Function readTruncatedFile

source code/utils/attachments.ts:3130–3171

()

    }

    async function readTruncatedFile(): Promise<
      | FileAttachment
      | CompactFileReferenceAttachment
      | AlreadyReadFileAttachment
      | null
    > {
      if (mode === 'compact') {
        return {
          type: 'compact_file_reference',
          filename,
          displayPath: relative(getCwd(), filename),
        }
      }

      // Check deny rules before reading truncated file
      const appState = toolUseContext.getAppState()
      if (isFileReadDenied(filename, appState.toolPermissionContext)) {
        return null
      }

      try {
        // Read only the first MAX_LINES_TO_READ lines for files that are too large
        const truncatedInput = {
          file_path: filename,
          offset: offset ?? 1,
          limit: MAX_LINES_TO_READ,
        }
        const result = await FileReadTool.call(truncatedInput, toolUseContext)
        logEvent(successEventName, {})

        return {
          type: 'file' as const,
          filename,
          content: result.data,
          truncated: true,
          displayPath: relative(getCwd(), filename),
        }
      } catch {
        logEvent(errorEventName, {})
        return null
      }
    }

    // Validate file path is valid
    const isValid = await FileReadTool.validateInput(fileInput, toolUseContext)