unjs · harlan-zw · Apr 10, 2026 · Apr 10, 2026 · Apr 10, 2026 · Apr 10, 2026
diff --git a/packages/angular/src/public-api.ts b/packages/angular/src/public-api.ts
@@ -5,3 +5,4 @@
 export { useHead, useHeadSafe, useScript, useSeoMeta, useUnhead } from './composables'
 export { headSymbol, UnheadInjectionToken } from './context'
 export { Head } from './head.component'
+export { defineLink, defineScript } from 'unhead'
diff --git a/packages/react/src/index.ts b/packages/react/src/index.ts
@@ -1,3 +1,4 @@
 export { hookImports } from './autoImports'
 export { Head } from './components'
 export { useHead, useHeadSafe, useScript, useSeoMeta, useUnhead } from './composables'
+export { defineLink, defineScript } from 'unhead'
diff --git a/packages/solid-js/src/index.ts b/packages/solid-js/src/index.ts
@@ -1,2 +1,3 @@
 export { hookImports } from './autoImports'
 export { useHead, useHeadSafe, useScript, useSeoMeta, useUnhead } from './composables'
+export { defineLink, defineScript } from 'unhead'
diff --git a/packages/svelte/src/index.ts b/packages/svelte/src/index.ts
@@ -1,3 +1,4 @@
 export { autoImports } from './autoImports'
 export { useHead, useHeadSafe, useScript, useSeoMeta, useUnhead } from './composables'
 export { UnheadContextKey } from './context'
+export { defineLink, defineScript } from 'unhead'
diff --git a/packages/unhead/src/types/schema/link.ts b/packages/unhead/src/types/schema/link.ts
@@ -1,3 +1,4 @@
+import type { DeepReadonly } from '../util'
 import type { DataKeys } from './attributes/data'
 import type { HttpEventAttributes } from './attributes/event'
 import type { GlobalAttributes } from './attributes/global'
@@ -847,8 +848,8 @@ type MatchLinkByRel<R>
 export type InferLink<T>
   = T extends { rel: infer R }
     ? R extends KnownLinkRel
-      ? MatchLinkByRel<R>
+      ? DeepReadonly<MatchLinkByRel<R>>
       : R extends string
-        ? GenericLink & { rel: R }
+        ? DeepReadonly<GenericLink> & { rel: R }
         : never
     : never
diff --git a/packages/unhead/src/types/schema/metaFlat.ts b/packages/unhead/src/types/schema/metaFlat.ts
@@ -7,7 +7,7 @@ export interface MetaFlatArticle {
    * Writers of the article.
    * @example ['https://example.com/some.html', 'https://example.com/one.html']
    */
-  articleAuthor?: string[]
+  articleAuthor?: readonly string[]
 
   /**
    * When the article is out of date after.
@@ -36,15 +36,15 @@ export interface MetaFlatArticle {
    * Tag words associated with this article.
    * @example ['Apple', 'Steve Jobs']
    */
-  articleTag?: string[]
+  articleTag?: readonly string[]
 }
 
 export interface MetaFlatBook {
   /**
    * Who wrote this book.
    * @example ['https://example.com/some.html', 'https://example.com/one.html']
    */
-  bookAuthor?: string[]
+  bookAuthor?: readonly string[]
 
   /**
    * The ISBN.
@@ -62,7 +62,7 @@ export interface MetaFlatBook {
    * Tag words associated with this book.
    * @example ['Apple', 'Steve Jobs']
    */
-  bookTag?: string[]
+  bookTag?: readonly string[]
 }
 
 export interface MetaFlatProfile {

diff --git a/packages/unhead/src/types/schema/script.ts b/packages/unhead/src/types/schema/script.ts
@@ -1,4 +1,4 @@
-import type { Booleanable } from '../util'
+import type { Booleanable, DeepReadonly } from '../util'
 import type { DataKeys } from './attributes/data'
 import type { HttpEventAttributes } from './attributes/event'
 import type { GlobalAttributes } from './attributes/global'
@@ -489,7 +489,7 @@ export type InferScript<T>
   = T extends { type: infer U }
     ? U extends string
       ? U extends KnownScriptType
-        ? MatchScriptByType<U>
-        : GenericScript & { type: U }
-      : Script
-    : Script
+        ? DeepReadonly<MatchScriptByType<U>>
+        : DeepReadonly<GenericScript> & { type: U }
+      : DeepReadonly<Script>
+    : DeepReadonly<Script>
diff --git a/packages/unhead/src/types/schema/struct/speculationRules.ts b/packages/unhead/src/types/schema/struct/speculationRules.ts
@@ -1,8 +1,8 @@
 import type { ReferrerPolicy } from '../shared'
 
