refactor: simplify tool output truncation to single config (#18446)

docs/cli/settings.md

@@ -101,9 +101,7 @@ they appear in the UI.
 | Show Color                       | `tools.shell.showColor`              | Show color in shell output.                                                                                                                                                    | `false`     |
 | Approval Mode                    | `tools.approvalMode`                 | The default approval mode for tool execution. 'default' prompts for approval, 'auto_edit' auto-approves edit tools, and 'plan' is read-only mode. 'yolo' is not supported yet. | `"default"` |
 | Use Ripgrep                      | `tools.useRipgrep`                   | Use ripgrep for file content search instead of the fallback implementation. Provides faster search performance.                                                                | `true`      |
-| Enable Tool Output Truncation    | `tools.enableToolOutputTruncation`   | Enable truncation of large tool outputs.                                                                                                                                       | `true`      |
+| Tool Output Truncation Threshold | `tools.truncateToolOutputThreshold`  | Maximum characters to show when truncating large tool outputs. Set to 0 or negative to disable truncation.                                                                     | `40000`     |
-| Tool Output Truncation Threshold | `tools.truncateToolOutputThreshold`  | Truncate tool output if it is larger than this many characters. Set to -1 to disable.                                                                                          | `4000000`   |
-| Tool Output Truncation Lines     | `tools.truncateToolOutputLines`      | The number of lines to keep when truncating tool output.                                                                                                                       | `1000`      |
 | Disable LLM Correction           | `tools.disableLLMCorrection`         | Disable LLM-based error correction for edit tools. When enabled, tools will fail immediately if exact string matches are not found, instead of attempting to self-correct.     | `true`      |
 
 ### Security

docs/get-started/configuration.md

@@ -716,20 +716,10 @@ their corresponding top-level category object in your `settings.json` file.
     implementation. Provides faster search performance.
   - **Default:** `true`
 
-- **`tools.enableToolOutputTruncation`** (boolean):
-  - **Description:** Enable truncation of large tool outputs.
-  - **Default:** `true`
-  - **Requires restart:** Yes
-
 - **`tools.truncateToolOutputThreshold`** (number):
-  - **Description:** Truncate tool output if it is larger than this many
+  - **Description:** Maximum characters to show when truncating large tool
-    characters. Set to -1 to disable.
+    outputs. Set to 0 or negative to disable truncation.
-  - **Default:** `4000000`
+  - **Default:** `40000`
-  - **Requires restart:** Yes
-
-- **`tools.truncateToolOutputLines`** (number):
-  - **Description:** The number of lines to keep when truncating tool output.
-  - **Default:** `1000`
   - **Requires restart:** Yes
 
 - **`tools.disableLLMCorrection`** (boolean):

packages/a2a-server/src/utils/testing_utils.ts

@@ -12,7 +12,6 @@ import type {
 import {
   ApprovalMode,
   DEFAULT_GEMINI_MODEL,
-  DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES,
   DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD,
   GeminiClient,
   HookSystem,
@@ -47,7 +46,6 @@ export function createMockConfig(
     } as Storage,
     getTruncateToolOutputThreshold: () =>
       DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD,
-    getTruncateToolOutputLines: () => DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES,
     getActiveModel: vi.fn().mockReturnValue(DEFAULT_GEMINI_MODEL),
     getDebugMode: vi.fn().mockReturnValue(false),
     getContentGeneratorConfig: vi.fn().mockReturnValue({ model: 'gemini-pro' }),

packages/cli/src/config/config.ts

@@ -800,8 +800,6 @@ export async function loadCliConfig(
     skipNextSpeakerCheck: settings.model?.skipNextSpeakerCheck,
     enablePromptCompletion: settings.general?.enablePromptCompletion,
     truncateToolOutputThreshold: settings.tools?.truncateToolOutputThreshold,
-    truncateToolOutputLines: settings.tools?.truncateToolOutputLines,
-    enableToolOutputTruncation: settings.tools?.enableToolOutputTruncation,
     eventEmitter: coreEvents,
     useWriteTodos: argv.useWriteTodos ?? settings.useWriteTodos,
     output: {

