Remove prefetch from instant config (vercel#92761)

prefetching is now controlled with the prefetch export and this option
is inert on the instant export. this removes the prefetch option as a
valid property on the instant config type.

also updates the ts plugin for this export and adds the definition for
the previously landed prefetch export

Author: gnoff

packages/next/src/build/segment-config/app/app-segment-config.ts

@@ -19,9 +19,8 @@ const RuntimeSampleSchema = z
   })
   .strict()
 
-const InstantConfigStaticSchema = z
+const InstantConfigObjectSchema = z
   .object({
-    prefetch: z.literal('static'),
     samples: z.array(RuntimeSampleSchema).min(1).optional(),
     from: z.array(z.string()).optional(),
     unstable_disableValidation: z.literal(true).optional(),
@@ -30,22 +29,9 @@ const InstantConfigStaticSchema = z
   })
   .strict()
 
-const InstantConfigRuntimeSchema = z
-  .object({
-    prefetch: z.literal('runtime'),
-    samples: z.array(RuntimeSampleSchema).min(1),
-    from: z.array(z.string()).optional(),
-    unstable_disableValidation: z.literal(true).optional(),
-    unstable_disableDevValidation: z.literal(true).optional(),
-    unstable_disableBuildValidation: z.literal(true).optional(),
-  })
-  .strict()
-
 const InstantConfigSchema = z.union([
-  z.discriminatedUnion('prefetch', [
-    InstantConfigStaticSchema,
-    InstantConfigRuntimeSchema,
-  ]),
+  InstantConfigObjectSchema,
+  z.literal(true),
   z.literal(false),
 ])
 
@@ -56,7 +42,7 @@ const PrefetchSchema = z.enum([
   'force-runtime',
 ])
 
-export type Instant = InstantConfigStatic | InstantConfigRuntime | false
+export type Instant = InstantConfig | true | false
 
 export type Prefetch =
   | 'auto'
@@ -65,46 +51,35 @@ export type Prefetch =
   | 'force-runtime'
 
 export type InstantConfigForTypeCheckInternal = __GenericInstantConfig | Instant
-// the __GenericPrefetch type is used to avoid type widening issues with
+// the __GenericInstantConfig type is used to avoid type widening issues with
 // our choice to make exports the medium for programming a Next.js application
 // With exports the type is controlled by the module and all we can do is assert on it
 // from a consumer. However with string literals in objects these are by default typed widely
 // and thus cannot match the discriminated union type. If we figure out a better way we should
-// delete the __GenericPrefetch member.
+// delete the __GenericInstantConfig member.
 interface __GenericInstantConfig {
-  prefetch: string
   samples?: Array<WideInstantSample>
   from?: string[]
   unstable_disableValidation?: boolean
   unstable_disableDevValidation?: boolean
   unstable_disableBuildValidation?: boolean
 }
 
-interface InstantConfigStatic {
-  prefetch: 'static'
-  samples?: Array<InstantSample>
-  from?: string[]
-  unstable_disableValidation?: true
-  unstable_disableDevValidation?: true
-  unstable_disableBuildValidation?: true
+type WideInstantSample = {
+  cookies?: InstantSample['cookies']
+  headers?: Array<string[]>
+  params?: InstantSample['params']
+  searchParams?: InstantSample['searchParams']
 }
 
-interface InstantConfigRuntime {
-  prefetch: 'runtime'
-  samples: Array<InstantSample>
+export interface InstantConfig {
+  samples?: Array<InstantSample>
   from?: string[]
   unstable_disableValidation?: true
   unstable_disableDevValidation?: true
   unstable_disableBuildValidation?: true
 }
 
-type WideInstantSample = {
-  cookies?: InstantSample['cookies']
-  headers?: Array<string[]>
-  params?: InstantSample['params']
-  searchParams?: InstantSample['searchParams']
-}
-
 export type InstantSample = {
   cookies?: Array<{
     name: string
@@ -212,7 +187,7 @@ export function parseAppSegmentConfig(
           case 'unstable_instant': {
             return {
               // @TODO replace this link with a link to the docs when they are written
-              message: `Invalid unstable_instant value ${JSON.stringify(ctx.data)} on "${route}", must be an object with \`prefetch: "static"\` or \`prefetch: "runtime"\`, or \`false\`. Read more at https://nextjs.org/docs/messages/invalid-instant-configuration`,
+              message: `Invalid unstable_instant value ${JSON.stringify(ctx.data)} on "${route}", must be \`true\`, \`false\`, or an object. Read more at https://nextjs.org/docs/messages/invalid-instant-configuration`,
             }
           }
           case 'unstable_prefetch': {

packages/next/src/server/app-render/create-flight-router-state-from-loader-tree.ts

@@ -88,7 +88,10 @@ async function createFlightRouterStateFromLoaderTreeImpl(
     prefetchHints |= PrefetchHint.IsRootLayout
   }
 
-  if (instantConfig && typeof instantConfig === 'object') {
+  if (
+    instantConfig === true ||
+    (typeof instantConfig === 'object' && instantConfig !== null)
+  ) {
     prefetchHints |= PrefetchHint.SubtreeHasInstant
   }
 

packages/next/src/server/app-render/instant-validation/instant-config.tsx

@@ -49,10 +49,10 @@ export async function isPageAllowedToBlock(tree: LoaderTree): Promise<boolean> {
   // instant UI, so we should make sure that a static shell exists.
   // (even if it'd use runtime prefetching for client navs)
   if (instantConfig !== undefined) {
-    if (typeof instantConfig === 'object') {
-      return false
-    } else if (instantConfig === false) {
+    if (instantConfig === false) {
       return true
+    } else {
+      return false
     }
   }
 
