fix(ui): Correct footer measurement and prevent negative terminal height (#8362)

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

@@ -40,6 +40,14 @@ vi.mock('./App.js', () => ({
   App: TestContextConsumer,
 }));
 
+vi.mock('ink', async (importOriginal) => {
+  const original = await importOriginal<typeof import('ink')>();
+  return {
+    ...original,
+    measureElement: vi.fn(),
+  };
+});
+
 vi.mock('./hooks/useQuotaAndFallback.js');
 vi.mock('./hooks/useHistoryManager.js');
 vi.mock('./hooks/useThemeCommand.js');
@@ -92,6 +100,9 @@ import { useSessionStats } from './contexts/SessionContext.js';
 import { useTextBuffer } from './components/shared/text-buffer.js';
 import { useLogger } from './hooks/useLogger.js';
 import { useLoadingIndicator } from './hooks/useLoadingIndicator.js';
+import { measureElement } from 'ink';
+import { useTerminalSize } from './hooks/useTerminalSize.js';
+import { ShellExecutionService } from '@google/gemini-cli-core';
 
 describe('AppContainer State Management', () => {
   let mockConfig: Config;
@@ -556,4 +567,42 @@ describe('AppContainer State Management', () => {
       expect(mockHandler).toHaveBeenCalledWith('auth');
     });
   });
+
+  describe('Terminal Height Calculation', () => {
+    const mockedMeasureElement = measureElement as Mock;
+    const mockedUseTerminalSize = useTerminalSize as Mock;
+
+    it('should prevent terminal height from being less than 1', () => {
+      const resizePtySpy = vi.spyOn(ShellExecutionService, 'resizePty');
+      // Arrange: Simulate a small terminal and a large footer
+      mockedUseTerminalSize.mockReturnValue({ columns: 80, rows: 5 });
+      mockedMeasureElement.mockReturnValue({ width: 80, height: 10 }); // Footer is taller than the screen
+      mockedUseGeminiStream.mockReturnValue({
+        streamingState: 'idle',
+        submitQuery: vi.fn(),
+        initError: null,
+        pendingHistoryItems: [],
+        thought: null,
+        cancelOngoingRequest: vi.fn(),
+        activePtyId: 'some-id',
+      });
+
+      render(
+        <AppContainer
+          config={mockConfig}
+          settings={mockSettings}
+          version="1.0.0"
+          initializationResult={mockInitResult}
+        />,
+      );
+
+      // Assert: The shell should be resized to a minimum height of 1, not a negative number.
+      // The old code would have tried to set a negative height.
+      expect(resizePtySpy).toHaveBeenCalled();
+      const lastCall =
+        resizePtySpy.mock.calls[resizePtySpy.mock.calls.length - 1];
+      // Check the height argument specifically
+      expect(lastCall[2]).toBe(1);
+    });
+  });
 });

packages/cli/src/ui/AppContainer.tsx

@@ -4,7 +4,14 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import { useMemo, useState, useCallback, useEffect, useRef } from 'react';
+import {
+  useMemo,
+  useState,
+  useCallback,
+  useEffect,
+  useRef,
+  useLayoutEffect,
+} from 'react';
 import { type DOMElement, measureElement } from 'ink';
 import { App } from './App.js';
 import { AppContext } from './contexts/AppContext.js';
@@ -622,18 +629,27 @@ Logging in with Google... Please restart Gemini CLI to continue.
       streamingState === StreamingState.Responding) &&
     !proQuotaRequest;
 
-  // Compute available terminal height based on controls measurement
-  const availableTerminalHeight = useMemo(() => {
+  const [controlsHeight, setControlsHeight] = useState(0);
+
+  useLayoutEffect(() => {
     if (mainControlsRef.current) {
       const fullFooterMeasurement = measureElement(mainControlsRef.current);
-      return terminalHeight - fullFooterMeasurement.height - staticExtraHeight;
+      if (fullFooterMeasurement.height > 0) {
+        setControlsHeight(fullFooterMeasurement.height);
+      }
     }
-    return terminalHeight - staticExtraHeight;
-  }, [terminalHeight]);
+  }, [buffer, terminalWidth, terminalHeight]);
+
+  // Compute available terminal height based on controls measurement
+  const availableTerminalHeight =
+    terminalHeight - controlsHeight - staticExtraHeight;
 
   config.setShellExecutionConfig({
     terminalWidth: Math.floor(terminalWidth * SHELL_WIDTH_FRACTION),
-    terminalHeight: Math.floor(availableTerminalHeight - SHELL_HEIGHT_PADDING),
+    terminalHeight: Math.max(
+      Math.floor(availableTerminalHeight - SHELL_HEIGHT_PADDING),
+      1,
+    ),
     pager: settings.merged.tools?.shell?.pager,
     showColor: settings.merged.tools?.shell?.showColor,
   });
@@ -660,16 +676,10 @@ Logging in with Google... Please restart Gemini CLI to continue.
       ShellExecutionService.resizePty(
         activePtyId,
         Math.floor(terminalWidth * SHELL_WIDTH_FRACTION),
-        Math.floor(availableTerminalHeight - SHELL_HEIGHT_PADDING),
+        Math.max(Math.floor(availableTerminalHeight - SHELL_HEIGHT_PADDING), 1),
       );
     }
-  }, [
-    terminalHeight,
-    terminalWidth,
-    availableTerminalHeight,
-    activePtyId,
-    geminiClient,
-  ]);
+  }, [terminalWidth, availableTerminalHeight, activePtyId]);
 
   useEffect(() => {
     if (