feat(nuxt): auto-register layers in layers/ directory (#27221)

packages/kit/src/loader/config.ts

@@ -4,6 +4,8 @@ import type { ConfigLayer, ConfigLayerMeta, LoadConfigOptions } from 'c12'
 import { loadConfig } from 'c12'
 import type { NuxtConfig, NuxtOptions } from '@nuxt/schema'
 import { NuxtConfigSchema } from '@nuxt/schema'
+import { globby } from 'globby'
+import defu from 'defu'
 
 export interface LoadNuxtConfigOptions extends LoadConfigOptions<NuxtConfig> {}
 
@@ -11,12 +13,19 @@ const layerSchemaKeys = ['future', 'srcDir', 'rootDir', 'dir']
 const layerSchema = Object.fromEntries(Object.entries(NuxtConfigSchema).filter(([key]) => layerSchemaKeys.includes(key)))
 
 export async function loadNuxtConfig (opts: LoadNuxtConfigOptions): Promise<NuxtOptions> {
+  // Automatically detect and import layers from `~~/layers/` directory
+  opts.overrides = defu(opts.overrides, {
+    _extends: await globby('layers/*', {
+      onlyDirectories: true,
+      cwd: opts.cwd || process.cwd(),
+    }),
+  });
   (globalThis as any).defineNuxtConfig = (c: any) => c
   const result = await loadConfig<NuxtConfig>({
     name: 'nuxt',
     configFile: 'nuxt.config',
     rcFile: '.nuxtrc',
-    extend: { extendKey: ['theme', 'extends'] },
+    extend: { extendKey: ['theme', 'extends', '_extends'] },
     dotenv: true,
     globalRc: true,
     ...opts,

packages/nuxt/src/core/nuxt.ts

@@ -10,7 +10,7 @@ import { readPackageJSON, resolvePackageJSON } from 'pkg-types'
 
 import escapeRE from 'escape-string-regexp'
 import fse from 'fs-extra'
-import { withoutLeadingSlash } from 'ufo'
+import { withTrailingSlash, withoutLeadingSlash } from 'ufo'
 
 import defu from 'defu'
 import pagesModule from '../pages/module'
@@ -71,6 +71,17 @@ async function initNuxt (nuxt: Nuxt) {
     }
   }
 
+  // Restart Nuxt when layer directories are added or removed
+  const layersDir = withTrailingSlash(resolve(nuxt.options.rootDir, 'layers'))
+  nuxt.hook('builder:watch', (event, relativePath) => {
+    const path = resolve(nuxt.options.srcDir, relativePath)
+    if (event === 'addDir' || event === 'unlinkDir') {
+      if (path.startsWith(layersDir)) {
+        return nuxt.callHook('restart', { hard: true })
+      }
+    }
+  })
+
   // Set nuxt instance for useNuxt
   nuxtCtx.set(nuxt)
   nuxt.hook('close', () => nuxtCtx.unset())

test/fixtures/basic/layers/bar/nuxt.config.ts

@@ -0,0 +1,8 @@
+export default defineNuxtConfig({
+  modules: [
+    function (_options, nuxt) {
+      // @ts-expect-error not valid nuxt option
+      nuxt.options.__installed_layer = true
+    },
+  ],
+})

test/fixtures/basic/nuxt.config.ts

@@ -92,6 +92,14 @@ export default defineNuxtConfig({
     },
   },
   modules: [
+    function (_options, nuxt) {
+      nuxt.hook('modules:done', () => {
+        // @ts-expect-error not valid nuxt option
+        if (!nuxt.options.__installed_layer) {
+          throw new Error('layer in layers/ directory was not auto-registered')
+        }
+      })
+    },
     '~/modules/subpath',
     './modules/test',
     '~/modules/example',