Model user behavior and run distributed load tests before backend changes face real traffic with Locust

Use Locust when an agent needs to express user behavior as executable scenarios, run them at scale, and inspect latency or failure patterns before a release or capacity change. Invoke it instead of ad hoc curl loops or single-endpoint smoke checks when the real task is distributed scenario-based load testing. The scope boundary is specific and skill-shaped: model and run load scenarios against a target service, not general observability, generic backend development, or a plain load-testing product card.