Function stripUnsafeCharacters

packages/cli/src/ui/components/shared/text-buffer.ts:515–541

* Strip characters that can break terminal rendering. * * Uses Node.js built-in stripVTControlCharacters to handle VT sequences, * then filters remaining control characters that can disrupt display. * * Characters stripped: * - ANSI escape sequences (via strip-ansi) * - VT control sequences (

(str: string)

 * - CR/LF (0x0D/0x0A) - needed for line breaks
 */
function stripUnsafeCharacters(str: string): string {
  const strippedAnsi = stripAnsi(str);
  const strippedVT = stripVTControlCharacters(strippedAnsi);

  return toCodePoints(strippedVT)
    .filter((char) => {
      const code = char.codePointAt(0);
      if (code === undefined) return false;

      // Preserve CR/LF for line handling
      if (code === 0x0a || code === 0x0d) return true;

      // Remove C0 control chars (except CR/LF) that can break display
      // Examples: BELL(0x07) makes noise, BS(0x08) moves cursor, VT(0x0B), FF(0x0C)
      if (code >= 0x00 && code <= 0x1f) return false;

      // Remove C1 control chars (0x80-0x9F) - legacy 8-bit control codes
      if (code >= 0x80 && code <= 0x9f) return false;

      // Preserve DEL (0x7F) - it's handled functionally by applyOperations as backspace
      // and doesn't cause rendering issues when displayed

      // Preserve all other characters including Unicode/emojis
      return true;
    })
    .join('');
}

export interface Viewport {
  height: number;