Including a test harness for it, and making sure the cursor is always at the end.

package.json

@@ -14,13 +14,17 @@
     "format": "prettier --write ."
   },
   "devDependencies": {
+    "@testing-library/react": "^14.3.1",
+    "@vitejs/plugin-react": "^4.4.0",
     "eslint": "^9.24.0",
     "eslint-config-prettier": "^10.1.2",
     "eslint-plugin-import": "^2.31.0",
     "eslint-plugin-react": "^7.37.5",
     "eslint-plugin-react-hooks": "^5.2.0",
     "globals": "^16.0.0",
+    "ink-testing-library": "^4.0.0",
     "prettier": "^3.5.3",
-    "typescript-eslint": "^8.30.1"
+    "typescript-eslint": "^8.30.1",
+    "vitest": "^3.1.1"
   }
 }

packages/cli/package.json

@@ -8,6 +8,7 @@
     "build": "tsc && touch dist/.last_build",
     "start": "node dist/gemini.js",
     "debug": "node --inspect-brk dist/gemini.js",
+    "test": "vitest run",
     "lint": "eslint . --ext .ts,.tsx",
     "format": "prettier --write ."
   },
@@ -32,6 +33,7 @@
     "@types/node": "^20.11.24",
     "@types/react": "^19.1.0",
     "@types/yargs": "^17.0.32",
+    "jsdom": "^26.1.0",
     "typescript": "^5.3.3"
   },
   "engines": {

packages/cli/src/config/globalConfig.ts

@@ -47,4 +47,4 @@ export function getConfig(): GlobalConfig {
  */
 export function getModel(): string {
   return getConfig().model;
-} 
+}

packages/cli/src/core/gemini-client.ts

@@ -9,7 +9,7 @@ import {
   Content,
 } from '@google/genai';
 import { getApiKey } from '../config/env.js';
-import { getModel } from '../config/globalConfig.js';  
+import { getModel } from '../config/globalConfig.js';
 import { CoreSystemPrompt } from './prompts.js';
 import {
   type ToolCallEvent,

packages/cli/src/tools/terminal.tool.ts

@@ -142,10 +142,7 @@ export class TerminalTool extends BaseTool<
   private rejectShellReady: ((reason?: any) => void) | undefined; // Definite assignment assertion
   private readonly backgroundTerminalAnalyzer: BackgroundTerminalAnalyzer;
 
-  constructor(
+  constructor(rootDirectory: string, outputLimit: number = MAX_OUTPUT_LENGTH) {
-    rootDirectory: string,
-    outputLimit: number = MAX_OUTPUT_LENGTH,
-  ) {
     const toolDisplayName = 'Terminal';
     // --- LLM-Facing Description ---
     // Updated description for background tasks to mention polling and LLM analysis

