feat: added split notes function

src/components/Toolbar.test.tsx

@@ -1,5 +1,5 @@
 import React from 'react';
-import { fireEvent, render, screen } from '@testing-library/react';
+import { fireEvent, render, screen, waitFor } from '@testing-library/react';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 import Toolbar from './Toolbar';
 
@@ -52,13 +52,13 @@ const storeState = {
   setShowPianoRoll: vi.fn(),
   activeRegionId: null,
   setActiveRegionId: vi.fn(),
-  selectedRegionIds: [],
+  selectedRegionIds: [] as string[],
   selectedTrackId: null,
   playheadPosition: 0,
   refreshProjectState: vi.fn(),
   requestMainContentScroll: vi.fn(),
   requestPianoRollScroll: vi.fn(),
-  tracks: [],
+  tracks: [] as unknown[],
 };
 
 type StoreState = typeof storeState;
@@ -108,6 +108,14 @@ vi.mock('../core/state/KGMainContentState', () => ({ KGMainContentState: {} }));
 vi.mock('../util/regionDeleteUtil', () => ({ regionDeleteManager: { deleteSelectedRegions: vi.fn(() => false) } }));
 vi.mock('../core/commands/region/SplitRegionCommand', () => ({ SplitRegionCommand: class {} }));
 vi.mock('../core/commands/region/MergeMidiRegionsCommand', () => ({ MergeMidiRegionsCommand: class {} }));
+const regionEditUtilMocks = vi.hoisted(() => ({
+  splitSelectedRegionAtPlayheadMock: vi.fn(),
+  mergeSelectedMidiRegionsMock: vi.fn(),
+}));
+vi.mock('../util/regionEditUtil', () => ({
+  splitSelectedRegionAtPlayhead: regionEditUtilMocks.splitSelectedRegionAtPlayheadMock,
+  mergeSelectedMidiRegions: regionEditUtilMocks.mergeSelectedMidiRegionsMock,
+}));
 vi.mock('../util/copyPasteUtil', () => ({
   handleCopyOperation: vi.fn(() => false),
   handlePasteOperation: vi.fn(() => false),
@@ -135,6 +143,8 @@ vi.mock('../util/dialogUtil', () => ({
 
 describe('Toolbar settings side-panel behavior', () => {
   beforeEach(() => {
+    regionEditUtilMocks.splitSelectedRegionAtPlayheadMock.mockReset();
+    regionEditUtilMocks.mergeSelectedMidiRegionsMock.mockReset();
     storeState.toggleChatBox.mockClear();
     storeState.toggleKGOnePanel.mockClear();
     storeState.toggleEventListPanel.mockClear();
@@ -162,4 +172,25 @@ describe('Toolbar settings side-panel behavior', () => {
     expect(storeState.activateSidePanel).toHaveBeenCalledWith('eventList');
     expect(storeState.toggleEventListPanel).not.toHaveBeenCalled();
   });
+
+  it('routes the split toolbar button through the shared split helper', async () => {
+    storeState.selectedRegionIds = ['region-1'];
+    storeState.playheadPosition = 12;
+    regionEditUtilMocks.splitSelectedRegionAtPlayheadMock.mockResolvedValue('Split 1 note at beat 12.00');
+
+    render(<Toolbar />);
+    fireEvent.click(screen.getByTitle('Split Region at Playhead'));
+
+    await waitFor(() => {
+      expect(regionEditUtilMocks.splitSelectedRegionAtPlayheadMock).toHaveBeenCalledWith({
+        selectedRegionIds: ['region-1'],
+        playheadPosition: 12,
+        refreshProjectState: storeState.refreshProjectState,
+      });
+    });
+
+    await waitFor(() => {
+      expect(storeState.setStatus).toHaveBeenCalledWith('Split 1 note at beat 12.00');
+    });
+  });
 });

src/components/Toolbar.tsx

@@ -16,6 +16,7 @@ import {
 } from 'react-icons/fa';
 import { KGProject, type KeySignature } from '../core/KGProject';
 import { KGMidiInput } from '../core/midi-input/KGMidiInput';
+import { KGMidiRegion } from '../core/region/KGMidiRegion';
 import { KGAudioTrack } from '../core/track/KGAudioTrack';
 import { plainToInstance } from 'class-transformer';
 import { FaPencil, FaCopy, FaPaste, FaTrash, FaWandMagicSparkles, FaListUl } from 'react-icons/fa6';