feat(nuxt): enable islands if server pages/components present (#26223)

docs/2.guide/2.directory-structure/1.pages.md

@@ -365,10 +365,6 @@ You can define a page as [client only](/docs/guide/directory-structure/component
 
 You can define a page as [server only](/docs/guide/directory-structure/components#server-components) by giving it a `.server.vue` suffix. While you will be able to navigate to the page using client-side navigation, controlled by `vue-router`, it will be rendered with a server component automatically, meaning the code required to render the page will not be in your client-side bundle.
 
-::note
-You will also need to enable `experimental.componentIslands` in order to make this possible.
-::
-
 ## Custom Routing
 
 As your app gets bigger and more complex, your routing might require more flexibility. For this reason, Nuxt directly exposes the router, routes and router options for customization in different ways.

docs/3.api/1.components/8.nuxt-island.md

@@ -12,10 +12,6 @@ When rendering an island component, the content of the island component is stati
 
 Changing the island component props triggers a refetch of the island component to re-render it again.
 
-::read-more{to="/docs/guide/going-further/experimental-features#componentislands" icon="i-ph-star-duotone"}
-This component is experimental and in order to use it you must enable the `experimental.componentIslands` option in your `nuxt.config`.
-::
-
 ::note
 Global styles of your application are sent with the response.
 ::

packages/nuxt/src/components/module.ts

@@ -176,6 +176,9 @@ export default defineNuxtModule<ComponentsOptions>({
             chunkName: 'components/' + component.kebabName
           })
         }
+        if (component.mode === 'server' && !nuxt.options.ssr) {
+          logger.warn(`Using server components with \`ssr: false\` is not supported with auto-detected component islands. If you need to use server component \`${component.pascalName}\`, set \`experimental.componentIslands\` to \`true\`.`)
+        }
       }
       context.components = newComponents
       app.components = newComponents

packages/nuxt/src/core/nitro.ts

@@ -217,7 +217,6 @@ export async function initNitro (nuxt: Nuxt & { _nitro?: Nitro }) {
       'process.env.NUXT_NO_SCRIPTS': !!nuxt.options.features.noScripts && !nuxt.options.dev,
       'process.env.NUXT_INLINE_STYLES': !!nuxt.options.features.inlineStyles,
       'process.env.NUXT_JSON_PAYLOADS': !!nuxt.options.experimental.renderJsonPayloads,
-      'process.env.NUXT_COMPONENT_ISLANDS': !!nuxt.options.experimental.componentIslands,
       'process.env.NUXT_ASYNC_CONTEXT': !!nuxt.options.experimental.asyncContext,
       'process.env.NUXT_SHARED_DATA': !!nuxt.options.experimental.sharedPrerenderData,
       'process.dev': nuxt.options.dev,

packages/nuxt/src/core/nuxt.ts

@@ -314,7 +314,7 @@ async function initNuxt (nuxt: Nuxt) {
       filePath: resolve(nuxt.options.appDir, 'components/nuxt-island')
     })
 
-    if (!nuxt.options.ssr) {
+    if (!nuxt.options.ssr && nuxt.options.experimental.componentIslands !== 'auto') {
       nuxt.options.ssr = true
       nuxt.options.nitro.routeRules ||= {}
       nuxt.options.nitro.routeRules['/**'] = defu(nuxt.options.nitro.routeRules['/**'], { ssr: false })

packages/nuxt/src/core/runtime/nitro/renderer.ts

@@ -29,7 +29,7 @@ import unheadPlugins from '#internal/unhead-plugins.mjs'
 // eslint-disable-next-line import/no-restricted-paths
 import type { NuxtPayload, NuxtSSRContext } from '#app'
 // @ts-expect-error virtual file
-import { appHead, appRootId, appRootTag, appTeleportId, appTeleportTag } from '#internal/nuxt.config.mjs'
+import { appHead, appRootId, appRootTag, appTeleportId, appTeleportTag, componentIslands } from '#internal/nuxt.config.mjs'
 // @ts-expect-error virtual file
 import { buildAssetsURL, publicAssetsURL } from '#paths'
 