packages/cli/src/ui/App.test.tsx

@@ -0,0 +1,121 @@
+// packages/cli/src/ui/App.test.tsx
+import React from 'react';
+import { render, cleanup } from 'ink-testing-library';
+import { vi, describe, test, expect, beforeEach, afterEach } from 'vitest';
+import App from './App.js';
+import { useInputHistory } from './hooks/useInputHistory.js';
+import { useGeminiStream } from './hooks/useGeminiStream.js';
+import { StreamingState } from '../core/gemini-stream.js';
+import type { HistoryItem } from './types.js';
+import fs from 'fs';
+import path from 'path';
+import os from 'os';
+import { initializeConfig } from '../config/globalConfig.js';
+
+// --- Mocks ---
+
+// Mock the useGeminiStream hook
+vi.mock('./hooks/useGeminiStream.js', () => ({
+  useGeminiStream: vi.fn(),
+}));
+
+// Mock the useInputHistory hook
+vi.mock('./hooks/useInputHistory.js', () => ({
+  useInputHistory: vi.fn(),
+}));
+
+// Mock fs/path/os used for warnings check
+vi.mock('fs', () => ({
+  default: {
+    existsSync: vi.fn().mockReturnValue(false),
+    readFileSync: vi.fn(),
+    unlinkSync: vi.fn(),
+    writeFileSync: vi.fn(),
+  },
+}));
+vi.mock('path', async (importOriginal) => {
+  const originalPath = await importOriginal<typeof import('path')>();
+  return {
+    ...originalPath,
+    default: originalPath,
+    join: originalPath.join,
+    resolve: originalPath.resolve,
+    relative: originalPath.relative,
+  };
+});
+vi.mock('os', async (importOriginal) => {
+  const originalOs = await importOriginal<typeof import('os')>();
+  return {
+    ...originalOs,
+    default: originalOs,
+    tmpdir: vi.fn().mockReturnValue('/tmp'),
+  };
+});
+
+// --- Test Suite ---
+describe('App Component Rendering', () => {
+  // Define mock return values for the hooks
+  let mockSetQuery: ReturnType<typeof vi.fn>;
+  let mockResetHistoryNav: ReturnType<typeof vi.fn>;
+  let mockSubmitQuery: ReturnType<typeof vi.fn>;
+
+  beforeEach(() => {
+    // Reset mocks
+    vi.clearAllMocks();
+    (fs.existsSync as ReturnType<typeof vi.fn>).mockReturnValue(false);
+
+    // Initialize global config
+    initializeConfig({ model: 'test-model-v1' });
+
+    // Setup mock return values for hooks
+    mockSetQuery = vi.fn();
+    mockResetHistoryNav = vi.fn();
+    mockSubmitQuery = vi.fn().mockResolvedValue(undefined);
+
+    (useInputHistory as ReturnType<typeof vi.fn>).mockReturnValue({
+      query: '',
+      setQuery: mockSetQuery,
+      resetHistoryNav: mockResetHistoryNav,
+      inputKey: 0,
+    });
+
+    (useGeminiStream as ReturnType<typeof vi.fn>).mockReturnValue({
+      streamingState: StreamingState.Idle,
+      submitQuery: mockSubmitQuery,
+      initError: null,
+    });
+  });
+
+  afterEach(() => {
+    cleanup();
+    vi.resetModules();
+  });
+
+  // Helper function to render App
+  const renderApp = (initialHookQuery = '') => {
+    (useInputHistory as ReturnType<typeof vi.fn>).mockReturnValue({
+      query: initialHookQuery,
+      setQuery: mockSetQuery,
+      resetHistoryNav: mockResetHistoryNav,
+      inputKey: 0,
+    });
+
+    return render(<App directory="/test/dir" />);
+  };
+
+  // --- Tests ---
+  test('should render initial placeholder with model', () => {
+    const { lastFrame } = renderApp();
+    expect(lastFrame()).toContain('Ask Gemini (test-model-v1)');
+  });
+
+  test('should pass query from useInputHistory to InputPrompt', () => {
+    const { lastFrame } = renderApp('test query from hook');
+    expect(lastFrame()).toContain('> test query from hook');
+  });
+
+  // Add more tests here for App's behavior, like:
+  // - Displaying startup warnings when the mocked fs.existsSync returns true
+  // - Displaying initError from useGeminiStream when it's not null
+  // - Ensuring handleInputSubmit calls the correct functions from the hooks
+});

packages/cli/src/ui/App.tsx

@@ -1,11 +1,12 @@
 import React, { useState, useEffect, useMemo } from 'react';
-import { Box, Text, useInput } from 'ink';
+import { Box, Text } from 'ink';
 import fs from 'fs';
 import path from 'path';
 import os from 'os';
 import type { HistoryItem } from './types.js';
 import { useGeminiStream } from './hooks/useGeminiStream.js';
 import { useLoadingIndicator } from './hooks/useLoadingIndicator.js';
+import { useInputHistory } from './hooks/useInputHistory.js';
 import Header from './components/Header.js';
 import Tips from './components/Tips.js';
 import HistoryDisplay from './components/HistoryDisplay.js';
@@ -22,11 +23,8 @@ interface AppProps {
 }
 
 const App = ({ directory }: AppProps) => {
-  const [query, setQuery] = useState('');
   const [history, setHistory] = useState<HistoryItem[]>([]);
   const [startupWarnings, setStartupWarnings] = useState<string[]>([]);
-  const [historyIndex, setHistoryIndex] = useState<number>(-1);
-  const [originalQueryBeforeNav, setOriginalQueryBeforeNav] = useState<string>('');
   const { streamingState, submitQuery, initError } =
     useGeminiStream(setHistory);
   const { elapsedTime, currentLoadingPhrase } =
@@ -34,34 +32,54 @@ const App = ({ directory }: AppProps) => {
 
