diff --git a/src/tui/components/WorkerGrid.test.ts b/src/tui/components/WorkerGrid.test.ts
new file mode 100644
index 0000000..83cfa80
--- /dev/null
+++ b/src/tui/components/WorkerGrid.test.ts
@@ -0,0 +1,486 @@
+/**
+ * Tests for WorkerGrid Component
+ *
+ * Tests the worker grid display with mocked blessed elements.
+ */
+
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import * as blessed from 'blessed';
+
+// Mock the blessed module before importing WorkerGrid
+vi.mock('blessed', () => {
+  // Create the mock box inside the factory
+  const mockBoxInstance = {
+    setContent: vi.fn(),
+    focus: vi.fn(),
+    key: vi.fn(),
+    screen: {
+      render: vi.fn(),
+    },
+  };
+
+  const mockBox = vi.fn(() => mockBoxInstance);
+
+  return {
+    default: {
+      box: mockBox,
+    },
+    box: mockBox,
+  };
+});
+
+// Import after mocking
+import { WorkerGrid } from './WorkerGrid.js';
+import { WorkerInfo } from '../../types.js';
+
+// Helper to create mock WorkerInfo
+function createMockWorker(overrides: Partial<WorkerInfo> = {}): WorkerInfo {
+  return {
+    id: 'w-test123',
+    status: 'active',
+    beadsCompleted: 5,
+    firstSeen: Date.now() - 60000,
+    lastActivity: Date.now(),
+    activeFiles: [],
+    hasCollision: false,
+    activeDirectories: [],
+    collisionTypes: [],
+    ...overrides,
+  };
+}
+
+// Helper to create mock screen
+function createMockScreen() {
+  return {
+    render: vi.fn(),
+    append: vi.fn(),
+    key: vi.fn(),
+    destroy: vi.fn(),
+  } as unknown as blessed.Widgets.Screen;
+}
+
+describe('WorkerGrid', () => {
+  let workerGrid: WorkerGrid;
+  let mockScreen: blessed.Widgets.Screen;
+  let mockBoxInstance: any;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+
+    mockScreen = createMockScreen();
+
+    // Get the mock box instance from the mock
+    const blessedMock = blessed as unknown as { box: vi.Mock };
+    mockBoxInstance = blessedMock.box();
+
+    workerGrid = new WorkerGrid({
+      parent: mockScreen,
+      top: 0,
+      left: 0,
+      width: '50%',
+      bottom: 0,
+    });
+  });
+
+  afterEach(() => {
+    vi.clearAllMocks();
+  });
+
+  describe('constructor', () => {
+    it('should create a blessed box with correct options', () => {
+      const blessedMock = blessed as unknown as { box: vi.Mock };
+      expect(blessedMock.box).toHaveBeenCalledWith(
+        expect.objectContaining({
+          parent: mockScreen,
+          top: 0,
+          left: 0,
+          width: '50%',
+          bottom: 0,
+          label: ' Workers ',
+          scrollable: true,
+          alwaysScroll: true,
+          keys: true,
+          vi: true,
+          mouse: true,
+        })
+      );
+    });
+
+    it('should bind key handlers on construction', () => {
+      // Key bindings should be registered
+      expect(mockBoxInstance.key).toHaveBeenCalled();
+    });
+  });
+
+  describe('updateWorkers', () => {
+    it('should update workers list and render', () => {
+      const workers = [
+        createMockWorker({ id: 'w-abc123', status: 'active' }),
+        createMockWorker({ id: 'w-def456', status: 'idle' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      expect(mockBoxInstance.setContent).toHaveBeenCalled();
+      // Component calls this.box.screen.render() which is the box's internal screen reference
+      expect(mockBoxInstance.screen.render).toHaveBeenCalled();
+    });
+
+    it('should show "No workers detected" when empty', () => {
+      workerGrid.updateWorkers([]);
+
+      expect(mockBoxInstance.setContent).toHaveBeenCalledWith(
+        expect.stringContaining('No workers detected')
+      );
+    });
+
+    it('should show worker count in header', () => {
+      const workers = [
+        createMockWorker({ id: 'w-abc123' }),
+        createMockWorker({ id: 'w-def456' }),
+        createMockWorker({ id: 'w-ghi789' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      expect(mockBoxInstance.setContent).toHaveBeenCalledWith(
+        expect.stringContaining('Total: 3 workers')
+      );
+    });
+
+    it('should reset selected index if out of bounds', () => {
+      // First set some workers
+      workerGrid.updateWorkers([
+        createMockWorker({ id: 'w-1' }),
+        createMockWorker({ id: 'w-2' }),
+      ]);
+
+      // Update to fewer workers
+      workerGrid.updateWorkers([createMockWorker({ id: 'w-1' })]);
+
+      // Should not throw and selection should be valid
+      const selected = workerGrid.getSelected();
+      expect(selected).toBeDefined();
+      expect(selected?.id).toBe('w-1');
+    });
+  });
+
+  describe('selectNext', () => {
