feat: added support for real time MIDI CC input (CC1, CC2, CC7, CC11 -> velocity; CC64 -> sustain)

src/core/audio-interface/KGAudioBus.test.ts

@@ -1,5 +1,5 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest';
-import { MockBufferSource, MockSampler } from '../../test/mocks/tone';
+import { MockBufferSource, MockGain, MockSampler } from '../../test/mocks/tone';
 
 vi.mock('tone', async () => {
   const { ToneMock } = await import('../../test/mocks/tone');
@@ -32,6 +32,7 @@ describe('KGAudioBus live MIDI pitch bend', () => {
     vi.clearAllMocks();
     MockSampler.mockClear();
     MockBufferSource.mockClear();
+    MockGain.mockClear();
 
     const sampler = MockSampler();
     createSamplerMock.mockResolvedValue(sampler);
@@ -77,4 +78,69 @@ describe('KGAudioBus live MIDI pitch bend', () => {
 
     expect(source.playbackRate.setValueAtTime).toHaveBeenCalledWith(Math.pow(2, 2 / 12), 2);
   });
+
+  it('updates held live MIDI note gain when expression changes', async () => {
+    const audioBus = await KGAudioBus.create('acoustic_grand_piano');
+
+    audioBus.triggerLiveMidiAttack(60, 0, 1);
+    const gainNode = MockGain.mock.results[0].value;
+
+    audioBus.setLiveMidiExpression(0.25);
+
+    expect(gainNode.gain.value).toBeCloseTo(0.25, 5);
+  });
+
+  it('applies current expression to newly triggered notes', async () => {
+    const audioBus = await KGAudioBus.create('acoustic_grand_piano');
+
+    audioBus.setLiveMidiExpression(0.4);
+    audioBus.triggerLiveMidiAttack(60, 0, 1);
+
+    const gainNode = MockGain.mock.results[0].value;
+    expect(MockGain).toHaveBeenCalledWith(0.4);
+    expect(gainNode.gain.value).toBeCloseTo(0.4, 5);
+  });
+
+  it('defers release while sustain is held and flushes on pedal up', async () => {
+    const audioBus = await KGAudioBus.create('acoustic_grand_piano');
+
+    audioBus.triggerLiveMidiAttack(60, 0, 0.5);
+    const source = MockBufferSource.mock.results[0].value;
+
+    audioBus.setLiveMidiSustain(true);
+    audioBus.releaseLiveMidiNote(60, 1.25);
+    expect(source.stop).not.toHaveBeenCalled();
+
+    audioBus.setLiveMidiSustain(false, 2);
+    expect(source.stop).toHaveBeenCalledWith(2);
+  });
+
+  it('keeps physically held notes sounding when sustain is released', async () => {
+    const audioBus = await KGAudioBus.create('acoustic_grand_piano');
+
+    audioBus.triggerLiveMidiAttack(60, 0, 0.5);
+    const source = MockBufferSource.mock.results[0].value;
+
+    audioBus.setLiveMidiSustain(true);
+    audioBus.setLiveMidiSustain(false, 2);
+
+    expect(source.stop).not.toHaveBeenCalled();
+  });
+
+  it('resets live CC state on releaseAll', async () => {
+    const audioBus = await KGAudioBus.create('acoustic_grand_piano');
+
+    audioBus.triggerLiveMidiAttack(60, 0, 0.5);
+    const source = MockBufferSource.mock.results[0].value;
+    const gainNode = MockGain.mock.results[0].value;
+
+    audioBus.setLiveMidiExpression(0.2);
+    audioBus.setLiveMidiSustain(true);
+    audioBus.releaseAll();
+    audioBus.triggerLiveMidiAttack(60, 0, 0.5);
+
+    expect(source.stop).toHaveBeenCalled();
+    expect(gainNode.dispose).toHaveBeenCalled();
+    expect(MockGain.mock.calls[1]?.[0]).toBe(1);
+  });
 });

src/core/audio-interface/KGAudioBus.ts

@@ -9,7 +9,10 @@ import { KGToneSamplerFactory } from './KGToneSamplerFactory';
 
 interface LiveMidiSource {
   source: Tone.ToneBufferSource;
+  gainNode: Tone.Gain;
   basePlaybackRate: number;
+  isPressed: boolean;
+  pendingSustainRelease: boolean;
 }
 
