perf(cli): memoize btw message component

packages/cli/src/ui/components/messages/BtwMessage.test.tsx

@@ -0,0 +1,34 @@
+/**
+ * @license
+ * Copyright 2025 Qwen Code
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, expect, it } from 'vitest';
+import { render } from 'ink-testing-library';
+import { BtwMessage } from './BtwMessage.js';
+
+describe('BtwMessage', () => {
+  it('is wrapped in React.memo to avoid unnecessary layout rerenders', () => {
+    expect((BtwMessage as unknown as { $$typeof?: symbol }).$$typeof).toBe(
+      Symbol.for('react.memo'),
+    );
+  });
+
+  it('renders the side question and answer', () => {
+    const { lastFrame } = render(
+      <BtwMessage
+        btw={{
+          question: 'side question',
+          answer: 'side answer',
+          isPending: false,
+        }}
+      />,
+    );
+
+    const output = lastFrame() ?? '';
+    expect(output).toContain('/btw');
+    expect(output).toContain('side question');
+    expect(output).toContain('side answer');
+  });
+});