fix(ui): resolve inconsistent Ctrl+O expansion and truncation detection

packages/cli/src/ui/AppContainer.tsx

@@ -1754,7 +1754,8 @@ Logging in with Google... Restarting Gemini CLI to continue.
         if (!isAlternateBuffer) {
           refreshStatic();
         }
-        return true;
+        // Return false to allow other components (e.g. ToolConfirmationMessage) to also handle expansion.
+        return false;
       } else if (
         (keyMatchers[Command.FOCUS_SHELL_INPUT](key) ||
           keyMatchers[Command.UNFOCUS_BACKGROUND_SHELL_LIST](key)) &&

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

@@ -176,7 +176,8 @@ export const ToolConfirmationMessage: React.FC<
           callId,
           expanded: !isMcpToolDetailsExpanded,
         });
-        return true;
+        // Return false to let the global app container also expand its view.
+        return false;
       }
       if (keyMatchers[Command.ESCAPE](key)) {
         handleConfirm(ToolConfirmationOutcome.Cancel);

packages/cli/src/ui/components/shared/MaxSizedBox.test.tsx

@@ -6,7 +6,7 @@
 
 import { render, renderWithProviders } from '../../../test-utils/render.js';
 import { OverflowProvider } from '../../contexts/OverflowContext.js';
-import { MaxSizedBox } from './MaxSizedBox.js';
+import { MaxSizedBox, ceilHeight } from './MaxSizedBox.js';
 import { MarkdownDisplay } from '../../utils/MarkdownDisplay.js';
 import { Box, Text } from 'ink';
 import { act } from 'react';
@@ -316,4 +316,17 @@ describe('<MaxSizedBox />', () => {
     expect(lastFrame()).toMatchSnapshot();
     unmount();
   });
+
+  describe('ceilHeight', () => {
+    it('should round up fractional heights to next integer', () => {
+      expect(ceilHeight(2.1)).toBe(3);
+      expect(ceilHeight(2.9)).toBe(3);
+      expect(ceilHeight(2.0)).toBe(2);
+      expect(ceilHeight(0.1)).toBe(1);
+    });
+
+    it('should handle zero correctly', () => {
+      expect(ceilHeight(0)).toBe(0);
+    });
+  });
 });

packages/cli/src/ui/components/shared/MaxSizedBox.tsx

@@ -28,6 +28,9 @@ export interface MaxSizedBoxProps {
   additionalHiddenLinesCount?: number;
 }
 
+/** Ensures that fractional heights are correctly identified as overflowing. */
+export const ceilHeight = (height: number): number => Math.ceil(height);
+
 /**
  * A React component that constrains the size of its children and provides
  * content-aware truncation when the content exceeds the specified `maxHeight`.
@@ -55,7 +58,8 @@ export const MaxSizedBox: React.FC<MaxSizedBoxProps> = ({
         const observer = new ResizeObserver((entries) => {
           const entry = entries[0];
           if (entry) {
-            setContentHeight(Math.round(entry.contentRect.height));
+            // Use ceilHeight to ensure that fractional heights (e.g. from zooming) that exceed the limit are correctly identified as overflowing.
+            setContentHeight(ceilHeight(entry.contentRect.height));
           }
         });
         observer.observe(node);