 /**
@@ -33,6 +36,8 @@ export class KGAudioBus {
   private muted: boolean;
   private solo: boolean;
   private liveMidiPitchBend: number = 0;
+  private liveExpressionNormalized: number = 1;
+  private sustainPedalDown: boolean = false;
   private liveMidiSources: Map<number, LiveMidiSource[]> = new Map();
   
   // Audio processing chain (for future expansion)
@@ -199,15 +204,18 @@ export class KGAudioBus {
         return;
       }
 
-      const stopTime = time ?? Tone.now();
-      activeSources.forEach(({ source }) => {
-        try {
-          source.stop(stopTime);
-        } catch (error) {
-          console.error(`Error stopping live MIDI source for pitch ${pitch} on ${this.instrument}:`, error);
-        }
-      });
-      this.liveMidiSources.delete(pitch);
+      const liveSource = [...activeSources].reverse().find((entry) => entry.isPressed) ?? activeSources[activeSources.length - 1];
+      if (!liveSource) {
+        return;
+      }
+
+      liveSource.isPressed = false;
+      if (this.sustainPedalDown) {
+        liveSource.pendingSustainRelease = true;
+        return;
+      }
+
+      this.stopLiveMidiSource(pitch, liveSource, time ?? Tone.now());
     } catch (error) {
       console.error(`Error releasing live MIDI note ${pitch} on ${this.instrument}:`, error);
     }
@@ -237,6 +245,30 @@ export class KGAudioBus {
     this.setLiveMidiPitchBend(0);
   }
 
+  public setLiveMidiExpression(normalizedValue: number): void {
+    this.liveExpressionNormalized = Math.max(0, Math.min(1, normalizedValue));
+
+    for (const activeSources of this.liveMidiSources.values()) {
+      activeSources.forEach(({ gainNode }) => {
+        this.setGainValue(gainNode, this.liveExpressionNormalized);
+      });
+    }
+  }
+
+  public setLiveMidiSustain(isDown: boolean, time?: number): void {
+    this.sustainPedalDown = isDown;
+    if (isDown) {
+      return;
+    }
+
+    const releaseTime = time ?? Tone.now();
+    for (const [pitch, activeSources] of this.liveMidiSources.entries()) {
+      [...activeSources]
+        .filter((entry) => !entry.isPressed && entry.pendingSustainRelease)
+        .forEach((entry) => this.stopLiveMidiSource(pitch, entry, releaseTime));
+    }
+  }
+
   /**
    * Release all currently playing notes
    */
@@ -244,16 +276,19 @@ export class KGAudioBus {
     try {
       this.sampler.releaseAll();
       this.liveMidiSources.forEach((activeSources) => {
-        activeSources.forEach(({ source }) => {
+        activeSources.forEach(({ source, gainNode }) => {
           try {
             source.stop();
           } catch (error) {
             console.error(`Error stopping live MIDI source on ${this.instrument}:`, error);
           }
+          gainNode.dispose();
         });
       });
       this.liveMidiSources.clear();
       this.resetLiveMidiPitchBend();
+      this.liveExpressionNormalized = 1;
+      this.sustainPedalDown = false;
     } catch (error) {
       console.error(`Error releasing all notes on ${this.instrument}:`, error);
     }
@@ -498,17 +533,22 @@ export class KGAudioBus {
     }
 
     const basePlaybackRate = Math.pow(2, (pitch - closestPitch) / 12);
+    const gainNode = new Tone.Gain(this.liveExpressionNormalized);
     const source = new Tone.ToneBufferSource({
       url: buffer,
       fadeIn: this.sampler.attack,
       fadeOut: this.sampler.release,
       curve: this.sampler.curve,
       playbackRate: this.applyPitchBendToPlaybackRate(basePlaybackRate),
-    }).connect(this.sampler.output);
+    });
+
+    source.connect(gainNode);
+    gainNode.connect(this.sampler.output);
 
     source.onended = () => {
       const currentSources = this.liveMidiSources.get(pitch);
       if (!currentSources) {
+        gainNode.dispose();
         return;
       }
 
