scaling-evolution

This skill should be used when the user asks "how does this scale", "scale to millions", "scaling roadmap", "where is the bottleneck", "what breaks first", "10x growth", "vertical vs horizontal scaling", "scale from zero", or "what's the next scale curve". It gives the order-of-magnitude evolution path (single server → tiers → replicas → cache → CDN → stateless tier → multi-region → sharding) and a way to diagnose the *next* bottleneck instead of memorizing one big diagram. Use it whenever a design must grow by orders of magnitude or a load increase is on the table, even if the user doesn't say "scaling".