   const userMessages = useMemo(() => {
     return history
-      .filter((item): item is HistoryItem & { type: 'user'; text: string } =>
+      .filter(
-          item.type === 'user' && typeof item.text === 'string' && item.text.trim() !== ''
+        (item): item is HistoryItem & { type: 'user'; text: string } =>
-       )
+          item.type === 'user' &&
-      .map(item => item.text);
+          typeof item.text === 'string' &&
+          item.text.trim() !== '',
+      )
+      .map((item) => item.text);
   }, [history]);
 
   useEffect(() => {
     try {
       if (fs.existsSync(warningsFilePath)) {
-        console.log('[App] Found warnings file:', warningsFilePath);
         const warningsContent = fs.readFileSync(warningsFilePath, 'utf-8');
-        setStartupWarnings(warningsContent.split('\n').filter(line => line.trim() !== ''));
+        setStartupWarnings(
+          warningsContent.split('\n').filter((line) => line.trim() !== ''),
+        );
         try {
-            fs.unlinkSync(warningsFilePath);
+          fs.unlinkSync(warningsFilePath);
         } catch (unlinkErr: any) {
-             console.warn(`[App] Warning: Could not delete warnings file: ${unlinkErr.message}`);
+          console.warn(
+            `[App] Warning: Could not delete warnings file: ${unlinkErr.message}`,
+          );
         }
-      } else {
-         console.log('[App] No warnings file found.');
       }
     } catch (err: any) {
-      console.error(`[App] Error checking/reading warnings file: ${err.message}`);
+      console.error(
+        `[App] Error checking/reading warnings file: ${err.message}`,
+      );
     }
   }, []);
 
+  const isWaitingForToolConfirmation = history.some(
+    (item) =>
+      item.type === 'tool_group' &&
+      item.tools.some((tool) => tool.confirmationDetails !== undefined),
+  );
+  const isInputActive =
+    streamingState === StreamingState.Idle &&
+    !initError &&
+    !isWaitingForToolConfirmation;
+
+  const { query, setQuery, resetHistoryNav, inputKey } = useInputHistory({
+    userMessages,
+    isActive: isInputActive,
+  });
+
   const handleInputSubmit = (value: PartListUnion) => {
-    setHistoryIndex(-1);
+    resetHistoryNav();
-    setOriginalQueryBeforeNav('');
     submitQuery(value)
       .then(() => {
         setQuery('');
@@ -89,47 +107,6 @@ const App = ({ directory }: AppProps) => {
     }
   }, [initError, history]);
 
-  const isWaitingForToolConfirmation = history.some(
-    (item) =>
-      item.type === 'tool_group' &&
-      item.tools.some((tool) => tool.confirmationDetails !== undefined),
-  );
-  const isInputActive = streamingState === StreamingState.Idle && !initError;
-
-  useInput((input, key) => {
-    if (!isInputActive || isWaitingForToolConfirmation) {
-      return;
-    }
-
-    if (key.upArrow) {
-      if (userMessages.length === 0) return;
-      if (historyIndex === -1) {
-        setOriginalQueryBeforeNav(query);
-      }
-      const nextIndex = Math.min(historyIndex + 1, userMessages.length - 1);
-      if (nextIndex !== historyIndex) {
-         setHistoryIndex(nextIndex);
-         setQuery(userMessages[userMessages.length - 1 - nextIndex]);
-      }
-    } else if (key.downArrow) {
-      if (historyIndex < 0) return;
-      const nextIndex = Math.max(historyIndex - 1, -1);
-      setHistoryIndex(nextIndex);
-      if (nextIndex === -1) {
-        setQuery(originalQueryBeforeNav);
-      } else {
-        setQuery(userMessages[userMessages.length - 1 - nextIndex]);
-      }
-    } else {
-      if (input || key.backspace || key.delete || key.leftArrow || key.rightArrow) {
-        if (historyIndex !== -1) {
-           setHistoryIndex(-1);
-           setOriginalQueryBeforeNav('');
-        }
-      }
-    }
-  }, { isActive: isInputActive });
-
   return (
     <Box flexDirection="column" padding={1} marginBottom={1} width="100%">
       <Header cwd={directory} />
@@ -193,12 +170,13 @@ const App = ({ directory }: AppProps) => {
         />
       </Box>
 