 export interface SpeculationRules {
-  prefetch?: (SpeculationRuleList | SpeculationRuleDocument)[]
-  prerender?: (SpeculationRuleList | SpeculationRuleDocument)[]
+  prefetch?: readonly (SpeculationRuleList | SpeculationRuleDocument)[]
+  prerender?: readonly (SpeculationRuleList | SpeculationRuleDocument)[]
 }
 
 export interface SpeculationRuleBase {
@@ -23,7 +23,7 @@ export interface SpeculationRuleBase {
    *
    * @see https://github.com/WICG/nav-speculation/blob/main/triggers.md#requirements
    */
-  requires?: 'anonymous-client-ip-when-cross-origin'[]
+  requires?: readonly 'anonymous-client-ip-when-cross-origin'[]
   /**
    * Indicating where the page expects the prerendered content to be activated.
    *
@@ -40,11 +40,11 @@ export interface SpeculationRuleBase {
 
 export interface SpeculationRuleList extends SpeculationRuleBase {
   source: 'list'
-  urls: string[]
+  urls: readonly string[]
 }
 
 export type SpeculationRuleFn = 'and' | 'or' | 'href_matches' | 'selector_matches' | 'not'
-export type SpeculationRuleWhere = Partial<Record<SpeculationRuleFn, Partial<(Record<SpeculationRuleFn, (Partial<Record<SpeculationRuleFn, string>>) | string>)>[]>>
+export type SpeculationRuleWhere = Partial<Record<SpeculationRuleFn, readonly Partial<(Record<SpeculationRuleFn, (Partial<Record<SpeculationRuleFn, string>>) | string>)>[]>>
 
 export interface SpeculationRuleDocument extends SpeculationRuleBase {
   source: 'document'

diff --git a/packages/unhead/src/types/util.ts b/packages/unhead/src/types/util.ts
@@ -26,6 +26,19 @@ export type ResolvableUnion<T> = T extends string | number | boolean
     ? DeepResolvableProperties<T>
     : ResolvableValue<T>
 
+/**
+ * Recursively marks all properties and arrays as readonly.
+ * Applied to `InferScript`/`InferLink` return types so that
+ * `defineScript`/`defineLink` accept both mutable and `as const` inputs.
+ */
+export type DeepReadonly<T> = T extends (...a: any[]) => any
+  ? T
+  : T extends ReadonlyArray<infer U>
+    ? readonly DeepReadonly<U>[]
+    : T extends object
+      ? { readonly [K in keyof T]: DeepReadonly<T[K]> }
+      : T
+
 export type DeepResolvableProperties<T> = {
   [K in keyof T]?: T[K] extends string | object
     ? T[K] extends string

