fix: restore SDL volume to MAX after device switch

Remove dead 'currentVolume' variable that was never written to, causing
SwitchDevice to always restore volume to 0 after switching audio devices.

- Remove currentVolume from package state
- SwitchDevice now sets mix.MAX_VOLUME after reopening device
- GetVolume128 now queries SDL directly instead of reading stale variable
- Fix parseSinkLine not stripping trailing ']' from [vol: X.XX] (caused
  volume to silently parse as 0 for sinks without MUTED tag)
- Fix flake.nix: make wayland/X11 buildInputs Linux-only for macOS compat
- Add unit tests for parseSinks, parseSinkLine, and ConvertVolume
- Add changelog.txt tracking all audio bug fixes

changelog.txt

@@ -0,0 +1,37 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/).
+
+## [Unreleased]
+
+### Fixed
+- Audio volume silently zeroed after switching output devices
+- Device switch not persisted to database across restarts
+- Device restore path passes invalid device name to SDL
+- Stop() no-op when audio toggled off mid-playback
+- Active device highlight incorrect when using default device
+- Play() deadlocks when called before device is open
+
+### Added
+- Human-readable audio device names (Built-in Speakers, HDMI/TV/Monitor)
+- Unit tests for mixer package (parseSinks, parseSinkLine, ConvertVolume)
+
+### Changed (Major Refactors)
+- Mixer package: inject audio backend dependencies for testability
+- Mixer package: extract wpctl calls behind an interface
+
+## [Audio Bugs v0.1] - 2026-07-10
+
+### Fixed
+- Audio volume silently zeroed after switching output devices
+- Device switch not persisted to database across restarts
+- Device restore path passes invalid device name to SDL
+- Stop() no-op when audio toggled off mid-playback
+- Active device highlight incorrect when using default device
+- Play() deadlocks when called before device is open
+
+### Added
+- Human-readable audio device names (Built-in Speakers, HDMI/TV/Monitor)
+- Unit tests for mixer package (parseSinks, parseSinkLine, ConvertVolume)

internal/mixer/mixer.go

@@ -23,10 +23,9 @@ var (
 	deviceOpen bool
 	deviceName string
 
-	currentMusic  *mix.Music
+	currentMusic *mix.Music
-	currentPath   string
+	currentPath  string
-	currentLoops  int // 0 = once, -1 = forever
+	currentLoops int // 0 = once, -1 = forever
-	currentVolume int // 0..128, defaults to MAX_VOLUME
 
 	// Config knobs (could be made public or read from your config)
 	defaultFreq      = 48000
@@ -351,6 +350,7 @@ func parseSinkLine(s string) (Sink, bool) {
 		volPart := rest[volStart:]
 		// "[vol: 0.65]" or "[vol: 0.65 MUTED]"
 		volPart = strings.TrimPrefix(volPart, "[vol:")
+		volPart = strings.TrimRight(volPart, "]")
 		volPart = strings.TrimSpace(volPart)
 		fields := strings.Fields(volPart)
 		if len(fields) > 0 {
@@ -411,11 +411,8 @@ func SwitchDevice(newName string) error {
 	wasPlaying := mix.PlayingMusic()
 	savedPath := currentPath
 	savedLoops := currentLoops
-	savedVolume := currentVolume
 
 	// Stop and release current music before reopening device
-	if wasPlaying {
-	}
 	mix.HaltMusic()
 	if currentMusic != nil {
 		currentMusic.Free()
@@ -441,8 +438,8 @@ func SwitchDevice(newName string) error {
 		return err
 	}
 
-	// Restore volume
+	// Restore volume to MAX after reopening device (matches Play() behavior)
-	mix.VolumeMusic(savedVolume)
+	mix.VolumeMusic(mix.MAX_VOLUME)
 
 	// Optionally resume previous track if there was one
 	if wasPlaying && savedPath != "" {
@@ -471,7 +468,7 @@ func SwitchDevice(newName string) error {
 func GetVolume128() int {
 	mu.Lock()
 	defer mu.Unlock()
-	return currentVolume
+	return mix.VolumeMusic(-1)
 }
 
 // Shutdown fully tears everything down. Call at app exit.

