add pid file, add context for go routines + add proper logging

internal/bus/bus.go

@@ -2,12 +2,15 @@ package bus
 
 import (
 	"bufio"
+	"fmt"
 	"net"
 	"os"
 	"path/filepath"
+	"strconv"
 )
 
 const SockName = "control.sock"
+const PidName = "hyprvoice.pid"
 const ProtoVer = "0.1"
 
 // ~/.cache/hyprvoice/control.sock
@@ -20,6 +23,16 @@ func SockPath() (string, error) {
 	return filepath.Join(hd, SockName), nil
 }
 
+// ~/.cache/hyprvoice/hyprvoice.pid
+func PidPath() (string, error) {
+	dir, err := os.UserCacheDir()
+	if err != nil {
+		return "", err
+	}
+	hd := filepath.Join(dir, "hyprvoice")
+	return filepath.Join(hd, PidName), nil
+}
+
 func Listen() (net.Listener, error) {
 	sp, err := SockPath()
 	if err != nil {
@@ -55,3 +68,58 @@ func SendCommand(cmd byte) (string, error) {
 	resp, err := bufio.NewReader(c).ReadString('\n')
 	return resp, err
 }
+
+func CheckExistingDaemon() error {
+	pidPath, err := PidPath()
+	if err != nil {
+		return err
+	}
+
+	pidData, err := os.ReadFile(pidPath)
+	if os.IsNotExist(err) {
+		return nil // no existing daemon
+	}
+	if err != nil {
+		return err
+	}
+
+	pid, err := strconv.Atoi(string(pidData))
+	if err != nil {
+		return nil // invalid pid file, assume stale
+	}
+
+	// Check if process exists
+	proc, err := os.FindProcess(pid)
+	if err != nil {
+		return nil
+	}
+
+	// Try to signal the process to check if it's alive
+	if err := proc.Signal(os.Signal(nil)); err != nil {
+		return nil // process not alive, stale pid file
+	}
+
+	return fmt.Errorf("daemon already running with PID %d", pid)
+}
+
+func CreatePidFile() error {
+	pidPath, err := PidPath()
+	if err != nil {
+		return err
+	}
+
+	if err := os.MkdirAll(filepath.Dir(pidPath), 0o700); err != nil {
+		return err
+	}
+
+	pid := os.Getpid()
+	return os.WriteFile(pidPath, []byte(strconv.Itoa(pid)), 0o600)
+}
+
+func RemovePidFile() error {
+	pidPath, err := PidPath()
+	if err != nil {
+		return err
+	}
+	return os.Remove(pidPath)
+}