Why scalability testing changes the conversation From objectives to guardrails: defining SLAs and acceptance criteria Performance KPIs and observability signals that reveal root cause Building realistic load test scenarios and production-like test environments Reporting, repeatability, and governance to operationalize results Practical protocol: checklist and step‑by‑‑step scalability test plan Scalability failures are not surprises — they are predictable consequences of unstated assumptions about load, data, and user behavior. A good scalability testing plan converts those assumptions into measurable objectives and repeatable experiments so you can make capacity decisions with evidence, not gut feel. The symptoms are familiar: production slowdowns during promotions, autoscaling that reacts too late, flood-of-errors after a deploy, and load tests that “pass” in staging but fail in production.…