Function computeFingerprint

src/utils/fingerprint.ts:50–63

(
  messageText: string,
  version: string,
)

 * @returns 3-character hex fingerprint
 */
export function computeFingerprint(
  messageText: string,
  version: string,
): string {
  // Extract chars at indices [4, 7, 20], use "0" if index not found
  const indices = [4, 7, 20]
  const chars = indices.map(i => messageText[i] || '0').join('')

  const fingerprintInput = `${FINGERPRINT_SALT}${chars}${version}`

  // SHA256 hash, return first 3 hex chars
  const hash = createHash('sha256').update(fingerprintInput).digest('hex')
  return hash.slice(0, 3)
}

/**
 * Computes fingerprint from the first user message.