feat: added visual feedback when pressing piano keys

src/core/midi-input/KGMidiInput.test.ts

@@ -2,6 +2,9 @@ import { beforeEach, describe, expect, it, vi } from 'vitest';
 import { KGAudioTrack } from '../track/KGAudioTrack';
 import { KGMidiTrack } from '../track/KGMidiTrack';
 
+type TestMidiEvent = { data: Uint8Array };
+type TestLiveNoteActivityListener = (...args: [{ pitch: number; isNoteOn: boolean }]) => void;
+
 const { getStateMock, audioInterfaceMock } = vi.hoisted(() => ({
   getStateMock: vi.fn(),
   audioInterfaceMock: {
@@ -45,19 +48,40 @@ describe('KGMidiInput pitch bend', () => {
 
   it('routes live MIDI note on/off through the live monitoring path', () => {
     const midiInput = KGMidiInput.instance() as unknown as {
-      handleMIDIMessage: (event: { data: Uint8Array }) => void;
+      handleMIDIMessage: (...args: [TestMidiEvent]) => void;
+      addLiveNoteActivityListener: (...args: [TestLiveNoteActivityListener]) => void;
     };
+    const listener = vi.fn();
+
+    midiInput.addLiveNoteActivityListener(listener);
 
     midiInput.handleMIDIMessage({ data: new Uint8Array([0x90, 60, 100]) });
     midiInput.handleMIDIMessage({ data: new Uint8Array([0x80, 60, 0]) });
 
     expect(audioInterfaceMock.triggerLiveMidiNoteAttack).toHaveBeenCalledWith('1', 60, 100);
     expect(audioInterfaceMock.releaseLiveMidiNote).toHaveBeenCalledWith('1', 60);
+    expect(listener).toHaveBeenNthCalledWith(1, { pitch: 60, isNoteOn: true });
+    expect(listener).toHaveBeenNthCalledWith(2, { pitch: 60, isNoteOn: false });
+  });
+
+  it('stops notifying removed live note activity listeners', () => {
+    const midiInput = KGMidiInput.instance() as unknown as {
+      handleMIDIMessage: (...args: [TestMidiEvent]) => void;
+      addLiveNoteActivityListener: (...args: [TestLiveNoteActivityListener]) => void;
+      removeLiveNoteActivityListener: (...args: [TestLiveNoteActivityListener]) => void;
+    };
+    const listener = vi.fn();
+
+    midiInput.addLiveNoteActivityListener(listener);
+    midiInput.removeLiveNoteActivityListener(listener);
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0x90, 60, 100]) });
+
+    expect(listener).not.toHaveBeenCalled();
   });
 
   it('latches live note ownership to the note-on track', () => {
     const midiInput = KGMidiInput.instance() as unknown as {
-      handleMIDIMessage: (event: { data: Uint8Array }) => void;
+      handleMIDIMessage: (...args: [TestMidiEvent]) => void;
     };
 
     midiInput.handleMIDIMessage({ data: new Uint8Array([0x90, 60, 100]) });
@@ -73,7 +97,7 @@ describe('KGMidiInput pitch bend', () => {
 
   it('normalizes MIDI pitch bend and forwards it to the selected track', () => {
     const midiInput = KGMidiInput.instance() as unknown as {
-      handleMIDIMessage: (event: { data: Uint8Array }) => void;
+      handleMIDIMessage: (...args: [TestMidiEvent]) => void;
     };
 
     midiInput.handleMIDIMessage({ data: new Uint8Array([0xe0, 0x00, 0x40]) });
@@ -87,7 +111,7 @@ describe('KGMidiInput pitch bend', () => {
 
   it('maps supported CC messages to live expression and sustain for standard pedals', () => {
     const midiInput = KGMidiInput.instance() as unknown as {
-      handleMIDIMessage: (event: { data: Uint8Array }) => void;
+      handleMIDIMessage: (...args: [TestMidiEvent]) => void;
     };
 
     midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x01, 0x20]) });
@@ -106,7 +130,7 @@ describe('KGMidiInput pitch bend', () => {
 