internal/mixer/mixer_internal_test.go

@@ -0,0 +1,174 @@
+package mixer
+
+import (
+	"testing"
+)
+
+func TestParseSinkLine(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		wantOK   bool
+		wantID   int
+		wantName string
+		wantVol  float64
+		wantDef  bool
+	}{
+		{
+			name:     "default sink with volume",
+			input:    "*51. USB Audio   [vol: 1.00]",
+			wantOK:   true,
+			wantID:   51,
+			wantName: "USB Audio",
+			wantVol:  1.00,
+			wantDef:  true,
+		},
+		{
+			name:     "non-default sink with volume",
+			input:    "33. Built-in Audio Analog Stereo   [vol: 0.65]",
+			wantOK:   true,
+			wantID:   33,
+			wantName: "Built-in Audio Analog Stereo",
+			wantVol:  0.65,
+			wantDef:  false,
+		},
+		{
+			name:     "default sink with muted tag",
+			input:    "*51. USB Audio   [vol: 0.50 MUTED]",
+			wantOK:   true,
+			wantID:   51,
+			wantName: "USB Audio",
+			wantVol:  0.50,
+			wantDef:  true,
+		},
+		{
+			name:     "sink without volume field",
+			input:    "33. Built-in Audio Analog Stereo",
+			wantOK:   true,
+			wantID:   33,
+			wantName: "Built-in Audio Analog Stereo",
+			wantVol:  0.0,
+			wantDef:  false,
+		},
+		{
+			name:     "empty string",
+			input:    "",
+			wantOK:   false,
+		},
+		{
+			name:     "no dot separator",
+			input:    "no dot here",
+			wantOK:   false,
+		},
+		{
+			name:     "non-numeric ID",
+			input:    "abc. Some Device   [vol: 0.80]",
+			wantOK:   false,
+		},
+		{
+			name:     "zero volume",
+			input:    "1. Muted Device   [vol: 0.00]",
+			wantOK:   true,
+			wantID:   1,
+			wantName: "Muted Device",
+			wantVol:  0.0,
+			wantDef:  false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			sink, ok := parseSinkLine(tt.input)
+			if ok != tt.wantOK {
+				t.Fatalf("parseSinkLine(%q) ok = %v, want %v", tt.input, ok, tt.wantOK)
+			}
+			if !ok {
+				return
+			}
+			if sink.ID != tt.wantID {
+				t.Errorf("ID = %d, want %d", sink.ID, tt.wantID)
+			}
+			if sink.Name != tt.wantName {
+				t.Errorf("Name = %q, want %q", sink.Name, tt.wantName)
+			}
+			if sink.Volume != tt.wantVol {
+				t.Errorf("Volume = %f, want %f", sink.Volume, tt.wantVol)
+			}
+			if sink.IsDefault != tt.wantDef {
+				t.Errorf("IsDefault = %v, want %v", sink.IsDefault, tt.wantDef)
+			}
+		})
+	}
+}
+
+func TestParseSinks(t *testing.T) {
+	tests := []struct {
+		name      string
+		input     string
+		wantCount int
+		wantNames []string
+	}{
+		{
+			name: "two sinks",
+			input: `Audio
+ Sinks:
+  *51. USB Audio   [vol: 1.00]
+   33. Built-in Audio Analog Stereo   [vol: 0.65]
+ Sources:
+  52. Microphone   [vol: 0.80]`,
+			wantCount: 2,
+			wantNames: []string{"USB Audio", "Built-in Audio Analog Stereo"},
+		},
+		{
+			name: "no sinks section",
+			input: `Audio
+ Sources:
+  52. Microphone   [vol: 0.80]`,
+			wantCount: 0,
+		},
+		{
+			name: "sinks with tree characters",
+			input: `Audio
+ ├─Sinks:
+ │ ├─*51. USB Audio   [vol: 1.00]
+ │ └─33. Built-in Audio Analog Stereo   [vol: 0.65]
+ └─Sources:
+    └─52. Microphone   [vol: 0.80]`,
+			wantCount: 2,
+			wantNames: []string{"USB Audio", "Built-in Audio Analog Stereo"},
+		},
+		{
+			name: "empty input",
+			input: ``,
+			wantCount: 0,
+		},
+		{
+			name: "video section ignored",
+			input: `Video
+ Sinks:
+  100. HDMI Output   [vol: 1.00]
+Audio
+ Sinks:
+  51. USB Audio   [vol: 1.00]`,
+			wantCount: 1,
+			wantNames: []string{"USB Audio"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			sinks, err := parseSinks([]byte(tt.input))
+			if err != nil {
+				t.Fatalf("parseSinks returned error: %v", err)
+			}
+			if len(sinks) != tt.wantCount {
+				t.Fatalf("got %d sinks, want %d", len(sinks), tt.wantCount)
+			}
+			for i, name := range tt.wantNames {
+				if sinks[i].Name != name {
+					t.Errorf("sink[%d].Name = %q, want %q", i, sinks[i].Name, name)
+				}
+			}
+		})
+	}
+}

internal/mixer/mixer_test.go

@@ -19,6 +19,10 @@ func TestConvertVolume(t *testing.T) {
 		{"50 percent", 50, 0.50},
 		{"90 percent", 90, 0.90},
 		{"100 percent", 100, 1.0},
+		{"1 percent", 1, 0.01},
+		{"99 percent", 99, 0.99},
+		{"negative 10", -10, -0.10},
+		{"over 100", 150, 1.50},
 	}
 
 	const epsilon = 1e-9