Function truncateOutputFromEnd

extensions/cli/src/util/truncateOutput.ts:91–119

(
  output: string,
  maxChars: number,
  context?: string,
)

 * @param context - Optional context for the truncation message (e.g., "file content", "diff")
 */
export function truncateOutputFromEnd(
  output: string,
  maxChars: number,
  context?: string,
): TruncationResult {
  if (!output || output.length <= maxChars) {
    return { output, wasTruncated: false };
  }

  const truncatedContent = output.slice(0, maxChars);

  // Try to end at a clean line boundary
  const lastNewline = truncatedContent.lastIndexOf("\n");
  const shouldSnapToLine =
    lastNewline !== -1 &&
    truncatedContent.length - lastNewline < TRUNCATION_LINE_SNAP_THRESHOLD;
  const cleanContent = shouldSnapToLine
    ? truncatedContent.slice(0, lastNewline)
    : truncatedContent;

  const actualCharsRemoved = output.length - cleanContent.length;
  const contextStr = context ? ` of ${context}` : "";
  const suffix = `\n\n(${actualCharsRemoved} characters${contextStr} truncated)`;

  return {
    output: cleanContent + suffix,
    wasTruncated: true,
  };
}

/**
 * Truncates output by line count from the end, preserving the beginning.