packages/cli/src/config/settingsSchema.ts

@@ -10,7 +10,6 @@
 // --------------------------------------------------------------------------
 
 import {
-  DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES,
   DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD,
   DEFAULT_MODEL_CONFIGS,
   type MCPServerConfig,
@@ -1149,15 +1148,6 @@ const SETTINGS_SCHEMA = {
           'Use ripgrep for file content search instead of the fallback implementation. Provides faster search performance.',
         showInDialog: true,
       },
-      enableToolOutputTruncation: {
-        type: 'boolean',
-        label: 'Enable Tool Output Truncation',
-        category: 'General',
-        requiresRestart: true,
-        default: true,
-        description: 'Enable truncation of large tool outputs.',
-        showInDialog: true,
-      },
       truncateToolOutputThreshold: {
         type: 'number',
         label: 'Tool Output Truncation Threshold',
@@ -1165,16 +1155,7 @@ const SETTINGS_SCHEMA = {
         requiresRestart: true,
         default: DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD,
         description:
-          'Truncate tool output if it is larger than this many characters. Set to -1 to disable.',
+          'Maximum characters to show when truncating large tool outputs. Set to 0 or negative to disable truncation.',
-        showInDialog: true,
-      },
-      truncateToolOutputLines: {
-        type: 'number',
-        label: 'Tool Output Truncation Lines',
-        category: 'General',
-        requiresRestart: true,
-        default: DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES,
-        description: 'The number of lines to keep when truncating tool output.',
         showInDialog: true,
       },
       disableLLMCorrection: {

packages/cli/src/config/settings_repro.test.ts

@@ -149,7 +149,6 @@ describe('Settings Repro', () => {
           showColor: true,
           enableInteractiveShell: true,
         },
-        truncateToolOutputLines: 100,
       },
       experimental: {
         useModelRouter: false,

packages/cli/src/ui/components/SettingsDialog.test.tsx

@@ -1396,7 +1396,6 @@ describe('SettingsDialog', () => {
           },
           tools: {
             truncateToolOutputThreshold: 50000,
-            truncateToolOutputLines: 1000,
           },
           context: {
             discoveryMaxDirs: 500,
@@ -1465,7 +1464,6 @@ describe('SettingsDialog', () => {
             enableInteractiveShell: true,
             useRipgrep: true,
             truncateToolOutputThreshold: 25000,
-            truncateToolOutputLines: 500,
           },
           security: {
             folderTrust: {

packages/cli/src/ui/hooks/useToolScheduler.test.ts

@@ -25,7 +25,6 @@ import type {
   AnyToolInvocation,
 } from '@google/gemini-cli-core';
 import {
-  DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES,
   DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD,
   ToolConfirmationOutcome,
   ApprovalMode,
@@ -70,7 +69,6 @@ const mockConfig = {
     getProjectTempDir: () => '/tmp',
   },
   getTruncateToolOutputThreshold: () => DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD,
-  getTruncateToolOutputLines: () => DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES,
   getAllowedTools: vi.fn(() => []),
   getActiveModel: () => PREVIEW_GEMINI_MODEL,
   getContentGeneratorConfig: () => ({

packages/core/index.ts

@@ -19,10 +19,7 @@ export {
   type AnsiLine,
   type AnsiToken,
 } from './src/utils/terminalSerializer.js';
-export {
+export { DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD } from './src/config/config.js';
-  DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES,
-  DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD,
-} from './src/config/config.js';
 export { detectIdeFromEnv } from './src/ide/detect-ide.js';
 export {
   logExtensionEnable,

packages/core/src/config/config.test.ts

@@ -1104,8 +1104,8 @@ describe('Server Config (config.ts)', () => {
         1000,
       );
       // 4 * (32000 - 1000) = 4 * 31000 = 124000
-      // default is 4_000_000
+      // default is 40_000, so min(124000, 40000) = 40000
-      expect(config.getTruncateToolOutputThreshold()).toBe(124000);
+      expect(config.getTruncateToolOutputThreshold()).toBe(40_000);
     });
 
