fix(cli): correct shell height reporting (#21492)

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

@@ -232,10 +232,7 @@ import { useInputHistoryStore } from './hooks/useInputHistoryStore.js';
 import { useKeypress, type Key } from './hooks/useKeypress.js';
 import * as useKeypressModule from './hooks/useKeypress.js';
 import { useSuspend } from './hooks/useSuspend.js';
-import { measureElement } from 'ink';
-import { useTerminalSize } from './hooks/useTerminalSize.js';
 import {
-  ShellExecutionService,
   writeToStdout,
   enableMouseEvents,
   disableMouseEvents,
@@ -2197,35 +2194,6 @@ describe('AppContainer State Management', () => {
     });
   });
 
-  describe('Terminal Height Calculation', () => {
-    const mockedMeasureElement = measureElement as Mock;
-    const mockedUseTerminalSize = useTerminalSize as Mock;
-
-    it('should prevent terminal height from being less than 1', async () => {
-      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({
-        ...DEFAULT_GEMINI_STREAM_MOCK,
-        activePtyId: 'some-id',
-      });
-
-      let unmount: () => void;
-      await act(async () => {
-        const result = renderAppContainer();
-        unmount = result.unmount;
-      });
-      await waitFor(() => expect(resizePtySpy).toHaveBeenCalled());
-      const lastCall =
-        resizePtySpy.mock.calls[resizePtySpy.mock.calls.length - 1];
-      // Check the height argument specifically
-      expect(lastCall[2]).toBe(1);
-      unmount!();
-    });
-  });
-
   describe('Keyboard Input Handling (CTRL+C / CTRL+D)', () => {
     let mockHandleSlashCommand: Mock;
     let mockCancelOngoingRequest: Mock;
@@ -3141,30 +3109,6 @@ describe('AppContainer State Management', () => {
     });
   });
 
-  describe('Shell Interaction', () => {
-    it('should not crash if resizing the pty fails', async () => {
-      const resizePtySpy = vi
-        .spyOn(ShellExecutionService, 'resizePty')
-        .mockImplementation(() => {
-          throw new Error('Cannot resize a pty that has already exited');
-        });
-
-      mockedUseGeminiStream.mockReturnValue({
-        ...DEFAULT_GEMINI_STREAM_MOCK,
-        activePtyId: 'some-pty-id', // Make sure activePtyId is set
-      });
-
-      // The main assertion is that the render does not throw.
-      let unmount: () => void;
-      await act(async () => {
-        const result = renderAppContainer();
-        unmount = result.unmount;
-      });
-
-      await waitFor(() => expect(resizePtySpy).toHaveBeenCalled());
-      unmount!();
-    });
-  });
   describe('Banner Text', () => {
     it('should render placeholder banner text for USE_GEMINI auth type', async () => {
       const config = makeFakeConfig();

packages/cli/src/ui/AppContainer.tsx

@@ -1420,32 +1420,6 @@ Logging in with Google... Restarting Gemini CLI to continue.
   const initialPromptSubmitted = useRef(false);
   const geminiClient = config.getGeminiClient();
 
-  useEffect(() => {
-    if (activePtyId) {
-      try {
-        ShellExecutionService.resizePty(
-          activePtyId,
-          Math.floor(terminalWidth * SHELL_WIDTH_FRACTION),
-          Math.max(
-            Math.floor(availableTerminalHeight - SHELL_HEIGHT_PADDING),
-            1,
-          ),
-        );
-      } catch (e) {
-        // This can happen in a race condition where the pty exits
-        // right before we try to resize it.
-        if (
-          !(
-            e instanceof Error &&
-            e.message.includes('Cannot resize a pty that has already exited')
-          )
-        ) {
-          throw e;
-        }
-      }
-    }
-  }, [terminalWidth, availableTerminalHeight, activePtyId]);
-
   useEffect(() => {
     if (
       initialPrompt &&

