From 9850f01894f88e01d4d3b0cd9d176853e26b341c Mon Sep 17 00:00:00 2001
From: Christian Gunderman <gundermanc@google.com>
Date: Mon, 2 Mar 2026 18:48:56 -0800
Subject: [PATCH] feat(core): centralize line truncation and apply to all tools

---
 .../core/src/scheduler/tool-executor.test.ts  | 14 +--
 packages/core/src/scheduler/tool-executor.ts  | 24 +++---
 packages/core/src/utils/textUtils.ts          | 86 +++++++++++++++++++
 3 files changed, 104 insertions(+), 20 deletions(-)

diff --git a/packages/core/src/scheduler/tool-executor.test.ts b/packages/core/src/scheduler/tool-executor.test.ts
index d5f92806f5..e21e1f51c9 100644
--- a/packages/core/src/scheduler/tool-executor.test.ts
+++ b/packages/core/src/scheduler/tool-executor.test.ts
@@ -40,23 +40,17 @@ vi.mock('../core/coreToolHookTriggers.js', () => ({
   executeToolWithHooks: vi.fn(),
 }));
 // Mock runInDevTraceSpan
-const runInDevTraceSpan = vi.hoisted(() =>
-  vi.fn(async (opts, fn) => {
+vi.mock('../telemetry/trace.js', () => ({
+  runInDevTraceSpan: vi.fn(async (opts, fn) => {
     const metadata = { attributes: opts.attributes || {} };
     return fn({
       metadata,
       endSpan: vi.fn(),
     });
   }),
-);
+}));
 
-vi.mock('../index.js', async (importOriginal) => {
-  const actual = await importOriginal<Record<string, unknown>>();
-  return {
-    ...actual,
-    runInDevTraceSpan,
-  };
-});
+import { runInDevTraceSpan } from '../telemetry/trace.js';
 
 describe('ToolExecutor', () => {
   let config: Config;
diff --git a/packages/core/src/scheduler/tool-executor.ts b/packages/core/src/scheduler/tool-executor.ts
index e358c53c8b..904d893b67 100644
--- a/packages/core/src/scheduler/tool-executor.ts
+++ b/packages/core/src/scheduler/tool-executor.ts
@@ -5,19 +5,17 @@
  */
 
 import type {
-  ToolCallRequestInfo,
-  ToolCallResponseInfo,
   ToolResult,
-  Config,
   ToolResultDisplay,
   ToolLiveOutput,
-} from '../index.js';
-import {
-  ToolErrorType,
-  ToolOutputTruncatedEvent,
-  logToolOutputTruncated,
-  runInDevTraceSpan,
-} from '../index.js';
+} from '../tools/tools.js';
+import type { Config } from '../config/config.js';
+import { ToolErrorType } from '../tools/tool-error.js';
+import { logToolOutputTruncated } from '../telemetry/loggers.js';
+import { ToolOutputTruncatedEvent } from '../telemetry/types.js';
+import { runInDevTraceSpan } from '../telemetry/trace.js';
+import { truncateLongLines } from '../utils/textUtils.js';
+import { DEFAULT_MAX_LINE_LENGTH } from '../utils/constants.js';
 import { SHELL_TOOL_NAME } from '../tools/tool-names.js';
 import { DiscoveredMCPTool } from '../tools/mcp-tool.js';
 import { ShellToolInvocation } from '../tools/shell.js';
@@ -34,6 +32,8 @@ import type {
   ErroredToolCall,
   SuccessfulToolCall,
   CancelledToolCall,
+  ToolCallRequestInfo,
+  ToolCallResponseInfo,
 } from './types.js';
 import { CoreToolCallStatus } from './types.js';
 import {
@@ -237,6 +237,10 @@ export class ToolExecutor {
     const toolName = call.request.originalRequestName || call.request.name;
     const callId = call.request.callId;
 
+    if (typeof content === 'string') {
+      content = truncateLongLines(content, DEFAULT_MAX_LINE_LENGTH);
+    }
+
     if (typeof content === 'string' && toolName === SHELL_TOOL_NAME) {
       const threshold = this.config.getTruncateToolOutputThreshold();
 
diff --git a/packages/core/src/utils/textUtils.ts b/packages/core/src/utils/textUtils.ts
index 1066896bc4..d2f7b2877d 100644
--- a/packages/core/src/utils/textUtils.ts
+++ b/packages/core/src/utils/textUtils.ts
@@ -83,6 +83,92 @@ export function truncateString(
   return str.slice(0, maxLength) + suffix;
 }
 
+/**
+ * Options for line truncation.
+ */
+export interface TruncateLineOptions {
+  maxLength: number;
+  centerIndex?: number;
+  includeStats?: boolean;
+}
+
+/**
+ * Truncates a single line, optionally centering around a specific index.
+ */
+export function truncateLine(
+  line: string,
+  options: TruncateLineOptions,
+): string {
+  const { maxLength, centerIndex, includeStats } = options;
+  const originalLength = line.length;
+
+  if (originalLength <= maxLength) {
+    return line;
+  }
+
+  let truncated: string;
+  let start = 0;
+  let end = maxLength;
+
+  if (centerIndex !== undefined) {
+    const halfLength = Math.floor(maxLength / 2);
+    start = Math.max(0, centerIndex - halfLength);
+    end = start + maxLength;
+
+    if (end > originalLength) {
+      end = originalLength;
+      start = Math.max(0, end - maxLength);
+    }
+
+    const prefix = start > 0 ? '... ' : '';
+    const suffix = end < originalLength ? ' ...' : '';
+    truncated = prefix + line.substring(start, end) + suffix;
+  } else {
+    truncated = line.substring(0, maxLength) + ' ...';
+  }
+
+  if (includeStats) {
+    const stats =
+      centerIndex !== undefined
+        ? `[Truncated: showing characters ${start} to ${end} of ${originalLength}]`
+        : `[Truncated to ${maxLength} characters (total length: ${originalLength})]`;
+
+    if (centerIndex !== undefined) {
+      // For centered, we put stats at both ends if they are truncated
+      const prefix = start > 0 ? `${stats} ... ` : '';
+      const suffix = end < originalLength ? ` ... ${stats}` : '';
+      truncated = prefix + line.substring(start, end) + suffix;
+    } else {
+      truncated = line.substring(0, maxLength) + ` ${stats}`;
+    }
+  }
+
+  return truncated;
+}
+
+/**
+ * Truncates all lines in a string that exceed the maximum length.
+ */
+export function truncateLongLines(
+  text: string,
+  maxLength: number,
+  includeStats = true,
+): string {
+  if (!text) return text;
+  const lines = text.split('\n');
+  let modified = false;
+
+  const processed = lines.map((line) => {
+    if (line.length > maxLength) {
+      modified = true;
+      return truncateLine(line, { maxLength, includeStats });
+    }
+    return line;
+  });
+
+  return modified ? processed.join('\n') : text;
+}
+
 /**
  * Safely replaces placeholders in a template string with values from a replacements object.
  * This performs a single-pass replacement to prevent double-interpolation attacks.