Add system tray icon, file logging, and fix Windows hotkey conflict

- Adds fyne.io/systray with a programmatic monkey face icon and Quit menu item
- Logs to discord-lobby-mute.log next to the exe so startup errors are visible
  without a console window
- Windows now uses raw Win32 RegisterHotKey in a locked goroutine instead of
  golang.design/x/hotkey, avoiding a deadlock where systray and the hotkey
  library both try to own the main thread message loop
- Build with: GOOS=windows GOARCH=amd64 go build -ldflags "-H windowsgui" -o discord-lobby-mute.exe .

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

go.mod

@@ -9,7 +9,9 @@ require (
 )
 
 require (
+	fyne.io/systray v1.12.1 // indirect
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
 	github.com/gorilla/websocket v1.4.2 // indirect
 	golang.org/x/crypto v0.0.0-20210421170649-83a5a9bb288b // indirect
-	golang.org/x/sys v0.0.0-20201119102817-f84b799fce68 // indirect
+	golang.org/x/sys v0.15.0 // indirect
 )

go.sum

@@ -1,5 +1,9 @@
+fyne.io/systray v1.12.1 h1:ygBD6aZXwiOmZoY5N+ukbH9pih0Kq6fYgVeMYbr5skQ=
+fyne.io/systray v1.12.1/go.mod h1:RVwqP9nYMo7h5zViCBHri2FgjXF7H2cub7MAq4NSoLs=
 github.com/bwmarrin/discordgo v0.29.0 h1:FmWeXFaKUwrcL3Cx65c20bTRW+vOb6k8AnaP+EgjDno=
 github.com/bwmarrin/discordgo v0.29.0/go.mod h1:NJZpH+1AfhIcyQsPeuBKsUtYrRnjkyu0kIVMCHkZtRY=
+github.com/godbus/dbus/v5 v5.1.0 h1:4KLkAxT3aOY8Li4FRJe/KvhoNFFxo0m6fNuFUO8QJUk=
+github.com/godbus/dbus/v5 v5.1.0/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/gorilla/websocket v1.4.2 h1:+/TMaTYc4QFitKJxsQ7Yye35DkWvkdLcvGKqM+x0Ufc=
 github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 golang.design/x/hotkey v0.4.1 h1:zLP/2Pztl4WjyxURdW84GoZ5LUrr6hr69CzJFJ5U1go=
@@ -12,6 +16,8 @@ golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v
 golang.org/x/sys v0.0.0-20201022201747-fb209a7c41cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68 h1:nxC68pudNYkKU6jWhgrqdreuFiOQWj1Fs7T3VrH4Pjw=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.15.0 h1:h48lPFYpsTvQJZF4EKyI4aLHaev3CxivZmv7yZig9pc=
+golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

hotkey_notwindows.go

@@ -0,0 +1,24 @@
+//go:build !windows
+
+package main
+
+import "golang.design/x/hotkey"
+
+func startHotkey(keybind string) (<-chan struct{}, error) {
+	mods, key, err := parseKeybind(keybind)
+	if err != nil {
+		return nil, err
+	}
+	hk := hotkey.New(mods, key)
+	if err := hk.Register(); err != nil {
+		return nil, err
+	}
+	out := make(chan struct{})
+	go func() {
+		for range hk.Keydown() {
+			out <- struct{}{}
+		}
+		close(out)
+	}()
+	return out, nil
+}

