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base repository: vercel/next.js
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compare: appshells-migrate-prefetch-tests
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  • 2 commits
  • 12 files changed
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Commits on Jun 8, 2026

  1. Enable experimental.appShells by default with cacheComponents 

    Turns on `experimental.appShells` by default for projects already on
`cacheComponents`, unless explicitly disabled.

A handful of tests are incidentally coupled to the previous behavior. In
this PR, the fixtures for those tests set `appShells` back to `false`.
In subsequent PRs, I will incrementally update the tests until there are
no more overrides.

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    @acdlite
    acdlite committed Jun 8, 2026
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  2. Make router-act ignore App Shell prefetch requests 

    When App Shells is enabled, prefetching is split into two phases: a
prefetch for the shell, and a separate phase for the per-page content.

This causes a handful of the existing prefetch-related tests to fail.
However, the fact that the shell is prefetched separately from the page
content is an incidental detail of how prefetching works. The App Shell
is conceptually part of the route, not part of the "prefetch". Or in
other words, App Shell prefetching has more in common with incremental
module loading than it does with prefetching in the traditional sense
used in the context of web apps.

So, this updates router-act to ignore App Shell requests for the
purposes of making assertions about prefetch responses.

As a result, most of the prefetching tests now pass regardless of
whether App Shells is enabled.

(There are a few remaining `appShells` overrides in test fixtures that
we'll address in subsequent PRs.)

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    @acdlite
    acdlite committed Jun 8, 2026
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