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

@@ -195,7 +195,7 @@ describe('<ShellToolMessage />', () => {
       [
         'uses ACTIVE_SHELL_MAX_LINES when availableTerminalHeight is large',
         100,
-        ACTIVE_SHELL_MAX_LINES,
+        ACTIVE_SHELL_MAX_LINES - 3,
         false,
       ],
       [
@@ -207,7 +207,7 @@ describe('<ShellToolMessage />', () => {
       [
         'defaults to ACTIVE_SHELL_MAX_LINES in alternate buffer when availableTerminalHeight is undefined',
         undefined,
-        ACTIVE_SHELL_MAX_LINES,
+        ACTIVE_SHELL_MAX_LINES - 3,
         false,
       ],
     ])('%s', async (_, availableTerminalHeight, expectedMaxLines, focused) => {
@@ -301,8 +301,8 @@ describe('<ShellToolMessage />', () => {
       await waitUntilReady();
       await waitFor(() => {
         const frame = lastFrame();
-        // Should still be constrained to ACTIVE_SHELL_MAX_LINES (15) because isExpandable is false
+        // Should still be constrained to 12 (15 - 3) because isExpandable is false
-        expect(frame.match(/Line \d+/g)?.length).toBe(15);
+        expect(frame.match(/Line \d+/g)?.length).toBe(12);
       });
       expect(lastFrame()).toMatchSnapshot();
       unmount();

packages/cli/src/ui/components/messages/ShellToolMessage.tsx

@@ -24,8 +24,16 @@ import type { ToolMessageProps } from './ToolMessage.js';
 import { ACTIVE_SHELL_MAX_LINES } from '../../constants.js';
 import { useAlternateBuffer } from '../../hooks/useAlternateBuffer.js';
 import { useUIState } from '../../contexts/UIStateContext.js';
-import { type Config } from '@google/gemini-cli-core';
+import {
-import { calculateShellMaxLines } from '../../utils/toolLayoutUtils.js';
+  type Config,
+  ShellExecutionService,
+  CoreToolCallStatus,
+} from '@google/gemini-cli-core';
+import {
+  calculateShellMaxLines,
+  calculateToolContentMaxLines,
+  SHELL_CONTENT_OVERHEAD,
+} from '../../utils/toolLayoutUtils.js';
 
 export interface ShellToolMessageProps extends ToolMessageProps {
   config?: Config;
@@ -78,6 +86,47 @@ export const ShellToolMessage: React.FC<ShellToolMessageProps> = ({
     embeddedShellFocused,
   );
 
+  const maxLines = calculateShellMaxLines({
+    status,
+    isAlternateBuffer,
+    isThisShellFocused,
+    availableTerminalHeight,
+    constrainHeight,
+    isExpandable,
+  });
+
+  const availableHeight = calculateToolContentMaxLines({
+    availableTerminalHeight,
+    isAlternateBuffer,
+    maxLinesLimit: maxLines,
+  });
+
+  React.useEffect(() => {
+    const isExecuting = status === CoreToolCallStatus.Executing;
+    if (isExecuting && ptyId) {
+      try {
+        const childWidth = terminalWidth - 4; // account for padding and borders
+        const finalHeight =
+          availableHeight ?? ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD;
+
+        ShellExecutionService.resizePty(
+          ptyId,
+          Math.max(1, childWidth),
+          Math.max(1, finalHeight),
+        );
+      } catch (e) {
+        if (
+          !(
+            e instanceof Error &&
+            e.message.includes('Cannot resize a pty that has already exited')
+          )
+        ) {
+          throw e;
+        }
+      }
+    }
+  }, [ptyId, status, terminalWidth, availableHeight]);
+
   const { setEmbeddedShellFocused } = useUIActions();
   const wasFocusedRef = React.useRef(false);
 
@@ -166,14 +215,7 @@ export const ShellToolMessage: React.FC<ShellToolMessageProps> = ({
           terminalWidth={terminalWidth}
           renderOutputAsMarkdown={renderOutputAsMarkdown}
           hasFocus={isThisShellFocused}
-          maxLines={calculateShellMaxLines({
+          maxLines={maxLines}
-            status,
-            isAlternateBuffer,
-            isThisShellFocused,
-            availableTerminalHeight,
-            constrainHeight,
-            isExpandable,
-          })}
         />
         {isThisShellFocused && config && (
           <ShellInputPrompt

packages/cli/src/ui/components/messages/__snapshots__/ShellToolMessage.test.tsx.snap