     it('should return the default threshold when the calculated value is larger', () => {
@@ -1115,8 +1115,8 @@ describe('Server Config (config.ts)', () => {
         500_000,
       );
       // 4 * (2_000_000 - 500_000) = 4 * 1_500_000 = 6_000_000
-      // default is 4_000_000
+      // default is 40_000
-      expect(config.getTruncateToolOutputThreshold()).toBe(4_000_000);
+      expect(config.getTruncateToolOutputThreshold()).toBe(40_000);
     });
 
     it('should use a custom truncateToolOutputThreshold if provided', () => {

packages/core/src/config/config.ts

@@ -303,8 +303,7 @@ export {
   DEFAULT_MEMORY_FILE_FILTERING_OPTIONS,
 };
 
-export const DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD = 4_000_000;
+export const DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD = 40_000;
-export const DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES = 1000;
 
 export class MCPServerConfig {
   constructor(
@@ -442,8 +441,6 @@ export interface ConfigParameters {
   extensionManagement?: boolean;
   enablePromptCompletion?: boolean;
   truncateToolOutputThreshold?: number;
-  truncateToolOutputLines?: number;
-  enableToolOutputTruncation?: boolean;
   eventEmitter?: EventEmitter;
   useWriteTodos?: boolean;
   policyEngineConfig?: PolicyEngineConfig;
@@ -586,9 +583,7 @@ export class Config {
   private readonly extensionManagement: boolean = true;
   private readonly enablePromptCompletion: boolean = false;
   private readonly truncateToolOutputThreshold: number;
-  private readonly truncateToolOutputLines: number;
   private compressionTruncationCounter = 0;
-  private readonly enableToolOutputTruncation: boolean;
   private initialized: boolean = false;
   readonly storage: Storage;
   private readonly fileExclusions: FileExclusions;
@@ -778,9 +773,6 @@ export class Config {
     this.truncateToolOutputThreshold =
       params.truncateToolOutputThreshold ??
       DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD;
-    this.truncateToolOutputLines =
-      params.truncateToolOutputLines ?? DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES;
-    this.enableToolOutputTruncation = params.enableToolOutputTruncation ?? true;
     // // TODO(joshualitt): Re-evaluate the todo tool for 3 family.
     this.useWriteTodos = isPreviewModel(this.model)
       ? false
@@ -2063,10 +2055,6 @@ export class Config {
     return this.enablePromptCompletion;
   }
 
-  getEnableToolOutputTruncation(): boolean {
-    return this.enableToolOutputTruncation;
-  }
-
   getTruncateToolOutputThreshold(): number {
     return Math.min(
       // Estimate remaining context window in characters (1 token ~= 4 chars).
@@ -2076,10 +2064,6 @@ export class Config {
     );
   }
 
-  getTruncateToolOutputLines(): number {
-    return this.truncateToolOutputLines;
-  }
-
   getNextCompressionTruncationId(): number {
     return ++this.compressionTruncationCounter;
   }

packages/core/src/core/coreToolScheduler.test.ts

@@ -23,7 +23,6 @@ import type {
   MessageBus,
 } from '../index.js';
 import {
-  DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES,
   DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD,
   BaseDeclarativeTool,
   BaseToolInvocation,
@@ -271,7 +270,6 @@ function createMockConfig(overrides: Partial<Config> = {}): Config {
     },
     getTruncateToolOutputThreshold: () =>
       DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD,
-    getTruncateToolOutputLines: () => DEFAULT_TRUNCATE_TOOL_OUTPUT_LINES,
     getToolRegistry: () => defaultToolRegistry,
     getActiveModel: () => DEFAULT_GEMINI_MODEL,
     getGeminiClient: () => null,

packages/core/src/scheduler/tool-executor.test.ts

@@ -44,7 +44,6 @@ describe('ToolExecutor', () => {
     // Default mock implementation
     vi.mocked(fileUtils.saveTruncatedToolOutput).mockResolvedValue({
       outputFile: '/tmp/truncated_output.txt',
-      totalLines: 100,
     });
     vi.mocked(fileUtils.formatTruncatedToolOutput).mockReturnValue(
       'TruncatedContent...',
@@ -180,9 +179,7 @@ describe('ToolExecutor', () => {
 