@@ -263,7 +263,7 @@ export default defineRenderHandler(async (event): Promise<Partial<RenderResponse
   }
 
   // Check for island component rendering
-  const isRenderingIsland = (process.env.NUXT_COMPONENT_ISLANDS as unknown as boolean && event.path.startsWith('/__nuxt_island'))
+  const isRenderingIsland = (componentIslands as unknown as boolean && event.path.startsWith('/__nuxt_island'))
   const islandContext = isRenderingIsland ? await getIslandContext(event) : undefined
 
   if (import.meta.prerender && islandContext && event.path && await islandCache!.hasItem(event.path)) {
@@ -468,7 +468,7 @@ export default defineRenderHandler(async (event): Promise<Partial<RenderResponse
     bodyAttrs: bodyAttrs ? [bodyAttrs] : [],
     bodyPrepend: normalizeChunks([bodyTagsOpen, ssrContext.teleports?.body]),
     body: [
-      process.env.NUXT_COMPONENT_ISLANDS ? replaceIslandTeleports(ssrContext, _rendered.html) : _rendered.html,
+      componentIslands ? replaceIslandTeleports(ssrContext, _rendered.html) : _rendered.html,
       APP_TELEPORT_OPEN_TAG + (HAS_APP_TELEPORTS ? joinTags([ssrContext.teleports?.[`#${appTeleportId}`]]) : '') + APP_TELEPORT_CLOSE_TAG
     ],
     bodyAppend: [bodyTags]

packages/nuxt/src/core/templates.ts

@@ -374,10 +374,13 @@ export const nuxtConfigTemplate: NuxtTemplate = {
       baseURL: undefined,
       headers: undefined
     }
+    const shouldEnableComponentIslands = ctx.nuxt.options.experimental.componentIslands && (
+      ctx.nuxt.options.dev || ctx.nuxt.options.experimental.componentIslands !== 'auto' || ctx.app.pages?.some(p => p.mode === 'server') || ctx.app.components?.some(c => c.mode === 'server')
+    )
     return [
       ...Object.entries(ctx.nuxt.options.app).map(([k, v]) => `export const ${camelCase('app-' + k)} = ${JSON.stringify(v)}`),
       `export const renderJsonPayloads = ${!!ctx.nuxt.options.experimental.renderJsonPayloads}`,
-      `export const componentIslands = ${!!ctx.nuxt.options.experimental.componentIslands}`,
+      `export const componentIslands = ${shouldEnableComponentIslands}`,
       `export const payloadExtraction = ${!!ctx.nuxt.options.experimental.payloadExtraction}`,
       `export const cookieStore = ${!!ctx.nuxt.options.experimental.cookieStore}`,
       `export const appManifest = ${!!ctx.nuxt.options.experimental.appManifest}`,

packages/nuxt/src/pages/module.ts

@@ -79,6 +79,10 @@ export default defineNuxtModule({
     nuxt.hook('app:templates', async (app) => {
       app.pages = await resolvePagesRoutes()
       await nuxt.callHook('pages:extend', app.pages)
+
+      if (!nuxt.options.ssr && app.pages.some(p => p.mode === 'server')) {
+        logger.warn('Using server pages with `ssr: false` is not supported with auto-detected component islands. Set `experimental.componentIslands` to `true`.')
+      }
     })
 
     // Restart Nuxt when pages dir is added or removed

packages/schema/src/config/experimental.ts

@@ -172,7 +172,10 @@ export default defineUntypedSchema({
 
     /**
      * Experimental component islands support with <NuxtIsland> and .island.vue files.
-     * @type {true | 'local' | 'local+remote' | Partial<{ remoteIsland: boolean, selectiveClient: boolean }> | false}
+     *
+     * By default it is set to 'auto', which means it will be enabled only when there are islands,
+     * server components or server pages in your app.
+     * @type {true | 'auto' | 'local' | 'local+remote' | Partial<{ remoteIsland: boolean, selectiveClient: boolean }> | false}
      */
     componentIslands: {
       $resolve: (val) => {
@@ -182,7 +185,7 @@ export default defineUntypedSchema({
         if (val === 'local') {
           return true
         }
-        return val ?? false
+        return val ?? 'auto'
       }
     },