@@ -518,10 +558,17 @@ export class KGAudioBus {
       } else {
         this.liveMidiSources.set(pitch, nextSources);
       }
+      gainNode.dispose();
     };
 
     source.start(time, 0, duration ?? buffer.duration / basePlaybackRate, velocity ?? 1);
-    return { source, basePlaybackRate };
+    return {
+      source,
+      gainNode,
+      basePlaybackRate,
+      isPressed: true,
+      pendingSustainRelease: false,
+    };
   }
 
   public static applyNormalizedPitchBendToPlaybackRate(basePlaybackRate: number, normalizedBend: number): number {
@@ -575,4 +622,29 @@ export class KGAudioBus {
 
     playbackRate.value = value;
   }
+
+  private setGainValue(gainNode: Tone.Gain, value: number, time?: number): void {
+    if (time !== undefined && typeof gainNode.gain.setValueAtTime === 'function') {
+      gainNode.gain.setValueAtTime(value, time);
+      return;
+    }
+
+    gainNode.gain.value = value;
+  }
+
+  private stopLiveMidiSource(pitch: number, liveSource: LiveMidiSource, time: number): void {
+    try {
+      liveSource.pendingSustainRelease = false;
+      liveSource.source.stop(time);
+    } catch (error) {
+      console.error(`Error stopping live MIDI source for pitch ${pitch} on ${this.instrument}:`, error);
+      const remainingSources = this.liveMidiSources.get(pitch)?.filter((entry) => entry !== liveSource) ?? [];
+      if (remainingSources.length === 0) {
+        this.liveMidiSources.delete(pitch);
+      } else {
+        this.liveMidiSources.set(pitch, remainingSources);
+      }
+      liveSource.gainNode.dispose();
+    }
+  }
 }

src/core/audio-interface/KGAudioInterface.test.ts

@@ -214,3 +214,33 @@ describe('KGAudioInterface preroll playback', () => {
     expect(scheduledTimes).toContain(2);
   });
 });
+
+describe('KGAudioInterface live MIDI CC forwarding', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    ;(KGAudioInterface as unknown as { _instance: KGAudioInterface | null })._instance = null;
+  });
+
+  it('forwards live expression and sustain to the target audio bus', () => {
+    const audio = KGAudioInterface.instance();
+    const audioBus = {
+      setLiveMidiExpression: vi.fn(),
+      setLiveMidiSustain: vi.fn(),
+    };
+
+    ;(audio as unknown as { trackAudioBuses: Map<string, unknown> }).trackAudioBuses.set('1', audioBus);
+
+    audio.setLiveMidiExpression('1', 0.5);
+    audio.setLiveMidiSustain('1', true, 2);
+
+    expect(audioBus.setLiveMidiExpression).toHaveBeenCalledWith(0.5);
+    expect(audioBus.setLiveMidiSustain).toHaveBeenCalledWith(true, 2);
+  });
+
+  it('safely ignores live expression and sustain when the bus is missing', () => {
+    const audio = KGAudioInterface.instance();
+
+    expect(() => audio.setLiveMidiExpression('missing', 0.5)).not.toThrow();
+    expect(() => audio.setLiveMidiSustain('missing', true)).not.toThrow();
+  });
+});

