Apply this skill when designing, building, or reviewing API routes, Server Actions, or data fetching patterns in a Next.js + TypeScript + Drizzle application. Triggers on requests like "create an API endpoint", "add a server action", "design the API", "add pagination", "handle this request", "validate query params", or any time you are building the boundary between client and server. Use proactively — all API design decisions should follow these patterns.