When you're working on Next.js edge runtime code or touching conditional imports that need to work across Node and edge environments, this keeps you from breaking dead code elimination. Webpack can only strip out unused requires when they're structured exactly right, with DefinePlugin-evaluable conditions wrapping them. The skill knows the pattern that actually works (checking process.env flags in a clean if/else) versus the stuff that looks fine but silently bloats your edge bundle because webpack can't analyze it. Honestly pretty narrow in scope, but if you're deep in Next.js internals or debugging why your edge function is suddenly 500KB, this is the guardrail you want.
npx skills add https://github.com/vercel/next.js --skill dce-edge