icon.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"bytes"
+	"image"
+	"image/color"
+	"image/png"
+)
+
+func monkeyIcon() []byte {
+	const size = 32
+	img := image.NewRGBA(image.Rect(0, 0, size, size))
+
+	brown := color.RGBA{110, 72, 38, 255}
+	tan   := color.RGBA{210, 175, 130, 255}
+	pink  := color.RGBA{190, 130, 110, 255}
+	dark  := color.RGBA{15, 8, 3, 255}
+	white := color.RGBA{255, 255, 255, 255}
+
+	// Ears drawn first so the head circle overlaps the inner edge naturally.
+	fillCircle(img, 4, 13, 5, brown)
+	fillCircle(img, 28, 13, 5, brown)
+	fillCircle(img, 4, 13, 3, pink)
+	fillCircle(img, 28, 13, 3, pink)
+
+	fillCircle(img, 16, 15, 13, brown) // head
+
+	fillEllipse(img, 16, 21, 7, 4, tan) // muzzle
+
+	// Eyes: light surround, dark iris, white highlight.
+	fillCircle(img, 11, 12, 3, tan)
+	fillCircle(img, 21, 12, 3, tan)
+	fillCircle(img, 11, 12, 2, dark)
+	fillCircle(img, 21, 12, 2, dark)
+	fillCircle(img, 12, 11, 1, white)
+	fillCircle(img, 22, 11, 1, white)
+
+	// Nostrils.
+	fillCircle(img, 14, 21, 1, dark)
+	fillCircle(img, 18, 21, 1, dark)
+
+	var buf bytes.Buffer
+	_ = png.Encode(&buf, img)
+	return buf.Bytes()
+}
+
+func fillCircle(img *image.RGBA, cx, cy, r int, c color.RGBA) {
+	for y := cy - r; y <= cy+r; y++ {
+		for x := cx - r; x <= cx+r; x++ {
+			dx, dy := x-cx, y-cy
+			if dx*dx+dy*dy <= r*r {
+				img.SetRGBA(x, y, c)
+			}
+		}
+	}
+}
+
+func fillEllipse(img *image.RGBA, cx, cy, rx, ry int, c color.RGBA) {
+	for y := cy - ry; y <= cy+ry; y++ {
+		for x := cx - rx; x <= cx+rx; x++ {
+			dx := float64(x-cx) / float64(rx)
+			dy := float64(y-cy) / float64(ry)
+			if dx*dx+dy*dy <= 1.0 {
+				img.SetRGBA(x, y, c)
+			}
+		}
+	}
+}

keybind_windows.go

@@ -2,7 +2,14 @@
 
 package main
 
-import "golang.design/x/hotkey"
+import (
+	"fmt"
+	"runtime"
+	"syscall"
+	"unsafe"
+
+	"golang.design/x/hotkey"
+)
 
 var modMap = map[string]hotkey.Modifier{
 	"ctrl":  hotkey.ModCtrl,
@@ -11,3 +18,71 @@ var modMap = map[string]hotkey.Modifier{
 	"win":   hotkey.ModWin,
 	"super": hotkey.ModWin,
 }
+
+var (
+	user32             = syscall.NewLazyDLL("user32.dll")
+	procRegisterHotKey = user32.NewProc("RegisterHotKey")
+	procGetMessageW    = user32.NewProc("GetMessageW")
+)
+
+// winMsg mirrors the Win32 MSG struct.
+type winMsg struct {
+	hwnd    uintptr
+	message uint32
+	wParam  uintptr
+	lParam  uintptr
+	time    uint32
+	ptX     int32
+	ptY     int32
+}
+
+func startHotkey(keybind string) (<-chan struct{}, error) {
+	mods, key, err := parseKeybind(keybind)
+	if err != nil {
+		return nil, err
+	}
+
+	// hotkey.Modifier and hotkey.Key values on Windows are the native Win32
+	// MOD_* and VK_* constants, so they can be passed directly to RegisterHotKey.
+	var modFlags uintptr
+	for _, m := range mods {
+		modFlags |= uintptr(m)
+	}
+	vk := uintptr(key)
+
+	ch := make(chan struct{}, 1)
+	ready := make(chan error, 1)
+
+	go func() {
+		runtime.LockOSThread()
+		// Intentionally no defer UnlockOSThread — this goroutine owns its OS
+		// thread for the lifetime of the app to keep the hotkey message queue alive.
+
+		ret, _, e := procRegisterHotKey.Call(0, 1, modFlags, vk)
+		if ret == 0 {
+			ready <- fmt.Errorf("RegisterHotKey: %w", e)
+			return
+		}
+		close(ready)
+
+		const wmHotkey = 0x0312
+		var msg winMsg
+		for {
+			r, _, _ := procGetMessageW.Call(
+				uintptr(unsafe.Pointer(&msg)), 0, wmHotkey, wmHotkey,
+			)
+			if r == 0 || r == ^uintptr(0) { // WM_QUIT or error
+				return
+			}
+			select {
+			case ch <- struct{}{}:
+			default:
+			}
+		}
+	}()
+
+	if err := <-ready; err != nil {
+		return nil, err
+	}
+	return ch, nil
+}

main.go

@@ -3,14 +3,15 @@ package main
 import (
 	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"os"
 	"path/filepath"
 	"strings"
 
