[Segment Cache] Support <Link prefetch={true}>

packages/next/src/client/components/app-router.tsx

@@ -279,11 +279,12 @@ function Router({
         ? // Unlike the old implementation, the Segment Cache doesn't store its
           // data in the router reducer state; it writes into a global mutable
           // cache. So we don't need to dispatch an action.
-          (href) =>
+          (href, options) =>
             prefetchWithSegmentCache(
               href,
               actionQueue.state.nextUrl,
-              actionQueue.state.tree
+              actionQueue.state.tree,
+              options?.kind === PrefetchKind.FULL
             )
         : (href, options) => {
             // Use the old prefetch implementation.

packages/next/src/client/components/segment-cache/cache.ts

@@ -147,6 +147,7 @@ export type RouteCacheEntry =
 
 export const enum FetchStrategy {
   PPR,
+  Full,
   LoadingBoundary,
 }
 
@@ -1005,24 +1006,31 @@ export async function fetchSegmentOnCacheMiss(
   }
 }
 
-export async function fetchSegmentPrefetchesForPPRDisabledRoute(
+export async function fetchSegmentPrefetchesUsingDynamicRequest(
   task: PrefetchTask,
   route: FulfilledRouteCacheEntry,
+  fetchStrategy: FetchStrategy,
   dynamicRequestTree: FlightRouterState,
   spawnedEntries: Map<string, PendingSegmentCacheEntry>
 ): Promise<PrefetchSubtaskResult<null> | null> {
   const href = task.key.href
   const nextUrl = task.key.nextUrl
   const headers: RequestHeaders = {
     [RSC_HEADER]: '1',
-    [NEXT_ROUTER_PREFETCH_HEADER]: '1',
     [NEXT_ROUTER_STATE_TREE_HEADER]: encodeURIComponent(
       JSON.stringify(dynamicRequestTree)
     ),
   }
   if (nextUrl !== null) {
     headers[NEXT_URL] = nextUrl
   }
+  // Only set the prefetch header if we're not doing a "full" prefetch. We
+  // omit the prefetch header from a full prefetch because it's essentially
+  // just a navigation request that happens ahead of time — it should include
+  // all the same data in the response.
+  if (fetchStrategy !== FetchStrategy.Full) {
+    headers[NEXT_ROUTER_PREFETCH_HEADER] = '1'
+  }
   try {
     const response = await fetchPrefetchResponse(href, headers)
     if (!response || !response.ok || !response.body) {

packages/next/src/client/components/segment-cache/prefetch.ts

@@ -7,17 +7,24 @@ import { schedulePrefetchTask } from './scheduler'
  * Entrypoint for prefetching a URL into the Segment Cache.
  * @param href - The URL to prefetch. Typically this will come from a <Link>,
  * or router.prefetch. It must be validated before we attempt to prefetch it.
+ * @param nextUrl - A special header used by the server for interception routes.
+ * Roughly  corresponds to the current URL.
+ * @param treeAtTimeOfPrefetch - The FlightRouterState at the time the prefetch
+ * was requested. This is only used when PPR is disabled.
+ * @param includeDynamicData - Whether to prefetch dynamic data, in addition to
+ * static data. This is used by <Link prefetch={true}>.
  */
 export function prefetch(
   href: string,
   nextUrl: string | null,
-  treeAtTimeOfPrefetch: FlightRouterState
+  treeAtTimeOfPrefetch: FlightRouterState,
+  includeDynamicData: boolean
 ) {
   const url = createPrefetchURL(href)
   if (url === null) {
     // This href should not be prefetched.
     return
   }
   const cacheKey = createCacheKey(url.href, nextUrl)
-  schedulePrefetchTask(cacheKey, treeAtTimeOfPrefetch)
+  schedulePrefetchTask(cacheKey, treeAtTimeOfPrefetch, includeDynamicData)
 }