feat(notify): add --silent flag, volume knob, and level sound files

The touchpad toggle's notification was too loud, and the eight notify sounds varied by ~13 dB in RMS loudness — bug and fail came out two to three times louder than info or security.

I added a --silent flag to notify (shows the popup, plays no sound) and a NOTIFY_VOLUME knob (paplay scale, default 65536) so the master level can drop without re-encoding. toggle-touchpad now passes --silent on both enable and disable. normalize-notify-sounds.sh measures each .ogg and shifts it to a uniform -31 dB mean. It writes through the file instead of mv-ing over it, so the stow symlinks survive when the script runs against the live sound dir. I re-encoded all eight sounds to the new level.

Tests: a new tests/notify suite (12 tests) covers --silent, the volume knob, flag composition, and the error paths.

1 files changed, 48 insertions, 0 deletions

diff --git a/scripts/normalize-notify-sounds.sh b/scripts/normalize-notify-sounds.sh
new file mode 100755
index 0000000..52c1d36
--- /dev/null
+++ b/scripts/normalize-notify-sounds.sh
@@ -0,0 +1,48 @@
+#!/bin/bash
+# Normalize notify sound files to a uniform RMS loudness so every notification
+# plays at the same perceived level. Re-encodes each file in place (ogg -> ogg).
+# Run once after adding or changing a sound in the notify set.
+#
+# Each file is measured with ffmpeg's volumedetect, then shifted by a constant
+# gain so its mean (RMS) volume lands on TARGET_DB. Peaks sit near 0 dB already,
+# so the spread was all in the RMS; leveling the RMS makes them match by ear.
+#
+# Usage:
+#   normalize-notify-sounds.sh [SOUND_DIR]
+#
+# Environment:
+#   TARGET_DB   Target mean (RMS) loudness in dB. Default -31 (gentle + even).
+#               Lower is quieter. The notify script's NOTIFY_VOLUME knob tunes
+#               the master level at playback time without re-encoding.
+
+set -euo pipefail
+
+SOUND_DIR="${1:-$HOME/.local/share/sounds/notify}"
+TARGET_DB="${TARGET_DB:--31}"
+
+command -v ffmpeg  >/dev/null || { echo "ffmpeg not found"  >&2; exit 1; }
+command -v ffprobe >/dev/null || { echo "ffprobe not found" >&2; exit 1; }
+
+shopt -s nullglob
+files=("$SOUND_DIR"/*.ogg)
+(( ${#files[@]} )) || { echo "No .ogg files in $SOUND_DIR" >&2; exit 1; }
+
+for f in "${files[@]}"; do
+    mean=$(ffmpeg -hide_banner -nostats -i "$f" -af volumedetect -f null /dev/null 2>&1 \
+           | grep -oP 'mean_volume: \K[-0-9.]+' || true)
+    if [ -z "$mean" ]; then
+        echo "skip (could not measure): $f" >&2
+        continue
+    fi
+    gain=$(awk -v t="$TARGET_DB" -v m="$mean" 'BEGIN { printf "%.1f", t - m }')
+    tmp=$(mktemp --suffix=.ogg)
+    ffmpeg -hide_banner -loglevel error -y -i "$f" \
+        -af "volume=${gain}dB" -c:a libvorbis -q:a 6 "$tmp"
+    # Write through the file rather than mv over it: when SOUND_DIR is the
+    # stow-symlinked ~/.local copy, mv would replace the symlink with a real
+    # file and decouple it from the repo. cat preserves the symlink target.
+    cat "$tmp" > "$f"
+    rm -f "$tmp"
+    printf "%-14s mean %7s dB  gain %+6s dB  -> target %s dB\n" \
+        "$(basename "$f")" "$mean" "$gain" "$TARGET_DB"
+done