update shell output at an interval to reduce flicker (#614)

packages/server/src/tools/shell.ts

@@ -25,6 +25,8 @@ export interface ShellToolParams {
 }
 import { spawn } from 'child_process';
 
+const OUTPUT_UPDATE_INTERVAL_MS = 1000;
+
 export class ShellTool extends BaseTool<ShellToolParams, ToolResult> {
   static Name: string = 'execute_bash_command';
   private whitelist: Set<string> = new Set();
@@ -124,7 +126,7 @@ export class ShellTool extends BaseTool<ShellToolParams, ToolResult> {
   async execute(
     params: ShellToolParams,
     abortSignal: AbortSignal,
-    onOutputChunk?: (chunk: string) => void,
+    updateOutput?: (output: string) => void,
   ): Promise<ToolResult> {
     const validationError = this.validateToolParams(params);
     if (validationError) {
@@ -155,6 +157,19 @@ export class ShellTool extends BaseTool<ShellToolParams, ToolResult> {
     let exited = false;
     let stdout = '';
     let output = '';
+    let lastUpdateTime = Date.now();
+
+    const appendOutput = (str: string) => {
+      output += str;
+      if (
+        updateOutput &&
+        Date.now() - lastUpdateTime > OUTPUT_UPDATE_INTERVAL_MS
+      ) {
+        updateOutput(output);
+        lastUpdateTime = Date.now();
+      }
+    };
+
     shell.stdout.on('data', (data: Buffer) => {
       // continue to consume post-exit for background processes
       // removing listeners can overflow OS buffer and block subprocesses
@@ -162,10 +177,7 @@ export class ShellTool extends BaseTool<ShellToolParams, ToolResult> {
       if (!exited) {
         const str = data.toString();
         stdout += str;
-        output += str;
-        if (onOutputChunk) {
-          onOutputChunk(str);
-        }
+        appendOutput(str);
       }
     });
 
@@ -174,10 +186,7 @@ export class ShellTool extends BaseTool<ShellToolParams, ToolResult> {
       if (!exited) {
         const str = data.toString();
         stderr += str;
-        output += str;
-        if (onOutputChunk) {
-          onOutputChunk(str);
-        }
+        appendOutput(str);
       }
     });
 

packages/server/src/tools/tools.ts

@@ -68,7 +68,7 @@ export interface Tool<
   execute(
     params: TParams,
     signal: AbortSignal,
-    onOutputChunk?: (chunk: string) => void,
+    updateOutput?: (output: string) => void,
   ): Promise<TResult>;
 }
 
@@ -154,7 +154,7 @@ export abstract class BaseTool<
   abstract execute(
     params: TParams,
     signal: AbortSignal,
-    onOutputChunk?: (chunk: string) => void,
+    updateOutput?: (output: string) => void,
   ): Promise<TResult>;
 }