-      {!isWaitingForToolConfirmation && isInputActive && (
+      {!isWaitingForToolConfirmation && (
         <InputPrompt
           query={query}
           setQuery={setQuery}
           onSubmit={handleInputSubmit}
           isActive={isInputActive}
+          forceKey={inputKey}
         />
       )}
 

packages/cli/src/ui/components/InputPrompt.tsx

@@ -8,12 +8,14 @@ interface InputPromptProps {
   setQuery: (value: string) => void;
   onSubmit: (value: string) => void;
   isActive: boolean;
+  forceKey: number;
 }
 
 const InputPrompt: React.FC<InputPromptProps> = ({
   query,
   setQuery,
   onSubmit,
+  forceKey,
 }) => {
   const model = getModel();
 
@@ -22,6 +24,7 @@ const InputPrompt: React.FC<InputPromptProps> = ({
       <Text color={'white'}>&gt; </Text>
       <Box flexGrow={1}>
         <TextInput
+          key={forceKey}
           value={query}
           onChange={setQuery}
           onSubmit={onSubmit}

packages/cli/src/ui/hooks/useInputHistory.test.ts

@@ -0,0 +1,177 @@
+// packages/cli/src/ui/hooks/useInputHistory.test.ts
+import { renderHook, act } from '@testing-library/react';
+import { useInput } from 'ink';
+import { vi, describe, test, expect, beforeEach, Mock } from 'vitest';
+import { useInputHistory } from './useInputHistory.js';
+
+// Mock the useInput hook from Ink
+vi.mock('ink', async (importOriginal) => {
+  const originalInk = await importOriginal<typeof import('ink')>();
+  return {
+    ...originalInk, // Keep other exports
+    useInput: vi.fn(), // Mock useInput
+  };
+});
+
+// Helper type for the mocked useInput callback
+type UseInputCallback = (input: string, key: any) => void;
+
+describe('useInputHistory Hook', () => {
+  let mockUseInputCallback: UseInputCallback | undefined;
+  const mockUserMessages = ['msg1', 'msg2', 'msg3']; // Sample history
+
+  beforeEach(() => {
+    // Reset the mock before each test and capture the callback
+    (useInput as Mock).mockImplementation((callback, options) => {
+      // Only store the callback if the hook is active in the test
+      if (options?.isActive !== false) {
+        mockUseInputCallback = callback;
+      } else {
+        mockUseInputCallback = undefined;
+      }
+    });
+  });
+
+  // Helper function to simulate key press by invoking the captured callback
+  const simulateKeyPress = (key: object, input: string = '') => {
+    act(() => {
+      if (mockUseInputCallback) {
+        mockUseInputCallback(input, key);
+      } else {
+        // Optionally throw an error if trying to press key when inactive
+        // console.warn('Simulated key press while useInput was inactive');
+      }
+    });
+  };
+
+  test('should initialize with empty query', () => {
+    const { result } = renderHook(() =>
+      useInputHistory({ userMessages: [], isActive: true }),
+    );
+    expect(result.current.query).toBe('');
+  });
+
+  test('up arrow should do nothing if history is empty', () => {
+    const { result } = renderHook(() =>
+      useInputHistory({ userMessages: [], isActive: true }),
+    );
+    simulateKeyPress({ upArrow: true });
+    expect(result.current.query).toBe('');
+  });
+
+  test('up arrow should recall the last message', () => {
+    const { result } = renderHook(() =>
+      useInputHistory({ userMessages: mockUserMessages, isActive: true }),
+    );
+    simulateKeyPress({ upArrow: true });
+    expect(result.current.query).toBe('msg3'); // Last message
+  });
+
+  test('repeated up arrows should navigate history', () => {
+    const { result } = renderHook(() =>
+      useInputHistory({ userMessages: mockUserMessages, isActive: true }),
+    );
+    simulateKeyPress({ upArrow: true }); // -> msg3
+    simulateKeyPress({ upArrow: true }); // -> msg2
+    expect(result.current.query).toBe('msg2');
