How would you improve card-type detection?

### Scenario You have a service that needs to determine a credit/debit card **network/type** (e.g., Visa, Mastercard, AmEx, Discover, etc.) from the card number. Today the logic is simplistic: it checks only the **first few digits** (a fixed prefix) and maps that prefix to a card type. ### Question How would you **improve** this approach so it is more accurate and maintainable in production? Discuss: - What data/logic you would use instead of (or in addition to) a few hard-coded starting digits. - How you would handle **new/updated ranges**, overlaps, and unknown card types. - How you would validate correctness and ensure safe rollout. *(No coding required; explain the design and reasoning.)*