Answer both independent system design prompts. For each one, clarify requirements, propose APIs, describe core data models, explain the architecture, discuss scaling and reliability, and identify trade-offs. 1. Design a durable queue or event-streaming service Design a distributed queue service similar in spirit to a high-throughput log-based messaging platform. It should allow producers to publish messages, consumers to read messages, consumer groups to track offsets, and users to replay historical messages within a retention window. The system should support ordering within a partition, high throughput, durability, replication, backpressure, monitoring, and failure recovery. 2. Design a taxi request service with user-selected drivers Design the request and matching flow for a ride-hailing service. The requirements differ from a standard one-driver assignment model: - A rider creates a ride request. - The system notifies many nearby drivers. - Multiple drivers may accept or express interest in the same request. - The rider chooses one driver from the accepted drivers. - The chosen driver must explicitly confirm the rider's selection. - Only after confirmation should the trip become assigned. Handle driver/rider cancellations, timeouts, concurrent acceptances, duplicate requests, stale locations, and race conditions.