Setting the skill. One moment.
Skills
Skill 5 of 24
How to add or modify Next.js experimental feature flags end-to-end.
1 minute · 276 words · 5 sections
Install
npx skills add vercel/next.js --skill flagsnpx skills add vercel/next.js/plugin marketplace add vercel/next.jsThe first command installs just this skill, by the name in its SKILL.md; the second installs the whole repository.
Use this skill when adding or changing framework feature flags in Next.js internals.
All flags need: config-shared.ts (type) → config-schema.ts (zod). If the flag is consumed in user-bundled code (client components, edge routes, app-page.ts template), also add it to define-env.ts for build-time injection. Runtime-only flags consumed exclusively in pre-compiled bundles can skip define-env.ts.
Client/bundled code only (e.g. __NEXT_PPR in client components): define-env.ts is sufficient. Webpack/Turbopack replaces process.env.X at the user’s build time.
Pre-compiled runtime bundles (e.g. code in app-render.tsx): The flag must also be set as a real process.env var at runtime, because app-render.tsx runs from pre-compiled bundles where define-env.ts doesn’t reach. Two approaches:
next-server.ts + export/worker.ts. Both code paths stay in one bundle. Simple but increases bundle size.next-runtime.webpack-config.js (scoped to bundleType === 'app'), new taskfile tasks, update module.compiled.js selector, and still set env var in next-server.ts + export/worker.ts for bundle selection. Eliminates dead code but adds build complexity.For runtime flags, also add the field to the NextConfigRuntime Pick type in config-shared.ts.
next-runtime.webpack-config.js (rspack) via taskfile.js bundle tasks.src/server/route-modules/app-page/module.compiled.js based on process.env vars.{turbo/webpack} × {experimental/stable/nodestreams/experimental-nodestreams} × {dev/prod} = up to 16 bundles per route type.define-env.ts affects user bundling, not pre-compiled runtime internals.process.env.X checks in app-render.tsx are either replaced by DefinePlugin at runtime-bundle-build time, or read as actual env vars at server startup. They are NOT affected by the user’s defines from define-env.ts.next-runtime.webpack-config.js must be scoped to the correct bundleType (e.g. app only, not server) to avoid replacing assignment targets in next-server.ts.$dce-edge - DCE-safe require patterns and edge constraints$react-vendoring - entry-base boundaries and vendored React$runtime-debug - reproduction and verification workflowHow to add or modify Next.js experimental feature flags end-to-end. Use when editing config-shared.ts, config-schema.ts, define-env-plugin.ts, next-server.ts, export/worker.ts, or module.compiled.js. Covers type declaration, zod schema, build-time injection, runtime env plumbing, and the decision between runtime env-var branching vs separate bundle variants.
The verbatim description from this skill’s front matter — the string an agent matches on to decide whether to load it.
canary, last pushed 28 August 2026.SKILL.md, not by matching a directory convention. 2 distinct layouts observed: .agents/skills/*/SKILL.md, skills/*/SKILL.md.h1 and no skipped levels:.claude-plugin/marketplace.json by Vercel, declaring 1 plugin. It is read for editorial metadata only — never as the skill index, which is always the repository tree./vercel/next.js.md, and each skill at its own .md URL.