+    it('should move to next worker', () => {
+      const workers = [
+        createMockWorker({ id: 'w-1' }),
+        createMockWorker({ id: 'w-2' }),
+        createMockWorker({ id: 'w-3' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      // Initially selected is first worker
+      expect(workerGrid.getSelected()?.id).toBe('w-1');
+
+      workerGrid.selectNext();
+      expect(workerGrid.getSelected()?.id).toBe('w-2');
+    });
+
+    it('should wrap to first worker when at end', () => {
+      const workers = [
+        createMockWorker({ id: 'w-1' }),
+        createMockWorker({ id: 'w-2' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      // Move to last
+      workerGrid.selectNext();
+      expect(workerGrid.getSelected()?.id).toBe('w-2');
+
+      // Wrap to first
+      workerGrid.selectNext();
+      expect(workerGrid.getSelected()?.id).toBe('w-1');
+    });
+
+    it('should do nothing when no workers', () => {
+      workerGrid.updateWorkers([]);
+
+      // Should not throw
+      expect(() => workerGrid.selectNext()).not.toThrow();
+    });
+  });
+
+  describe('selectPrevious', () => {
+    it('should move to previous worker', () => {
+      const workers = [
+        createMockWorker({ id: 'w-1' }),
+        createMockWorker({ id: 'w-2' }),
+        createMockWorker({ id: 'w-3' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      // Move to second
+      workerGrid.selectNext();
+      expect(workerGrid.getSelected()?.id).toBe('w-2');
+
+      // Move back to first
+      workerGrid.selectPrevious();
+      expect(workerGrid.getSelected()?.id).toBe('w-1');
+    });
+
+    it('should wrap to last worker when at beginning', () => {
+      const workers = [
+        createMockWorker({ id: 'w-1' }),
+        createMockWorker({ id: 'w-2' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      // At first, wrap to last
+      workerGrid.selectPrevious();
+      expect(workerGrid.getSelected()?.id).toBe('w-2');
+    });
+
+    it('should do nothing when no workers', () => {
+      workerGrid.updateWorkers([]);
+
+      // Should not throw
+      expect(() => workerGrid.selectPrevious()).not.toThrow();
+    });
+  });
+
+  describe('getSelected', () => {
+    it('should return currently selected worker', () => {
+      const workers = [
+        createMockWorker({ id: 'w-1' }),
+        createMockWorker({ id: 'w-2' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+      expect(workerGrid.getSelected()?.id).toBe('w-1');
+
+      workerGrid.selectNext();
+      expect(workerGrid.getSelected()?.id).toBe('w-2');
+    });
+
+    it('should return undefined when no workers', () => {
+      workerGrid.updateWorkers([]);
+      expect(workerGrid.getSelected()).toBeUndefined();
+    });
+  });
+
+  describe('focus', () => {
+    it('should focus the box element', () => {
+      workerGrid.focus();
+      expect(mockBoxInstance.focus).toHaveBeenCalled();
+    });
+  });
+
+  describe('getElement', () => {
+    it('should return the box element', () => {
+      const element = workerGrid.getElement();
+      expect(element).toBe(mockBoxInstance);
+    });
+  });
+
+  describe('render output', () => {
+    it('should include worker status icons', () => {
+      const workers = [
+        createMockWorker({ id: 'w-1', status: 'active' }),
+        createMockWorker({ id: 'w-2', status: 'idle' }),
+        createMockWorker({ id: 'w-3', status: 'error' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      const content = mockBoxInstance.setContent.mock.calls[0][0];
+
+      // Check for status icons
+      expect(content).toContain('●'); // active
+      expect(content).toContain('○'); // idle
+      expect(content).toContain('✗'); // error
+    });
+
+    it('should show collision indicator when worker has collision', () => {
+      const workers = [
+        createMockWorker({ id: 'w-1', hasCollision: true }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      const content = mockBoxInstance.setContent.mock.calls[0][0];
+      expect(content).toContain('⚠');
+    });
+
+    it('should not show collision indicator when no collision', () => {
+      const workers = [
+        createMockWorker({ id: 'w-1', hasCollision: false }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      const content = mockBoxInstance.setContent.mock.calls[0][0];
+      expect(content).not.toContain('⚠');
+    });
+
+    it('should truncate worker ID to 12 characters', () => {
+      const workers = [
+        createMockWorker({ id: 'w-verylongworkerid123456' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      const content = mockBoxInstance.setContent.mock.calls[0][0];
