disable static prefetching behavior for dynamic segments

[ztanner]

What?

When a layout segment forces dynamic rendering (such as with force-dynamic or revalidate: 0), navigating to sub-pages of that layout will attempt to re-render the layout, also resulting in side effects re-running. This means if your layout relies on a data fetch and you render the result of that data in the layout, it will unexpectedly change when navigating between sub-paths, as described in #57326.

As a separate issue (but caused by the same underlying mechanism), when using searchParams on a dynamic page, changes to those search params will be erroneously ignored when navigating, as described in #57075

Why?

As a performance optimization we generate static prefetch files for dynamic segments (original PR). This makes it so that when prefetching is turned on, the prefetch can be served quickly from the edge without needing to invoke unnecessarily. We're able to eagerly serve things that can be safely prefetched. This is nice for cases where a path has a loading.js that we can eagerly render while waiting for the dynamic data to be loaded.

This causes a problem with layouts that opt into dynamic rendering: when the page loads and a prefetch is kicked off for the sub-page, it'll load the static prefetch, which won't be generated with the same router state as the dynamically rendered page. This causes a mismatch between the two trees, and when navigating within the same segment, a refetch will be added to the router because it thinks that it's navigating to a new layout.

This also causes issues for dynamic pages that use searchParams. The static prefetch will be generated without any knowledge of search params, and when the prefetch occurs, we still match to the prefetch generated without search params. This will make the router think that no change occurs, and the UI will not update to reflect the change.

How?

There's ongoing work by @acdlite to refactor the client router. Hopefully it will be easier to re-land this once that work is finished. For now, I've reverted the behavior as it doesn't seem to be worth the bugs it currently causes. I've also added tests so that when we do re-land this behavior, we can catch these subtleties.

Fixes #57326
Fixes #57075

[ztanner]

Current dependencies on/for this PR:

• canary
  • PR disable static prefetching behavior for dynamic segments #58609 👈

This stack of pull requests is managed by Graphite.

[ijjk]

Stats from current PR

Default Build

General Overall increase ⚠️

	vercel/next.js canary	vercel/next.js 11-17-fix_don_t_create_static_prefetch_when_using_force-dynamic	Change
buildDuration	10.3s	10.3s	N/A
buildDurationCached	5.7s	6s	⚠️ +209ms
nodeModulesSize	199 MB	199 MB	⚠️ +2.22 kB
nextStartRea..uration (ms)	422ms	423ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js 11-17-fix_don_t_create_static_prefetch_when_using_force-dynamic	Change
199-HASH.js gzip	28.7 kB	28.7 kB	N/A
3f784ff6-HASH.js gzip	53.3 kB	53.3 kB	✓
494.HASH.js gzip	180 B	181 B	N/A
framework-HASH.js gzip	45.2 kB	45.2 kB	✓
main-app-HASH.js gzip	241 B	238 B	N/A
main-HASH.js gzip	31.7 kB	31.7 kB	N/A
webpack-HASH.js gzip	1.7 kB	1.7 kB	✓
Overall change	100 kB	100 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js 11-17-fix_don_t_create_static_prefetch_when_using_force-dynamic	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js 11-17-fix_don_t_create_static_prefetch_when_using_force-dynamic	Change
_app-HASH.js gzip	194 B	195 B	N/A
_error-HASH.js gzip	182 B	181 B	N/A
amp-HASH.js gzip	501 B	503 B	N/A
css-HASH.js gzip	322 B	323 B	N/A
dynamic-HASH.js gzip	2.5 kB	2.5 kB	✓
edge-ssr-HASH.js gzip	253 B	255 B	N/A
head-HASH.js gzip	348 B	347 B	N/A
hooks-HASH.js gzip	369 B	368 B	N/A
image-HASH.js gzip	4.28 kB	4.27 kB	N/A
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	2.61 kB	2.6 kB	N/A
routerDirect..HASH.js gzip	311 B	311 B	✓
script-HASH.js gzip	384 B	383 B	N/A
withRouter-HASH.js gzip	307 B	308 B	N/A
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	3.17 kB	3.17 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js 11-17-fix_don_t_create_static_prefetch_when_using_force-dynamic	Change
_buildManifest.js gzip	484 B	483 B	N/A
Overall change	0 B	0 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js 11-17-fix_don_t_create_static_prefetch_when_using_force-dynamic	Change
index.html gzip	527 B	528 B	N/A
link.html gzip	538 B	542 B	N/A
withRouter.html gzip	524 B	523 B	N/A
Overall change	0 B	0 B	✓

Edge SSR bundle Size

	vercel/next.js canary	vercel/next.js 11-17-fix_don_t_create_static_prefetch_when_using_force-dynamic	Change
edge-ssr.js gzip	92.4 kB	92.4 kB	N/A
page.js gzip	145 kB	145 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	vercel/next.js 11-17-fix_don_t_create_static_prefetch_when_using_force-dynamic	Change
middleware-b..fest.js gzip	625 B	625 B	✓
middleware-r..fest.js gzip	150 B	151 B	N/A
middleware.js gzip	24.8 kB	24.8 kB	N/A
edge-runtime..pack.js gzip	1.92 kB	1.92 kB	✓
Overall change	2.55 kB	2.55 kB	✓

Next Runtimes

	vercel/next.js canary	vercel/next.js 11-17-fix_don_t_create_static_prefetch_when_using_force-dynamic	Change
app-page-exp...dev.js gzip	167 kB	167 kB	✓
app-page-exp..prod.js gzip	93.2 kB	93.2 kB	✓
app-page-tur..prod.js gzip	94 kB	94 kB	✓
app-page-tur..prod.js gzip	88.5 kB	88.5 kB	✓
app-page.run...dev.js gzip	137 kB	137 kB	✓
app-page.run..prod.js gzip	87.9 kB	87.9 kB	✓
app-route-ex...dev.js gzip	23.8 kB	23.8 kB	✓
app-route-ex..prod.js gzip	16.4 kB	16.4 kB	✓
app-route-tu..prod.js gzip	16.5 kB	16.5 kB	✓
app-route-tu..prod.js gzip	16 kB	16 kB	✓
app-route.ru...dev.js gzip	23.2 kB	23.2 kB	✓
app-route.ru..prod.js gzip	16 kB	16 kB	✓
pages-api-tu..prod.js gzip	9.37 kB	9.37 kB	✓
pages-api.ru...dev.js gzip	9.64 kB	9.64 kB	✓
pages-api.ru..prod.js gzip	9.37 kB	9.37 kB	✓
pages-turbo...prod.js gzip	21.8 kB	21.8 kB	✓
pages.runtim...dev.js gzip	22.5 kB	22.5 kB	✓
pages.runtim..prod.js gzip	21.8 kB	21.8 kB	✓
server.runti..prod.js gzip	49.1 kB	49.1 kB	N/A
Overall change	874 kB	874 kB	✓

Diff details

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Diff for edge-ssr.js

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Diff for server.runtime.prod.js

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Commit: 37b1dce

[ijjk]

Tests Passed