   it('should truncate large shell output', async () => {
     // 1. Setup Config for Truncation
-    vi.spyOn(config, 'getEnableToolOutputTruncation').mockReturnValue(true);
     vi.spyOn(config, 'getTruncateToolOutputThreshold').mockReturnValue(10);
-    vi.spyOn(config, 'getTruncateToolOutputLines').mockReturnValue(5);
 
     const mockTool = new MockTool({ name: SHELL_TOOL_NAME });
     const invocation = mockTool.build({});
@@ -227,7 +224,7 @@ describe('ToolExecutor', () => {
     expect(fileUtils.formatTruncatedToolOutput).toHaveBeenCalledWith(
       longOutput,
       '/tmp/truncated_output.txt',
-      5, // lines
+      10, // threshold (maxChars)
     );
 
     expect(result.status).toBe('success');

packages/core/src/scheduler/tool-executor.ts

@@ -204,18 +204,11 @@ export class ToolExecutor {
     const toolName = call.request.name;
     const callId = call.request.callId;
 
-    if (
+    if (typeof content === 'string' && toolName === SHELL_TOOL_NAME) {
-      typeof content === 'string' &&
-      toolName === SHELL_TOOL_NAME &&
-      this.config.getEnableToolOutputTruncation() &&
-      this.config.getTruncateToolOutputThreshold() > 0 &&
-      this.config.getTruncateToolOutputLines() > 0
-    ) {
-      const originalContentLength = content.length;
       const threshold = this.config.getTruncateToolOutputThreshold();
-      const lines = this.config.getTruncateToolOutputLines();
 
-      if (content.length > threshold) {
+      if (threshold > 0 && content.length > threshold) {
+        const originalContentLength = content.length;
         const { outputFile: savedPath } = await saveTruncatedToolOutput(
           content,
           toolName,
@@ -224,7 +217,7 @@ export class ToolExecutor {
           this.config.getSessionId(),
         );
         outputFile = savedPath;
-        content = formatTruncatedToolOutput(content, outputFile, lines);
+        content = formatTruncatedToolOutput(content, outputFile, threshold);
 
         logToolOutputTruncated(
           this.config,
@@ -233,7 +226,6 @@ export class ToolExecutor {
             originalContentLength,
             truncatedContentLength: content.length,
             threshold,
-            lines,
           }),
         );
       }

packages/core/src/services/chatCompressionService.test.ts

@@ -183,6 +183,7 @@ describe('ChatCompressionService', () => {
       getMessageBus: vi.fn().mockReturnValue(undefined),
       getHookSystem: () => undefined,
       getNextCompressionTruncationId: vi.fn().mockReturnValue(1),
+      getTruncateToolOutputThreshold: vi.fn().mockReturnValue(40000),
       storage: {
         getProjectTempDir: vi.fn().mockReturnValue(testTempDir),
       },
@@ -581,10 +582,10 @@ describe('ChatCompressionService', () => {
       const truncatedPart = shellResponse!.parts![0].functionResponse;
       const content = truncatedPart?.response?.['output'] as string;
 
+      // DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD = 40000 -> head=8000 (20%), tail=32000 (80%)
       expect(content).toContain(
-        'Output too large. Showing the last 4,000 characters of the output.',
+        'Showing first 8,000 and last 32,000 characters',
       );
-      // It's a single line, so NO [LINE WIDTH TRUNCATED]
     });
 
     it('should use character-based truncation for massive single-line raw strings', async () => {
@@ -645,8 +646,9 @@ describe('ChatCompressionService', () => {
       const truncatedPart = rawResponse!.parts![0].functionResponse;
       const content = truncatedPart?.response?.['output'] as string;
 
