Set default volume and brightness at login

Add three `systemd` user units that reset
volume, screen brightness, and keyboard backlight,
so that every session starts from a known state.

Values come from ~/.config/environment.d/50-defaults.conf,
and can be overridden per machine via an untracked 90-local.conf

.config/environment.d/50-defaults.conf

@@ -0,0 +1,19 @@
+# Session defaults, read by `systemd --user` at login
+#
+# Applied by:
+#  - set-brightness-default.service
+#  - set-keyboard-brightness-default.service
+#  - set-volume-default.service
+#
+# For machine-local overrides create an untracked
+# ~/.config/environment.d/90-local.conf instead
+# and repeat only the keys you want to change
+#
+# Apply with: `systemctl --user daemon-reload`,
+#              then log out and back in
+#
+# Verify with: `systemctl --user show-environment`
+
+DEFAULT_BRIGHTNESS=30
+DEFAULT_KEYBOARD_BRIGHTNESS=50
+DEFAULT_VOLUME=30

.config/environment.d/README.md

@@ -0,0 +1,6 @@
+# Session Environment Defaults
+
+This folder contains environment variables
+    read by `systemd --user` at login.
+
+Machine-local overrides go into an untracked `90-local.conf`.

.config/systemd/user/set-brightness-default.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=Set default screen brightness
+After=graphical-session.target
+ConditionPathExistsGlob=/sys/class/backlight/*
+PartOf=graphical-session.target
+
+[Service]
+Type=oneshot
+ExecStart=%h/.local/bin/set-brightness-default
+TimeoutStartSec=30
+
+[Install]
+WantedBy=graphical-session.target

.config/systemd/user/set-keyboard-brightness-default.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=Set default keyboard backlight brightness
+After=graphical-session.target
+PartOf=graphical-session.target
+
+[Service]
+Type=oneshot
+ExecStart=%h/.local/bin/set-keyboard-brightness-default
+TimeoutStartSec=30
+
+[Install]
+WantedBy=graphical-session.target

.config/systemd/user/set-volume-default.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=Set default output volume
+After=wireplumber.service
+PartOf=graphical-session.target
+Wants=wireplumber.service
+
+[Service]
+Type=oneshot
+ExecStart=%h/.local/bin/set-volume-default
+TimeoutStartSec=30
+
+[Install]
+WantedBy=graphical-session.target

.local/bin/dotfiles-install

@@ -176,6 +176,9 @@ fi
 if systemctl --user daemon-reload 2>/dev/null; then
     systemctl --user enable gnome-restore.service
     systemctl --user enable night-light-reset.timer
+    systemctl --user enable set-brightness-default.service
+    systemctl --user enable set-keyboard-brightness-default.service
+    systemctl --user enable set-volume-default.service
     systemctl --user enable xcape.service
 else
     echo "WARN: no systemd user session, units not enabled" >&2

.local/bin/set-brightness-default

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+set -eu
+
+
+# Loaded from ~/.config/environment.d/50-defaults.conf or a local override
+BRIGHTNESS="${DEFAULT_BRIGHTNESS:?unset, check ~/.config/environment.d/}"
+
+
+gdbus wait --session --timeout 10 org.gnome.SettingsDaemon.Power
+
+gdbus call --session \
+    --dest org.gnome.SettingsDaemon.Power \
+    --object-path /org/gnome/SettingsDaemon/Power \
+    --method org.freedesktop.DBus.Properties.Set \
+    org.gnome.SettingsDaemon.Power.Screen Brightness "<int32 $BRIGHTNESS>" \
+    >/dev/null
+
+
+echo "Set screen brightness to $BRIGHTNESS"

.local/bin/set-keyboard-brightness-default

@@ -0,0 +1,47 @@
+#!/bin/sh
+
+set -eu
+
+
+# Loaded from ~/.config/environment.d/50-defaults.conf or a local override
+BRIGHTNESS="${DEFAULT_KEYBOARD_BRIGHTNESS:?unset, check ~/.config/environment.d/}"
+
+
+# Nothing to do on machines without a keyboard backlight
+KBD_DEVICE=
+for led in /sys/class/leds/*kbd_backlight*; do
+    [ -e "$led" ] || break
+    KBD_DEVICE=$led
+    break
+done
+
+if [ -z "$KBD_DEVICE" ]; then
+    echo "No keyboard backlight, skipping"
+    exit 0
+fi
+
+
+kbd_set() {
+    gdbus call --session \
+        --dest org.gnome.SettingsDaemon.Power \
+        --object-path /org/gnome/SettingsDaemon/Power \
+        --method org.freedesktop.DBus.Properties.Set \
+        org.gnome.SettingsDaemon.Power.Keyboard Brightness "<int32 $BRIGHTNESS>" \
+        >/dev/null
+}
+
+
+gdbus wait --session --timeout 10 org.gnome.SettingsDaemon.Power
+
+
+# `gsd-power` owns its bus name before it has probed the keyboard
+# backlight, so at login the first write may silently be discarded
+kbd_set
+
+if [ "$(cat "$KBD_DEVICE/brightness")" = "0" ]; then
+    sleep 3
+    kbd_set
+fi
+
+
+echo "Set keyboard brightness to $BRIGHTNESS"

.local/bin/set-volume-default

@@ -0,0 +1,25 @@
+#!/bin/sh
+
+set -eu
+
+
+# Loaded from ~/.config/environment.d/50-defaults.conf or a local override
+VOLUME="${DEFAULT_VOLUME:?unset, check ~/.config/environment.d/}"
+
+
+i=0
+while ! wpctl status >/dev/null 2>&1; do
+    i=$((i + 1))
+    if [ "$i" -ge 20 ]; then
+      echo "no PipeWire sink after 10s" >&2
+      exit 1
+    fi
+    sleep 0.5
+done
+
+
+wpctl set-volume @DEFAULT_AUDIO_SINK@ "$VOLUME%"
+wpctl set-mute @DEFAULT_AUDIO_SINK@ 0
+
+
+echo "Set volume to $VOLUME%"