Design a Discounted Flight Alert System

Get flight details from external api like skyscanner, exponent. User should be able to subscribe to the route User should be notified when subscribed route price droped via email notification within 10 minutes. User should not be notified for same route again, deduplicate the notification There will be a service in the system that determines price is dropped or not, you provide current flight price and it's 10 days hitstory and proce drop service return True or False. Interviewer looking for how you design the flight crawler, managing external API failure, and scalability of the system and managing 10 minute notifying requirement with deduplicating the notification,