src/core/audio-interface/KGAudioInterface.ts

@@ -914,6 +914,36 @@ export class KGAudioInterface {
     }
   }
 
+  public setLiveMidiExpression(trackId: string, normalizedValue: number): void {
+    try {
+      const audioBus = this.trackAudioBuses.get(trackId);
+      if (!audioBus) {
+        console.warn(`No audio bus found for track ${trackId}`);
+        return;
+      }
+
+      audioBus.setLiveMidiExpression(normalizedValue);
+      console.log(`Set live MIDI expression to ${normalizedValue} on track ${trackId}`);
+    } catch (error) {
+      console.error(`Error setting live MIDI expression for track ${trackId}:`, error);
+    }
+  }
+
+  public setLiveMidiSustain(trackId: string, isDown: boolean, time?: number): void {
+    try {
+      const audioBus = this.trackAudioBuses.get(trackId);
+      if (!audioBus) {
+        console.warn(`No audio bus found for track ${trackId}`);
+        return;
+      }
+
+      audioBus.setLiveMidiSustain(isDown, time);
+      console.log(`Set live MIDI sustain to ${isDown} on track ${trackId}`);
+    } catch (error) {
+      console.error(`Error setting live MIDI sustain for track ${trackId}:`, error);
+    }
+  }
+
   /**
    * Clear all scheduled events
    */

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

@@ -1,4 +1,6 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { KGAudioTrack } from '../track/KGAudioTrack';
+import { KGMidiTrack } from '../track/KGMidiTrack';
 
 const { getStateMock, audioInterfaceMock } = vi.hoisted(() => ({
   getStateMock: vi.fn(),
@@ -9,6 +11,8 @@ const { getStateMock, audioInterfaceMock } = vi.hoisted(() => ({
     triggerLiveMidiNoteAttack: vi.fn(),
     releaseLiveMidiNote: vi.fn(),
     setLiveMidiPitchBend: vi.fn(),
+    setLiveMidiExpression: vi.fn(),
+    setLiveMidiSustain: vi.fn(),
   },
 }));
 
@@ -29,7 +33,10 @@ import { KGMidiInput } from './KGMidiInput';
 describe('KGMidiInput pitch bend', () => {
   beforeEach(() => {
     vi.clearAllMocks();
-    getStateMock.mockReturnValue({ selectedTrackId: 'track-1' });
+    getStateMock.mockReturnValue({
+      selectedTrackId: '1',
+      tracks: [new KGMidiTrack('Track 1', 1)],
+    });
     audioInterfaceMock.getIsInitialized.mockReturnValue(true);
     audioInterfaceMock.getIsAudioContextStarted.mockReturnValue(true);
     audioInterfaceMock.startAudioContext.mockResolvedValue(undefined);
@@ -44,8 +51,24 @@ describe('KGMidiInput pitch bend', () => {
     midiInput.handleMIDIMessage({ data: new Uint8Array([0x90, 60, 100]) });
     midiInput.handleMIDIMessage({ data: new Uint8Array([0x80, 60, 0]) });
 
-    expect(audioInterfaceMock.triggerLiveMidiNoteAttack).toHaveBeenCalledWith('track-1', 60, 100);
-    expect(audioInterfaceMock.releaseLiveMidiNote).toHaveBeenCalledWith('track-1', 60);
+    expect(audioInterfaceMock.triggerLiveMidiNoteAttack).toHaveBeenCalledWith('1', 60, 100);
+    expect(audioInterfaceMock.releaseLiveMidiNote).toHaveBeenCalledWith('1', 60);
+  });
+
+  it('latches live note ownership to the note-on track', () => {
+    const midiInput = KGMidiInput.instance() as unknown as {
+      handleMIDIMessage: (event: { data: Uint8Array }) => void;
+    };
+
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0x90, 60, 100]) });
+    getStateMock.mockReturnValue({
+      selectedTrackId: '2',
+      tracks: [new KGMidiTrack('Track 1', 1), new KGMidiTrack('Track 2', 2)],
+    });
+
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0x80, 60, 0]) });
+
+    expect(audioInterfaceMock.releaseLiveMidiNote).toHaveBeenCalledWith('1', 60);
   });
 
   it('normalizes MIDI pitch bend and forwards it to the selected track', () => {
@@ -56,9 +79,59 @@ describe('KGMidiInput pitch bend', () => {
     midiInput.handleMIDIMessage({ data: new Uint8Array([0xe0, 0x00, 0x40]) });
     midiInput.handleMIDIMessage({ data: new Uint8Array([0xe0, 0x7f, 0x7f]) });
 