+      expect(content).toContain('w-verylongwo');
+    });
+
+    it('should show selection marker on selected worker', () => {
+      const workers = [
+        createMockWorker({ id: 'w-1' }),
+        createMockWorker({ id: 'w-2' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      const firstContent = mockBoxInstance.setContent.mock.calls[0][0];
+      expect(firstContent).toContain('>'); // Selection marker
+
+      // Select second worker
+      workerGrid.selectNext();
+
+      const secondContent = mockBoxInstance.setContent.mock.calls[1][0];
+      expect(secondContent).toContain('>');
+    });
+
+    it('should include current task from lastEvent', () => {
+      const workers = [
+        createMockWorker({
+          id: 'w-1',
+          lastEvent: {
+            ts: Date.now(),
+            worker: 'w-1',
+            level: 'info',
+            msg: 'Processing bead',
+            bead: 'bd-abc123',
+          },
+        }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      const content = mockBoxInstance.setContent.mock.calls[0][0];
+      expect(content).toContain('bd-abc123');
+      expect(content).toContain('Processing bead');
+    });
+  });
+
+  describe('key bindings', () => {
+    it('should bind up and k keys to selectPrevious', () => {
+      expect(mockBoxInstance.key).toHaveBeenCalledWith(['up', 'k'], expect.any(Function));
+    });
+
+    it('should bind down and j keys to selectNext', () => {
+      expect(mockBoxInstance.key).toHaveBeenCalledWith(['down', 'j'], expect.any(Function));
+    });
+
+    it('should bind g key to select first', () => {
+      expect(mockBoxInstance.key).toHaveBeenCalledWith(['g'], expect.any(Function));
+
+      const workers = [
+        createMockWorker({ id: 'w-1' }),
+        createMockWorker({ id: 'w-2' }),
+        createMockWorker({ id: 'w-3' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      // Move to last worker
+      workerGrid.selectNext();
+      workerGrid.selectNext();
+      expect(workerGrid.getSelected()?.id).toBe('w-3');
+
+      // Find the 'g' handler and call it
+      const gCall = mockBoxInstance.key.mock.calls.find((call: unknown[]) => Array.isArray(call?.[0]) && call[0].includes('g'));
+      const gHandler = gCall?.[1];
+      if (gHandler) {
+        gHandler();
+      }
+
+      expect(workerGrid.getSelected()?.id).toBe('w-1');
+    });
+
+    it('should bind G (shift+g) key to select last', () => {
+      expect(mockBoxInstance.key).toHaveBeenCalledWith(['G'], expect.any(Function));
+
+      const workers = [
+        createMockWorker({ id: 'w-1' }),
+        createMockWorker({ id: 'w-2' }),
+        createMockWorker({ id: 'w-3' }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      // Initially at first
+      expect(workerGrid.getSelected()?.id).toBe('w-1');
+
+      // Find the 'G' handler and call it
+      const GCall = mockBoxInstance.key.mock.calls.find((call: unknown[]) => Array.isArray(call?.[0]) && call[0].includes('G'));
+      const GHandler = GCall?.[1];
+      if (GHandler) {
+        GHandler();
+      }
+
+      expect(workerGrid.getSelected()?.id).toBe('w-3');
+    });
+  });
+
+  describe('edge cases', () => {
+    it('should handle workers with no lastEvent', () => {
+      const workers = [
+        createMockWorker({
+          id: 'w-1',
+          lastEvent: undefined,
+        }),
+      ];
+
+      // Should not throw
+      expect(() => workerGrid.updateWorkers(workers)).not.toThrow();
+    });
+
+    it('should handle empty message in lastEvent', () => {
+      const workers = [
+        createMockWorker({
+          id: 'w-1',
+          lastEvent: {
+            ts: Date.now(),
+            worker: 'w-1',
+            level: 'info',
+            msg: '',
+          },
+        }),
+      ];
+
+      // Should not throw
+      expect(() => workerGrid.updateWorkers(workers)).not.toThrow();
+    });
+
+    it('should handle very long task descriptions', () => {
+      const workers = [
+        createMockWorker({
+          id: 'w-1',
+          lastEvent: {
+            ts: Date.now(),
+            worker: 'w-1',
+            level: 'info',
+            msg: 'This is a very long task description that should be truncated to 25 characters',
+            bead: 'bd-test',
+          },
+        }),
+      ];
+
+      workerGrid.updateWorkers(workers);
+
+      const content = mockBoxInstance.setContent.mock.calls[0][0];
+      // Message should be truncated (25 chars)
+      expect(content).toContain('This is a very long ta');
+    });
+  });
+});