Next Cache Components Adoption

# next-cache-components-adoption

Enable Cache Components on an app and walk it to a passing build. This skill sequences the work; per-error recipes live in the dev overlay fix cards and the build's terminal output. The [migrating to Cache Components guide](https://nextjs.org/docs/app/guides/migrating-to-cache-components) is the canonical reference for the concepts and per-API recipes this skill applies — consult it whenever the skill steps reference a pattern (`"use cache"`, `cacheLife`, `<Suspense>` placement, etc.) and you want the full explanation.

## requires

- **App Router project.** Cache Components is an App Router feature; `cacheComponents: true` does nothing for `pages/` routes. If the project has a `pages/` or `src/pages/` tree but no `app/` or `src/app/` tree, stop and tell the user — Pages → App migration is its own project, not part of this skill. A hybrid app (both `pages/` and `app/`) is fine: the flag affects the `app/` routes; `pages/` routes are unaffected and don't need opt-outs.

- **A resolved app directory.** Locate `next.config.{js,ts,mjs,cjs}` first: that's the project root, and an agent invoked from a subdirectory would otherwise test for `app/` against the wrong `cwd` and find nothing. Look for `app/` and `src/app/` under it, and treat every command and glob in this skill as relative to whichever one exists. If both exist, Next.js builds `app/` and never looks at `src/app/`, so its routes are shadowed and unbuilt — tell the user that and ask which tree to migrate instead of picking one.

- **A runnable app.** The whole loop verifies against `next dev` and a browser, so the app has to boot. If it reads a database or required env at import (e.g. an `env.ts` that throws on a missing `DATABASE_URL`), confirm it actually starts — with the real environment, or local data you stand up — before step 1. Adoption can't be verified against an app that won't run.

- **Next.js 16.3 or later.** That release is where the pieces this skill relies on land: top-level `cacheComponents`, `export const instant`, the dev-overlay instant-navigation validation warnings, and the `cache-components-instant-false` codemod. If `next --version` reports below 16.3, upgrade first: - `npx @next/codemod@latest upgrade latest` to apply the version-to-version codemods. - Read the relevant [version upgrade guide](https://nextjs.org/docs/app/guides/upgrading) (e.g. [Version 16](https://nextjs.org/docs/app/guides/upgrading/version-16)) for what the codemod doesn't cover.

- **No incompatible config keys.** `cacheComponents: true` errors on any file that still exports `dynamic`, `revalidate`, or `fetchCache`. Inventory these exports before running the codemod, then follow the [migration guide's per-key sections](https://nextjs.org/docs/app/guides/migrating-to-cache-components). The guide is the source of truth for translating each value. The `cache-components-instant-false` codemod does not remove these configs.

- **`experimental.dynamicIO` is fatal.** It was renamed to top-level `cacheComponents` and the old key now aborts before any build can run — remove it (or replace with `cacheComponents: true`) first. `experimental.useCache` is still accepted as a deprecated alias; redundant once `cacheComponents: true` is set, so remove it for clarity.

### notes

- **No passing baseline before the flag.** If the app already uses `"use cache"`, the pre-flag build errors with `please enable the feature flag cacheComponents`. Enabling the flag is the first thing you do (in Incremental, before the codemod; in Direct, before fixing routes) — not a thing to do _after_ getting a passing build. Note this in your starting summary so it doesn't read as a regression.

- **Existing caches can stay.** Follow the migration guide's [`fetch` and `unstable_cache` sections](https://nextjs.org/docs/app/guides/migrating-to-cache-components#fetch-cache-options). Do not rewrite them solely to enable Cache Components.

- **Offline docs.** Guide links have offline copies under `node_modules/next/dist/docs/` (bundled since Next.js 16.2), with the directory layout numbered for ordering (e.g. `node_modules/next/dist/docs/01-app/02-guides/migrating-to-cache-components.md`). If you can't predict the numbered prefix, `find node_modules/next/dist/docs -name '<slug>.md'` resolves it. The `/docs/messages/*` error pages are not bundled.

- **Older versions without bundled docs.** Suggest `npx @next/codemod@latest agents-md` to the user before starting: it downloads a version-matched copy to `.next-docs/` and writes an index into `AGENTS.md`. It touches files in their repo, so ask first and run it only if they want it.

## the shape of the work

There's one loop: walk the route tree top-down, one feature at a time, adopting each route against `next dev` + a browser. The build is a final check for each feature, not the working surface.

The choice in step 1 is whether to opt every route out of validation first or fix routes as you go. Either way the loop