-    expect(audioInterfaceMock.setLiveMidiPitchBend).toHaveBeenNthCalledWith(1, 'track-1', 0);
+    expect(audioInterfaceMock.setLiveMidiPitchBend).toHaveBeenNthCalledWith(1, '1', 0);
     expect(audioInterfaceMock.setLiveMidiPitchBend).toHaveBeenCalledTimes(2);
-    expect(audioInterfaceMock.setLiveMidiPitchBend.mock.calls[1]?.[0]).toBe('track-1');
+    expect(audioInterfaceMock.setLiveMidiPitchBend.mock.calls[1]?.[0]).toBe('1');
     expect(audioInterfaceMock.setLiveMidiPitchBend.mock.calls[1]?.[1]).toBeCloseTo(8191 / 8192, 5);
   });
+
+  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;
+    };
+
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x01, 0x20]) });
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x02, 0x30]) });
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x07, 0x40]) });
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x0b, 0x50]) });
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x40, 0x7f]) });
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x40, 0x00]) });
+
+    expect(audioInterfaceMock.setLiveMidiExpression).toHaveBeenCalledTimes(4);
+    expect(audioInterfaceMock.setLiveMidiExpression).toHaveBeenNthCalledWith(1, '1', 0x20 / 127);
+    expect(audioInterfaceMock.setLiveMidiExpression).toHaveBeenNthCalledWith(4, '1', 0x50 / 127);
+    expect(audioInterfaceMock.setLiveMidiSustain).toHaveBeenNthCalledWith(1, '1', true);
+    expect(audioInterfaceMock.setLiveMidiSustain).toHaveBeenNthCalledWith(2, '1', false);
+  });
+
+  it('calibrates inverted sustain pedals from the first observed CC64 message', () => {
+    const midiInput = KGMidiInput.instance() as unknown as {
+      handleMIDIMessage: (event: { data: Uint8Array }) => void;
+    };
+
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x40, 0x00]) });
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x40, 0x7f]) });
+
+    expect(audioInterfaceMock.setLiveMidiSustain).toHaveBeenNthCalledWith(1, '1', true);
+    expect(audioInterfaceMock.setLiveMidiSustain).toHaveBeenNthCalledWith(2, '1', false);
+  });
+
+  it('ignores live MIDI input when the selected track is not a MIDI track', () => {
+    getStateMock.mockReturnValue({
+      selectedTrackId: '1',
+      tracks: [new KGAudioTrack('Audio Track', 1)],
+    });
+
+    const midiInput = KGMidiInput.instance() as unknown as {
+      handleMIDIMessage: (event: { data: Uint8Array }) => void;
+    };
+
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0x90, 60, 100]) });
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0xe0, 0x00, 0x40]) });
+    midiInput.handleMIDIMessage({ data: new Uint8Array([0xb0, 0x40, 0x7f]) });
+
+    expect(audioInterfaceMock.triggerLiveMidiNoteAttack).not.toHaveBeenCalled();
+    expect(audioInterfaceMock.setLiveMidiPitchBend).not.toHaveBeenCalled();
+    expect(audioInterfaceMock.setLiveMidiSustain).not.toHaveBeenCalled();
+  });
 });

src/core/midi-input/KGMidiInput.ts

@@ -1,5 +1,6 @@
 import { KGAudioInterface } from '../audio-interface/KGAudioInterface';
 import { useProjectStore } from '../../stores/projectStore';
+import { KGMidiTrack } from '../track/KGMidiTrack';
 
