fix(nextjs): Keep the Pages Router runtime out of App Router client bundles - #24188
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…undles The client SDK statically imports `next/router` for Pages Router navigation spans, and the app/pages decision is only made at runtime. That put Next.js' entire Pages Router client runtime (~80 KB raw) into the client bundle of every App Router app. Move the navigation instrumentation, the only code needing `next/router`, into its own module and call it behind a build-time constant. `withSentryConfig` sets `_sentryHasPagesRouter` to `'false'` when the project has an `app` directory and no page files outside `pages/api`, so the dead branch lets webpack and Turbopack drop the module and the import. Pageload instrumentation stays, since App Router builds still render `404.html` and `500.html` through the Pages Router. Fixes #24032 Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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The client SDK statically imports
next/routerfor Pages Router navigation spans, which pulls Next.js' whole Pages Router client runtime (~80 KB raw) into every App Router client bundle.The navigation instrumentation now lives in its own module and is called behind a build-time constant.
withSentryConfigsets_sentryHasPagesRouterto'false'when the project has anappdirectory and no page files outsidepages/api, so webpack and Turbopack drop the module and itsnext/routerimport. Pageload instrumentation stays, since App Router builds still serve404.html/500.htmlthrough the Pages Router. Mixed app/pages projects are unaffected.Chosen over the dynamic
import()in #24033 to keep the SDK statically analyzable, keep navigation listener registration synchronous, and leave Pages Router apps untouched.Fixes #24032
Refs #24033