Added brightnessctl on IS_DESKTOP=0 and configured waybar to include a power profiles daemon switch if the service is available

02-system/10-packages.sh

@@ -15,3 +15,8 @@ case "$GPU" in
   intel) pac_file packages/graphics-intel.txt ;;
   *)     info "no GPU group for GPU='$GPU'" ;;
 esac
+
+# Laptop only: backlight control. Desktop monitors (DP/HDMI) don't expose a
+# /sys/class/backlight device — they use DDC/CI (ddcutil) — so brightnessctl has
+# nothing to control there and the XF86MonBrightness* binds just no-op.
+[ "$IS_DESKTOP" = 0 ] && pacman -S --needed --noconfirm brightnessctl

03-user/dotfiles/.config/waybar/config.jsonc

@@ -23,6 +23,7 @@
         "cpu",
 	"memory",
         "battery",
+        "custom/power_profile",
         "custom/studio-sound",
 	"bluetooth",
 	"wireplumber",
@@ -195,6 +196,16 @@
     "return-type": "json"
   },
 
+"custom/power_profile": {
+        "format": "{}",
+        "exec": "~/.config/waybar/scripts/power-profile.sh",
+        "on-click": "~/.config/waybar/scripts/power-profile.sh toggle",
+        "interval": "once",
+        "signal": 9,
+        "return-type": "json",
+        "tooltip": true
+    },
+
 "custom/studio-sound": {
         "format": "{}",
         "exec": "~/.config/waybar/scripts/studio-sound.py",

03-user/dotfiles/.config/waybar/scripts/power-profile.sh

@@ -0,0 +1,71 @@
+#!/bin/bash
+
+# Waybar power-profiles-daemon module.
+#   default : print the current profile as JSON (empty -> Waybar hides the module)
+#   toggle  : cycle to the next available profile, then signal Waybar to refresh
+#
+# Wired as interval:"once" + signal in config.jsonc, so the script runs exactly
+# once at Waybar startup and thereafter only when we signal it on click. On a
+# desktop the single startup run hits an unavailable PPD, prints empty, and the
+# module stays hidden forever with no recurring cost.
+#
+# Availability keys off the systemd unit being *enabled* rather than
+# `powerprofilesctl get` succeeding: PPD is D-Bus-activatable and desktop CPUs
+# expose EPP too, so `get` would answer on a desktop as well. The repo only
+# enables the service on laptops (IS_DESKTOP=0), so `is-enabled` is the honest
+# "is this a laptop that uses PPD" signal.
+
+SERVICE=power-profiles-daemon.service
+
+available() {
+    command -v powerprofilesctl >/dev/null 2>&1 || return 1
+    systemctl is-enabled "$SERVICE" >/dev/null 2>&1
+}
+
+# Available profile names in the order PPD lists them (power-saver … performance).
+# Profile header lines are just "name:" (optionally "* name:" for the active one);
+# every other line (Driver:, Degraded:, …) has text after the colon.
+profiles() {
+    powerprofilesctl list 2>/dev/null | sed -nE 's/^[[:space:]]*\*?[[:space:]]*([a-z-]+):[[:space:]]*$/\1/p'
+}
+
+# FontAwesome glyphs (Nerd Font): f0e7 bolt, f6ad yin-yang, f06c leaf, f011 power.
+icon() {
+    case "$1" in
+        performance) printf '' ;;
+        balanced)    printf '' ;;
+        power-saver) printf '' ;;
+        *)           printf '' ;;   # power symbol, fallback
+    esac
+}
+
+cycle() {
+    mapfile -t list < <(profiles)
+    [ "${#list[@]}" -eq 0 ] && exit 0
+    cur=$(powerprofilesctl get 2>/dev/null)
+    next=0
+    for i in "${!list[@]}"; do
+        if [ "${list[$i]}" = "$cur" ]; then
+            next=$(( (i + 1) % ${#list[@]} ))
+            break
+        fi
+    done
+    powerprofilesctl set "${list[$next]}"
+    pkill -SIGRTMIN+9 waybar
+}
+
+output() {
+    if ! available; then
+        printf '{"text":""}\n'
+        exit 0
+    fi
+    cur=$(powerprofilesctl get 2>/dev/null)
+    [ -z "$cur" ] && { printf '{"text":""}\n'; exit 0; }
+    printf '{"text":"%s","tooltip":"Power profile: %s\\nClick to cycle","class":"%s"}\n' \
+        "$(icon "$cur")" "$cur" "$cur"
+}
+
+case "$1" in
+    toggle|cycle) cycle ;;
+    *)            output ;;
+esac

03-user/dotfiles/.config/waybar/style.css

@@ -137,6 +137,7 @@ tooltip {
     color: #a6e3a1;
     border-left: 0px;
     border-right: 0px;
+    min-width: 20px;
 }
 
 #window {