improve performance of shell commands with lots of output (#7680)

packages/core/src/tools/shell.test.ts

@@ -313,7 +313,7 @@ describe('ShellTool', () => {
         // Send a second chunk. THIS event triggers the update with the CUMULATIVE content.
         mockShellOutputCallback({
           type: 'data',
-          chunk: 'hello world',
+          chunk: 'world',
         });
 
         // It should have been called once now with the combined output.

packages/core/src/tools/shell.ts

@@ -132,6 +132,7 @@ class ShellToolInvocation extends BaseToolInvocation<
       );
 
       let cumulativeOutput = '';
+      let outputChunks: string[] = [cumulativeOutput];
       let lastUpdateTime = Date.now();
       let isBinaryStream = false;
 
@@ -149,9 +150,11 @@ class ShellToolInvocation extends BaseToolInvocation<
           switch (event.type) {
             case 'data':
               if (isBinaryStream) break;
-              cumulativeOutput = event.chunk;
-              currentDisplayOutput = cumulativeOutput;
+              outputChunks.push(event.chunk);
               if (Date.now() - lastUpdateTime > OUTPUT_UPDATE_INTERVAL_MS) {
+                cumulativeOutput = outputChunks.join('');
+                outputChunks = [cumulativeOutput];
+                currentDisplayOutput = cumulativeOutput;
                 shouldUpdate = true;
               }
               break;