 /**
  * KGMidiInput - MIDI input manager for the DAW
@@ -9,6 +10,12 @@ import { useProjectStore } from '../../stores/projectStore';
 export class KGMidiInput {
   private static readonly PITCH_BEND_CENTER = 8192;
   private static readonly PITCH_BEND_MAX_OFFSET = 8192;
+  private static readonly CONTROL_CHANGE_MODULATION = 1;
+  private static readonly CONTROL_CHANGE_BREATH = 2;
+  private static readonly CONTROL_CHANGE_CHANNEL_VOLUME = 7;
+  private static readonly CONTROL_CHANGE_EXPRESSION = 11;
+  private static readonly CONTROL_CHANGE_SUSTAIN = 64;
+  private static readonly SUSTAIN_ON_THRESHOLD = 64;
 
   // Private static instance for singleton pattern
   private static _instance: KGMidiInput | null = null;
@@ -22,6 +29,8 @@ export class KGMidiInput {
   private onRecordNoteOn: ((pitch: number, velocity: number) => void) | null = null;
   private onRecordNoteOff: ((pitch: number) => void) | null = null;
   private onRecordPitchBend: ((value: number) => void) | null = null;
+  private liveNoteTrackOwnership: Map<number, string[]> = new Map();
+  private sustainPolarityInverted: boolean | null = null;
 
   // Private constructor to prevent direct instantiation
   private constructor() {
@@ -180,7 +189,7 @@ export class KGMidiInput {
     // Control Change: command = 0xB0 (176)
     else if (command === 0xb0) {
       console.log(`MIDI Control Change: controller=${pitch}, value=${velocity}, channel=${channel}`);
-      // TODO: Handle control changes (modulation, sustain pedal, etc.)
+      this.handleControlChange(pitch, velocity);
     }
     // Pitch Bend: command = 0xE0 (224)
     else if (command === 0xe0) {
@@ -196,12 +205,8 @@ export class KGMidiInput {
    */
   private triggerNoteOn(pitch: number, velocity: number): void {
     try {
-      // Get the selected track ID from the store
-      const selectedTrackId = useProjectStore.getState().selectedTrackId;
-
-      // Don't play if no track is selected
+      const selectedTrackId = this.getSelectedMidiTrackId();
       if (!selectedTrackId) {
-        console.log('No track selected - MIDI input ignored');
         return;
       }
 
@@ -217,6 +222,9 @@ export class KGMidiInput {
 
         // Trigger note attack if audio context is ready
         if (audioInterface.getIsAudioContextStarted()) {
+          const latchedTracks = this.liveNoteTrackOwnership.get(pitch) ?? [];
+          latchedTracks.push(selectedTrackId);
+          this.liveNoteTrackOwnership.set(pitch, latchedTracks);
           audioInterface.triggerLiveMidiNoteAttack(selectedTrackId, pitch, velocity);
           console.log(`MIDI triggered note attack: pitch=${pitch}, velocity=${velocity}, track=${selectedTrackId}`);
         }
@@ -231,10 +239,7 @@ export class KGMidiInput {
    */
   private triggerNoteOff(pitch: number): void {
     try {
-      // Get the selected track ID from the store
-      const selectedTrackId = useProjectStore.getState().selectedTrackId;
-
-      // Don't try to release if no track is selected
+      const selectedTrackId = this.consumeLatchedTrackIdForPitch(pitch);
       if (!selectedTrackId) {
         return;
       }
@@ -252,7 +257,7 @@ export class KGMidiInput {
 
   private triggerPitchBend(normalizedBend: number): void {
     try {
-      const selectedTrackId = useProjectStore.getState().selectedTrackId;
+      const selectedTrackId = this.getSelectedMidiTrackId();
       if (!selectedTrackId) {
         return;
       }
@@ -271,6 +276,79 @@ export class KGMidiInput {
     return Math.max(-1, Math.min(1, normalizedBend));
   }
 
