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Andrew ClarkandGitHub
27e225f468
With `cacheComponents` + `partialPrefetching`, navigating to an already-prefetched route with a dynamic `generateMetadata` left `document.title` permanently empty until a hard reload. The prefetch cached the head as complete using the server's `isHeadPartial` flag, which is unreliable under Cache Components. Derive the head's partiality from `isResponsePartial` instead, as segment data already does, so a dynamic head is fetched and applied on navigation while a fully static head stays complete. Fixing the flag exposed a latent issue in the prefetch scheduler: during a speculative prefetch, the head was unconditionally runtime-prefetched, which previously went unnoticed because the head was mismarked as complete. The head is now runtime-prefetched only when a segment in the new part of the tree is a candidate for runtime prefetching — it rides along with that request rather than spawning a standalone one. If nothing in the new part of the tree is a runtime prefetch candidate, the head is fetched during the navigation instead. This makes the scheduler's metadata-only request path dead code, so it's removed. Fixes #95268. <!-- NEXT_JS_LLM_PR -->