Design reliable high-volume chatbot system

You are designing the backend for a chatbot / AI assistant service (similar to a support bot or meeting assistant). Many users may send messages at the same time.

Answer the following:

1. Failure modes under high load
   When a large number of messages are sent to the chatbot concurrently, what kinds of failures or problems can occur in the system? Consider both infrastructure and application-level issues.
2. Handling and mitigating failures
   For each failure type you identify, describe how you would detect it and what mechanisms you would use to prevent or mitigate it (e.g., architectural choices, patterns, or specific components).
3. Recovery after a bot system crash
   Suppose the chatbot service (or one of its core components) suddenly goes down and then comes back up.
   • How would you design the system so that you can restore previous state , such as users' ongoing conversations, without losing context?
   • What data would you persist, where would you store it, and how would a restarted instance reconstruct the necessary state to continue conversations smoothly?

Assume the following:

• The chatbot keeps conversational context (previous messages) to generate good responses.
• You are allowed to use typical cloud primitives: load balancers, queues, caches, databases, and multiple stateless service instances.
• The system should be highly available and reliable , even under sudden traffic spikes.