feat: added an option to allow user choose whether to trim leading silence when bouncing audio

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

@@ -1,7 +1,37 @@
-import { describe, it, expect } from 'vitest';
-import { applyOfflinePitchBendAutomation, encodeWav, getOfflineTrackGain, getOfflineTrackVolumeDb } from './KGOfflineRenderer';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { createMockMidiNote, createMockMidiRegion, createMockMidiTrack, createMockProject } from '../../test/utils/mock-data';
 import { bakeMidiAutomationPointsInWindow } from '../../util/midiAutomationUtil';
 
+const { offlineMock, configGetMock } = vi.hoisted(() => ({
+  offlineMock: vi.fn(),
+  configGetMock: vi.fn(),
+}));
+
+vi.mock('tone', () => ({
+  Offline: offlineMock,
+}));
+
+vi.mock('./KGAudioInterface', () => ({
+  KGAudioInterface: {
+    instance: vi.fn(() => ({
+      getTrackVolume: vi.fn().mockReturnValue(0),
+      getTrackMuted: vi.fn().mockReturnValue(false),
+      getTrackSolo: vi.fn().mockReturnValue(false),
+      getAudioBuffer: vi.fn().mockReturnValue(null),
+    })),
+  },
+}));
+
+vi.mock('../config/ConfigManager', () => ({
+  ConfigManager: {
+    instance: vi.fn(() => ({
+      get: configGetMock,
+    })),
+  },
+}));
+
+import { KGOfflineRenderer, applyOfflinePitchBendAutomation, encodeWav, getOfflineTrackGain, getOfflineTrackVolumeDb } from './KGOfflineRenderer';
+
 /**
  * Create a minimal AudioBuffer-like object for testing.
  * In the jsdom test environment, AudioBuffer is not available,
@@ -228,3 +258,77 @@ describe('offline pitch bend automation', () => {
     expect(calls[0][1]).toBe(0.26);
   });
 });
+
+describe('renderToBuffer bounce range', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    configGetMock.mockImplementation((key: string) => {
+      if (key === 'audio.bounce_starts_from_beat_1') return true;
+      if (key === 'audio.midi_automation_interpolation_interval_ms') return 10;
+      return null;
+    });
+    offlineMock.mockResolvedValue({
+      duration: 0,
+      numberOfChannels: 2,
+      get: vi.fn(),
+    });
+    ;(KGOfflineRenderer as unknown as { _instance: KGOfflineRenderer | null })._instance = null;
+  });
+
+  it('starts non-looping bounce at beat 0 when configured to include leading silence', async () => {
+    const region = createMockMidiRegion({
+      startFromBeat: 8,
+      notes: [createMockMidiNote({ startBeat: 0, endBeat: 4 })],
+    });
+    const track = createMockMidiTrack({ id: 1, regions: [region] });
+    const project = createMockProject({ bpm: 120, tracks: [track] });
+
+    await KGOfflineRenderer.instance().renderToBuffer(project, { tailSeconds: 0 });
+
+    expect(offlineMock).toHaveBeenCalledWith(expect.any(Function), 6, 2, 44100);
+  });
+
+  it('starts non-looping bounce at first content when the setting is disabled', async () => {
+    configGetMock.mockImplementation((key: string) => {
+      if (key === 'audio.bounce_starts_from_beat_1') return false;
+      if (key === 'audio.midi_automation_interpolation_interval_ms') return 10;
+      return null;
+    });
+
+    const region = createMockMidiRegion({
+      startFromBeat: 8,
+      notes: [createMockMidiNote({ startBeat: 0, endBeat: 4 })],
+    });
+    const track = createMockMidiTrack({ id: 1, regions: [region] });
+    const project = createMockProject({ bpm: 120, tracks: [track] });
+
+    await KGOfflineRenderer.instance().renderToBuffer(project, { tailSeconds: 0 });
+
+    expect(offlineMock).toHaveBeenCalledWith(expect.any(Function), 2, 2, 44100);
+  });
+
+  it('keeps looping bounce bounds regardless of the beat-1 setting', async () => {
+    configGetMock.mockImplementation((key: string) => {
+      if (key === 'audio.bounce_starts_from_beat_1') return false;
+      if (key === 'audio.midi_automation_interpolation_interval_ms') return 10;
+      return null;
+    });
+
+    const project = createMockProject({ bpm: 120, tracks: [] });
+    project.setIsLooping(true);
+    project.setLoopingRange([2, 5]);
+
+    await KGOfflineRenderer.instance().renderToBuffer(project, { tailSeconds: 0 });
+
+    expect(offlineMock).toHaveBeenCalledWith(expect.any(Function), 8, 2, 44100);
+  });
+
+  it('falls back to the full project length when there is no renderable content', async () => {
+    const project = createMockProject({ bpm: 120, tracks: [] });
+    project.setMaxBars(16);
+
+    await KGOfflineRenderer.instance().renderToBuffer(project, { tailSeconds: 0 });
+
+    expect(offlineMock).toHaveBeenCalledWith(expect.any(Function), 32, 2, 44100);
+  });
+});

