orca/src/shared/returned-draft-text.ts

/**
 * Puts text a chat handed back after what the composer already holds, a blank line apart. It never
 * replaces typed text (a whitespace-only draft counts as empty), and adds nothing when the draft
 * already ends with that text, so handing the same text back twice leaves one copy.
 */
export function appendReturnedDraftText(draft: string, text: string): string {
  const returned = text.trimEnd()
  if (returned.trim() === '') {
    return draft
  }
  const kept = draft.trimEnd()
  if (kept === '') {
    return text
  }
  if (kept === returned || kept.endsWith(`\n\n${returned}`)) {
    return draft
  }
  return `${kept}\n\n${text}`
}