fix: Flex with multiple slices opened was always showing slice A s-meter.

main.go

@@ -36,6 +36,15 @@ func profileArg(args []string) string {
 }
 
 func main() {
+	// Single-instance guard: if OpsLog is already running, focus that window and
+	// exit instead of spawning a duplicate. A second process would open its own
+	// CAT (FlexRadio) connection and Ultrabeam follow loop, and the two would
+	// fight over the rig/antenna frequency — the cause of "the antenna re-tunes on
+	// its own" when a windowless zombie instance was left running.
+	if !acquireSingleInstance() {
+		return
+	}
+
 	// Create an instance of the app structure
 	app := NewApp()
 	app.startupProfile = profileArg(os.Args[1:])