+    simulateKeyPress({ upArrow: true }); // -> msg1
+    expect(result.current.query).toBe('msg1');
+    simulateKeyPress({ upArrow: true }); // -> stays on msg1
+    expect(result.current.query).toBe('msg1');
+  });
+
+  test('down arrow should navigate history forward', () => {
+    const { result } = renderHook(() =>
+      useInputHistory({ userMessages: mockUserMessages, isActive: true }),
+    );
+    simulateKeyPress({ upArrow: true }); // -> msg3
+    simulateKeyPress({ upArrow: true }); // -> msg2
+    simulateKeyPress({ upArrow: true }); // -> msg1
+    expect(result.current.query).toBe('msg1');
+
+    simulateKeyPress({ downArrow: true }); // -> msg2
+    expect(result.current.query).toBe('msg2');
+    simulateKeyPress({ downArrow: true }); // -> msg3
+    expect(result.current.query).toBe('msg3');
+  });
+
+  test('down arrow should restore original query', () => {
+    const { result } = renderHook(() =>
+      useInputHistory({ userMessages: mockUserMessages, isActive: true }),
+    );
+
+    // Set initial query
+    act(() => {
+      result.current.setQuery('original typing');
+    });
+    expect(result.current.query).toBe('original typing');
+
+    simulateKeyPress({ upArrow: true }); // -> msg3
+    expect(result.current.query).toBe('msg3');
+
+    simulateKeyPress({ downArrow: true }); // -> original typing
+    expect(result.current.query).toBe('original typing');
+
+    // Pressing down again should do nothing
+    simulateKeyPress({ downArrow: true });
+    expect(result.current.query).toBe('original typing');
+  });
+
+  test('typing should reset navigation', () => {
+    const { result } = renderHook(() =>
+      useInputHistory({ userMessages: mockUserMessages, isActive: true }),
+    );
+
+    simulateKeyPress({ upArrow: true }); // -> msg3
+    expect(result.current.query).toBe('msg3');
+
+    // Simulate typing 'x' (Note: we manually call setQuery here, as useInput is mocked)
+    act(() => {
+      result.current.setQuery(result.current.query + 'x');
+    });
+    // Also simulate the input event that would trigger the reset
+    simulateKeyPress({}, 'x');
+    expect(result.current.query).toBe('msg3x');
+
+    simulateKeyPress({ upArrow: true }); // Should restart navigation -> msg3
+    expect(result.current.query).toBe('msg3');
+  });
+
+  test('calling resetHistoryNav should clear navigation state', () => {
+    const { result } = renderHook(() =>
+      useInputHistory({ userMessages: mockUserMessages, isActive: true }),
+    );
+
+    // Set initial query and navigate
+    act(() => {
+      result.current.setQuery('original');
+    });
+    simulateKeyPress({ upArrow: true }); // -> msg3
+    expect(result.current.query).toBe('msg3');
+
+    // Reset
+    act(() => {
+      result.current.resetHistoryNav();
+    });
+
+    // Press down - should restore original query ('original') because nav was reset
+    // However, our current resetHistoryNav also clears originalQueryBeforeNav.
+    // Let's test that down does nothing because historyIndex is -1
+    simulateKeyPress({ downArrow: true });
+    expect(result.current.query).toBe('msg3'); // Stays msg3 because downArrow doesn't run when index is -1
+
+    // Press up - should start nav again from the top
+    simulateKeyPress({ upArrow: true });
+    expect(result.current.query).toBe('msg3');
+  });
+
+  test('should not trigger callback if isActive is false', () => {
+    renderHook(() =>
+      useInputHistory({ userMessages: mockUserMessages, isActive: false }),
+    );
+    // mockUseInputCallback should be undefined because isActive was false
+    expect(mockUseInputCallback).toBeUndefined();
+    // Attempting to simulate should not throw error (or check internal state if possible)
+    expect(() => simulateKeyPress({ upArrow: true })).not.toThrow();
+  });
+});

