scalability-foundations

Frame scalability as a primary design driver, distinguish scaling strategies (replication vs optimization, scale-up vs scale-out), apply Amdahl's law to reason about hardware ceilings, and walk through the canonical multitier scaling moves (load-balanced stateless services, distributed caching, partitioned databases, async queueing). Use when starting a new system, explaining scalability trade-offs to non-architects, deciding whether and how to invest in scaling, or diagnosing whether the right scaling strategy is being applied. Triggers - "how do we scale this", "scale up vs scale out", "do we need a load balancer / cache / queue", "Amdahl's law", "multitier architecture", "we're hitting a bottleneck", "premature optimization vs premature distribution". Produces a scaling-strategy recommendation grounded in concrete bottleneck and trade-off analysis.