diff --git a/apps/web/src/components/dashboard/widgets/stopwatch-widget.test.tsx b/apps/web/src/components/dashboard/widgets/stopwatch-widget.test.tsx
new file mode 100644
index 0000000..a58a3f8
--- /dev/null
+++ b/apps/web/src/components/dashboard/widgets/stopwatch-widget.test.tsx
@@ -0,0 +1,198 @@
+import { act, fireEvent, render, screen } from '@testing-library/react';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+// Mock next-intl — passthrough t(key) => key
+vi.mock('next-intl', () => ({
+  useTranslations: () => (key: string) => key,
+}));
+
+// Mock @/lib/dashboard-api — spy on updateWidgetConfig
+vi.mock('@/lib/dashboard-api', () => ({
+  updateWidgetConfig: vi.fn().mockResolvedValue(undefined),
+}));
+
+// Import mocked function for assertions
+import { updateWidgetConfig } from '@/lib/dashboard-api';
+
+// Must import AFTER mocks
+import { StopwatchWidget } from './stopwatch-widget';
+
+describe('StopwatchWidget', () => {
+  beforeEach(() => {
+    // Use fake timers for deterministic testing
+    vi.useFakeTimers();
+    vi.clearAllMocks();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+    vi.restoreAllMocks();
+  });
+
+  it('renders 00:00 and Start button with empty config', () => {
+    render(<StopwatchWidget instanceId="sw-1" config={{}} isEditMode={false} />);
+
+    expect(screen.getByTestId('stopwatch-display')).toHaveTextContent('00:00');
+    // Button with accessible name matching the translation key 'stopwatch.start'
+    expect(
+      screen.getByRole('button', { name: /stopwatch\.start/i }),
+    ).toBeInTheDocument();
+  });
+
+  it('clicking Start persists state=running with startedAt ISO string', async () => {
+    render(<StopwatchWidget instanceId="sw-1" config={{}} isEditMode={false} />);
+
+    const startBtn = screen.getByRole('button', { name: /stopwatch\.start/i });
+    await act(async () => {
+      fireEvent.click(startBtn);
+    });
+
+    expect(updateWidgetConfig).toHaveBeenCalledWith(
+      'sw-1',
+      expect.objectContaining({
+        state: 'running',
+        startedAt: expect.stringMatching(/^\d{4}-\d{2}-\d{2}T/),
+      }),
+      expect.anything(),
+    );
+  });
+
+  it('advances display after 3000ms while running', async () => {
+    render(<StopwatchWidget instanceId="sw-1" config={{}} isEditMode={false} />);
+
+    await act(async () => {
+      fireEvent.click(screen.getByRole('button', { name: /stopwatch\.start/i }));
+    });
+
+    await act(async () => {
+      vi.advanceTimersByTime(3000);
+    });
+
+    const display = screen.getByTestId('stopwatch-display').textContent ?? '';
+    // Display should show 00:03 (or similar — just not 00:00)
+    expect(display).not.toBe('00:00');
+  });
+
+  it('Stop/Pause freezes display and persists state=paused', async () => {
+    render(<StopwatchWidget instanceId="sw-1" config={{}} isEditMode={false} />);
+
+    // Start the stopwatch
+    await act(async () => {
+      fireEvent.click(screen.getByRole('button', { name: /stopwatch\.start/i }));
+    });
+
+    await act(async () => {
+      vi.advanceTimersByTime(2000);
+    });
+
+    // Stop it
+    await act(async () => {
+      fireEvent.click(screen.getByRole('button', { name: /stopwatch\.stop/i }));
+    });
+
+    expect(updateWidgetConfig).toHaveBeenLastCalledWith(
+      'sw-1',
+      expect.objectContaining({
+        state: 'paused',
+        startedAt: null,
+        elapsed: expect.any(Number),
+      }),
+      expect.anything(),
+    );
+  });
+
+  it('Reset returns display to 00:00 and persists state=stopped with elapsed=0 laps=[]', async () => {
+    render(<StopwatchWidget instanceId="sw-1" config={{}} isEditMode={false} />);
+
+    await act(async () => {
+      fireEvent.click(screen.getByRole('button', { name: /stopwatch\.start/i }));
+    });
+
+    await act(async () => {
+      vi.advanceTimersByTime(1500);
+    });
+
+    await act(async () => {
+      fireEvent.click(screen.getByRole('button', { name: /stopwatch\.reset/i }));
+    });
+
+    expect(screen.getByTestId('stopwatch-display')).toHaveTextContent('00:00');
+    expect(updateWidgetConfig).toHaveBeenLastCalledWith(
+      'sw-1',
+      expect.objectContaining({
+        state: 'stopped',
+        startedAt: null,
+        elapsed: 0,
+        laps: [],
+      }),
+      expect.anything(),
+    );
+  });
+
+  it('Lap while running appends elapsed to laps list', async () => {
+    render(<StopwatchWidget instanceId="sw-1" config={{}} isEditMode={false} />);
+
+    await act(async () => {
+      fireEvent.click(screen.getByRole('button', { name: /stopwatch\.start/i }));
+    });
+
+    await act(async () => {
+      vi.advanceTimersByTime(1000);
+    });
+
+    await act(async () => {
+      fireEvent.click(screen.getByRole('button', { name: /stopwatch\.lap/i }));
+    });
+
+    // At least one lap entry visible
+    expect(updateWidgetConfig).toHaveBeenLastCalledWith(
+      'sw-1',
+      expect.objectContaining({
+        laps: expect.arrayContaining([expect.any(Number)]),
+      }),
+      expect.anything(),
+    );
+
+    // Lap entry rendered in the DOM
+    const lapItems = screen.getAllByRole('listitem');
+    expect(lapItems.length).toBeGreaterThanOrEqual(1);
+  });
+
+  it('reload reconstruction: renders ~7000ms elapsed from config with startedAt 5s ago', async () => {
+    // Fix system time so Date.now() is deterministic
+    const fixedNow = new Date('2026-07-01T12:00:00.000Z');
+    vi.setSystemTime(fixedNow);
+
+    // startedAt is 5 seconds before fixedNow
+    const startedAt = new Date(fixedNow.getTime() - 5000).toISOString();
+
+    // Render with a running config: 2000ms already accumulated + 5s since startedAt = ~7000ms total
+    render(
+      <StopwatchWidget
+        instanceId="sw-reload"
+        config={{
+          state: 'running',
+          startedAt,
+          elapsed: 2000,
+          laps: [],
+        }}
+        isEditMode={false}
+      />,
+    );
+
+    // Tick the interval once
+    await act(async () => {
+      vi.advanceTimersByTime(100);
+    });
+
+    const display = screen.getByTestId('stopwatch-display').textContent ?? '';
+    // 7000ms = 7 seconds → should show 00:07
+    // More precisely: display must not show 00:00, 00:01, or 00:02 (which would ignore startedAt)
+    // Accept any display > 5s
+    const parts = display.split(':');
+    const seconds = parseInt(parts[parts.length - 1] ?? '0', 10);
+    const minutes = parseInt(parts[parts.length - 2] ?? '0', 10);
+    const totalSeconds = minutes * 60 + seconds;
+    expect(totalSeconds).toBeGreaterThanOrEqual(5);
+  });
+});