fix(ui): flatten multiline summaries in compact ToolGroupDisplay and fix populateToolDisplay merge logic

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

@@ -179,7 +179,10 @@ const ToolDisplayMessage: React.FC<ToolDisplayMessageProps> = ({ tool }) => {
         </Text>
         {description && <Text color={theme.text.secondary}>{description}</Text>}
         {resultSummary && (
-          <Text color={theme.text.accent}> → {resultSummary}</Text>
+          <Text color={theme.text.accent}>
+            {' '}
+            → {resultSummary.replace(/\n/g, ' ')}
+          </Text>
         )}
       </Box>
     );

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

@@ -17,7 +17,7 @@ exports[`<ToolGroupDisplay /> > Border & Margin Logic > forces top border on box
 `;
 
 exports[`<ToolGroupDisplay /> > Golden Snapshots > renders error message when display info is missing 1`] = `
-"  ⊷   Error: Tool display missing
+"  ⊶   Error: Tool display missing
 "
 `;
 

packages/core/src/agent/tool-display-utils.ts

@@ -30,9 +30,9 @@ export function populateToolDisplay({
   display?: ToolDisplay;
 }): ToolDisplay {
   const display: ToolDisplay = {
-    ...prevDisplay,
     name: displayName || name,
     description: invocation?.getDescription?.(),
+    ...prevDisplay,
   };
 
   if (resultDisplay !== undefined && display.result === undefined) {