   it('calibrates inverted sustain pedals from the first observed CC64 message', () => {
     const midiInput = KGMidiInput.instance() as unknown as {
-      handleMIDIMessage: (event: { data: Uint8Array }) => void;
+      handleMIDIMessage: (...args: [TestMidiEvent]) => void;
     };
 
     midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x40, 0x00]) });
@@ -123,7 +147,7 @@ describe('KGMidiInput pitch bend', () => {
     });
 
     const midiInput = KGMidiInput.instance() as unknown as {
-      handleMIDIMessage: (event: { data: Uint8Array }) => void;
+      handleMIDIMessage: (...args: [TestMidiEvent]) => void;
     };
 
     midiInput.handleMIDIMessage({ data: new Uint8Array([0x90, 60, 100]) });

src/core/midi-input/KGMidiInput.ts

@@ -2,6 +2,13 @@ import { KGAudioInterface } from '../audio-interface/KGAudioInterface';
 import { useProjectStore } from '../../stores/projectStore';
 import { KGMidiTrack } from '../track/KGMidiTrack';
 
+export interface LiveMidiNoteActivityEvent {
+  pitch: number;
+  isNoteOn: boolean;
+}
+
+type LiveNoteActivityListener = (...args: [LiveMidiNoteActivityEvent]) => void;
+
 /**
  * KGMidiInput - MIDI input manager for the DAW
  * Implements the singleton pattern for global MIDI device management
@@ -32,6 +39,7 @@ export class KGMidiInput {
   private onRecordControlChange: ((controller: number, value: number) => void) | null = null;
   private liveNoteTrackOwnership: Map<number, string[]> = new Map();
   private sustainPolarityInverted: boolean | null = null;
+  private liveNoteActivityListeners: LiveNoteActivityListener[] = [];
 
   // Private constructor to prevent direct instantiation
   private constructor() {
@@ -178,12 +186,14 @@ export class KGMidiInput {
     // Note On: command = 0x90 (144)
     if (command === 0x90 && velocity > 0) {
       console.log(`MIDI Note On: pitch=${pitch}, velocity=${velocity}, channel=${channel}`);
+      this.emitLiveNoteActivity({ pitch, isNoteOn: true });
       this.triggerNoteOn(pitch, velocity);
       this.onRecordNoteOn?.(pitch, velocity);
     }
     // Note Off: command = 0x80 (128) or Note On with velocity 0
     else if (command === 0x80 || (command === 0x90 && velocity === 0)) {
       console.log(`MIDI Note Off: pitch=${pitch}, channel=${channel}`);
+      this.emitLiveNoteActivity({ pitch, isNoteOn: false });
       this.triggerNoteOff(pitch);
       this.onRecordNoteOff?.(pitch);
     }
@@ -354,6 +364,16 @@ export class KGMidiInput {
     return this.sustainPolarityInverted ? !rawPressed : rawPressed;
   }
 
+  private emitLiveNoteActivity(event: LiveMidiNoteActivityEvent): void {
+    for (const listener of this.liveNoteActivityListeners) {
+      try {
+        listener(event);
+      } catch {
+        // Swallow listener errors to avoid disrupting MIDI handling.
+      }
+    }
+  }
+
   /**
    * Clean up MIDI resources
    */
@@ -374,6 +394,7 @@ export class KGMidiInput {
       this.isInitialized = false;
       this.liveNoteTrackOwnership.clear();
       this.sustainPolarityInverted = null;
+      this.liveNoteActivityListeners = [];
 
       console.log("MIDI resources disposed successfully");
     } catch (error) {
@@ -395,6 +416,14 @@ export class KGMidiInput {
     this.onRecordControlChange = onControlChange;
   }
 
+  public addLiveNoteActivityListener(listener: LiveNoteActivityListener): void {
+    this.liveNoteActivityListeners.push(listener);
+  }
+
+  public removeLiveNoteActivityListener(listener: LiveNoteActivityListener): void {
+    this.liveNoteActivityListeners = this.liveNoteActivityListeners.filter(current => current !== listener);
+  }
+
   // ===== GETTERS =====
 
   public getIsInitialized(): boolean {