@@ -4,9 +4,6 @@ exports[`<ShellToolMessage /> > Height Constraints > defaults to ACTIVE_SHELL_MA
 "╭──────────────────────────────────────────────────────────────────────────────╮
 │ ⊶  Shell Command A shell command                                             │
 │                                                                              │
-│ Line 86                                                                      │
-│ Line 87                                                                      │
-│ Line 88                                                                      │
 │ Line 89                                                                      │
 │ Line 90                                                                      │
 │ Line 91                                                                      │
@@ -16,8 +13,8 @@ exports[`<ShellToolMessage /> > Height Constraints > defaults to ACTIVE_SHELL_MA
 │ Line 95                                                                      │
 │ Line 96                                                                      │
 │ Line 97                                                                      │
-│ Line 98                                                                    ▄ │
+│ Line 98                                                                      │
-│ Line 99                                                                    █ │
+│ Line 99                                                                    ▄ │
 │ Line 100                                                                   █ │
 "
 `;
@@ -148,9 +145,6 @@ exports[`<ShellToolMessage /> > Height Constraints > stays constrained in altern
 "╭──────────────────────────────────────────────────────────────────────────────╮
 │ ✓  Shell Command A shell command                                             │
 │                                                                              │
-│ Line 86                                                                      │
-│ Line 87                                                                      │
-│ Line 88                                                                      │
 │ Line 89                                                                      │
 │ Line 90                                                                      │
 │ Line 91                                                                      │
@@ -160,8 +154,8 @@ exports[`<ShellToolMessage /> > Height Constraints > stays constrained in altern
 │ Line 95                                                                      │
 │ Line 96                                                                      │
 │ Line 97                                                                      │
-│ Line 98                                                                    ▄ │
+│ Line 98                                                                      │
-│ Line 99                                                                    █ │
+│ Line 99                                                                    ▄ │
 │ Line 100                                                                   █ │
 "
 `;
@@ -170,9 +164,6 @@ exports[`<ShellToolMessage /> > Height Constraints > uses ACTIVE_SHELL_MAX_LINES
 "╭──────────────────────────────────────────────────────────────────────────────╮
 │ ⊶  Shell Command A shell command                                             │
 │                                                                              │
-│ Line 86                                                                      │
-│ Line 87                                                                      │
-│ Line 88                                                                      │
 │ Line 89                                                                      │
 │ Line 90                                                                      │
 │ Line 91                                                                      │
@@ -182,8 +173,8 @@ exports[`<ShellToolMessage /> > Height Constraints > uses ACTIVE_SHELL_MAX_LINES
 │ Line 95                                                                      │
 │ Line 96                                                                      │
 │ Line 97                                                                      │
-│ Line 98                                                                    ▄ │
+│ Line 98                                                                      │
-│ Line 99                                                                    █ │
+│ Line 99                                                                    ▄ │
 │ Line 100                                                                   █ │
 "
 `;

packages/cli/src/ui/utils/toolLayoutUtils.ts

@@ -20,6 +20,13 @@ export const TOOL_RESULT_ASB_RESERVED_LINE_COUNT = 6;
 export const TOOL_RESULT_STANDARD_RESERVED_LINE_COUNT = 2;
 export const TOOL_RESULT_MIN_LINES_SHOWN = 2;
 
+/**
+ * The vertical space (in lines) consumed by the shell UI elements
+ * (1 line for the shell title/header and 2 lines for the top and bottom borders).
+ */
+export const SHELL_CONTENT_OVERHEAD =
+  TOOL_RESULT_STATIC_HEIGHT + TOOL_RESULT_STANDARD_RESERVED_LINE_COUNT;
+
 /**
  * Calculates the final height available for the content of a tool result display.
  *
@@ -88,7 +95,9 @@ export function calculateShellMaxLines(options: {
 
   // 2. Handle cases where height is unknown (Standard mode history).
   if (availableTerminalHeight === undefined) {
-    return isAlternateBuffer ? ACTIVE_SHELL_MAX_LINES : undefined;
+    return isAlternateBuffer
+      ? ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD
+      : undefined;
   }
 
   const maxLinesBasedOnHeight = Math.max(1, availableTerminalHeight - 2);
@@ -103,8 +112,8 @@ export function calculateShellMaxLines(options: {
   // 4. Fall back to process-based constants.
   const isExecuting = status === CoreToolCallStatus.Executing;
   const shellMaxLinesLimit = isExecuting
-    ? ACTIVE_SHELL_MAX_LINES
+    ? ACTIVE_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD
-    : COMPLETED_SHELL_MAX_LINES;
+    : COMPLETED_SHELL_MAX_LINES - SHELL_CONTENT_OVERHEAD;
 
   return Math.min(maxLinesBasedOnHeight, shellMaxLinesLimit);
 }