Fix external monitor brightness OSD

config/dot/quickshell/scripts/panama-osd

@@ -2,6 +2,8 @@
 
 set -u
 
+readonly PANAMA_OSD_SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+
 strict_delivery() {
     [[ ${PANAMA_OSD_STRICT:-false} == true || ${PANAMA_OSD_STRICT:-false} == 1 ]]
 }
@@ -67,18 +69,151 @@ adjust_microphone() {
     show_volume "$target" microphone
 }
 
+brightness_percent() {
+    local output="$1" percent
+    percent="$(awk -F, 'NR == 1 { value=$5; gsub(/%/, "", value); print value }' <<<"$output")"
+    [[ $percent =~ ^[0-9]+$ ]] || return 1
+    printf '%s\n' "$percent"
+}
+
+brightness_error() {
+    local detail="$1" label="External brightness unavailable"
+    if [[ $detail == *udev* || $detail == *accessible* || $detail == *permission* ]]; then
+        label="Brightness needs permission"
+    fi
+
+    show_message dialog-warning-symbolic "$label" || true
+    if command -v notify-send >/dev/null 2>&1; then
+        notify-send --app-name=Panama --icon=display-brightness-symbolic \
+            "Brightness unavailable" "$detail" >/dev/null 2>&1 || true
+    fi
+}
+
+discover_ddc_bus() {
+    local helper="$1" cache_file="$2" list_json focused selected error bus connector
+
+    command -v jq >/dev/null 2>&1 || {
+        brightness_error "jq is required to discover DDC/CI displays."
+        return 1
+    }
+
+    list_json="$("$helper" list 2>/dev/null)" || {
+        brightness_error "The external brightness helper could not inspect connected displays."
+        return 1
+    }
+    if ! jq -e 'type == "object" and (.displays | type == "array")' >/dev/null 2>&1 <<<"$list_json"; then
+        brightness_error "The external brightness helper returned invalid display information."
+        return 1
+    fi
+
+    error="$(jq -r '.error // empty' <<<"$list_json")"
+    if [[ -n $error ]]; then
+        brightness_error "$error"
+        return 1
+    fi
+
+    focused="$(hyprctl -j monitors 2>/dev/null \
+        | jq -r '.[] | select(.focused == true) | .name' 2>/dev/null \
+        | head -n1)"
+    selected="$(jq -r --arg connector "$focused" '
+        ([.displays[] | select(.connector == $connector)][0] // .displays[0] // empty)
+        | [.bus, .connector]
+        | @tsv
+    ' <<<"$list_json")"
+    IFS=$'\t' read -r bus connector <<<"$selected"
+    if [[ ! $bus =~ ^[0-9]+$ ]]; then
+        brightness_error "No connected monitor exposes DDC/CI brightness control."
+        return 1
+    fi
+
+    umask 077
+    printf '%s\t%s\n' "$bus" "$connector" >"$cache_file"
+    printf '%s\n' "$bus"
+}
+
+adjust_ddc_brightness() {
+    local action="$1" step="$2"
+    local helper="${PANAMA_OSD_BRIGHTNESS_HELPER:-$PANAMA_OSD_SCRIPT_DIR/panama-brightness}"
+    local runtime_dir="${PANAMA_OSD_RUNTIME_DIR:-${XDG_RUNTIME_DIR:-/tmp}/panama-osd-${UID}}"
+    local cache_file="$runtime_dir/brightness-bus" lock_file="$runtime_dir/brightness.lock"
+    local bus="" connector="" current target lock_fd
+
+    [[ -x $helper ]] || {
+        brightness_error "The external brightness helper is not installed."
+        return 0
+    }
+    mkdir -p "$runtime_dir" || return 0
+    chmod 700 "$runtime_dir" 2>/dev/null || true
+
+    exec {lock_fd}>"$lock_file" || return 0
+    # DDC transactions on one I2C bus cannot safely overlap. A short wait also
+    # sheds an excessive key-repeat backlog instead of replaying it seconds later.
+    flock -w 2 "$lock_fd" || return 0
+
+    if [[ -r $cache_file ]]; then
+        IFS=$'\t' read -r bus connector <"$cache_file" || true
+        [[ $bus =~ ^[0-9]+$ ]] || bus=""
+    fi
+
+    if [[ -n $bus ]]; then
+        current="$("$helper" get "$bus" 2>/dev/null)" || current=""
+        if [[ ! $current =~ ^[0-9]+$ ]]; then
+            : >"$cache_file"
+            bus=""
+        fi
+    fi
+
+    if [[ -z $bus ]]; then
+        bus="$(discover_ddc_bus "$helper" "$cache_file")" || return 0
+        current="$("$helper" get "$bus" 2>/dev/null)" || current=""
+    fi
+    if [[ ! $current =~ ^[0-9]+$ ]]; then
+        brightness_error "The selected monitor stopped responding over DDC/CI."
+        return 0
+    fi
+
+    if [[ $action == up ]]; then
+        target=$(( current + step ))
+    else
+        target=$(( current - step ))
+    fi
+    (( target > 100 )) && target=100
+    (( target < 0 )) && target=0
+
+    if ! "$helper" set "$bus" "$target" >/dev/null 2>&1; then
+        brightness_error "The selected monitor did not accept the brightness change."
+        return 0
+    fi
+    show_progress brightness "$target" "${target}%"
+}
+
 adjust_brightness() {
     local action="${1:-}" step="${2:-5}" output percent
+    [[ $step =~ ^[0-9]+$ ]] || {
+        printf 'Usage: panama-osd brightness up|down [step]\n' >&2
+        return 2
+    }
     case "$action" in
-        up) brightnessctl -e4 -n2 set "${step}%+" >/dev/null || return ;;
-        down) brightnessctl -e4 -n2 set "${step}%-" >/dev/null || return ;;
+        up|down) ;;
         *) printf 'Usage: panama-osd brightness up|down [step]\n' >&2; return 2 ;;
     esac
 
-    output="$(brightnessctl -m -c backlight 2>/dev/null)" || return 0
-    percent="$(awk -F, 'NR == 1 { value=$5; gsub(/%/, "", value); print value }' <<<"$output")"
-    [[ $percent =~ ^[0-9]+$ ]] || return 0
-    show_progress brightness "$percent" "${percent}%"
+    # Laptop panels expose a kernel backlight class and remain the fastest,
+    # most reliable path. Desktops fall through to DDC/CI monitor control.
+    output="$(brightnessctl -m -c backlight 2>/dev/null)" || output=""
+    if percent="$(brightness_percent "$output")"; then
+        if [[ $action == up ]]; then
+            brightnessctl -e4 -n2 -c backlight set "${step}%+" >/dev/null || return 0
+        else
+            brightnessctl -e4 -n2 -c backlight set "${step}%-" >/dev/null || return 0
+        fi
+        output="$(brightnessctl -m -c backlight 2>/dev/null)" || return 0
+        percent="$(brightness_percent "$output")" || return 0
+        show_progress brightness "$percent" "${percent}%"
+        return
+    fi
+
+    adjust_ddc_brightness "$action" "$step"
 }
 
 media_action() {