Next Partial Prefetching AdoptionBLOCK

The React Framework

The instruction file, verbatim from the audited commit — this is the text the model reads, and the surface the audit's instruction layer examines. Quoted here so you can judge it without cloning anything.

---
name: next-partial-prefetching-adoption
description: >
  Turn on Partial Prefetching in a Next.js app and work through the
  insights it surfaces. Use when the user wants to enable or adopt
  Partial Prefetching, flip the `partialPrefetching` flag, opt routes
  in with `export const prefetch = 'partial'`, audit
  `Link prefetch={true}` behavior, preserve existing prefetched UI
  with `instant()` tests, or resolve the
  instant-link-prefetch-partial and instant-shell-url-data insights.
---

# next-partial-prefetching-adoption

Enable Partial Prefetching and walk the app until every link reuses a shared App Shell. This skill sequences the work; per-insight recipes live in the dev overlay fix cards and their docs pages. The [Adopting Partial Prefetching guide](https://nextjs.org/docs/app/guides/adopting-partial-prefetching) is the canonical reference for the concepts this skill applies.

The development insights and the preservation tests are two different paths. Insights surface only in `next dev`, in the dev overlay's Insights tab. Test-backed preservation runs against a production-like build with `instant()` and does not need a development server. After the flag is enabled, the separate URL-data insight sweep still uses `next dev`.

## preservation gate

When using test-backed preservation, the first implementation milestone is a passing flag-off `instant()` suite. Set up the production test rig, write the selected assertions, run them with `partialPrefetching` disabled, and record the command and exit status. Test-only configuration required by the rig, including [`experimental.exposeTestingApiInProductionBuild`](https://nextjs.org/docs/app/api-reference/config/next-config-js/exposeTestingApiInProductionBuild), is allowed, but until that baseline passes, do not enable `partialPrefetching` or edit the destination, cache boundaries, or Link props. Installing missing test dependencies is part of reaching the baseline, not a reason to adopt first. Use the manual path only when `rig-template.md` identifies a concrete blocker the repository cannot resolve, and record the blocker and deferred test coverage.

Talk to the user in terms of what they'll see — PRs, features, and how the app behaves after — never the insight slugs or step labels. Before you start, tell them briefly what Partial Prefetching changes: links to a route prefetch one shared App Shell, and `prefetch={true}` can also resolve cached URL-specific content. The audit determines which UI from the legacy full prefetch to preserve.

## requires

- **Cache Components adopted (`cacheComponents: true`) with a passing build.** Both `partialPrefetching` and the route-level `prefetch` export require Cache Components. If it is off, use [`next-cache-components-adoption`](https://github.com/vercel/next.js/tree/canary/skills/next-cache-components-adoption) first and return after its build-blocking prerender errors are resolved. Those errors can fail `next build`; only the Partial Prefetching insights handled by this skill are non-blocking development signals.

- **Next.js 16.3 or later.** `partialPrefetching`, the `prefetch` route segment config, and the prefetch insights all land there.

- **A browser you can drive.** Test-backed preservation uses an existing or minimal production-mode Playwright suite; manual preservation and the final demonstration use the running production app. The development insight path and the post-flag URL-data sweep use [`next-dev-loop`](https://github.com/vercel/next.js/tree/canary/skills/next-dev-loop); install it before either development pass unless it is already available (`npx skills add https://github.com/vercel/next.js/tree/canary/skills/next-dev-loop`). If the app is webpack-pinned, drive a browser directly (`agent-browser`, Playwright) — you lose the framework cross-checks, not the insights; they're still in the overlay and the dev log.

- **A runnable app.** Preservation and the final demonstration need a production-like build because automatic prefetching runs only in production. The development server is required only when using the insight path or running the post-flag URL-data sweep; do not start it merely to confirm a test-backed preservation case. If the app reads a database or required environment at import, confirm the environment used by the chosen path can start before step 1.

### notes

- **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/adopting-partial-prefetching.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.

## background

Adopting Partial Prefetching means every route preserves the prefetched UI that matters, now split between the shared App Shell and any extra per-link data a link explicitly asks for. The [guide](https://nextjs.org/docs/app/guides/adopting-partial-prefetching) is the canonical reference for what a prefetch contains and how to decide each case; this skill sequences that work against a running app.

The catch that decides most of the sweep: a default link warms only the shared App Shell. A route keyed by `params` or `searchParams` can prefetch more only after it has adopted Partial Prefetching and a specific link uses [`<Link prefetch={true}>`](https://nextjs.org/docs/app/api-reference/components/link#prefetch); then Next.js resolves the URL data and any cached content behind it before the click (the guide's [URL data](https://nextjs.org/docs/app/guides/adopting-partial-prefetching#url-data) section).

BLOCKgrade D · trust 69/100 Do not install this without reading the findings. The audit found something that could harm you or your machine.

What the source does

Filesystem

none-observed

Network

none-observed

Shell

none-observed

Dependencies

pinned

Secrets in source

none-found

Findings (6)

Loading a route with the flag on prerenders its App Shell, which validates more of the route than the Cache Components build did. So a route that built cleanly under Cache Components (every route `◐`,

.claude/skills

readme.md

test/development/app-dir/hmr-symlink/app/symlink-chain/page.tsx

test/development/app-dir/hmr-symlink/app/symlink-link/page.tsx

test/e2e/app-dir/next-condition/fixtures/instrumentation/sym-linked-packages

Gates applied: critical_finding, no_behavioural_pass, undeclared_transfer.

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