feat: added mock up global tracks

src/components/MainContent.css

@@ -180,6 +180,113 @@
   min-height: fit-content;
 }
 
+.global-tracks-section {
+  display: flex;
+  position: relative;
+  z-index: 1003;
+}
+
+.global-tracks-info-shell,
+.global-tracks-grid-shell {
+  max-height: calc(var(--global-track-count) * var(--global-track-height));
+  opacity: 1;
+  transform: translateY(0);
+  transition:
+    max-height 0.22s ease,
+    opacity 0.18s ease,
+    transform 0.22s ease;
+  will-change: max-height, opacity, transform;
+}
+
+.global-tracks-info-shell {
+  position: sticky;
+  left: 0;
+  width: var(--track-info-panel-width);
+  z-index: 1003;
+  overflow: hidden;
+  align-self: flex-start;
+}
+
+.global-tracks-grid-shell {
+  overflow: hidden;
+}
+
+.global-tracks-info-shell.collapsed,
+.global-tracks-grid-shell.collapsed {
+  max-height: 0;
+  opacity: 0;
+  transform: translateY(-8px);
+  pointer-events: none;
+}
+
+.global-tracks-info {
+  width: var(--track-info-panel-width);
+  background-color: #2d2d2d;
+  border-right: 1px solid #3a3a3a;
+}
+
+.global-track-info-row {
+  height: var(--global-track-height);
+  padding: 0 10px 0 12px;
+  border-bottom: 1px solid #3a3a3a;
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  box-sizing: border-box;
+  color: #e0e0e0;
+  background-color: #4a4a4a;
+}
+
+.global-track-name {
+  font-size: 11px;
+  font-weight: 500;
+  letter-spacing: 0.01em;
+}
+
+.global-track-add-button {
+  width: 16px;
+  height: 16px;
+  border: 1px solid #e0e0e0;
+  border-radius: 999px;
+  background: transparent;
+  color: #e0e0e0;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0;
+  cursor: default;
+}
+
+.global-track-add-button svg {
+  font-size: 9px;
+}
+
+.global-track-add-button:focus,
+.global-track-add-button:focus-visible {
+  outline: none;
+  box-shadow: none;
+}
+
+.global-tracks-grid {
+  min-width: calc(var(--max-number-of-bars) * var(--track-grid-bar-width));
+  background-color: #2d2d2d;
+}
+
+.global-track-grid-row {
+  height: var(--global-track-height);
+  min-width: calc(var(--max-number-of-bars) * var(--track-grid-bar-width));
+  box-sizing: border-box;
+  border-bottom: 1px solid #3a3a3a;
+  background-color: #2d2d2d;
+  background-size: var(--track-grid-bar-width) var(--global-track-height);
+  background-image: linear-gradient(
+    to right,
+    transparent calc(var(--track-grid-bar-width) - 1px),
+    #3a3a3a calc(var(--track-grid-bar-width) - 1px),
+    #3a3a3a var(--track-grid-bar-width)
+  );
+}
+
 .info-container {
   position: sticky;
   left: 0;