packages/cli/src/ui/hooks/useInputHistory.ts

@@ -0,0 +1,92 @@
+import { useState, useCallback } from 'react';
+import { useInput } from 'ink';
+
+interface UseInputHistoryProps {
+  userMessages: readonly string[]; // Use readonly string[] instead
+  isActive: boolean; // To enable/disable the useInput hook
+}
+
+interface UseInputHistoryReturn {
+  query: string;
+  setQuery: React.Dispatch<React.SetStateAction<string>>;
+  resetHistoryNav: () => void;
+  inputKey: number; // Key to force input reset
+}
+
+export function useInputHistory({
+  userMessages,
+  isActive,
+}: UseInputHistoryProps): UseInputHistoryReturn {
+  const [query, setQuery] = useState('');
+  const [historyIndex, setHistoryIndex] = useState<number>(-1); // -1 means current query
+  const [originalQueryBeforeNav, setOriginalQueryBeforeNav] =
+    useState<string>('');
+  const [inputKey, setInputKey] = useState<number>(0); // Add key state
+
+  const resetHistoryNav = useCallback(() => {
+    setHistoryIndex(-1);
+    setOriginalQueryBeforeNav('');
+    // Don't reset inputKey here, only on explicit nav actions
+  }, []);
+
+  useInput(
+    (input, key) => {
+      // Do nothing if the hook is not active
+      if (!isActive) {
+        return;
+      }
+
+      if (key.upArrow) {
+        if (userMessages.length === 0) return;
+        // Store current query if starting navigation
+        if (historyIndex === -1) {
+          setOriginalQueryBeforeNav(query);
+        }
+        const nextIndex = Math.min(historyIndex + 1, userMessages.length - 1);
+        if (nextIndex !== historyIndex) {
+          setHistoryIndex(nextIndex);
+          const newValue = userMessages[userMessages.length - 1 - nextIndex];
+          setQuery(newValue);
+          setInputKey(k => k + 1); // Increment key on navigation change
+        }
+      } else if (key.downArrow) {
+        if (historyIndex < 0) return; // Already at the bottom
+        const nextIndex = Math.max(historyIndex - 1, -1);
+        setHistoryIndex(nextIndex);
+        if (nextIndex === -1) {
+          // Restore original query
+          setQuery(originalQueryBeforeNav);
+          setInputKey(k => k + 1); // Increment key on navigation change
+        } else {
+          // Set query based on reversed index
+          const newValue = userMessages[userMessages.length - 1 - nextIndex];
+          setQuery(newValue);
+          setInputKey(k => k + 1); // Increment key on navigation change
+        }
+      } else {
+        // If user types anything other than arrows, reset history navigation state
+        // This check might be too broad, adjust if handling more special keys
+        if (
+          input ||
+          key.backspace ||
+          key.delete ||
+          key.leftArrow ||
+          key.rightArrow
+        ) {
+          if (historyIndex !== -1) {
+            resetHistoryNav();
+            // Note: The actual input change is handled by the component using setQuery/onChange
+          }
+        }
+      }
+    },
+    { isActive }, // Pass isActive to useInput
+  );
+
+  return {
+    query,
+    setQuery, // Return setQuery directly for flexibility
+    resetHistoryNav,
+    inputKey, // Return the key
+  };
+}

packages/cli/vitest.config.ts

@@ -0,0 +1,22 @@
+import { defineConfig } from 'vitest/config';
+import react from '@vitejs/plugin-react'; // For JSX support
+import path from 'path'; // Import path
+
+export default defineConfig({
+  root: path.resolve(__dirname), // Explicitly set root to the current directory (packages/cli)
+  plugins: [react()], // Add React plugin for JSX/TSX
+  test: {
+    globals: true, // Use global APIs (describe, test, expect, vi)
+    environment: 'jsdom', // Changed environment to jsdom
+    // More specific include pattern to find the test file
+    include: ['src/**/*.test.{ts,tsx}'],
+    // Add setup files if needed (e.g., for global mocks, testing-library config)
+    // setupFiles: './src/test/setup.ts',
+    mockReset: true, // Reset mocks between tests
+    clearMocks: true, // Clear mock history between tests
+    alias: {
+      // Add path aliases if you use them in your src code
+      // Example: '@/*': path.resolve(__dirname, './src/*'),
+    },
+  },
+});