refactor(core): extract static concerns from CoreToolScheduler (#15589)

packages/core/src/utils/fileUtils.ts

@@ -15,6 +15,7 @@ import { ToolErrorType } from '../tools/tool-error.js';
 import { BINARY_EXTENSIONS } from './ignorePatterns.js';
 import { createRequire as createModuleRequire } from 'node:module';
 import { debugLogger } from './debugLogger.js';
+import { READ_FILE_TOOL_NAME } from '../tools/tool-names.js';
 
 const requireModule = createModuleRequire(import.meta.url);
 
@@ -515,3 +516,67 @@ export async function fileExists(filePath: string): Promise<boolean> {
     return false;
   }
 }
+
+export async function saveTruncatedContent(
+  content: string,
+  callId: string,
+  projectTempDir: string,
+  threshold: number,
+  truncateLines: number,
+): Promise<{ content: string; outputFile?: string }> {
+  if (content.length <= threshold) {
+    return { content };
+  }
+
+  let lines = content.split('\n');
+  let fileContent = content;
+
+  // If the content is long but has few lines, wrap it to enable line-based truncation.
+  if (lines.length <= truncateLines) {
+    const wrapWidth = 120; // A reasonable width for wrapping.
+    const wrappedLines: string[] = [];
+    for (const line of lines) {
+      if (line.length > wrapWidth) {
+        for (let i = 0; i < line.length; i += wrapWidth) {
+          wrappedLines.push(line.substring(i, i + wrapWidth));
+        }
+      } else {
+        wrappedLines.push(line);
+      }
+    }
+    lines = wrappedLines;
+    fileContent = lines.join('\n');
+  }
+
+  const head = Math.floor(truncateLines / 5);
+  const beginning = lines.slice(0, head);
+  const end = lines.slice(-(truncateLines - head));
+  const truncatedContent =
+    beginning.join('\n') + '\n... [CONTENT TRUNCATED] ...\n' + end.join('\n');
+
+  // Sanitize callId to prevent path traversal.
+  const safeFileName = `${path.basename(callId)}.output`;
+  const outputFile = path.join(projectTempDir, safeFileName);
+  try {
+    await fsPromises.writeFile(outputFile, fileContent);
+
+    return {
+      content: `Tool output was too large and has been truncated.
+The full output has been saved to: ${outputFile}
+To read the complete output, use the ${READ_FILE_TOOL_NAME} tool with the absolute file path above. For large files, you can use the offset and limit parameters to read specific sections:
+- ${READ_FILE_TOOL_NAME} tool with offset=0, limit=100 to see the first 100 lines
+- ${READ_FILE_TOOL_NAME} tool with offset=N to skip N lines from the beginning
+- ${READ_FILE_TOOL_NAME} tool with limit=M to read only M lines at a time
+The truncated output below shows the beginning and end of the content. The marker '... [CONTENT TRUNCATED] ...' indicates where content was removed.
+This allows you to efficiently examine different parts of the output without loading the entire file.
+Truncated part of the output:
+${truncatedContent}`,
+      outputFile,
+    };
+  } catch (_error) {
+    return {
+      content:
+        truncatedContent + `\n[Note: Could not save full output to file]`,
+    };
+  }
+}