src/components/MainContent.test.tsx

@@ -301,4 +301,52 @@ describe('MainContent', () => {
     fireEvent.click(globalTracksButton);
     expect(globalTracksButton.className).not.toContain('active');
   });
+
+  it('renders the four mock global tracks only when toggled on', () => {
+    render(<MainContent />);
+
+    expect(screen.queryByText('Marker')).not.toBeInTheDocument();
+    expect(screen.queryByText('Tempo')).not.toBeInTheDocument();
+    expect(screen.queryByText('Signature')).not.toBeInTheDocument();
+    expect(screen.queryByText('Chord')).not.toBeInTheDocument();
+
+    fireEvent.click(screen.getByRole('button', { name: 'Show global tracks' }));
+
+    expect(screen.getByText('Marker')).toBeInTheDocument();
+    expect(screen.getByText('Tempo')).toBeInTheDocument();
+    expect(screen.getByText('Signature')).toBeInTheDocument();
+    expect(screen.getByText('Chord')).toBeInTheDocument();
+
+    const globalTracksInfoShell = screen.getByRole('button', { name: 'Add Marker global track item' }).closest('.global-tracks-info-shell') as HTMLElement;
+
+    fireEvent.click(screen.getByRole('button', { name: 'Show global tracks' }));
+    fireEvent.transitionEnd(globalTracksInfoShell);
+
+    expect(screen.queryByText('Marker')).not.toBeInTheDocument();
+    expect(screen.queryByText('Tempo')).not.toBeInTheDocument();
+    expect(screen.queryByText('Signature')).not.toBeInTheDocument();
+    expect(screen.queryByText('Chord')).not.toBeInTheDocument();
+  });
+
+  it('renders visual-only add buttons for mock global tracks without mutating track state', () => {
+    render(<MainContent />);
+
+    fireEvent.click(screen.getByRole('button', { name: 'Show global tracks' }));
+
+    const addButtons = [
+      screen.getByRole('button', { name: 'Add Marker global track item' }),
+      screen.getByRole('button', { name: 'Add Tempo global track item' }),
+      screen.getByRole('button', { name: 'Add Signature global track item' }),
+      screen.getByRole('button', { name: 'Add Chord global track item' }),
+    ];
+
+    expect(addButtons).toHaveLength(4);
+
+    addButtons.forEach(button => {
+      fireEvent.click(button);
+    });
+
+    expect(storeState.addTrack).not.toHaveBeenCalled();
+    expect(storeState.addAudioTrack).not.toHaveBeenCalled();
+  });
 });

src/components/MainContent.tsx

@@ -25,6 +25,18 @@ interface MainContentProps {
   onTrackClick?: () => void;
 }
 
+interface GlobalTrackDefinition {
+  id: 'marker' | 'tempo' | 'signature' | 'chord';
+  label: string;
+}
+
+const GLOBAL_TRACKS: GlobalTrackDefinition[] = [
+  { id: 'marker', label: 'Marker' },
+  { id: 'tempo', label: 'Tempo' },
+  { id: 'signature', label: 'Signature' },
+  { id: 'chord', label: 'Chord' },
+];
+
 const MainContent: React.FC<MainContentProps> = ({
   onTrackClick = () => { } // Default to empty function if not provided
 }) => {
@@ -81,6 +93,8 @@ const MainContent: React.FC<MainContentProps> = ({
   const [selectedRegionId, setSelectedRegionId] = useState<string | null>(null);
   const [showCreateTrackModal, setShowCreateTrackModal] = useState(false);
   const [showGlobalTracksMock, setShowGlobalTracksMock] = useState(false);
+  const [renderGlobalTracksMock, setRenderGlobalTracksMock] = useState(false);
+  const [animateGlobalTracksMock, setAnimateGlobalTracksMock] = useState(false);
 
   // Use the region operations hook
   const { deleteSelectedRegions } = useRegionOperations({
@@ -1004,6 +1018,29 @@ const MainContent: React.FC<MainContentProps> = ({
   const { showInstrumentSelection, isLooping, loopingRange } = useProjectStore();
   const beatTicksPerBar = Math.max(0, timeSignature.numerator - 1);
 
