Collect and Query Recent User Activity

Design a service that records user actions and can answer questions about activity inside rolling windows such as the most recent minute, hour, and day. Trace the complete write-to-read path: the ingestion endpoint, any intermediate processing or buffering layer, durable storage, and the endpoint used for queries. Specify the fields of an activity record, decide whether query answers should contain raw events or aggregated counts/metrics, explain how filtering by user ID and…