fix(cli): avoid agent composer unmount reset

packages/cli/src/ui/components/agent-view/AgentComposer.test.tsx

@@ -0,0 +1,102 @@
+/**
+ * @license
+ * Copyright 2026 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { render } from 'ink-testing-library';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { AgentStatus } from '@qwen-code/qwen-code-core';
+import {
+  useAgentViewActions,
+  useAgentViewState,
+} from '../../contexts/AgentViewContext.js';
+import { useConfig } from '../../contexts/ConfigContext.js';
+import { useAgentStreamingState } from '../../hooks/useAgentStreamingState.js';
+import { useKeypress } from '../../hooks/useKeypress.js';
+import { usePreferredEditor } from '../../hooks/usePreferredEditor.js';
+import { useTerminalSize } from '../../hooks/useTerminalSize.js';
+import { StreamingState } from '../../types.js';
+import { useTextBuffer } from '../shared/text-buffer.js';
+import { AgentComposer } from './AgentComposer.js';
+
+vi.mock('../../contexts/AgentViewContext.js');
+vi.mock('../../contexts/ConfigContext.js');
+vi.mock('../../hooks/useAgentStreamingState.js');
+vi.mock('../../hooks/useKeypress.js');
+vi.mock('../../hooks/usePreferredEditor.js');
+vi.mock('../../hooks/useTerminalSize.js');
+vi.mock('../shared/text-buffer.js');
+vi.mock('../BaseTextInput.js', () => ({ BaseTextInput: () => null }));
+vi.mock('../LoadingIndicator.js', () => ({ LoadingIndicator: () => null }));
+vi.mock('../QueuedMessageDisplay.js', () => ({
+  QueuedMessageDisplay: () => null,
+}));
+vi.mock('./AgentFooter.js', () => ({ AgentFooter: () => null }));
+
+describe('AgentComposer', () => {
+  const setAgentInputBufferText = vi.fn();
+  const setAgentTabBarFocused = vi.fn();
+  const setAgentApprovalMode = vi.fn();
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+
+    vi.mocked(useAgentViewState).mockReturnValue({
+      activeView: 'agent-1',
+      agents: new Map([
+        [
+          'agent-1',
+          {
+            modelId: 'qwen',
+            color: 'cyan',
+            interactiveAgent: {
+              cancelCurrentRound: vi.fn(),
+              enqueueMessage: vi.fn(),
+              getError: vi.fn(),
+              getLastRoundError: vi.fn(),
+            },
+          },
+        ],
+      ]),
+      agentShellFocused: false,
+      agentInputBufferText: '',
+      agentTabBarFocused: false,
+      agentApprovalModes: new Map(),
+    } as never);
+    vi.mocked(useAgentViewActions).mockReturnValue({
+      setAgentInputBufferText,
+      setAgentTabBarFocused,
+      setAgentApprovalMode,
+    } as never);
+    vi.mocked(useConfig).mockReturnValue({
+      getContentGeneratorConfig: () => undefined,
+    } as never);
+    vi.mocked(usePreferredEditor).mockReturnValue(undefined);
+    vi.mocked(useTerminalSize).mockReturnValue({ columns: 80, rows: 24 });
+    vi.mocked(useKeypress).mockImplementation(() => {});
+    vi.mocked(useAgentStreamingState).mockReturnValue({
+      status: AgentStatus.IDLE,
+      streamingState: StreamingState.Idle,
+      isInputActive: true,
+      elapsedTime: 0,
+      lastPromptTokenCount: 0,
+    } as never);
+    vi.mocked(useTextBuffer).mockReturnValue({
+      text: 'draft',
+      allVisualLines: ['draft'],
+      visualCursor: [0, 5],
+    } as never);
+  });
+
+  it('does not reset the parent input-buffer state during unmount', () => {
+    const { unmount } = render(<AgentComposer agentId="agent-1" />);
+
+    expect(setAgentInputBufferText).toHaveBeenCalledWith('draft');
+    setAgentInputBufferText.mockClear();
+
+    unmount();
+
+    expect(setAgentInputBufferText).not.toHaveBeenCalled();
+  });
+});

packages/cli/src/ui/components/agent-view/AgentComposer.tsx

@@ -133,10 +133,9 @@ export const AgentComposer: React.FC<AgentComposerProps> = ({ agentId }) => {
     preferredEditor,
   });
 
-  // Sync agent buffer text to context so AgentTabBar can guard tab switching
+  // Sync the active agent buffer text to context.
   useEffect(() => {
     setAgentInputBufferText(buffer.text);
-    return () => setAgentInputBufferText('');
   }, [buffer.text, setAgentInputBufferText]);
 
   // When agent input is not active (agent running, completed, etc.),

packages/cli/src/ui/contexts/AgentViewContext.tsx

@@ -48,7 +48,7 @@ export interface AgentViewState {
   agents: ReadonlyMap<string, RegisteredAgent>;
   /** Whether any agent tab's embedded shell currently has input focus. */
   agentShellFocused: boolean;
-  /** Current text in the active agent tab's input buffer (empty when on main). */
+  /** Last synced text from the active agent tab's input buffer. */
   agentInputBufferText: string;
   /** Whether the tab bar has keyboard focus (vs the agent input). */
   agentTabBarFocused: boolean;