIndexOf(" ");
+                    if (i <= 0) continue;
+                    const pct = parseInt(line.slice(i + 1), 10);
+                    if (!isNaN(pct)) map[line.slice(0, i).slice(-17).toLowerCase()] = pct;
+                }
+                mod.batteryPct = map;
+            }
+        }
+    }
+
+    // ponytail: 30s poll, matches how slowly a gamepad charge moves. Move to a
+    // uevent watch only if a lagging percentage is ever noticed.
+    property Timer batTimer: Timer {
+        interval: 30000
+        repeat: true
+        running: mod.anyConnected
+        onTriggered: mod.refreshBatteries()
+    }
+
+    onAnyConnectedChanged: if (mod.anyConnected) mod.refreshBatteries()
+    Component.onCompleted: mod.refreshBatteries()
+
     // Null for the first ~2s, then filled. Safe navigation everywhere.
     icon: mod.adapter && mod.adapter.enabled ? "\uf293" : "\uf05e"
 
diff --git a/desktop/modules/bluetooth/BluetoothRow.qml b/desktop/modules/bluetooth/BluetoothRow.qml
index a7aecd0..297dc02 100644
--- a/desktop/modules/bluetooth/BluetoothRow.qml
+++ b/desktop/modules/bluetooth/BluetoothRow.qml
@@ -20,6 +20,14 @@ Rectangle {
     required property var bt
     required property var device
 
+    // BlueZ's org.bluez.Battery1 pushes a live value when the device reports
+    // one. A gamepad does not, so fall back to the module's power_supply map.
+    // Null means neither source knows, and the field stays hidden.
+    readonly property var battPct: {
+        if (row.device.batteryAvailable) return Math.round((row.device.battery ?? 0) * 100);
+        return row.bt.batteryFor(row.device.address);
+    }
+
     implicitHeight: col.implicitHeight + 16
     radius: 8
     color: device.connected ? Qt.alpha(Theme.accent, 0.10) : Qt.alpha(Theme.surface, 0.35)
@@ -49,8 +57,8 @@ Rectangle {
 
                 Text {
                     anchors.verticalCenter: parent.verticalCenter
-                    visible: row.device.batteryAvailable ?? false
-                    text: Math.round((row.device.battery ?? 0) * 100) + "%"
+                    visible: row.battPct !== null
+                    text: row.battPct + "%"
                     font { family: Theme.fontFamily; pixelSize: Theme.fontSize - 4 }
                     color: Theme.overlay
                 }
diff --git a/desktop/modules/bluetooth/README.md b/desktop/modules/bluetooth/README.md
index 2de634a..5a79060 100644
--- a/desktop/modules/bluetooth/README.md
+++ b/desktop/modules/bluetooth/README.md
@@ -10,6 +10,22 @@ then the connected devices, the paired ones, and anything found while
 scanning. A paired device offers Connect, Trust and Forget; an unpaired one
 offers Pair.
 
+## Battery has two sources
+
+The row shows a percentage when it can find one, from either of two places:
+
+- `BluetoothDevice.battery` / `batteryAvailable`, which is BlueZ's
+  `org.bluez.Battery1`. Audio devices push this live. Nothing to poll.
+- A kernel `power_supply`, read by the module on a 30s timer while anything is
+  connected. Gamepads are the reason: a Sony pad publishes no `Battery1`, it
+  exposes the charge as `/sys/class/power_supply/ps-controller-battery-<mac>`
+  (DualSense) or `sony_controller_battery_<mac>` (DS4). The module reads every
+  supply whose name ends in a MAC and keys it by the address, so the driver
+  and its separator do not matter.
+
+BlueZ wins when both exist. Neither source knowing the device leaves the field
+empty, never a zero.
+
 ## Pairing is the one shell-out
 
 Quickshell ships no BlueZ pairing agent and no generic D-Bus module, so a