perf(flags): use single dynamic import of next/headers
#179
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dferber90
reviewed
Oct 13, 2025
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| // async import required as turbopack errors in Pages Router | ||
| // when next/headers is imported at the top-level | ||
| const headersPromise = import('next/headers').then((mod) => mod.headers); |
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I have not tested, but I believe this would lead to an issue in Pages Router, as we can currently do the following at the top level
const foo = dedupe(() => Math.random())
The next/headers import would originally only happen once foo is called. But with this change we would now cause the import of next/headers even if foo is not called.
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I think this should be slightly more performant than re-importing every time we call the deduped function.
(though in honesty I'm raising it as otherwise the mocks for
next/headersin vitest v3+ fail, which I think is a vitest bug)