+      // DEFAULT_TRUNCATE_TOOL_OUTPUT_THRESHOLD = 40000 -> head=8000 (20%), tail=32000 (80%)
       expect(content).toContain(
-        'Output too large. Showing the last 4,000 characters of the output.',
+        'Showing first 8,000 and last 32,000 characters',
       );
     });
 

packages/core/src/services/chatCompressionService.ts

@@ -49,11 +49,6 @@ export const COMPRESSION_PRESERVE_THRESHOLD = 0.3;
  */
 export const COMPRESSION_FUNCTION_RESPONSE_TOKEN_BUDGET = 50_000;
 
-/**
- * The number of lines to keep when truncating a function response during compression.
- */
-export const COMPRESSION_TRUNCATE_LINES = 30;
-
 /**
  * Returns the index of the oldest item to keep when compressing. May return
  * contents.length which indicates that everything should be compressed.
@@ -189,11 +184,10 @@ async function truncateHistoryToBudget(
                 config.storage.getProjectTempDir(),
               );
 
-              // Prepare a honest, readable snippet of the tail.
               const truncatedMessage = formatTruncatedToolOutput(
                 contentStr,
                 outputFile,
-                COMPRESSION_TRUNCATE_LINES,
+                config.getTruncateToolOutputThreshold(),
               );
 
               newParts.unshift({

packages/core/src/telemetry/clearcut-logger/clearcut-logger.ts

@@ -1213,10 +1213,6 @@ export class ClearcutLogger {
           EventMetadataKey.GEMINI_CLI_TOOL_OUTPUT_TRUNCATED_THRESHOLD,
         value: JSON.stringify(event.threshold),
       },
-      {
-        gemini_cli_key: EventMetadataKey.GEMINI_CLI_TOOL_OUTPUT_TRUNCATED_LINES,
-        value: JSON.stringify(event.lines),
-      },
     ];
 
     const logEvent = this.createLogEvent(

packages/core/src/telemetry/loggers.test.ts

@@ -1663,7 +1663,6 @@ describe('loggers', () => {
         originalContentLength: 1000,
         truncatedContentLength: 100,
         threshold: 500,
-        lines: 10,
       });
 
       logToolOutputTruncated(mockConfig, event);
@@ -1683,7 +1682,6 @@ describe('loggers', () => {
           original_content_length: 1000,
           truncated_content_length: 100,
           threshold: 500,
-          lines: 10,
         },
       });
     });

packages/core/src/telemetry/types.ts

@@ -1334,7 +1334,6 @@ export class ToolOutputTruncatedEvent implements BaseTelemetryEvent {
   original_content_length: number;
   truncated_content_length: number;
   threshold: number;
-  lines: number;
   prompt_id: string;
 
   constructor(
@@ -1344,7 +1343,6 @@ export class ToolOutputTruncatedEvent implements BaseTelemetryEvent {
       originalContentLength: number;
       truncatedContentLength: number;
       threshold: number;
-      lines: number;
     },
   ) {
     this['event.name'] = this.eventName;
@@ -1353,7 +1351,6 @@ export class ToolOutputTruncatedEvent implements BaseTelemetryEvent {
     this.original_content_length = details.originalContentLength;
     this.truncated_content_length = details.truncatedContentLength;
     this.threshold = details.threshold;
-    this.lines = details.lines;
   }
 
   toOpenTelemetryAttributes(config: Config): LogAttributes {
@@ -1366,7 +1363,6 @@ export class ToolOutputTruncatedEvent implements BaseTelemetryEvent {
       original_content_length: this.original_content_length,
       truncated_content_length: this.truncated_content_length,
       threshold: this.threshold,
-      lines: this.lines,
       prompt_id: this.prompt_id,
     };
   }

packages/core/src/utils/fileUtils.test.ts

@@ -1125,7 +1125,6 @@ describe('fileUtils', () => {
         'shell_123.txt',
       );
       expect(result.outputFile).toBe(expectedOutputFile);
-      expect(result.totalLines).toBe(1);
 
       const savedContent = await fsPromises.readFile(
         expectedOutputFile,
@@ -1200,43 +1199,32 @@ describe('fileUtils', () => {
       expect(result.outputFile).toBe(expectedOutputFile);
     });
 
