[oBusk]

Adopts Partial Prefetching from Next.js 16.4. With it on, a default <Link> prefetches the route's static App Shell, which is shared by every link to that route, instead of each link prefetching its own URL.

Changes

• Enable partialPrefetching: Next 16.4 warns when cacheComponents is on without it set, and it becomes the default in Next 17.
• Skeleton fallback for [...parts]: the shell used to be an empty <Suspense>. It now has a skeleton shaped like the top of the diff page, so clicking any diff or catalog link paints immediately.
• Remove prefetch={false} from the catalog's suggested diffs and the split/unified toggle. A default prefetch now only fetches the shared shell, so these opt-outs no longer prevent any server work.
• prefetch={true} on the home page examples, only while the options are at their defaults. Each example gets a full prefetch from cached content. With custom options, typing in the Files field would trigger a fresh diff on the server for every keystroke, so those links fall back to the shell prefetch.
• Prefetch the diff from the main form: when a version is picked in B's autocomplete and both A and B are exact versions, the page calls router.prefetch(url, { kind: "full" }). This is the same full prefetch as <Link prefetch={true}>, so pressing Diff is instant once it has finished (it skips custom options, like the examples).
• ensureStatic = "navigation" on / and the /-/about pages, so the build fails if they accidentally become dynamic.

Testing (preview vs. production)

In DevTools, open the Network tab, filter on _rsc, and throttle to Slow 4G.

Check	Production (before)	Preview (expected)
Click the @types/node… example	Skeleton, then the diff after a round trip	Full diff immediately, with no request
Click lodash@4.17.0...4.17.21	Two round trips (redirect, then the page)	Skeleton immediately, then one round trip
Type in Options → Files on the home page	No prefetches	No prefetches
Click a suggested diff on a catalog page (e.g. /is-even)	Stays on the old page until the server responds	URL changes and the skeleton shows immediately
Pick A and B from the autocompletes, wait a few seconds, press Diff	Skeleton, then the diff	Full diff immediately, with no request
Toggle Split/Unified on a diff page	No skeleton	No skeleton

Measured locally on a production build: about 100 ms from click to diff for the canonical example (before: about 700 ms), and about 50 ms from click to skeleton for catalog links.

Server cost: each home page view sends up to 4 extra requests for the example prefetches, which are normally cache hits. On a cold cache, such as right after a deploy, a prefetch computes the example diff, which the first click would have done anyway.

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated
npm-diff	Ready	Preview	Oct 21, 2026 9:38pm UTC