+	"fyne.io/systray"
 	"github.com/bwmarrin/discordgo"
 	"golang.design/x/hotkey"
-	"golang.design/x/mainthread"
 )
 
 type Config struct {
@@ -107,21 +108,27 @@ func toggleMute(dg *discordgo.Session, cfg *Config, muted bool) {
 	for _, vs := range guild.VoiceStates {
 		if vs.ChannelID == cfg.ChannelID && !exempt[vs.UserID] {
 			if err := dg.GuildMemberMute(cfg.GuildID, vs.UserID, muted); err != nil {
-				log.Printf("  warning: user %s: %v", vs.UserID, err)
+				log.Printf("warning: user %s: %v", vs.UserID, err)
 			}
 			count++
 		}
 	}
 	if count == 0 {
-		fmt.Println("  (no users found in channel)")
+		log.Println("(no users found in channel)")
 	} else {
-		fmt.Printf("  %d user(s) affected\n", count)
+		log.Printf("%d user(s) affected", count)
 	}
 }
 
-func main() { mainthread.Init(run) }
-
 func run() {
+	// Log to file next to the executable so errors are visible even without a console.
+	if exe, err := os.Executable(); err == nil {
+		logPath := filepath.Join(filepath.Dir(exe), "discord-lobby-mute.log")
+		if f, err := os.OpenFile(logPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644); err == nil {
+			log.SetOutput(io.MultiWriter(os.Stderr, f))
+		}
+	}
+
 	cfg, err := loadConfig()
 	if err != nil {
 		log.Fatal(err)
@@ -144,29 +151,38 @@ func run() {
 	defer dg.Close()
 
 	<-ready
-	fmt.Println("Connected to Discord.")
+	log.Println("Connected to Discord.")
 
-	mods, key, err := parseKeybind(cfg.Keybind)
+	keydownCh, err := startHotkey(cfg.Keybind)
 	if err != nil {
-		log.Fatalf("keybind: %v", err)
-	}
-
-	hk := hotkey.New(mods, key)
-	if err := hk.Register(); err != nil {
 		log.Fatalf("register hotkey %q: %v", cfg.Keybind, err)
 	}
-	defer hk.Unregister()
 
-	fmt.Printf("Listening on %s — toggles server mute for channel %s\n", cfg.Keybind, cfg.ChannelID)
+	log.Printf("Listening on %s — toggles server mute for channel %s", cfg.Keybind, cfg.ChannelID)
 
-	muted := false
+	go func() {
-	for range hk.Keydown() {
+		muted := false
-		muted = !muted
+		for range keydownCh {
-		if muted {
+			muted = !muted
-			fmt.Print("Muting all users... ")
+			if muted {
-		} else {
+				log.Print("Muting all users...")
-			fmt.Print("Unmuting all users... ")
+			} else {
+				log.Print("Unmuting all users...")
+			}
+			toggleMute(dg, cfg, muted)
 		}
-		toggleMute(dg, cfg, muted)
+	}()
-	}
+
+	systray.Run(
+		func() {
+			systray.SetIcon(monkeyIcon())
+			systray.SetTooltip("Discord Lobby Mute — " + cfg.Keybind)
+			mQuit := systray.AddMenuItem("Quit", "Quit Discord Lobby Mute")
+			go func() {
+				<-mQuit.ClickedCh
+				systray.Quit()
+			}()
+		},
+		func() {},
+	)
 }

main_other.go

@@ -0,0 +1,7 @@
+//go:build !windows
+
+package main
+
+import "golang.design/x/mainthread"
+
+func main() { mainthread.Init(run) }

main_windows.go

@@ -0,0 +1,5 @@
+//go:build windows
+
+package main
+
+func main() { run() }