fix: enhance second instance command handling and maintain backward compatibility

main_instance_unix.go

@@ -91,23 +91,22 @@ func runSecondInstanceListener() {
 				defer conn.Close()
 				buf := make([]byte, 1)
 				n, _ := conn.Read(buf)
+				cmd := instanceCmdShow
 				if n == 1 {
-					select {
-					case secondInstanceCommand <- buf[0]:
-					default:
+					cmd = buf[0]
 				}
-				} else {
 				// Backwards-compatible: any connection with no payload = show window.
 				select {
-					case secondInstanceCommand <- instanceCmdShow:
+				case secondInstanceCommand <- cmd:
 				default:
 				}
-				}
 				_, _ = io.Copy(io.Discard, conn)
+				if cmd == instanceCmdShow {
 					select {
 					case secondInstanceWake <- struct{}{}:
 					default:
 					}
+				}
 			}(c)
 		}
 	}()