test: configure Vitest testing framework

- Add vitest, @testing-library/react, @vitest/ui, jsdom dependencies
- Create vitest.config.ts with jsdom environment and coverage settings
- Add tests/setup.ts with localStorage mock and crypto mock
- Add tests/gateway/ws-client.test.ts for GatewayClient unit tests

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/gateway/ws-client.test.ts

@@ -0,0 +1,115 @@
+/**
+ * Tests for Gateway WebSocket Client (Browser version)
+ */
+
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import { GatewayClient } from '../../desktop/src/lib/gateway-client';
+
+describe('GatewayClient', () => {
+  let client: GatewayClient;
+  let mockWs: any;
+
+  beforeEach(() => {
+    client = new GatewayClient({
+      url: 'ws://localhost:18790',
+      token: '',
+      autoReconnect: false,
+      requestTimeout: 5000,
+    });
+  });
+
+  afterEach(() => {
+    client.disconnect();
+  });
+
+  describe('constructor', () => {
+    it('should initialize with default options', () => {
+    const defaultClient = new GatewayClient();
+    expect(defaultClient.getState()).toBe('disconnected');
+  });
+
+    it('should initialize with custom options', () => {
+    const customClient = new GatewayClient({
+      url: 'ws://custom:1234',
+      token: 'test-token',
+      autoReconnect: false,
+    });
+    expect(customClient.getState()).toBe('disconnected');
+  });
+  });
+
+  describe('connection state', () => {
+    it('should start in disconnected state', () => {
+    expect(client.getState()).toBe('disconnected');
+  });
+
+  it('should emit state changes', () => {
+    const stateChanges: string[] = [];
+    client.onStateChange = (state) => {
+      stateChanges.push(state);
+    };
+
+    // Note: actual connection requires a real WebSocket server
+    // This test verifies the callback mechanism
+    expect(typeof client.onStateChange).toBe('function');
+  });
+  });
+
+  describe('event subscription', () => {
+    it('should allow subscribing to events', () => {
+    const callback = vi.fn();
+    const unsubscribe = client.on('test', callback);
+
+    // Verify unsubscribe is a function
+    expect(typeof unsubscribe).toBe('function');
+  });
+
+    it('should allow multiple listeners for same event', () => {
+    const callback1 = vi.fn();
+    const callback2 = vi.fn();
+
+    client.on('test', callback1);
+    client.on('test', callback2);
+
+    // Both listeners should be registered
+    // (In real scenario, they would be called when event is emitted)
+  });
+  });
+
+  describe('agent stream subscription', () => {
+    it('should provide onAgentStream helper', () => {
+    const callback = vi.fn();
+    const unsubscribe = client.onAgentStream(callback);
+
+    expect(typeof unsubscribe).toBe('function');
+  });
+  });
+
+  describe('disconnect', () => {
+    it('should cleanup resources on disconnect', () => {
+    client.disconnect();
+    expect(client.getState()).toBe('disconnected');
+  });
+  });
+
+  describe('API methods', () => {
+    it('should have chat method', () => {
+    expect(typeof client.chat).toBe('function');
+  });
+
+    it('should have health method', () => {
+    expect(typeof client.health).toBe('function');
+  });
+
+    it('should have status method', () => {
+    expect(typeof client.status).toBe('function');
+  });
+
+    it('should have ZCLAW custom methods', () => {
+    expect(typeof client.listClones).toBe('function');
+    expect(typeof client.createClone).toBe('function');
+    expect(typeof client.getUsageStats).toBe('function');
+    expect(typeof client.getPluginStatus).toBe('function');
+  });
+  });
+});