+  private handleControlChange(controller: number, value: number): void {
+    const selectedTrackId = this.getSelectedMidiTrackId();
+    if (!selectedTrackId) {
+      return;
+    }
+
+    const audioInterface = KGAudioInterface.instance();
+    if (!audioInterface.getIsInitialized() || !audioInterface.getIsAudioContextStarted()) {
+      return;
+    }
+
+    if (controller === KGMidiInput.CONTROL_CHANGE_SUSTAIN) {
+      audioInterface.setLiveMidiSustain(
+        selectedTrackId,
+        this.normalizeSustainPedalValue(value)
+      );
+      return;
+    }
+
+    if (
+      controller === KGMidiInput.CONTROL_CHANGE_MODULATION ||
+      controller === KGMidiInput.CONTROL_CHANGE_BREATH ||
+      controller === KGMidiInput.CONTROL_CHANGE_CHANNEL_VOLUME ||
+      controller === KGMidiInput.CONTROL_CHANGE_EXPRESSION
+    ) {
+      audioInterface.setLiveMidiExpression(selectedTrackId, value / 127);
+    }
+  }
+
+  private getSelectedMidiTrackId(): string | null {
+    const { selectedTrackId, tracks } = useProjectStore.getState();
+    if (!selectedTrackId) {
+      console.log('No track selected - MIDI input ignored');
+      return null;
+    }
+
+    const selectedTrack = tracks.find((track) => track.getId().toString() === selectedTrackId);
+    if (!(selectedTrack instanceof KGMidiTrack)) {
+      console.log(`Selected track ${selectedTrackId} is not a MIDI track - MIDI input ignored`);
+      return null;
+    }
+
+    return selectedTrackId;
+  }
+
+  private consumeLatchedTrackIdForPitch(pitch: number): string | null {
+    const latchedTracks = this.liveNoteTrackOwnership.get(pitch);
+    if (!latchedTracks || latchedTracks.length === 0) {
+      return null;
+    }
+
+    const trackId = latchedTracks.pop() ?? null;
+    if (latchedTracks.length === 0) {
+      this.liveNoteTrackOwnership.delete(pitch);
+    } else {
+      this.liveNoteTrackOwnership.set(pitch, latchedTracks);
+    }
+
+    return trackId;
+  }
+
+  private normalizeSustainPedalValue(value: number): boolean {
+    const rawPressed = value >= KGMidiInput.SUSTAIN_ON_THRESHOLD;
+
+    if (this.sustainPolarityInverted === null) {
+      // Assume the pedal starts released. The first observed sustain CC therefore
+      // represents a press-down gesture and reveals whether the device is inverted.
+      this.sustainPolarityInverted = !rawPressed;
+    }
+
+    return this.sustainPolarityInverted ? !rawPressed : rawPressed;
+  }
+
   /**
    * Clean up MIDI resources
    */
@@ -289,6 +367,8 @@ export class KGMidiInput {
       }
 
       this.isInitialized = false;
+      this.liveNoteTrackOwnership.clear();
+      this.sustainPolarityInverted = null;
 
       console.log("MIDI resources disposed successfully");
     } catch (error) {

src/test/mocks/tone.ts

@@ -10,6 +10,7 @@ export const MockSampler = vi.fn().mockImplementation(() => ({
   triggerAttackRelease: vi.fn(),
   triggerAttack: vi.fn(),
   triggerRelease: vi.fn(),
+  releaseAll: vi.fn(),
   dispose: vi.fn(),
   loaded: true,
   attack: 0,
@@ -89,9 +90,9 @@ export const MockToneAudioBuffer = vi.fn().mockImplementation(() => ({
 }));
 
 // Mock Gain node
-export const MockGain = vi.fn().mockImplementation(() => ({
+export const MockGain = vi.fn().mockImplementation((initialValue: number = 1) => ({
   gain: {
-    value: 1,
+    value: initialValue,
     setValueAtTime: vi.fn(),
     linearRampToValueAtTime: vi.fn(),
     exponentialRampToValueAtTime: vi.fn()