diff --git a/components/dashboard/Heatmap.mouse-interactivity.test.tsx b/components/dashboard/Heatmap.mouse-interactivity.test.tsx
new file mode 100644
index 000000000..b032cda9c
--- /dev/null
+++ b/components/dashboard/Heatmap.mouse-interactivity.test.tsx
@@ -0,0 +1,144 @@
+import { render, screen, fireEvent } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import Heatmap from './Heatmap';
+import type { ActivityData } from '@/types/dashboard';
+
+// Mock TranslationContext to return translation keys or formatted fallback strings
+vi.mock('@/context/TranslationContext', () => ({
+  useTranslation: () => ({
+    t: (key: string, options?: Record<string, string>) => {
+      if (options?.count && options?.date) {
+        return `${options.count} contributions on ${options.date}`;
+      }
+      return key;
+    },
+  }),
+}));
+
+// Mock VisualizationTooltip component for precise inspection during tests
+vi.mock('./VisualizationTooltip', () => ({
+  default: ({
+    title,
+    children,
+    x,
+    y,
+  }: {
+    title: string;
+    children: React.ReactNode;
+    x: number;
+    y: number;
+  }) => (
+    <div role="tooltip" data-testid="visualization-tooltip" data-x={x} data-y={y}>
+      <div>{title}</div>
+      {children}
+    </div>
+  ),
+}));
+
+// Mock ResizeObserver which is used inside Heatmap.tsx
+global.ResizeObserver = class ResizeObserver {
+  observe() {}
+  unobserve() {}
+  disconnect() {}
+};
+
+describe('Heatmap Mouse Interactivity & Touch Event Propagation', () => {
+  const mockData: ActivityData[] = [
+    { date: '2026-06-01', count: 5, intensity: 3 },
+    { date: '2026-06-02', count: 0, intensity: 0 },
+  ];
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  // Test 1: Tooltip display & computed coordinates on mouseenter / hover
+  it('displays tooltip with computed coordinates on mouseenter over a grid cell', async () => {
+    render(<Heatmap data={mockData} />);
+
+    const gridCell = screen.getAllByRole('gridcell')[0];
+
+    // Mock bounding rectangle for coordinate calculations
+    vi.spyOn(gridCell, 'getBoundingClientRect').mockReturnValue({
+      left: 100,
+      top: 200,
+      width: 14,
+      height: 14,
+      right: 114,
+      bottom: 214,
+      x: 100,
+      y: 200,
+      toJSON: () => {},
+    });
+
+    await userEvent.hover(gridCell);
+
+    const tooltip = screen.getByTestId('visualization-tooltip');
+    expect(tooltip).toBeInTheDocument();
+
+    // Check calculated tooltip coordinates (x = 100 + 14/2 = 107, y = 200 - 10 = 190)
+    expect(tooltip).toHaveAttribute('data-x', '107');
+    expect(tooltip).toHaveAttribute('data-y', '190');
+    // formatTooltipDate formats '2026-06-01' -> 'Jun 1, 2026'
+    expect(tooltip).toHaveTextContent('5 contributions on Jun 1, 2026');
+  });
+
+  // Test 2: Hide tooltip on mouseleave
+  it('hides the temporary tooltip visual overlay on mouseleave', async () => {
+    render(<Heatmap data={mockData} />);
+
+    const gridCell = screen.getAllByRole('gridcell')[0];
+
+    await userEvent.hover(gridCell);
+    expect(screen.getByTestId('visualization-tooltip')).toBeInTheDocument();
+
+    await userEvent.unhover(gridCell);
+    expect(screen.queryByTestId('visualization-tooltip')).not.toBeInTheDocument();
+  });
+
+  // Test 3: Cursor styles and interactive feedback classes
+  it('applies interactive cursor classes (cursor-pointer) and focus styles to grid cells', () => {
+    render(<Heatmap data={mockData} />);
+
+    const gridCell = screen.getAllByRole('gridcell')[0];
+
+    expect(gridCell).toHaveClass('cursor-pointer');
+    expect(gridCell).toHaveClass('hover:scale-125');
+  });
+
+  // Test 4: Focus and Blur interactivity (Keyboard/Touch Accessibility)
+  it('shows and hides tooltip on focus and blur events for accessibility', () => {
+    render(<Heatmap data={mockData} />);
+
+    const gridCell = screen.getAllByRole('gridcell')[0];
+
+    fireEvent.focus(gridCell);
+    expect(screen.getByTestId('visualization-tooltip')).toBeInTheDocument();
+
+    fireEvent.blur(gridCell);
+    expect(screen.queryByTestId('visualization-tooltip')).not.toBeInTheDocument();
+  });
+
+  // Test 5: Touch gesture and event propagation on cell interaction
+  it('handles touch/click gesture propagation without throwing errors', () => {
+    const handleClick = vi.fn();
+
+    render(
+      <div onClick={handleClick}>
+        <Heatmap data={mockData} />
+      </div>
+    );
+
+    const gridCell = screen.getAllByRole('gridcell')[0];
+
+    // Trigger touchStart event
+    fireEvent.touchStart(gridCell, {
+      touches: [{ clientX: 105, clientY: 205 }],
+    });
+
+    // Trigger click to check propagation to parent containers
+    fireEvent.click(gridCell);
+    expect(handleClick).toHaveBeenCalledTimes(1);
+  });
+});