-    it('should format multi-line output correctly', () => {
+    it('should truncate showing first 20% and last 80%', () => {
-      const lines = Array.from({ length: 50 }, (_, i) => `line ${i}`);
+      const content = 'abcdefghijklmnopqrstuvwxyz'; // 26 chars
-      const content = lines.join('\n');
       const outputFile = '/tmp/out.txt';
 
+      // maxChars=10 -> head=2 (20%), tail=8 (80%)
       const formatted = formatTruncatedToolOutput(content, outputFile, 10);
 
-      expect(formatted).toContain(
+      expect(formatted).toContain('Showing first 2 and last 8 characters');
-        'Output too large. Showing the last 10 of 50 lines.',
-      );
       expect(formatted).toContain('For full output see: /tmp/out.txt');
-      expect(formatted).toContain('line 49');
+      expect(formatted).toContain('ab'); // first 2 chars
-      expect(formatted).not.toContain('line 0');
+      expect(formatted).toContain('stuvwxyz'); // last 8 chars
+      expect(formatted).toContain('[16 characters omitted]'); // 26 - 2 - 8 = 16
     });
 
-    it('should truncate "elephant lines" (long single line in multi-line output)', () => {
+    it('should format large content with head/tail truncation', () => {
-      const longLine = 'a'.repeat(2000);
-      const content = `line 1\n${longLine}\nline 3`;
-      const outputFile = '/tmp/out.txt';
-
-      const formatted = formatTruncatedToolOutput(content, outputFile, 3);
-
-      expect(formatted).toContain('(some long lines truncated)');
-      expect(formatted).toContain('... [LINE WIDTH TRUNCATED]');
-      expect(formatted.length).toBeLessThan(longLine.length);
-    });
-
-    it('should handle massive single-line string with character-based truncation', () => {
       const content = 'a'.repeat(50000);
       const outputFile = '/tmp/out.txt';
 
-      const formatted = formatTruncatedToolOutput(content, outputFile);
+      // maxChars=4000 -> head=800 (20%), tail=3200 (80%)
+      const formatted = formatTruncatedToolOutput(content, outputFile, 4000);
 
       expect(formatted).toContain(
-        'Output too large. Showing the last 4,000 characters',
+        'Showing first 800 and last 3,200 characters',
       );
-      expect(formatted.endsWith(content.slice(-4000))).toBe(true);
+      expect(formatted).toContain('For full output see: /tmp/out.txt');
+      expect(formatted).toContain('[46,000 characters omitted]'); // 50000 - 800 - 3200
     });
   });
 });

packages/core/src/utils/fileUtils.ts

@@ -569,9 +569,6 @@ export async function fileExists(filePath: string): Promise<boolean> {
   }
 }
 
-const MAX_TRUNCATED_LINE_WIDTH = 1000;
-const MAX_TRUNCATED_CHARS = 4000;
-
 /**
  * Sanitizes a string for use as a filename part by removing path traversal
  * characters and other non-alphanumeric characters.
@@ -581,43 +578,29 @@ export function sanitizeFilenamePart(part: string): string {
 }
 
 /**
- * Formats a truncated message for tool output, handling multi-line and single-line (elephant) cases.
+ * Formats a truncated message for tool output.
+ * Shows the first 20% and last 80% of the allowed characters with a marker in between.
  */
 export function formatTruncatedToolOutput(
   contentStr: string,
   outputFile: string,
-  truncateLines: number = 30,
+  maxChars: number,
 ): string {
-  const physicalLines = contentStr.split('\n');
+  if (contentStr.length <= maxChars) return contentStr;
-  const totalPhysicalLines = physicalLines.length;
 