+  const handleToggleGlobalTracksMock = (e: React.MouseEvent<HTMLButtonElement>) => {
+    e.stopPropagation();
+
+    if (!showGlobalTracksMock) {
+      setRenderGlobalTracksMock(true);
+      setShowGlobalTracksMock(true);
+      return;
+    }
+
+    setAnimateGlobalTracksMock(false);
+    setShowGlobalTracksMock(false);
+  };
+
+  useEffect(() => {
+    if (!renderGlobalTracksMock || !showGlobalTracksMock || animateGlobalTracksMock) return;
+
+    const frame = requestAnimationFrame(() => {
+      setAnimateGlobalTracksMock(true);
+    });
+
+    return () => cancelAnimationFrame(frame);
+  }, [renderGlobalTracksMock, showGlobalTracksMock, animateGlobalTracksMock]);
+
   // Helper function to check if a bar (0-indexed) is in the loop range
   const isBarInLoopRange = (barIndex: number): boolean => {
     if (!isLooping) return false;
@@ -1036,10 +1073,7 @@ const MainContent: React.FC<MainContentProps> = ({
               className={`track-header-button${showGlobalTracksMock ? ' active' : ''}`}
               aria-label="Show global tracks"
               title="Show global tracks"
-              onClick={(e) => {
+              onClick={handleToggleGlobalTracksMock}
-                e.stopPropagation();
-                setShowGlobalTracksMock(prev => !prev);
-              }}
             >
               <FaSquareArrowUpRight />
             </button>
@@ -1073,6 +1107,54 @@ const MainContent: React.FC<MainContentProps> = ({
           ))}
         </div>
 
+        {renderGlobalTracksMock && (
+          <div
+            className="global-tracks-section"
+            aria-label="Global tracks"
+            aria-hidden={!showGlobalTracksMock}
+            style={{ ['--global-track-count' as string]: String(GLOBAL_TRACKS.length) }}
+          >
+            <div
+              className={`global-tracks-info-shell${animateGlobalTracksMock ? ' expanded' : ' collapsed'}`}
+              onTransitionEnd={() => {
+                if (!showGlobalTracksMock) {
+                  setRenderGlobalTracksMock(false);
+                }
+              }}
+            >
+              <div className="global-tracks-info">
+                {GLOBAL_TRACKS.map(track => (
+                  <div key={track.id} className="global-track-info-row">
+                    <span className="global-track-name">{track.label}</span>
+                    <button
+                      type="button"
+                      className="global-track-add-button"
+                      aria-label={`Add ${track.label} global track item`}
+                      title={`Add ${track.label} global track item`}
+                      onClick={(e) => {
+                        e.preventDefault();
+                        e.stopPropagation();
+                      }}
+                    >
+                      <FaPlus />
+                    </button>
+                  </div>
+                ))}
+              </div>
+            </div>
+            <div className={`global-tracks-grid-shell${animateGlobalTracksMock ? ' expanded' : ' collapsed'}`}>
+              <div className="global-tracks-grid" aria-hidden="true">
+                {GLOBAL_TRACKS.map(track => (
+                  <div
+                    key={track.id}
+                    className="global-track-grid-row"
+                  />
+                ))}
+              </div>
+            </div>
+          </div>
+        )}
+
         <div className="main-content-body" onClick={handleEmptyMainContentClick}>
           {/* Fixed left panel with track info */}
           <TrackInfoPanel

src/components/common/Playhead.tsx

@@ -55,7 +55,7 @@ const Playhead: React.FC<PlayheadProps> = ({ context, pixelPositionOverride }) =
     bottom: 0,
     width: '2px',
     backgroundColor: '#4ECDC4', // Blue-green color similar to the reference image
-    zIndex: 1000,
+    zIndex: 150,
     pointerEvents: 'none', // Allow clicks to pass through
     boxShadow: '0 0 4px rgba(78, 205, 196, 0.5)', // Subtle glow effect
   };
@@ -70,7 +70,7 @@ const Playhead: React.FC<PlayheadProps> = ({ context, pixelPositionOverride }) =
     borderLeft: '6px solid transparent',
     borderRight: '6px solid transparent',
     borderTop: '8px solid #4ECDC4',
-    zIndex: 1001,
+    zIndex: 151,
     pointerEvents: 'none',
   };
 

src/styles/variables.css

@@ -3,6 +3,7 @@
   --max-number-of-bars: 32;
   --track-grid-bar-width: 40px;
   --track-info-panel-width: 200px;
+  --global-track-height: 20px;
   --region-piano-key-width: 60px;
   --region-piano-key-height: 20px;
   --region-grid-beat-width: 40px;