src/core/audio-interface/KGOfflineRenderer.ts

@@ -99,6 +99,7 @@ export class KGOfflineRenderer {
 
     let renderStartBeat = 0;
     let renderEndBeat: number;
+    const bounceStartsFromBeat1 = (ConfigManager.instance().get('audio.bounce_starts_from_beat_1') as boolean) ?? true;
 
     const isLooping = project.getIsLooping();
     // Looping range is determined up-front; non-looping range is computed
@@ -272,7 +273,7 @@ export class KGOfflineRenderer {
       }
 
       if (contentEnd > 0) {
-        renderStartBeat = contentStart;
+        renderStartBeat = bounceStartsFromBeat1 ? 0 : contentStart;
         renderEndBeat = contentEnd;
       }
       // else: no content found, keep the full project range as fallback

src/core/config-upgrader/KGConfigUpgrader.ts

@@ -3,6 +3,7 @@ import { CONFIG_UPGRADER_CONSTANTS } from '../../constants/coreConstants';
 import { upgradeConfigToV1 } from './upgradeConfigToV1';
 import { upgradeConfigToV2 } from './upgradeConfigToV2';
 import { upgradeConfigToV3 } from './upgradeConfigToV3';
+import { upgradeConfigToV4 } from './upgradeConfigToV4';
 
 /**
  * KGConfigUpgrader — Orchestrates app-level migrations (e.g., storage backend changes).
@@ -43,6 +44,10 @@ export class KGConfigUpgrader {
           await upgradeConfigToV3();
           break;
         }
+        case 4: {
+          await upgradeConfigToV4();
+          break;
+        }
         default: {
           throw new Error(`No config upgrader found for version ${nextVersion}`);
         }

src/core/config-upgrader/upgradeConfigToV4.test.ts

@@ -0,0 +1,64 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+const getRawMock = vi.fn();
+const saveRawMock = vi.fn();
+
+vi.mock('../io/KGConfigStorage', () => ({
+  KGConfigStorage: {
+    getInstance: vi.fn(() => ({
+      getRaw: getRawMock,
+      saveRaw: saveRawMock,
+    })),
+  },
+}));
+
+import { upgradeConfigToV4 } from './upgradeConfigToV4';
+
+describe('upgradeConfigToV4', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('creates the audio config and defaults bounce_starts_from_beat_1 to true when audio is missing', async () => {
+    const config: Record<string, unknown> = {
+      general: {},
+    };
+    getRawMock.mockResolvedValue(config);
+
+    await upgradeConfigToV4();
+
+    expect(config.audio).toEqual({ bounce_starts_from_beat_1: true });
+    expect(saveRawMock).toHaveBeenCalledWith('userConfig', config);
+  });
+
+  it('defaults bounce_starts_from_beat_1 to true when the key is missing', async () => {
+    const config: Record<string, unknown> = {
+      audio: {
+        playback_delay: 0.2,
+      },
+    };
+    getRawMock.mockResolvedValue(config);
+
+    await upgradeConfigToV4();
+
+    expect(config.audio).toEqual({
+      playback_delay: 0.2,
+      bounce_starts_from_beat_1: true,
+    });
+    expect(saveRawMock).toHaveBeenCalledWith('userConfig', config);
+  });
+
+  it('preserves an explicit false value', async () => {
+    const config: Record<string, unknown> = {
+      audio: {
+        bounce_starts_from_beat_1: false,
+      },
+    };
+    getRawMock.mockResolvedValue(config);
+
+    await upgradeConfigToV4();
+
+    expect(saveRawMock).not.toHaveBeenCalled();
+    expect((config.audio as Record<string, unknown>).bounce_starts_from_beat_1).toBe(false);
+  });
+});

src/core/config-upgrader/upgradeConfigToV4.ts

@@ -0,0 +1,30 @@
+import { KGConfigStorage } from '../io/KGConfigStorage';
+
+const CONFIG_KEY = 'userConfig';
+
+export async function upgradeConfigToV4(): Promise<void> {
+  const storage = KGConfigStorage.getInstance();
+  const rawConfig = await storage.getRaw(CONFIG_KEY);
+  if (!rawConfig || typeof rawConfig !== 'object') {
+    return;
+  }
+
+  const config = rawConfig as Record<string, unknown>;
+  const audio = config.audio;
+
+  if (!audio || typeof audio !== 'object') {
+    config.audio = {
+      bounce_starts_from_beat_1: true,
+    };
+    await storage.saveRaw(CONFIG_KEY, config);
+    return;
+  }
+
+  const audioRecord = audio as Record<string, unknown>;
+  if ('bounce_starts_from_beat_1' in audioRecord) {
+    return;
+  }
+
+  audioRecord.bounce_starts_from_beat_1 = true;
+  await storage.saveRaw(CONFIG_KEY, config);
+}

src/core/config/ConfigManager.ts

@@ -80,6 +80,7 @@ interface AppConfig {
     default_open: boolean;
   };
   audio: {
+    bounce_starts_from_beat_1: boolean;
     enable_audio_capture_for_screen_sharing: boolean;
     input_device_id: string;
     lookahead_time: number;
@@ -260,6 +261,7 @@ export class ConfigManager {
           default_open: true
         },
         audio: {
+          bounce_starts_from_beat_1: true,
           enable_audio_capture_for_screen_sharing: false,
           input_device_id: 'default',
           lookahead_time: 0.05,