What problem does it solve? Choosing the right Vercel runtime, configuring function limits, and debugging timeouts or cold starts is error-prone, especially with misconceptions about streaming, WebSockets, and Edge versus Node.js runtimes. ## Core Features & Use Cases - Runtime Selection Guidance: Compares Serverless (Node.js), Edge, Bun, and Rust runtimes with concrete criteria for latency, API compatibility, and workload type. - Fluid Compute & Streaming: Explains concurrency, Active CPU pricing, background work with waitUntil/after, and zero-config SSE streaming on the Node.js runtime. - WebSockets & Cron Jobs: Provides working patterns for ws, Socket.IO, and Next.js upgradeWebSocket, plus vercel.json cron configuration with CRON_SECRET verification. - Diagnostics: Decision trees for 504 timeouts, 500 errors, invocation failures, cold starts, and Edge timeouts. - Use Case: You are building a realtime chat API route and unsure whether to use Edge or Node.js; this Skill shows you how to hold WebSocket connections on Fluid Compute and handle reconnects with backoff. ## Quick Start Ask the assistant how to add a streaming SSE endpoint or WebSocket handler to a Vercel API route and which runtime to choose.
