Revert "[Link] Add prefetch="auto" option"

This reverts commit 6a588d5.

Author: eps1lon

packages/next/src/client/app-dir/link.tsx

@@ -133,7 +133,7 @@ type InternalLinkProps = {
    * Prefetching is only enabled in production.
    *
    * - In the **App Router**:
-   *   - `"auto"`, `null`, `undefined` (default): Prefetch behavior depends on static vs dynamic routes:
+   *   - `null` (default): Prefetch behavior depends on static vs dynamic routes:
    *     - Static routes: fully prefetched
    *     - Dynamic routes: partial prefetch to the nearest segment with a `loading.js`
    *   - `true`: Always prefetch the full route and data.
@@ -151,7 +151,7 @@ type InternalLinkProps = {
    * </Link>
    * ```
    */
-  prefetch?: boolean | 'auto' | null
+  prefetch?: boolean | null
 
   /**
    * (unstable) Switch to a dynamic prefetch on hover. Effectively the same as
@@ -366,9 +366,7 @@ export default function LinkComponent(
    * - 'unstable_dynamicOnHover': this starts in "auto" mode, but switches to "full" when the link is hovered
    */
   const appPrefetchKind =
-    prefetchProp === null || prefetchProp === 'auto'
-      ? PrefetchKind.AUTO
-      : PrefetchKind.FULL
+    prefetchProp === null ? PrefetchKind.AUTO : PrefetchKind.FULL
 
   if (process.env.NODE_ENV !== 'production') {
     function createPropError(args: {

packages/next/src/client/form-shared.tsx

@@ -19,7 +19,7 @@ type InternalFormProps = {
    * Prefetch can be disabled by passing `prefetch={false}`. Prefetching is only enabled in production.
    *
    * Options:
-   * - "auto", null, undefined (default): For statically generated pages, this will prefetch the full React Server Component data. For dynamic pages, this will prefetch up to the nearest route segment with a [`loading.js`](https://nextjs.org/docs/app/api-reference/file-conventions/loading) file. If there is no loading file, it will not fetch the full tree to avoid fetching too much data.
+   * - `null` (default): For statically generated pages, this will prefetch the full React Server Component data. For dynamic pages, this will prefetch up to the nearest route segment with a [`loading.js`](https://nextjs.org/docs/app/api-reference/file-conventions/loading) file. If there is no loading file, it will not fetch the full tree to avoid fetching too much data.
    * - `false`: This will not prefetch any data.
    *
    * In pages dir, prefetching is not supported, and passing this prop will emit a warning.

packages/next/src/client/link.tsx

@@ -73,7 +73,7 @@ type InternalLinkProps = {
    * Prefetch can be disabled by passing `prefetch={false}`. Prefetching is only enabled in production.
    *
    * In App Router:
-   * - "auto", null, undefined (default): For statically generated pages, this will prefetch the full React Server Component data. For dynamic pages, this will prefetch up to the nearest route segment with a [`loading.js`](https://nextjs.org/docs/app/api-reference/file-conventions/loading) file. If there is no loading file, it will not fetch the full tree to avoid fetching too much data.
+   * - `null` (default): For statically generated pages, this will prefetch the full React Server Component data. For dynamic pages, this will prefetch up to the nearest route segment with a [`loading.js`](https://nextjs.org/docs/app/api-reference/file-conventions/loading) file. If there is no loading file, it will not fetch the full tree to avoid fetching too much data.
    * - `true`: This will prefetch the full React Server Component data for all route segments, regardless of whether they contain a segment with `loading.js`.
    * - `false`: This will not prefetch any data, even on hover.
    *
@@ -82,7 +82,7 @@ type InternalLinkProps = {
    * - `false`: Prefetching will not happen when entering the viewport, but will still happen on hover.
    * @defaultValue `true` (pages router) or `null` (app router)
    */
-  prefetch?: boolean | 'auto' | null
+  prefetch?: boolean | null
   /**
    * The active locale is automatically prepended. `locale` allows for providing a different locale.
    * When `false` `href` has to include the locale as the default behavior is disabled.