@@ -84,12 +84,14 @@ async function anySegmentNeedsInstantValidation(
 ): Promise<boolean> {
   const segments = await findSegmentsWithInstantConfig(rootTree)
 
-  // Check if there's any configs with `prefetch: 'static'` or `mode: 'instant'`.
+  // Check if there's any non-false configs that need validation.
   // (If there's only `false`, there's no need to run validation).
   // If any segment has `unstable_disableValidation`, we skip validation for the whole tree.
   let needsValidation = false
   for (const { config } of segments) {
-    if (typeof config === 'object') {
+    if (config === true) {
+      needsValidation = true
+    } else if (typeof config === 'object') {
       if (
         config.unstable_disableValidation === true ||
         (mode === 'dev' && config.unstable_disableDevValidation === true) ||

packages/next/src/server/app-render/instant-validation/instant-validation.tsx

@@ -1155,7 +1155,10 @@ export async function createCombinedPayloadAtDepth(
         (layoutOrPageMod as AppSegmentConfig).unstable_instant ?? null
       prefetchConfig =
         (layoutOrPageMod as AppSegmentConfig).unstable_prefetch ?? null
-      if (instantConfig && typeof instantConfig === 'object') {
+      if (
+        instantConfig === true ||
+        (typeof instantConfig === 'object' && instantConfig !== null)
+      ) {
         const rawFactory: unknown = (layoutOrPageMod as any)
           .__debugCreateInstantConfigStack
         localCreateInstantStack =
@@ -1243,7 +1246,10 @@ export async function createCombinedPayloadAtDepth(
       requiresInstantUI = false
       createInstantStack = null
       configDepth = -1
-    } else if (instantConfig && typeof instantConfig === 'object') {
+    } else if (
+      instantConfig === true ||
+      (typeof instantConfig === 'object' && instantConfig !== null)
+    ) {
       requiresInstantUI = true
       createInstantStack = localCreateInstantStack
       configDepth = segmentDepth

packages/next/src/server/typescript/rules/config.ts

@@ -147,14 +147,14 @@ const API_DOCS: Record<
     link: 'https://nextjs.org/docs/app/api-reference/file-conventions/route-segment-config#maxduration',
   },
   unstable_instant: {
-    description: `Specifies the default prefetching behavior for this segment. This configuration is currently under development and will change.`,
+    description: `Enables instant navigation validation for this segment. This configuration is currently under development and will change.`,
     link: '(docs coming soon)',
-    type: 'object | false',
+    type: 'true | object | false',
     // TODO: ideally, we'd validate the config object somehow, but this is difficult to do
     // with the way this plugin is currently structured.
     // For now, since we don't provide an `options` here, we won't do any validation in
     // `getSemanticDiagnosticsForExportVariableStatement` below, and only provide hover a tooltip + autocomplete.
-    insertText: 'unstable_instant = { prefetch: "static" };',
+    insertText: 'unstable_instant = true;',
   },
   unstable_prefetch: {
     description: `Controls prefetching behavior for this segment. This configuration is currently under development and will change.`,

test/development/app-dir/cache-components-dev-warmup/fixtures/with-prefetch-config/app/apis/[param]/page.tsx

@@ -3,7 +3,7 @@ import { CachedData } from '../../data-fetching'
 import { connection } from 'next/server'
 import { Suspense } from 'react'
 
-export const unstable_instant = { prefetch: 'runtime', samples: [{}] }
+export const unstable_instant = true
 export const unstable_prefetch = 'force-runtime'
 
 const CACHE_KEY = __dirname + '/__PAGE__'

test/development/app-dir/cache-components-dev-warmup/fixtures/with-prefetch-config/app/private-cache/layout.tsx

@@ -2,7 +2,7 @@ import { Suspense } from 'react'
 import { UncachedFetch, CachedData } from '../data-fetching'
 import { PrivateCachedData } from './data-fetching'
 
-export const unstable_instant = { prefetch: 'runtime', samples: [{}] }
+export const unstable_instant = true
 export const unstable_prefetch = 'force-runtime'
 
 const CACHE_KEY = '/private-cache/__LAYOUT__'

test/development/app-dir/cache-components-dev-warmup/fixtures/with-prefetch-config/app/short-lived-cache/layout.tsx

@@ -2,7 +2,7 @@ import { Suspense } from 'react'
 import { UncachedFetch, CachedData } from '../data-fetching'
 import { ShortLivedCache } from './data-fetching'
 
-export const unstable_instant = { prefetch: 'runtime', samples: [{}] }
+export const unstable_instant = true
 export const unstable_prefetch = 'force-runtime'
 
 const CACHE_KEY = __dirname + '/__LAYOUT__'

test/development/app-dir/cache-components-dev-warmup/fixtures/with-prefetch-config/app/simple/layout.tsx

@@ -1,7 +1,7 @@
 import { Suspense } from 'react'
 import { UncachedFetch, CachedFetch, CachedData } from '../data-fetching'
 
-export const unstable_instant = { prefetch: 'runtime', samples: [{}] }
+export const unstable_instant = true
 export const unstable_prefetch = 'force-runtime'
 
 const CACHE_KEY = __dirname + '/__LAYOUT__'

test/development/app-dir/cache-components-dev-warmup/fixtures/with-prefetch-config/app/successive-caches/page.tsx

@@ -1,4 +1,4 @@
-export const unstable_instant = { prefetch: 'runtime', samples: [{}] }
+export const unstable_instant = true
 export const unstable_prefetch = 'force-runtime'
 
 export default async function Page() {