add config: tool output char limit

packages/cli/src/config/config.ts

@@ -605,6 +605,7 @@ export async function loadCliConfig(
     shouldUseNodePtyShell: settings.shouldUseNodePtyShell,
     skipStartupContext: settings.skipStartupContext,
     skipNextSpeakerCheck: settings.skipNextSpeakerCheck,
+    toolOutputCharLimit: settings.toolOutputCharLimit,
   });
 }
 

packages/cli/src/config/settingsSchema.ts

@@ -577,6 +577,16 @@ export const SETTINGS_SCHEMA = {
     description: 'The maximum number of tokens allowed in a session.',
     showInDialog: false,
   },
+  toolOutputCharLimit: {
+    type: 'number',
+    label: 'Tool Output Character Limit',
+    category: 'General',
+    requiresRestart: false,
+    default: undefined as number | undefined,
+    description:
+      'Max characters for tool outputs (read_file, read_many_files, shell). If set, text content is truncated to this limit.',
+    showInDialog: true,
+  },
   systemPromptMappings: {
     type: 'object',
     label: 'System Prompt Mappings',

packages/core/src/config/config.ts

@@ -239,6 +239,8 @@ export interface ConfigParameters {
   shouldUseNodePtyShell?: boolean;
   skipStartupContext?: boolean;
   skipNextSpeakerCheck?: boolean;
+  // Character limit for tool text outputs (files and shell)
+  toolOutputCharLimit?: number;
 }
 
 export class Config {
@@ -326,6 +328,7 @@ export class Config {
   private readonly skipStartupContext: boolean;
   private readonly skipNextSpeakerCheck: boolean;
   private initialized: boolean = false;
+  private readonly toolOutputCharLimit?: number;
 
   constructor(params: ConfigParameters) {
     this.sessionId = params.sessionId;
@@ -407,6 +410,7 @@ export class Config {
     this.shouldUseNodePtyShell = params.shouldUseNodePtyShell ?? false;
     this.skipStartupContext = params.skipStartupContext ?? true;
     this.skipNextSpeakerCheck = params.skipNextSpeakerCheck ?? true;
+    this.toolOutputCharLimit = params.toolOutputCharLimit;
 
     // Web search
     this.tavilyApiKey = params.tavilyApiKey;
@@ -873,6 +877,14 @@ export class Config {
     return this.skipNextSpeakerCheck;
   }
 
+  /**
+   * Returns the configured maximum number of characters for tool outputs.
+   * If undefined, no character-based truncation is applied by tools.
+   */
+  getToolOutputCharLimit(): number | undefined {
+    return this.toolOutputCharLimit;
+  }
+
   async getGitService(): Promise<GitService> {
     if (!this.gitService) {
       this.gitService = new GitService(this.targetDir);

packages/core/src/tools/read-file.ts

@@ -122,21 +122,31 @@ class ReadFileToolInvocation extends BaseToolInvocation<
     }
 
     let llmContent: PartUnion;
+    const charLimit = this.config.getToolOutputCharLimit();
     if (result.isTruncated) {
       const [start, end] = result.linesShown!;
       const total = result.originalLineCount!;
       const nextOffset = this.params.offset
         ? this.params.offset + end - start + 1
         : end;
-      llmContent = `
-IMPORTANT: The file content has been truncated.
-Status: Showing lines ${start}-${end} of ${total} total lines.
-Action: To read more of the file, you can use the 'offset' and 'limit' parameters in a subsequent 'read_file' call. For example, to read the next section of the file, use offset: ${nextOffset}.
-
---- FILE CONTENT (truncated) ---
-${result.llmContent}`;
+      const header = `\nIMPORTANT: The file content has been truncated.\nStatus: Showing lines ${start}-${end} of ${total} total lines.\nAction: To read more of the file, you can use the 'offset' and 'limit' parameters in a subsequent 'read_file' call. For example, to read the next section of the file, use offset: ${nextOffset}.\n\n--- FILE CONTENT (truncated) ---\n`;
+      const body = typeof result.llmContent === 'string' ? result.llmContent : '';
+      let truncatedBody = body;
+      if (typeof charLimit === 'number' && charLimit > 0 && body.length > charLimit) {
+        truncatedBody = `${body.slice(0, charLimit)}\n[... File content truncated to ${charLimit} characters ...]`;
+      }
+      llmContent = header + truncatedBody;
     } else {
-      llmContent = result.llmContent || '';
+      let body = result.llmContent || '';
+      if (
+        typeof body === 'string' &&
+        typeof charLimit === 'number' &&
+        charLimit > 0 &&
+        body.length > charLimit
+      ) {
+        body = `${body.slice(0, charLimit)}\n[... File content truncated to ${charLimit} characters ...]`;
+      }
+      llmContent = body;
     }
 
     const lines =

packages/core/src/tools/read-many-files.ts

@@ -228,6 +228,7 @@ ${finalExclusionPatternsForDescription
     const skippedFiles: Array<{ path: string; reason: string }> = [];
     const processedFilesRelativePaths: string[] = [];
     const contentParts: PartListUnion = [];
+    const charLimit = this.config.getToolOutputCharLimit();
 
