Co-host a frontend SPA and backend API in the same server process or container — separate codebases in development, single entry point in production. Use when integrating React/Next.js/Umi frontends with Node.js (Fastify/Egg.js) or ASP.NET Core backends. Trigger on keywords like "co-hosted frontend backend", "single container deployment", "SPA + API same server", "add frontend to backend project", "integrate Next.js with .NET", "static export", "SSR takeover", etc.
