feat(ux) Expandable (ctrl-O) and scrollable approvals in alternate buffer mode. (#17640)

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

@@ -7,6 +7,7 @@
 import type React from 'react';
 import { Box } from 'ink';
 import { MarkdownDisplay } from '../../utils/MarkdownDisplay.js';
+import { ShowMoreLines } from '../ShowMoreLines.js';
 import { useUIState } from '../../contexts/UIStateContext.js';
 import { useAlternateBuffer } from '../../hooks/useAlternateBuffer.js';
 
@@ -40,11 +41,18 @@ export const GeminiMessageContent: React.FC<GeminiMessageContentProps> = ({
         text={text}
         isPending={isPending}
         availableTerminalHeight={
-          isAlternateBuffer ? undefined : availableTerminalHeight
+          isAlternateBuffer || availableTerminalHeight === undefined
+            ? undefined
+            : Math.max(availableTerminalHeight - 1, 1)
         }
         terminalWidth={terminalWidth}
         renderMarkdown={renderMarkdown}
       />
+      <Box marginBottom={1}>
+        <ShowMoreLines
+          constrainHeight={availableTerminalHeight !== undefined}
+        />
+      </Box>
     </Box>
   );
 };