Fix volume control and note speed button functionality

- Make velocity static while channel volume (CC7) controls brightness
- Set volume once per note-on instead of constant updates to reduce MIDI traffic
- Fix note speed buttons to work with immediate changes (no armed state needed)
- Optimize volume changes to only affect channels with active notes
- Add visual dimming for inactive channels when notes end
- Remove conflicting volume update systems for cleaner implementation

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

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

core/arpeggiator_engine.py

@@ -529,6 +529,15 @@ class ArpeggiatorEngine(QObject):
             note_duration = self.step_duration * self.gate
             note_end_time = time.time() + note_duration + swing_offset
             
+            # Calculate and set volume for this channel (once per note)
+            active_channel_count = len(set(self.channel_manager.active_voices.keys()))
+            if active_channel_count == 0:
+                active_channel_count = 1  # At least count the channel we're about to play on
+            
+            volume = self.volume_engine.get_channel_volume(target_channel, active_channel_count)
+            midi_volume = int(volume * 127)
+            self.output_manager.send_volume_change(target_channel, midi_volume)
+            
             # Send note on
             self.output_manager.send_note_on(target_channel, note, static_velocity)
             
@@ -599,6 +608,7 @@ class ArpeggiatorEngine(QObject):
         """Check for notes that should be turned off"""
         current_time = time.time()
         notes_to_remove = []
+        channels_becoming_inactive = set()
         
         for (channel, note), end_time in self.active_notes.items():
             if current_time >= end_time:
@@ -606,9 +616,19 @@ class ArpeggiatorEngine(QObject):
                 self.channel_manager.release_voice(channel, note)
                 notes_to_remove.append((channel, note))
                 
+                # Check if this channel will have no more active notes
+                remaining_notes_on_channel = [k for k in self.active_notes.keys() if k[0] == channel and k != (channel, note)]
+                if not remaining_notes_on_channel:
+                    channels_becoming_inactive.add(channel)
+        
         for key in notes_to_remove:
             del self.active_notes[key]
             
+        # Dim visual display for channels that just became inactive
+        for channel in channels_becoming_inactive:
+            # Send volume change signal with low volume for visual feedback
+            self.output_manager.volume_sent.emit(channel, 20)  # Dim display
+    
     def get_current_state(self) -> Dict:
         """Get current arpeggiator state"""
         return {

main.py

@@ -56,8 +56,7 @@ class ArpeggiatorApp:
             self.maschine_controller
         )
         
-        # Volume changes are now handled directly in update_systems for active channels only
-        self.previous_active_channels = set()
+        # Volume changes are now handled once per note-on in arpeggiator engine
         
         # Setup update timer for real-time updates
         self.update_timer = QTimer()
@@ -76,35 +75,6 @@ class ArpeggiatorApp:
             # Advance pattern position (16ms delta at 60fps)
             self.volume_engine.update_pattern(0.016)
         
-            # Only update volumes for channels that have active notes
-            active_channels = set([ch for ch, voices in self.channel_manager.active_voices.items() if voices])
-            
-            if active_channels:
-                # Update volume patterns for active channels only
-                for channel in active_channels:
-                    volume = self.volume_engine.get_channel_volume(channel, len(active_channels))
-                    midi_volume = int(volume * 127)
-                    self.output_manager.send_volume_change(channel, midi_volume)
-                
-                # Handle channels that just became inactive
-                newly_inactive = self.previous_active_channels - active_channels
-                for channel in newly_inactive:
-                    # Send one CC7 message to reset to default volume
-                    self.output_manager.send_volume_change(channel, 100)
-                    # Dim the visual display
-                    if hasattr(self.main_window.arp_controls, 'simulator_display'):
-                        self.main_window.arp_controls.simulator_display.on_midi_volume_changed(channel, 20)
-                
-                # Update previous active channels
-                self.previous_active_channels = active_channels.copy()
-            else:
-                # No active channels - reset all previously active ones
-                for channel in self.previous_active_channels:
-                    self.output_manager.send_volume_change(channel, 100)
-                    if hasattr(self.main_window.arp_controls, 'simulator_display'):
-                        self.main_window.arp_controls.simulator_display.on_midi_volume_changed(channel, 20)
-                self.previous_active_channels = set()
-        
     def run(self):
         self.main_window.show()
         return self.app.exec_()