-  if (totalPhysicalLines > 1) {
+  const headChars = Math.floor(maxChars * 0.2);
-    // Multi-line case: show last N lines, but protect against "elephant" lines.
+  const tailChars = maxChars - headChars;
-    const lastLines = physicalLines.slice(-truncateLines);
-    let someLinesTruncatedInWidth = false;
-    const processedLines = lastLines.map((line) => {
-      if (line.length > MAX_TRUNCATED_LINE_WIDTH) {
-        someLinesTruncatedInWidth = true;
-        return (
-          line.substring(0, MAX_TRUNCATED_LINE_WIDTH) +
-          '... [LINE WIDTH TRUNCATED]'
-        );
-      }
-      return line;
-    });
 
-    const widthWarning = someLinesTruncatedInWidth
+  const head = contentStr.slice(0, headChars);
-      ? ' (some long lines truncated)'
+  const tail = contentStr.slice(-tailChars);
-      : '';
+  const omittedChars = contentStr.length - headChars - tailChars;
-    return `Output too large. Showing the last ${processedLines.length} of ${totalPhysicalLines} lines${widthWarning}. For full output see: ${outputFile}
+
-...
+  return `Output too large. Showing first ${headChars.toLocaleString()} and last ${tailChars.toLocaleString()} characters. For full output see: ${outputFile}
-${processedLines.join('\n')}`;
+${head}
-  } else {
+
-    // Single massive line case: use character-based truncation description.
+... [${omittedChars.toLocaleString()} characters omitted] ...
-    const snippet = contentStr.slice(-MAX_TRUNCATED_CHARS);
+
-    return `Output too large. Showing the last ${MAX_TRUNCATED_CHARS.toLocaleString()} characters of the output. For full output see: ${outputFile}
+${tail}`;
-...${snippet}`;
-  }
 }
 
 /**
@@ -631,7 +614,7 @@ export async function saveTruncatedToolOutput(
   id: string | number, // Accept string (callId) or number (truncationId)
   projectTempDir: string,
   sessionId?: string,
-): Promise<{ outputFile: string; totalLines: number }> {
+): Promise<{ outputFile: string }> {
   const safeToolName = sanitizeFilenamePart(toolName).toLowerCase();
   const safeId = sanitizeFilenamePart(id.toString()).toLowerCase();
   const fileName = `${safeToolName}_${safeId}.txt`;
@@ -646,9 +629,5 @@ export async function saveTruncatedToolOutput(
   await fsPromises.mkdir(toolOutputDir, { recursive: true });
   await fsPromises.writeFile(outputFile, content);
 
-  const lines = content.split('\n');
+  return { outputFile };
-  return {
-    outputFile,
-    totalLines: lines.length,
-  };
 }

schemas/settings.schema.json

@@ -1180,25 +1180,11 @@
           "default": true,
           "type": "boolean"
         },
-        "enableToolOutputTruncation": {
-          "title": "Enable Tool Output Truncation",
-          "description": "Enable truncation of large tool outputs.",
-          "markdownDescription": "Enable truncation of large tool outputs.\n\n- Category: `General`\n- Requires restart: `yes`\n- Default: `true`",
-          "default": true,
-          "type": "boolean"
-        },
         "truncateToolOutputThreshold": {
           "title": "Tool Output Truncation Threshold",
-          "description": "Truncate tool output if it is larger than this many characters. Set to -1 to disable.",
+          "description": "Maximum characters to show when truncating large tool outputs. Set to 0 or negative to disable truncation.",
-          "markdownDescription": "Truncate tool output if it is larger than this many characters. Set to -1 to disable.\n\n- Category: `General`\n- Requires restart: `yes`\n- Default: `4000000`",
+          "markdownDescription": "Maximum characters to show when truncating large tool outputs. Set to 0 or negative to disable truncation.\n\n- Category: `General`\n- Requires restart: `yes`\n- Default: `40000`",
-          "default": 4000000,
+          "default": 40000,
-          "type": "number"
-        },
-        "truncateToolOutputLines": {
-          "title": "Tool Output Truncation Lines",
-          "description": "The number of lines to keep when truncating tool output.",
-          "markdownDescription": "The number of lines to keep when truncating tool output.\n\n- Category: `General`\n- Requires restart: `yes`\n- Default: `1000`",
-          "default": 1000,
           "type": "number"
         },
         "disableLLMCorrection": {