Function checkOriginFileChanged

src/utils/fileHistory.ts:600–634

(
  originalFile: string,
  backupFileName: string,
  originalStatsHint?: Stats,
)

 * Exported for testing.
 */
export async function checkOriginFileChanged(
  originalFile: string,
  backupFileName: string,
  originalStatsHint?: Stats,
): Promise<boolean> {
  const backupPath = resolveBackupPath(backupFileName)

  let originalStats: Stats | null = originalStatsHint ?? null
  if (!originalStats) {
    try {
      originalStats = await stat(originalFile)
    } catch (e: unknown) {
      if (!isENOENT(e)) return true
    }
  }
  let backupStats: Stats | null = null
  try {
    backupStats = await stat(backupPath)
  } catch (e: unknown) {
    if (!isENOENT(e)) return true
  }

  return compareStatsAndContent(originalStats, backupStats, async () => {
    try {
      const [originalContent, backupContent] = await Promise.all([
        readFile(originalFile, 'utf-8'),
        readFile(backupPath, 'utf-8'),
      ])
      return originalContent !== backupContent
    } catch {
      // File deleted between stat and read -> treat as changed.
      return true
    }
  })
}

/**
 * Shared stat/content comparison logic for sync and async change checks.