Fix velocity display and GUI sync issues on startup

- Set default velocity to 20 in arpeggiator engine to match GUI slider
- Fix velocity slider override logic to respect checkbox state during GUI updates
- Add GUI sync call after loading first preset on startup
- Ensure velocity slider shows 20 and stays at 20 when override is checked
- Fix desync between engine settings and GUI display on application launch

🤖 Generated with [Claude Code](https://claude.ai/code)

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

core/arpeggiator_engine.py

@@ -83,7 +83,7 @@ class ArpeggiatorEngine(QObject):
         self.note_speed = "1/8"  # Note duration
         self.gate = 1.0  # Note length as fraction of step (0.1-2.0)
         self.swing = 0.0  # Swing amount (-100% to +100%)
-        self.velocity = 80  # Base velocity
+        self.velocity = 20  # Base velocity
         self.scale_note_start = 0  # Starting scale note index (0 = root)
         
         # Channel distribution settings

gui/arpeggiator_controls.py

@@ -1201,7 +1201,10 @@ class ArpeggiatorControls(QWidget):
             if hasattr(self, 'swing_slider'):
                 self.swing_slider.setValue(int(self.arpeggiator.swing * 100))
             if hasattr(self, 'velocity_slider'):
-                self.velocity_slider.setValue(self.arpeggiator.velocity)
+                # Only update velocity slider if not overridden
+                if not self.parameter_overrides.get('velocity', False):
+                    self.velocity_slider.setValue(self.arpeggiator.velocity)
+                    self.velocity_label.setText(str(self.arpeggiator.velocity))
             if hasattr(self, 'octave_range_combo'):
                 self.octave_range_combo.setCurrentIndex(self.arpeggiator.octave_range - 1)
             if hasattr(self, 'tempo_spin'):

gui/preset_controls.py

@@ -761,6 +761,10 @@ class PresetControls(QWidget):
                     # Apply immediately on startup (not armed)
                     self.apply_preset_settings(self.presets[preset_name])
                     self.preset_list.setCurrentItem(first_item)
+                    
+                    # Sync GUI controls to match the loaded preset values
+                    if self.arpeggiator_controls and hasattr(self.arpeggiator_controls, 'update_gui_from_engine'):
+                        self.arpeggiator_controls.update_gui_from_engine()
     
     def save_preset_to_file(self, name: str, preset_data: dict):
         """Save a preset to file"""