Attempt to make modifier key changes take affect when the dialogue closes. This means you don't have to restart Fenrir to apply them.

internal/console/native_linux.go

@@ -308,6 +308,25 @@ func (k *Keyboards) Close() error {
 	return errors.Join(errs...)
 }
 
+// Update_modifiers waits for every keyboard to release its old chord before
+// replacing the router; the existing evdev grabs remain owned throughout.
+func (k *Keyboards) Update_modifiers(fenrirKeys, scriptKeys []string) (bool, error) {
+	if k.router.Captured() || !k.router.Idle() {
+		return false, nil
+	}
+	for _, device := range k.devices {
+		if device.syncing || device.held() {
+			return false, nil
+		}
+	}
+	candidate := k.router
+	if err := candidate.Configure_modifiers(fenrirKeys, scriptKeys); err != nil {
+		return false, err
+	}
+	k.router = candidate
+	return true, nil
+}
+
 func (k *Keyboards) Poll(textMode, numLock bool, handle func(input.Decision)) error {
 	if !textMode {
 		for _, device := range k.devices {