From 45d494a8d86cd2d47ac34abb7b15d25124b44e5a Mon Sep 17 00:00:00 2001
From: Jacob MacDonald <jakemac@google.com>
Date: Thu, 4 Sep 2025 09:20:24 -0700
Subject: [PATCH] improve performance of shell commands with lots of output
 (#7680)

---
 .../core/src/services/shellExecutionService.test.ts    |  2 +-
 packages/core/src/services/shellExecutionService.ts    | 10 +++++-----
 packages/core/src/tools/shell.test.ts                  |  2 +-
 packages/core/src/tools/shell.ts                       |  7 +++++--
 4 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/packages/core/src/services/shellExecutionService.test.ts b/packages/core/src/services/shellExecutionService.test.ts
index 9b02995ee6..3edce90268 100644
--- a/packages/core/src/services/shellExecutionService.test.ts
+++ b/packages/core/src/services/shellExecutionService.test.ts
@@ -133,7 +133,7 @@ describe('ShellExecutionService', () => {
 
       expect(onOutputEventMock).toHaveBeenCalledWith({
         type: 'data',
-        chunk: 'file1.txt',
+        chunk: 'file1.txt\n',
       });
     });
 
diff --git a/packages/core/src/services/shellExecutionService.ts b/packages/core/src/services/shellExecutionService.ts
index e42cc9bc48..f6f7fff7b6 100644
--- a/packages/core/src/services/shellExecutionService.ts
+++ b/packages/core/src/services/shellExecutionService.ts
@@ -348,7 +348,6 @@ export class ShellExecutionService {
         });
         let processingChain = Promise.resolve();
         let decoder: TextDecoder | null = null;
-        let output = '';
         const outputChunks: Buffer[] = [];
         const error: Error | null = null;
         let exited = false;
@@ -385,9 +384,10 @@ export class ShellExecutionService {
                 if (isStreamingRawContent) {
                   const decodedChunk = decoder.decode(data, { stream: true });
                   headlessTerminal.write(decodedChunk, () => {
-                    const newStrippedOutput = getFullText(headlessTerminal);
-                    output = newStrippedOutput;
-                    onOutputEvent({ type: 'data', chunk: newStrippedOutput });
+                    onOutputEvent({
+                      type: 'data',
+                      chunk: stripAnsi(decodedChunk),
+                    });
                     resolve();
                   });
                 } else {
@@ -420,7 +420,7 @@ export class ShellExecutionService {
 
               resolve({
                 rawOutput: finalBuffer,
-                output,
+                output: getFullText(headlessTerminal),
                 exitCode,
                 signal: signal ?? null,
                 error,
diff --git a/packages/core/src/tools/shell.test.ts b/packages/core/src/tools/shell.test.ts
index e1874aaa42..88daa0cdfa 100644
--- a/packages/core/src/tools/shell.test.ts
+++ b/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.
diff --git a/packages/core/src/tools/shell.ts b/packages/core/src/tools/shell.ts
index f7275161fc..94e4bd85ec 100644
--- a/packages/core/src/tools/shell.ts
+++ b/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;