diff --git a/packages/unhead/test/unit/define.test.ts b/packages/unhead/test/unit/define.test.ts
@@ -131,4 +131,141 @@ describe('defineScript', () => {
       ],
     })
   })
+
+  // Nuxt cross-origin-prefetch: speculationrules with structured innerHTML object
+  it('accepts speculationrules with object innerHTML without defineScript', () => {
+    const head = createHead()
+    useHead(head, {
+      script: [{
+        type: 'speculationrules',
+        key: 'speculationrules',
+        innerHTML: {
+          prefetch: [
+            {
+              source: 'list',
+              urls: ['https://example.com'],
+              requires: ['anonymous-client-ip-when-cross-origin'],
+            },
+          ],
+        },
+      }],
+    })
+  })
+
+  // Nuxt importmap: structured innerHTML with imports object
+  it('accepts importmap with object innerHTML without defineScript', () => {
+    const head = createHead()
+    useHead(head, {
+      script: [{
+        type: 'importmap',
+        innerHTML: { imports: { '#entry': '/entry.mjs' } },
+      }],
+    })
+  })
+
+  // as const speculationrules should work directly with useHead
+  it('accepts as const speculationrules directly in useHead', () => {
+    const spec = {
+      type: 'speculationrules',
+      innerHTML: {
+        prerender: [{ source: 'list', urls: ['/next-page'] }],
+      },
+    } as const
+    const head = createHead()
+    useHead(head, { script: [spec] })
+  })
+
+  // as const importmap should work directly with useHead
+  it('accepts as const importmap directly in useHead', () => {
+    const map = {
+      type: 'importmap',
+      innerHTML: { imports: { '#entry': '/entry.mjs' } },
+    } as const
+    const head = createHead()
+    useHead(head, { script: [map] })
+  })
+
+  // Nuxt cross-origin-prefetch: helper function returning script for useHead
+  it('works from a helper function without defineScript', () => {
+    function generateRules() {
+      return {
+        type: 'speculationrules' as const,
+        key: 'speculationrules',
+        innerHTML: {
+          prefetch: [
+            {
+              source: 'list' as const,
+              urls: ['https://a.com', 'https://b.com'],
+              requires: ['anonymous-client-ip-when-cross-origin'] as const,
+            },
+          ],
+        },
+      }
+    }
+    const head = createHead()
+    useHead(head, { script: [generateRules()] })
+  })
+
+  // defineScript still works for custom types that need it
+  it('accepts as const objects via defineScript', () => {
+    const spec = {
+      type: 'speculationrules',
+      innerHTML: {
+        prerender: [{ source: 'list', urls: ['/next-page'] }],
+      },
+    } as const
+    defineScript(spec)
+  })
+})
+
+describe('useHead — as const link patterns', () => {
+  // Nuxt renderer: preload link directly in useHead
+  it('accepts preload link directly in useHead', () => {
+    const head = createHead()
+    useHead(head, {
+      link: [
+        { rel: 'preload', as: 'fetch', crossorigin: 'anonymous', href: '/payload.json' },
+      ],
+    })
+  })
+
+  // Nuxt renderer: stylesheet with crossorigin directly in useHead
+  it('accepts stylesheet with crossorigin directly', () => {
+    const head = createHead()
+    useHead(head, {
+      link: [
+        { rel: 'stylesheet', href: '/style.css', crossorigin: '' },
+      ],
+    })
+  })
+
+  // Nuxt renderer: preload as script directly in useHead
+  it('accepts preload as script directly', () => {
+    const head = createHead()
+    useHead(head, {
+      link: [
+        { rel: 'preload', as: 'script', href: '/chunk.js' },
+      ],
+    })
+  })
+
+  // Nuxt docs: preconnect directly in useHead
+  it('accepts preconnect directly', () => {
+    const head = createHead()
+    useHead(head, {
+      link: [
+        { rel: 'preconnect', href: 'https://fonts.googleapis.com' },
+      ],
+    })
+  })
+
+  // defineLink only needed for non-standard rels
+  it('needs defineLink only for non-standard rels', () => {
+    const head = createHead()
+    useHead(head, {
+      link: [
+        defineLink({ rel: 'openid2.provider', href: 'https://example.com/openid' }),
+      ],
+    })
+  })
 })
diff --git a/packages/vue/src/index.ts b/packages/vue/src/index.ts
@@ -5,4 +5,4 @@ export type * from './scripts/index'
 export type * from './types'
 export { resolveUnrefHeadInput } from './utils'
 export { VueHeadMixin } from './VueHeadMixin'
-export { createUnhead } from 'unhead'
+export { createUnhead, defineLink, defineScript } from 'unhead'
diff --git a/packages/vue/src/scripts/useScript.ts b/packages/vue/src/scripts/useScript.ts
@@ -18,7 +18,7 @@ export interface VueScriptInstance<T extends Record<symbol | string, any>> exten
 }
 
 export type UseScriptInput = string | (ResolvableProperties<Omit<GenericScript & DataKeys & SchemaAugmentations['script'], 'src'>> & { src: string })
-export interface UseScriptOptions<T extends Record<symbol | string, any> = Record<string, any>> extends Omit<HeadEntryOptions, 'head'>, Pick<BaseUseScriptOptions<T>, 'use' | 'eventContext' | 'beforeInit'> {
+export interface UseScriptOptions<T extends Record<symbol | string, any> = Record<string, any>> extends Omit<HeadEntryOptions, 'head'>, Partial<Pick<BaseUseScriptOptions<T>, 'use' | 'eventContext' | 'beforeInit'>> {
   /**
    * The trigger to load the script:
    * - `undefined` | `client` - (Default) Load the script on the client when this js is loaded.

diff --git a/test/exports/react.yaml b/test/exports/react.yaml
@@ -1,4 +1,6 @@
 .:
+  defineLink: function
+  defineScript: function
   Head: function
   hookImports: object
   useHead: function

diff --git a/test/exports/solid-js.yaml b/test/exports/solid-js.yaml
@@ -1,4 +1,6 @@
 .:
+  defineLink: function
+  defineScript: function
   hookImports: object
   useHead: function
   useHeadSafe: function

diff --git a/test/exports/svelte.yaml b/test/exports/svelte.yaml
@@ -1,5 +1,7 @@
 .:
   autoImports: object
+  defineLink: function
+  defineScript: function
   UnheadContextKey: symbol
   useHead: function
   useHeadSafe: function

diff --git a/test/exports/vue.yaml b/test/exports/vue.yaml
@@ -1,5 +1,7 @@
 .:
   createUnhead: function
+  defineLink: function
+  defineScript: function
   headSymbol: string
   injectHead: function
   resolveUnrefHeadInput: function