     const effectiveExcludes = useDefaultExcludes
       ? [...DEFAULT_EXCLUDES, ...exclude]
@@ -436,6 +437,9 @@ ${finalExclusionPatternsForDescription
     );
 
     const results = await Promise.allSettled(fileProcessingPromises);
+    let remainingContentChars =
+      typeof charLimit === 'number' && charLimit > 0 ? charLimit : Number.POSITIVE_INFINITY;
+    let globalTruncated = false;
 
     for (const result of results) {
       if (result.status === 'fulfilled') {
@@ -449,22 +453,47 @@ ${finalExclusionPatternsForDescription
           });
         } else {
           // Handle successfully processed files
-          const { filePath, relativePathForDisplay, fileReadResult } =
-            fileResult;
+          const { filePath, relativePathForDisplay, fileReadResult } = fileResult;
 
           if (typeof fileReadResult.llmContent === 'string') {
+            // Separator does not count toward char budget
             const separator = DEFAULT_OUTPUT_SEPARATOR_FORMAT.replace(
               '{filePath}',
               filePath,
             );
-            let fileContentForLlm = '';
+
+            let prefix = `${separator}\n\n`;
+            // Warning header (if any) does not count toward char budget
             if (fileReadResult.isTruncated) {
-              fileContentForLlm += `[WARNING: This file was truncated. To view the full content, use the 'read_file' tool on this specific file.]\n\n`;
+              prefix += `[WARNING: This file was truncated. To view the full content, use the 'read_file' tool on this specific file.]\n\n`;
+            }
+            contentParts.push(prefix);
+
+            // Apply global char budget to the actual file content only
+            if (remainingContentChars > 0) {
+              const body = fileReadResult.llmContent;
+              if (body.length <= remainingContentChars) {
+                contentParts.push(body + '\n\n');
+                remainingContentChars -= body.length;
+              } else {
+                contentParts.push(
+                  body.slice(0, Math.max(0, remainingContentChars)),
+                );
+                contentParts.push(
+                  `\n[... Content truncated to ${charLimit} characters across files ...]\n`,
+                );
+                remainingContentChars = 0;
+                globalTruncated = true;
+              }
+            } else if (!globalTruncated && typeof charLimit === 'number') {
+              // No remaining budget, emit a single global truncation marker after first overflow
+              contentParts.push(
+                `\n[... Content truncated to ${charLimit} characters across files ...]\n`,
+              );
+              globalTruncated = true;
             }
-            fileContentForLlm += fileReadResult.llmContent;
-            contentParts.push(`${separator}\n\n${fileContentForLlm}\n\n`);
           } else {
-            // This is a Part for image/pdf, which we don't add the separator to.
+            // Non-text parts (image/pdf) do not count toward char budget
             contentParts.push(fileReadResult.llmContent);
           }
 
@@ -538,6 +567,10 @@ ${finalExclusionPatternsForDescription
         'No files matching the criteria were found or all were skipped.',
       );
     }
+    if (globalTruncated && typeof charLimit === 'number') {
+      displayMessage += `\n\nNote: Output truncated to ${charLimit} characters (text content only).`;
+    }
+
     return {
       llmContent: contentParts,
       returnDisplay: displayMessage.trim(),

packages/core/src/tools/shell.ts

@@ -279,6 +279,24 @@ class ShellToolInvocation extends BaseToolInvocation<
         }
       }
 
+      // Apply character truncation (middle) to both llmContent and returnDisplay if configured
+      const charLimit = this.config.getToolOutputCharLimit();
+      const middleTruncate = (s: string, limit: number): string => {
+        if (!s || s.length <= limit) return s;
+        const marker = '\n[... Output truncated due to length ...]\n';
+        const keep = Math.max(0, Math.floor((limit - marker.length) / 2));
+        if (keep <= 0) {
+          return s.slice(0, limit);
+        }
+        return s.slice(0, keep) + marker + s.slice(s.length - keep);
+      };
+      if (typeof charLimit === 'number' && charLimit > 0) {
+        llmContent = middleTruncate(llmContent, charLimit);
+        if (returnDisplayMessage) {
+          returnDisplayMessage = middleTruncate(returnDisplayMessage, charLimit);
+        }
+      }
+
       const summarizeConfig = this.config.getSummarizeToolOutputConfig();
       if (summarizeConfig && summarizeConfig[ShellTool.Name]) {
         const summary = await summarizeToolOutput(

packages/core/src/utils/fileUtils.ts

@@ -11,7 +11,7 @@ import mime from 'mime-types';
 import { FileSystemService } from '../services/fileSystemService.js';
 
 // Constants for text file processing
-export const DEFAULT_MAX_LINES_TEXT_FILE = 2000;
+export const DEFAULT_MAX_LINES_TEXT_FILE = 500;
 const MAX_LINE_LENGTH_TEXT_FILE = 2000;
 
 // Default values for encoding and separator format